NEEC 2003 Abstracts

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1

Efficacy non-chemical options for the control of dodder (Cuscuta gronovii) and several broad-leaved species in commercial cranberry production in Southeastern Massachusetts.  Hilary Sandler*

Over 70 plant species have been classified as weeds commonly found on commercial cranberry farms.  Approximately half are broad-leaved species, one-quarter are sedges, with the remainder comprised of rushes, aquatic plants, and parasitic plants.  One of the most problematic of these weeds is swamp dodder, an obligate shoot parasite capable of significantly reducing cranberry yields.  Current recommendations include the use of cultural practices (e.g., sanding) along with herbicides to manage some of these pests.  Since cranberry farming in MA typically occurs in a wetland environment, substantial effort is made to minimize the input of synthetic chemicals into the agroecosystem.  Much of the research at the UMass Cranberry Station is focused on identifying non-chemical pest management alternatives that can be successfully integrated into commercial practice.  A project was initiated in 2002 to determine the efficacy of short-term floods (24 to 48 hr) for the control of dodder, as well as a long-term summer flood (10-day) for the control of broadleaf and grass species.  Dodder stem weights were lower on flooded pieces compared to nonflooded pieces in 3 out of 7 locations.  In two other locations, the flooded piece was paired with a historically low-infestation piece, and this may have masked the effectiveness of the flood.  Plant coverage surveys conducted on the long-term flood study indicated lower species richness, species diversity, and percentage weed coverage on the flooded piece compared to the nonflooded control.  Flooding offers a viable option that can be integrated into the management of several problematic weed species.

2

Spatial analysis of an invasion frontier: Dynamic inferences from static data.  Wei Fang*

Multiple threads of analyses on a spatially explicit data set were conducted to link the invasion of Norway maple (Acer platanoides), an exotic tree species, to a changed community pattern in the invasion frontier.  These approaches allowed dynamic inferences on the population dynamics of A. platanoides over time and space and its influence on the dynamics of native species and forest community.  The Ripley,s L-curves and importance values of each tree species suggested that the distribution of A. platanoides was highly clumped and was expanding over time; the distribution of its native congener A. rubrum was less clumped and expanding over time; while that of all other native tree species was least clumped and shrinking over time.  The size/stage distributions across indicated that A. platanoides was progressively invading the interior of the forest while the native species were not spreading back towards the A. platanoides monospecific patch.  The statistical significance of the edges of the size distributions was tested with quantile regressions.  There were negative correlations of A. platanoides density and densities of native species in different functional groups, and negative correlation of A. platanoides density and species diversity in forest understory.  Dutilleul's modified t-test was used to test the statistical significance of these correlations while considering the factor of spatial autocorrelation in the data.  The results of these analyses suggested that A. platanoides was aggressively invading the interior of the natural forest, hindering the natural distributions of native species and causing a decrease of diversity in the community understory.

3

The effects of dominant land use on the regeneration of plant species within riparian zones of headwater streams in the Piedmont region of New Jersey.  Daniel Van Nostrand*, Colleen A. Hatfield and Michele Bakacs

Riparian vegetation, particularly along headwater streams, is important to control nutrient and pollutant runoff from terrestrial ecosystems, to maintain bank morphology, and to control in-stream temperatures.  Previous research has indicated that riparian zones containing a high abundance and diversity of natural plant species protect the stream ecosystem most effectively.  Therefore, regeneration of natural and diverse plant communities is vital for the prolonged protection of stream environments.  This study was conducted to evaluate the impacts that different land uses had on regenerating plant communities along headwater streams in two adjacent watersheds of Hunterdon County, New Jersey.  Twelve sites were selected to reflect the predominant land uses within a subwatershed.  The predominant land uses were arranged along a disturbance gradient with urban dominated (UMix) representing the most disturbed, followed by agriculturally dominated (AgDom), agriculturally dominated forest/wetland (AgFw), and forest/wetland dominated (FwDom) representing the least disturbed.   Results indicate that sites located within the AgDom and AgFw subwatersheds have higher species richness than both the FwDom and UMix subwatersheds.  FwDom sites had the highest seedling density followed by UMix, AgFw, and AgDom, respectively.  The FwDom sites also had the highest species diversity index and were followed by AgFw, AgDom, and UMix, respectively.  At the species level, Acer rubrum and Fraxinus americana followed the disturbance gradient with higher importance values in the less disturbed habitats whereas Nyssa sylvatica followed the reverse trend.  Studies like this will increase our understanding of how riparian vegetation communities react to a diverse and changing landscape.

4

Land-use effects on riparian plant communities of headwater streams.  Michele Bakacs*, Colleen A. Hatfield and Daniel Van Nostrand

Riparian corridors occupy a small percentage of the land surface in a watershed, yet are critically important for water quality protection and have the highest biodiversity levels of any terrestrial system.  Human alterations of the landscape, including agricultural practices and urban sprawl, can severely impact riparian habitat, thereby altering plant community composition and allowing invasion of upland species and non-natives.  To increase our understanding of how mixed land uses impact riparian plant communities, this study examines plant species diversity and abundance along twelve headwater streams within subwatersheds dominated by either forest/wetland, agricultural or suburban land uses.  These headwater streams are part of two adjacent piedmont drainages located in New Jersey.  This study focuses on the following questions: 1) How does riparian corridor vegetation vary with different land uses?  2) How does the distribution and composition of invasive species vary with different land uses?  3) What are the riparian plant community patterns associated with sites that have undergone a land-use change since the 1960s?  Shrub density and volume was highest in agricultural subwatersheds as well as sites that have undergone local land-use change.  This is due to increased abundance of invasive and ruderal shrubs within these sites.  Shrub density and volume within forest/wetland dominated subwatersheds was not significantly different from agriculturally dominated subwatersheds.  This is due to local land-use change within the forest/wetland dominated subwatersheds.  The results suggest that local land-use change has a stronger influence on the abundance of invasive and ruderal shrubs than current dominant land use.

5

Hydrothermal vent communities of the southern east pacific rise.  Catherine Allen*, Andrew J. Reed and Richard A. Lutz

Since the first discovery of hydrothermal vents, numerous additional sites have been explored revealing new species, new symbioses and different adaptations to life in an extreme environment.  Steep gradients of temperature and seawater chemistry at hydrothermal vents are the basis for distinctive patterns of zonation of animals over small areas.  We present the first descriptions of the hydrothermal communities at 31ºS and 32ºS on the Southern East Pacific Rise that will form the basis for future studies of ecology at these sites.  These communities are similar to those found to the north, including alvinellid polychaetes, vestimentiferan tube worms, bythograeid crabs, bathymodiolid mussels and lepetodrilid limpets.  However, they also include buccinid gastropods, of a genus previously found only at western Pacific hydrothermal vents.  We have used video frame grabs and mosaics to examine faunal composition and patterns of zonation at these hydrothermal vents.  Faunal distributions appear similar to those at northern East Pacific Rise hydrothermal vents.

6

Effects of flow on predation in a laboratory setting.  Shannon Newby*

Since the late 1980's benthic ecologists have examined the effects of flow regime on predation success.  Some crustacean predators use physical and chemical signals carried by the flow to detect and locate prey.  The velocity (i.e. speed and direction), and turbulence of the flow are two characteristics that are important in transporting these signals, and they can be measured in laboratory flumes.  Flow characteristics are altered by the presence of habitat structure.  This study used two counter-rotating annular flumes to examine the predation success of a common, small, omnivorous crustacean, Pagurus longicarpus, in two flow environments.  One flume contained a flat bed, which was used to establish a standard flow regime.  Shell hash in the other flume decreased the velocity and increased the turbulence of the flow regime.  Predation success was measured as the number of prey (juvenile Atlantic surfclams, Spisula solidissima) lost from runs containing predators and compared to the number of prey lost from control runs without predators.  Preliminary analysis suggests that more prey were lost from the flume with the shell hash and the altered flow regime.  Juvenile S. solidissima in shell hash containing sediments of the New Jersey continental shelf may experience stronger predation pressure from P. longicarpus than those in sediments with little or no shell hash.  Differences in predation pressure, resulting from habitat induced flow differences, could be used to narrow broadly defined juvenile S. solidissima Essential Fish Habitat.

7

Successional Change in Vegetation of Chiricahua National Monument, Cochise County, Arizona.  Helen Mills* and Alan H. Taylor

Vegetation structure and composition within U.S. National Parks has changed in response to fire suppression.  Understanding how plant populations respond to alteration of fire regimes is an essential step in evaluating the feasibility of returning vegetation to a pre-fire suppression state.  Spatial vegetation patterns and trends during the 20th century in the Chiricahua National Monument (CHIR) have been identified using aerial and repeat ground photography.  While photographic interpretation characterizes coarse-scale shifts in vegetation types over time and space, it does not describe changes in species abundances, or the mechanisms responsible for change.  This study quantifies structural and compositional changes of vegetation in CHIR at the species level, using gradient analysis and stand structure analysis, and relates these to plant regeneration strategies.  Sampling points were selected based on geo-referenced maps of vegetation change between 1935 and 1993.  Vegetation was sampled using belt transects in areas of change and no change.  Recently burned sites were also sampled to assess the post-fire regeneration response of species.  Spatial patterns of plant population distributions and abundances were significantly correlated with potential soil moisture and elevation.  Age and size data of tree species indicate an increase in recruitment of fire sensitive tree species under fire suppression and a decrease in fire tolerant species.  Post-fire responses of sprouting and seeding species indicate that fire can be used as a tool to guide efforts to restore vegetation to a pre-fire suppression state, but that a complete return is not realistic.  Information from this study should be used as a framework for shaping future plant populations through fire use.

8

Responses of Scarabs and other Scavengers to Fire in a Pine Barrens Environment.  Kyle Beucke*

The pine barrens of Eastern Long Island are of several semi-xeric forest types dominated by pines and oaks, especially Pinus rigida and Quercus ilicifolia.  Fire is thought to play a major role in maintaining this community through eliminating competing vegetation.  A large-scale, intense fire occurred in these forests in August 1995.  The coprophagous, or dung-feeding (Coleoptera: Scarabaeidae) and necrophagous, or carrion-feeding (Coleoptera: Silphidae) beetle fauna of burned sites and un-burned sites of these pine barrens were compared in order to understand the impact of fire on such communities.  Baited pitfall trapping was carried out in two vegetatively different pine barrens, both impacted by the fire, from April to October 1996; 4,302 individuals and 26 species of Coleoptera were collected.  Species compositions of Coleoptera between the two pine barren types differed significantly from one another post fire suggesting that forest structure is an important factor in the response of beetle communities to this disturbance.    Furthermore, the fauna of both burned sites approached the composition of the un-burned sites over the trapping season, coinciding with a re-growth of vegetation.

 9

Patterns of plant diversity in pinelands fens.  Matthew Palmer*

One of the most diverse plant communities in the Eastern United States is found in the groundwater-fed wetlands found along the river corridors of the New Jersey Pinelands.  These wetlands support at least 177 plant species, including thirty-three rare plant species and the global endemic Narthecium americanum.  While the system as a whole is very diverse, individual sites often support a number of distinct community types with varying levels of diversity.  Furthermore, within a particular patch the diversity is often unevenly distributed along a microtopographic gradient created by hummocks.  In some communities a single hummock less than 0.1-m² supports over 20 species of vascular plants.  I present here some research on the patterns of diversity at both the patch (m) and plant neighborhood (cm) scale.  At the patch scale, I consider how diversity relates to the microtopographic heterogeneity, as diversity is theoretically predicted to increase as the environmental heterogeneity increases.  At the plant neighborhood scale, I examine how microtopography influences the fine-scale distribution of the vegetation using a variety of spatial statistics.  Finally, I consider some possible mechanisms by which hummocks may affect the patterns of diversity, including their influence on the soil environment, plant performance, and plant interactions.  A possible explanation for the high diversity on hummocks is that the combined effects of higher elevation and high plant density reduce the saturation of the soil, thereby improving the microhabitat and allowing for the colonization of a greater number of species.

10

Initial inspection of spatial and temporal variables influencing the attenuation of ultraviolet radiation in streams.  Patrick Belmont*

Ultraviolet radiation (UVR) is an intense stressor of aquatic ecosystems.  Although much work has focused on the UVR environment in lentic systems, little is known about the dynamics influencing UVR attenuation in streams.  For stream ecosystems, the implications of the inevitable increase in damaging UV-B radiation are compounded by the anticipated increasing trend in extreme weather patterns and continued anthropogenic disruption of landscapes.  In this study, sixteen stream sites were sampled from three small watersheds in the Lehigh Valley, Pennsylvania, to begin the investigation of the spatial and temporal variability controlling UVR attenuation.  A gradient of catchments were monitored, ranging from heavily agricultural to heavily forested.  The optical properties of the streams were monitored on a weekly basis from June through October 2002.  Dissolved absorbance was highly correlated to concentration of dissolved organic carbon (DOC) and particulate absorbance was closely linked to total suspended solids.  Land use within the watershed is shown to influence DOC concentration as well as chemical and optical properties.

11

ECOLOGY AND COMMUNITY STRUCTURE OF MONOGENEAN GILL PARASITES FROM THE SHOVELNOSE RAY, RHINOBATOS TYPUS.  Tavis K. Anderson*, Leslie A. Chisholm and Ian D. Whittington

Monogenean parasites of marine fish provide excellent models for understanding patterns and processes in community ecology.  This study examined the community structure of monogeneans from gills of the shovelnose ray, Rhinobatos typus.  Fifteen rays were studied, five collected in each of the three seasons; summer, autumn and winter.  Three species of monocotylid monogeneans were found on the gills: Neoheterocotyle rhinobatidis, Troglocephalus rhinobatidis and N. rhynchobatis.  There was no seasonal variation in parasite intensity for N. rhinobatidis and T. rhinobatidis.  Total parasite intensity for N. rhynchobatis did vary between seasons; the difference correlated with host size, abiotic variation was discounted as the responsible factor.  Constant recruitment of infective stages and a consistent mortality rate are thought to be the predominant causes for population stability.  Preferences for distinct regions on each gill arch were demonstrated for the three developmental stages of each species.  Microhabitat partitioning was striking for mature worms; mature N. rhinobatidis were concentrated on the lower proximal sections on secondary gill lamellae or in the septal canal whereas mature N. rhynchobatis were restricted to the upper distal sections on primary or secondary gill lamellae.  Troglocephalus rhinobatidis adults were located distally on the lower zone of secondary gill lamellae or on peribranchial tissue.  Immature stages of each species were distributed randomly on the upper zone of the gills and with increasing age the parasites migrated towards the specific adult microhabitat. The observed species segregation suggests that reproductive isolation may determine microhabitat.  Immature stage microhabitats were significantly wider; requirement to mate, and subsequent prevention of reproductive waste was not applicable.  These data support the 'mating hypothesis'.

12

The effects of organism size and community composition on ecosystem functioning.  Zachary T. Long* and Peter J. Morin

Early work suggested a link between biodiversity and ecosystem functioning, but more recent studies suggest that traits of the dominant species in a community, rather than diversity per se, drive observed relationships.  For instance, the size of the dominant organism may drive measures of functioning such as productivity or total biomass because more diverse communities may, by chance, contain larger species.  Alternatively, allometric theory predicts that communities receiving the same amount of energy will eventually support the same amount of biomass, regardless of the size of the organisms in the community.  Thus, early in community development the size of the dominant organism may determine functioning, but with enough time thinning or increases in density may occur, so that the size of dominant species may not strongly influence function in mature systems.  We tested if the size of dominant species or diversity determined levels of ecosystem functioning in food webs consisting of bacteria, algae, and protozoa.  We constructed food webs of high and low diversity using organisms of either large or small sizes.  We measured two aspects of ecosystem functioning: total biomass and respiration (total CO2 production).  Initially, the size of the organisms used to construct the community determined both measures of functioning.  With time, however, neither biomass or respiration significantly differed between communities dominated by large and small species.  After six weeks, respiration was lower in more diverse communities.  We conclude that, after sufficient time for development, any differences in ecosystem functioning resulted from differences in community composition, but not the size of the dominant organisms.

13

Macroinvertebrates and the decomposition of native and exotic leaf litter in forest communities.  Isabel Ashton*, Laura A. Hyatt, Jessica Gurevitch and Manuel Lerdau

Decomposition of leaf litter can regulate the rate of carbon and nitrogen cycling in forest ecosystems. Northeastern forests have experienced a large influx of exotic species and we expect that this change in species composition may have large effects on ecosystem dynamics. Macroinvertebrate decomposers may influence nutrient cycling by responding to the differences in litter quality and either avoiding or preferentially colonizing exotic litter.  To examine the influence of macroinvertebrates on decomposition rates and nitrogen dynamics we conducted a decomposition experiment using litter bags with mesh openings large enough to allow colonization.  We filled each bag with leaf litter from one of 4 exotic or 4 native species common to the forests of Long Island.  We collected, sorted, and identified all macroinvertebrates found in the litter bags to determine if there were differences in the decomposer communities found in native and exotic litter.  We found that decomposition rates are faster in exotic litter, but the decomposer community was not different between native and exotic litter. These results suggest that any shift in carbon and nitrogen cycling in invaded communities is caused primarily by a shift in litter chemistry or microbial community.

14

Atmosphere-canopy nitrogen exchange across a tropical forest moisture and fertility gradient.  Jon Benner*, Benjamin Z. Houlton and Lars O. Hedin

Little is known about whether soil fertility regulates atmosphere-canopy exchange of nitrogen in tropical forests, although it has been proposed that direct canopy uptake may be particularly important for forests growing on infertile soils.  We investigated factors controlling atmosphere-canopy nitrogen exchange in a tropical montane forest dominated by the tree Metrosideros polymorpha on Maui, Hawaii, U.S.A. along a combined precipitation (2200 - 4050 mm annual) and fertility (high vs. low N supply) gradient.  We installed five throughfall collectors and one bulk deposition collector at both high nitrogen/low rainfall and low nitrogen/high rainfall sites, and measured nitrogen forms in bulk deposition inputs and throughfall canopy losses over a 29-day period.  Analysis of volume-weighted mean fluxes showed net canopy uptake of nitrate (0.47 kg N ha-1 yr-1) at the high nitrogen site, and an even larger uptake (1.77 kg N ha-1 yr-1) at the low nitrogen site.  We experimentally examined gross canopy retention by simulating rainfall events using a solution containing nitrate and a conservative bromide tracer.  We found differences in nitrate uptake across the gradient (p<0.002) with strong effects by the N-fixing tree species A. koa and bryophytes.  In addition, M. polymorpha assimilated more nitrate in the low nitrogen site than in the high nitrogen site (p<0.04).  Because NO3--N bulk deposition input was higher at the wet end of the gradient (1.95 kg N ha-1 yr-1 vs. 0.52 kg N ha-1 yr-1), the low nitrogen/high rainfall forest appears to obtain more of its annual N requirement by direct canopy uptake of atmospheric nitrogen.  Our results have important implications for understanding atmosphere-forest nitrogen exchange in tropical forests.

15

Remote sensing analysis of forest cover and forest cover change along the Belize River system, Belize.  Sonia Di Fiore*

In this study, remotely sensed Landsat TM data and geographic information systems (GIS) technologies were employed to map and measure the dynamics of forest change along the Belize River, Belize over an 11-year interval.  Supervised classification of Landsat TM data approximate that 31% of the riparian corridor, an area enclosing 2.07 km on both sides of the River, was forested in 2001. This represents a 22% (7,200 ha) loss of forest cover from 1989 levels. The forest conversion rate in the Belize River corridor during 1989-2001 was 2% per year, which shows an alarming increase over previous countrywide deforestation estimates for Belize in the 1980,s (0.2% per year) and above average deforestation rates in Central America during the 1990,s (1.2% per year) (FAO 2001).  To understand deforestation along the River, data were divided into 12 regions, and forest cover (%) and forest cover change (%) were calculated for each region. Forest cover (%) and forest cover change (%) were significantly different among the regions (p< 0.01), signifying that developmental pressures were not uniform along the River between 1989-2001. Then the same two variables were studied with respect to forest cover in 90-meter-buffer gradations going away from the River on either side of the riverbanks. Here, it was found that most of the deforestation had taken place within the first 500 m of the River. In fact, many areas along the River were cleared right up to the riverbank, which is in violation of Belizean Law and detrimental to water quality and wildlife.

16

Slugs, Willow Seedlings and Nutrient Fertilization: Intrinsic Vigor Inversely Affects Palatability.  Benedicte Albrectsen*

This study evaluates how preference by a generalist slug herbivore Arion subfuscus changes inversely with seedling vigor across three levels of fertilization for three cohorts of willow seedlings (Salix eriocephala).  We analyzed seedlings for condensed tannin and protein concentration, and related these data to changes in palatability.  1) In a preference test over time leaf discs from more fertilized seedlings had an extended window of vulnerability compared to discs from less fertilized seedlings.  The latter ones were also more tannin-rich, when analyzed at the age of seven weeks.  2) In a whole seedling selection study, slugs readily attacked seedlings lower than 5 cm tall but rarely attacked seedlings taller than 10 cm in the most resistant family.  However, a general difference in damage risk close to 50% was true when comparing the smaller and larger individuals within each family and level of fertilizer.  3) The decrease in palatability with height suggests that seedling vigor is positively correlated with increased condensed tannin concentration.  Surprisingly, we found no effect of seedling vigor on protein concentration.  We used the Akaiki Index Criterion to evaluate the data, which suggested that only main effects were important for explaining seedling choice performed by the slugs and the ratio between proteins and condensed tannins in the seedlings.  Intrinsic seedling vigor had the largest effect, followed by fertilizer level and family.  The positive phenotypic correlation we found between vigor and an early on-set of tannin production in the less preferred willow seedlings highlights that several plant defense traits may be selected for simultaneously.  We discuss these results in the light of plant-defense theories that predict a negative correlation between the allocation to growth and the production of secondary defense compounds.

17

Anthocyanins and resistance of Brassica rapa.  Andre Levy*

Anthocyanins are flavanoid pigments that are widely distributed among angiosperms and perform a variety of functions, e.g., photoinhibition avoidance, UV-B protection, and pollinator and fruit-disperser attraction.  Less is known about their effect upon herbivores and pathogens.  Evidence implicates anthocyanins may play both a defensive role against herbivores and pathogens, but also as feeding and oviposition stimulants.  I selected populations of Rapid Cycling Brassica rapa for high and low expression of anthocyanins.  Several natural enemies were used to test differences in resistance between selection lines, including Pieris rapae (a specialist butterfly), Trichoplusia ni (a generalist moth), Phyllotreta sp. (a specialist beetle) and Alternaria brassicicola (a specialist fungus).  Results indicate anthocyanins affect herbivore consumption rates and levels of fungal infection, but whether their effect is positive or negative depends on the natural enemy.  This suggests anthocyanin expression may be the target of multiple conflicting selection pressures, including abiotic and biotic factors.

18

Evaluating White-tailed Deer Impact in Pennsylvania using Phyto-indicator Species.  Chad Kirschbaum*, Brian L. Anacker and Susan L. Stout

This paper evaluates the use of Trillium spp. and Maianthemum canadense as indicators of deer impact at a landscape level within the Kinzua Quality Deer Cooperative (KQDC, ~40,000 Ha) of northwestern Pennsylvania, where high levels of deer impact have been sustained for 60 years.  We hypothesized that deer impacts to Maianthemum and Trillium spp. populations across the KQDC would resemble those reported at much smaller scales in previous studies and would indicate spatial variation in deer impact within the KQDC.  We found that the phyto-indicator characteristics in the KQDC were below the “healthy” standards established in the literature and comparable to those associated with high deer impacts.  However, only equivocal evidence links spatial variation of indicator characteristics to deer impact variables.  No significant correlations were found between deer density and indicator variables and few significant but weak correlations were found between deer browsing and indicator variables.  Thus, the two species indicate high deer impact but do not track spatial variation in deer impact.  Relationships between deer impact and indicator characteristics could be clouded by factors such as unmeasured environmental variables, sample size and legacy effects of deer overabundance.  These factors compromise the utility of these species as indicators of deer impact across landscapes.  However, both species will bear further investigation in a long term monitoring project within the KQDC and may function better as temporal indicators of deer impact.

19

Relationship of sapling crown allometry to above canopy light environment in pioneer tree species of a Sri Lankan rainforest.  Uromi Goodale*, Robin E. Barr, Kushan Tennakoon and Graeme P. Berlyn

Although several studies have compared the light environment of tropical species with different life histories, few studies have investigated how the light environment differs among species of the pioneer guild.  We assessed both the light environment, measured with canopy hemispheric photography, and the plant allometric characteristics in saplings of six native pioneer tree species in the tropical wet lowland forests of Sri Lanka.  The species include Macaranga indica, Dillenia triquetra, Schumacheria castaneifolia, Wendlandia bicuspidata, Alastonia scholaris and Melastoma malabathricum.  We found significant differences among species in their crown volume and crown projection area related to the direct (direct site factor) radiation.  We believe that the differences in microenvironment among species as well as the maximum tree size differences can be used for species selection in reforestation.

20

Phylogenetic evidence against horizontal transfer of the lac operon into E. coli.  Daniel Stoebel*

Horizontal gene transfer has been implicated as major feature of bacterial macroevolution, yet we have few specific examples of its role in adaptation, particularly in non-pathogenic situations.  One proposed example of horizontal transfer leading to adaptation and speciation is the transfer of the lac operon into the ancestor of Escherichia coli.  This event is thought to have given E. coli the ability to use lactose, allowed it to in invade the mammalian gut, and diverge from Salmonella, which is typically only found in reptiles.  To test this hypothesis, I sequenced genes from the lac operon of several species in the family Enterobacteriaceae (which includes E. coli and Salmonella), and compared the phylogeny of these genes to the phylogeny of housekeeping genes from the same strains.  With few exceptions, the phylogeny of lac genes matches those for housekeeping genes.  These data argue that these genes are ancestral in the family and have been lost from multiple species.  If correct, we must explain not why E. coli gained the lac operon, but rather why some species have lost it.  We must also ask if there are any good examples of non-pathogenic adaptation via horizontal transfer.

21

The evolution and natural history of breeding systems in sub-arid tropical Solanum of Australia.  Christopher Martine*

Dioecy (male and female flowers borne on separate plants) is rare in the economically important plant genus Solanum (Solanaceae), having been recognized in about 1% of its ca. 1200 species.  Nine of the 13 known dioecious solanums inhabit the semi-arid tropics of northwestern Australia, where they co-occur with ten andromonoecious species (with male and hermaphrodite flowers on borne on the same plant) of the same subgenus (Leptostemonum).  Phylogenetic analysis of these 19 taxa is used to parse out the pathway(s) taken to dioecy (and andromonoecy) in this group.  One possible evolutionary scenario is that andromonoecy arose in this lineage from hermaphroditic ancestors and subsequently gave rise to the dioecious condition.  Thus, the andromonoecious species would be evolutionarily intermediate in form.  Few studies have attempted to show causality in the evolution of separate sexes in plants.  The andromonoecious and dioecious solanums of Australia offer a special opportunity to apply newer approaches in evolutionary biology to a group of species whose unusual reproductive biology and taxonomy sensu stricto is already well understood.  Potential implications of the project include conservation of rare plants and habitats and the preservation of genetic diversity in the eggplant lineage.

22

Introducing a new spatially discrete' resource limited individual-based model.  C. Grant Law

Individual based models (IBM’s) allow researchers to define the emergent characters of ecological systems in terms of the adaptations and behavior of the individual and the qualities of its habitat.  This approach is quite simple, but because every individual is defined and monitored, IBM’s naturally incorporate demography, the effects of space and scale, and intra-specific variation without resorting to synthetic algorithms.  These qualities give IBM’s great potential for the qualitative exploration of population and community level processes.  Ideveloped an IBM loosely based on macrobenthic inhabitants of soft sediment communities to explore issues of competition.  The models performed well, and showed results consistent with chemostat-based studies of phytoplankton growth and competition.  Additionally, despite the extreme variation between individual life history trajectories, the population level dynamics were very consistent from one run to the next.  In another application, the IBM was programmed to impose a slight, random variation in the parameters of newly born automatons.  These variations, acted upon by “natural” selection, caused populations to evolve parameterizations optimized to their environments.

23

Testing stochastic models of population dynamics against data using the Fourier transform.  Daniel Reuman*, Joel E. Cohen and Midori Tuda

A new method to evaluate stochastic population models computes the Fourier transform of many streams of model-generated data and compares the resulting distribution of transforms to the Fourier transform of the data.  We derive properties of the test by mathematical analysis and by simulation.  We apply the test to a model of a host-parasitoid system, and to a model of three interacting life stages of a single species.  The new test makes possible novel strong biological predictions.  It is an appropriate supplement, especially for non-linear models, to one-point-forecast maximal-likelihood fitting.

24

Invasibility and Vulnerability of Plant Communities to Biological Invasion: The Effects of community Properties.  Nan Shao* and Colleen A. Hatfield

Existing studies suggest that properties of communities are key factors affecting invasion success.  We developed a spatially-explicit stochastic model to systematically explore what and how attributes of the plant community affects its invasibility and vulnerability.  The explicit representation of space and uncertainty of demographic events enable realistic and explicit simulations of plant invasion.  Results suggest that community properties including native species richness and limited habitat resource were important in determining community invasibility and vulnerability.  Communities with higher pre-invasion species richness were less invadable, supporting the hypothesis that diversity promotes invasion resistance.  Communities with more available habitat resulted higher frequency of invasion success and higher post-invasion native species richness, suggesting habitat availability may act as a co-varying factor in driving a positive relationship between post-invasion diversity and invasion success.  However, the responses of communities with less habitats indicated that they were more vulnerable to the impacts of invaders due to demographic stochasticity causing extinction of small population.  Results also suggested that species richness was a dominant factor in determining community invisibility.  Species displacement at low habitat level and abundant resource at high habitat level may cause a complex relationship between invader abundance and habitat availability in plant communities.

25

Nitrogen Saturation in Urban Wetlands.  Emilie Stander* and Joan G. Ehrenfeld

Wetlands have high capacity to remove nitrogen (N) from upland land uses before it becomes a pollution problem in receiving bodies of water.  Wastewater wetlands and riparian buffer strips have successfully been used to remove nitrate from runoff through denitrification.  However, due to altered hydrology and high levels of atmospheric N deposition, wetlands in heavily urbanized northeastern New Jersey may be acting as sources rather than sinks of N.  High coverage of impervious surface in urban watersheds coupled with downcutting in urban streams results in lowered water tables and thus drier soils in urban wetlands.  This inhibits denitrification and may cause nitrate loss to receiving streams.  Drier soils may also stimulate nitrification, resulting in the production of nitrate within the system.  Added to the high levels of N entering wetlands from N deposition, this may result in N saturation, the condition in which N levels exceed plant and microbial demand and excess N is exported from the system.  I will test this conceptual model by looking for symptoms of N saturation in six wetlands in northeastern New Jersey.  I will monitor in situ nitrification and denitrification over the course of one year.  I will also analyze nitrate concentrations in soil porewater through lysimetry.  Increased levels of nitrification, decreased levels of denitrification, and high concentrations of nitrate in porewater will indicate the presence of N saturation.  I will investigate the timing of nitrate loss by sampling during dry periods, immediately following rain events, and during saturated conditions.  Preliminary data from other studies supports the conclusions of the conceptual model.

26

Exploring causes of decline in rare plant species.  Krissa Skogen

As many as forty seven percent of the world,s plant species may be threatened with extinction  (Pitman and Jorgensen, 2002).  Recent declines in New England populations of the large-bracted tick-trefoil, Desmodium cuspidatum, provide an excellent opportunity to explore causes of such declines as well as processes that may encourage population growth and ultimately species survival and persistence.  The best assessment of identifying such threats involves gathering demographic, genetic and reproductive information about the species of concern.  I propose to explore reproductive biology and demography, of which little is known, as the first step in determining what governs the growth of D. cuspidatum populations.  Demographic modeling provides a tool for measuring the viability of a population; aspects of reproductive biology provide insight into the recruitment and viability of individuals.  The integration of these two components of species biology will help determine the relationship between breeding system and rarity and will shed light on what may be limiting population growth. Future work with this species will involve genetic analyses of New England populations as well as those in other areas of this species' range.  Studies of Rhizobial bacteria symbioses with D. cuspidatum provide a unique opportunity to explore belowground processes and their relationship to species rarity, an often neglected component of rare species research. Ultimately, a better informed picture of the biology of this species will allow land managers to make decisions regarding the most effective methods of increasing and sustaining populations of D. cuspidatum and other species with similar conservation concerns.

27

Crocodile fears and the spirit of the king: A Madagscar story.  Joseph Paulin*, Robin L. Larson, Evon R. Hekkala, and Richard Fergusson

Within Madagascar's Ankarafantsika Strict Nature Reserve lies the mysterious Lake Ravelobe.  Local beliefs maintain that the lake is sacred.  Villagers say that ancestral spirits (tromba) of a royal family from the Sakalava Tribe reside within Ravelobe,s waters.  Their servants, now Crocodylus niloticus (Nile crocodile) also inhabit the lake.  Between 1996 and 2000, people increasingly broke Ravelobe's taboos, some of which promote conservation.  One such taboo, fishing with nets, depleted a main source of food for the lake's crocodile population.  This angered the spirits.  A sacred bond between the villagers and ancestral spirits had been violated.  Locals believe that the spirits unleashed the crocodiles on those who relied on the lake for their very survival.  According to villagers, the outcome was that, for the first time, crocodiles attacked people guilty of breaking Ravelobe's taboos, as well as innocent women and children.  Several deaths, including that of our friend and reserve guide Izo, gave impetus to an effort consisting of conservation research, education, and traditional ceremonies to consult the spirits themselves.  While management officials considered exterminating Ravelobe's crocodile population, a team comprised of local villagers, reserve managers, Peace Corps volunteers, and researchers from the United States and Zimbabwe raced to find solutions that would save human lives, crocodiles, and a traditional belief system that promoted conservation.  Results include a resurgence of the traditional belief system of the area, enforcement of taboos by local residents, construction of wells as an alternative source of water, and no crocodile-related deaths for over 22 months.

28

Complexity in mate choice: Age- and context-related differences in females, use of male display traits.  Seth Coleman*, Gail L. Patricelli, and Gerald Borgia

How females choose mates is of great interest to behavioral and evolutionary biologists, yet the details of mate assessment are unclear.  We augmented one male display trait and monitored individual female satin bowerbirds throughout mate assessment.  The effect of the augmentation depended on female age and the mate assessment context in which the augmented trait was assessed: young females used the augmented trait in all mating-related decisions; older females assessed the augmented trait only when additional traits were unavailable for assessment.  Our results suggest a clear understanding of mate choice requires monitoring individual females throughout the process of mate assessment.

29

Trade-offs for maternal provisioning of food and heat to young altricial nestlings.  Jeffrey Kovatch* and F. R. Hainsworth

Newly hatched altricial birds depend on parental attentiveness to maintain their temperatures.  Altricial nestlings collectively become homeothermic within a few days of hatching.  Prior to this, mothers of intermittently brooding species allocate time to the mutually exclusive activities of brooding the nestlings and spending time off nest foraging for their nestlings and their own self-maintenance.  We asked how effectively brooding mothers balance these conflicting demands.  Nestlings, ages, number of nestlings, and the environmental temperature influence parental interactions with the brood.  Information from nestling temperature variation can be used to evaluate the relative contributions of parents to the thermal versus feeding requirements of their young.  Small fluctuations in nestling body temperature were recorded during natural cycles of attentiveness.  Cloacal temperatures were logged every 10-15 sec for 2 hr periods for House Wren (Troglodytes aedon) nestlings, ages 0 to 7 days (n=90), in nest boxes (n=18).  Parental behavior was observed and the environmental temperature was logged during the 2 hr periods.  Age-specific and between nests comparisons of maternal time allocation to brooding and foraging, average nestling body temperature, and variance in average body temperature are discussed.  Trade-offs between maternal time allocation to brooding and time available for foraging, and nestling body temperature are evaluated.

30

Exemplar taxonomic position of Needle Clawed Galagos (Euoticus): A molecular characterization.  Eric Stiner *and Amy S. Turmelle

The family Galagonidae (commonly known as Bush Babies) is a distinct African primate lineage including four genera, seven subgroups, 16 to 18 species, and over 30 subspecies.   The group is primarily an equatorial group that extends into the seasonally dry woodlands of south and northeast Africa.  Bush babies are generally recognized as long-tailed, woolly nocturnal primates with elongated tarsi in the feet, and long spatulate digits adapted for life as an arboreal form.  Although several morphological types are found to range widely, the family,s cryptic lifestyle has inhibited (a well resolved) traditional lower level taxonomic evaluation. As a result regional or relict populations have been identified mainly through analysis of vocalization and limited morphological characteristics.  More recently, molecular characters have been used to classify systematics within Galagonidae and characterize the history of this radiation.  In this study, data from 12s, 16s, and cytochrome B mitochondrial gene regions were pooled with previous molecular data collected from exemplar taxa within Galagonidae.  The molecular data strongly support placement of Euoticus as its own genus, rather than sister to Galago, and also as the most basal genus within Galagonidae, as has been suggested in a phylogeny using craniodental characters.  Both maximum parsimony and maximum likelihood trees show consistent intrafamilial phylogenies within Galagonidae.  Bootstrap values for maximum parsimony trees strongly support monophyly of Otolemur, with 100% nodal support for a sister relationship between Otolemur and Galagoides zanzibaricus.  Monophyly of Galago is supported in maximum parsimony and maximum likelihood trees, but Galagoides remains polyphyletic.

31

Mitochondrial phylogeography of insular white footed mice (Peromyscus leucopus) from southeastern New England and Long Island, New York: a preliminary analysis.  George Argyros*, Gwilym S. Jones, Stephen M. Rich

A phylogenetic analysis of mtDNA control region sequence data was conducted to assess variation within and among insular and coastal mainland populations of white-footed mice (Peromyscus leucopus) from southeastern New England and Long Island, New York.  The complete mtDNA control region was examined for 70 individuals representing five insular, and 11 coastal mainland populations from Massachusetts to Georgia.  Forty-four unique haplotypes were identified, of which 18 were from insular populations. Intrapopulational genetic distances for insular populations range from: Martha's Vineyard-0.000 to 0.084 (n=10); Nantucket Island- 0.000 to 0.035 (n=5); Nashawena Island- 0.000 (n=5); Block Island- 0.000 to 0.023 (n=8); and Long Island- 0.011 to 0.110 (n=7).  Interpopulational genetic distances range from 0.000 to 0.193.  Genetic distances for inter-island, island to mainland, and mainland to mainland population comparisons were overlapping.  Degree of variation and haplotype diversity of the insular populations is proportional to island area and inversely proportional to island distance from the mainland.  We submit that observed sequence divergence among populations correlates with clinal differentiation resulting from a post-Pleistocene northward migration along the coastal plain from southern Appalachian glacial refugia.

32

An animal syngameon: differentiation and introgression in sympatric hybridizing Colias butterflies.  Baiqing Wang* and Adam H. Porter

Over the past 60 years, cases of sympatric hybridization have been documented in a variety of organisms including Darwin's finches, several pairs of Drosophila, and even marine fishes.  Those sympatric species pairs hybridize at rates that would allow them to share significant portions of their genomes.  Here we conduct genetic linkage analysis on one of such species pairs, Colias philodice and C. eurytheme (Lepidoptera: Pieridae).  The genetic map obtained provides the foundation for a fine-scale of analysis of the rates that genes in different regions of the genome are able to spread between species.  Based on some new statistical methods, we clarify the spatial distribution of the genetic differences on their chromosomes.  Our results provide a powerful demonstration of Grant's syngameon idea: they share a common gene pool, blended by constant hybridization, and some sort of natural selection acts to keep the remainder of the genome distinct.  Further study of the differentiation regions of the genome will help us understand much better the sorts of selection pressures that maintain the differences between these species.

33

The Nettlesome Questions of Gender Determination and Gender Expression in the Angiosperm Urtica dioica (Urticaceae).  Robynn Shannon

The herbaceous perennial Urtica dioica is one of only a few angiosperm species to exhibit both monoecy and dioecy.  There is some evidence of gender lability among monoecious plants of this species, and also evidence of limited monoecy occurring in dioecious populations.  My goal is to understand breeding system evolution in Urtica dioica through a combination of population biology and molecular and Mendelian genetics.  I am also conducting investigations into the genetics of gender determination in this species.

34

Spatial and Temporal Influences on Phosphorus Dynamics in a Large Cattail Wetland.  Oliver Pierson*, Rebecca L. Schneider, William F. Coon, and M. Todd Walter

Wetlands are now heavily regulated and recognized as key landscape features because of their roles in improving water quality through the removal of dissolved and sediment bound contaminants.  However wetland filtration processes, particularly those involving groundwater flow, are still the subjects of considerable research.  Limited evidence suggests that wetland filtration varies considerably as water levels follow natural rise and fall cycles.  Relatively few field-based studies have been undertaken that quantify internal phosphorus cycling within natural wetlands as hydrologic conditions vary temporally.  As precipitation patterns become variable due to global warming, improved knowledge about phosphorus retention mechanisms in natural wetlands will be useful for water quality improvement.  From April until November 2002, research was conducted in the Ellison Park Wetland, a cattail-dominated marsh near Rochester, NY, to determine how a varying hydrological regime affects phosphorus dynamics.  A mass balance approach was used to determine whether phosphorus retention processes vary seasonally or spatially.  Groundwater-surface water hydrology of the study site was carefully monitored to determine potential influences it has on the wetland's biogeochemistry.  Replicated samples of sediment, plant tissues, litter, surface water and groundwater have been collected at 18 stations seven times since May 2002.  Surface and groundwater have been monitored using stage gages and 7 nests of piezometers distributed throughout the study site.  Preliminary findings show distinct differences in phosphorus dynamics spatially, in near-stream vs. interior plots.  The effects of two distinct hydrologic phases during the study period (wet spring and dry summer), and cattail phenology during the growing season, on phosphorus processes will be presented.

35

The Purple Tide: A case study examining the effect of elevation on the patch distribution of Purple Loosestrife (Lythrum salicaria) in the Great Swamp of Quakertown.  Joseph Corona* and Lisamarie Windham

No studies to date have identified consistent characteristics of wetlands that either suppress or promote Lythrum salicaria (Purple Loosestrife) invasions.  Because microsite hydrology can play a fundamental role in plant community structure and L. salicaria invasions are often patchy within a given wetland, we investigated the spatial relationship between microtopography and L. salicaria patches in Quakertown Swamp (Bucks County, PA).  Data from an extensive site survey (816 points; 2 ha) were used to create a microelevation contour map (<130cm, 1 cm resolution) in ArcView 3.1.  Microsite hydroperiods were calculated based on elevations and water level data (collected at 1 cm increments from April-December) with a data logger in a survey-located monitoring well.  We collected 3 vegetation indices for 42 species from 68 stratified random, plots (1 m2) within the marsh boundaries.  L. salicaria stem density, % cover, and maximum plant height demonstrated positive, sigmoidal correlations with elevation (r2 = 0.27, 0.40, and 0.28 respectively; p<0.0001).  L. salicaria patches were significantly absent from low elevation (<25cm) sites (X2 = 17.47, d.f. = 5).  This zone was flooded >90% of the growing season, and was dominated by native macrophytes, such as Polygonum pennsylvanicum (concentrated at elevations < 40 cm, X2 = 19.33, d.f. = 5).  If L. salicaria has a competitive advantage over native plant species, it may be restricted to relatively higher elevations (> 60 cm) that exhibit shorter, less frequent hydroperiods.  An expanded survey of other wetland sites and systems is needed to further identify the role of hydrology-aided competition from native vegetation as a potential 'Achilles Heel' for L. salicaria invasions.

36

Invasibility and dispersal in urban wetlands.  Heather Bowman Cutway*

In urban fragments, the incidence of invasive exotic species is considered common.  Urbanized areas are exposed to many factors that are known to increase invasibility including high perimeter to area ratio, anthropogenic influence, and disturbance.  This study evaluates the effect of land use on the invasibility of forested wetlands in the highly urbanized Arthur Kill watershed in northeastern New Jersey.  The diversity of land use within the urban landscape is usually ignored, causing diverse urban fragments to be lumped together improperly.  Through a vegetation survey of 17 forested wetlands of different sizes and surrounding land, I determined that wetlands surrounded by residential land use had a significantly higher richness and density of exotic species than wetlands surrounded by industrial land use.  Large residential sites had a surprisingly high number of invaded plots (46.7±8.2%).  However, all industrial sites had a relatively low percentage of invaded plots (12.3±6.2%) when compared with small residential sites (52.6±21.9%).  Riverine sites proved to be the most invaded with 84.0±18.9% of the plots having at least one exotic species present.   Differences in invasibility of these urban forested wetland are likely the result of seed dispersal dynamics. I will discuss a series of experiments I am conducting that examine several components of seed dispersal.  The information garnered from these experiments will help to build on our current level of understanding regarding the function surrounding land use in determining seed flux and site invasibility.

37

Use of spectrographic cross-correlation to evaluate the role of interspecific vocal mimicry in the complex courtship display of the satin bowerbird, Ptilonorhynchus violaceus.  Brian Coyle*, Seth W. Coleman, Gail L. Patricelli, Jennifer Siani, and Gerald Borgia

Males in many bird species include vocal mimicry in their sexual displays, but with the exception of repertoire size, little is known about the function of vocal mimicry in mate choice.  Here, we provide definitive evidence that during courtship, male satin bowerbirds vocally mimic five model species.  Moreover, we show that successful males are highly accomplished mimics.  Mimicry quality (measured using spectrographic cross-correlation analysis) and the number of mimetic components a male included in courtship ('sequence completeness') contributed significantly to male mating success.  We found no relationship between a male's mimicry quality or sequence completeness and parasite load or condition.  We discuss these results and consider other information that choosing females may receive by attending to vocal mimicry in mate assessment.  Lastly, we show that males with the highest quality mimicry and the most complete mimetic sequences also produced the most intense displays, were the most effective at modulating display intensity in response to female signals, built the best bowers, and had the most bower decorations.  To our knowledge, this work is the first to empirically evaluate the degree of similarity between mimetic and model calls.  The spectrographic cross-correlation used to quantify this relationship provides a novel, objective, and highly informative method for elucidating the role of vocal mimicry in animal behaviour.

38

Colony productivity of a native wasp and an invasive wasp.  Tracy Armstrong* and Nancy E. Stamp

Prey utilization and colony productivity of a native wasp (Polistes fuscatus) versus an invasive wasp (Polistes dominulus) were investigated in a controlled field experiment with natural versus 'optimal' foraging conditions.  Colonies with the 'optimal' prey foraging conditions were provided with prey ad libitum within an enclosed area.  The other colonies foraged in the adjacent field-woodland but had the same nest conditions as the other treatment.  When given prey ad libitum, both Polistes dominulus and Polistes fuscatus captured similar amounts of prey and the conversion to total offspring biomass was similar.  But, P. dominulus colonies produced 2.5 times the number of workers as P. fuscatus colonies, reflecting the smaller size of P. dominulus wasps.  At the end of the experiment, P. dominulus colonies with optimal prey foraging conditions still had high egg-laying and peaked in the number of pupae then, whereas egg-laying and the number of pupae per colony of the other treatments began to decline 2-3 weeks earlier.  This result indicates that P. dominulus is more opportunistic than P. fuscatus, which may account in part for P. dominulus's success as an introduced species.

39

Small scale genetic and morphological differentiation in a population of Lake Malawi cichlids.  Rebecca Jordan*

The cichlid fishes of Lake Malawi, and in particular the rock-dwellers, exemplify an extreme case of rapid speciation.  We propose that depth is a factor guiding diversity and therefore we investigated characteristics that might differ along a depth gradient in single population.  We tested whether members of this population, separated by twenty-three meters, differed in four characteristics: mate choice, visual pigment complement, morphology, and microsatellites.  To do so we used behavioral mate choice experiments, microspectrophotometry, and morphometric and genetic analyses respectively.  We found that the two sub-populations did not differ significantly in visual sensitivity despite the difference in the visual environment.  In addition, females did not court assortatively with males from their own home depth.  These sub-populations, however, did differ morphologically and this difference is functionally most characterized by differences in eye diameter.  We also found indication of meaningful genetic separation as well.  These results will be discussed with regard to potential habitat change with depth.

40

Paleobiology by the numbers: quantifying global dinosaur diversity patterns.  Christopher Noto*

Most of our understanding of dinosaur distribution has revolved around biogeographic studies.  However, dinosaurs represent a group that is well suited for studying distribution as it relates to climate.  The largest problem that needs to be overcome is that of sampling bias.  To accomplish this, the Sampling Adjusted Diversity (SAD) index was developed.  Application of this method to dinosaur distribution data has revealed that, in many cases, diversity based on raw data alone leads to inflated estimates for certain regions.  Furthermore, there is an indication that arid areas are preserving more dinosaur fossils than humid areas, leading to a megabias.  Still, high-diversity areas tend to occur in seasonally wet areas at higher latitudes than seen today.  Latitudinal gradients in diversity as seen today then may not be indicative of gradients from times hundreds of millions of years in the past.  Marked changes in distribution patterns may also point to major shifts in climate.  Further work needs to be done to determine more accurately how, when, and where these patterns changed during the Mesozoic.

41

Convergence and divergence in the ecological structure of emydid turtle communities: the effects of phylogeny and dispersal.  Patrick Stephens*and John J. Wiens

Studies that have explored the origins of community structure from an evolutionary perspective have generally found one of two patterns: either convergence (similarity) in community structure between regions through adaptive evolution, or lack of convergence (dissimilarity) due to phylogenetic inertia in the ecological characteristics of lineages.  However, most of these studies have considered geographically isolated or distant communities where dispersal between communities is relatively unlikely.  In cases where lineages frequently disperse between regions, phylogenetic inertia in the ecological characteristics of dispersing lineages may contribute to convergence (similarity) in community structure between regions rather than prevent it.  We used a phylogenetic approach to examine the origins of geographic patterns in the ecological structure of emydid turtle communities.  An important pattern is the tendency for emydid communities in southeastern North America to have a higher proportion of aquatic species than those in the northeast.  This pattern reflects phylogenetic trends in the ecology and biogeography of the two basal emydid lineages, trends which prevent convergence in community structure between these regions.  However, these differences between regions have been blurred by dispersal of lineages with phylogenetically conserved ecological traits.  Dispersal of lineages with conserved ecological traits also explains the similarity in emydid community structure across the New World tropics.  This process may be a common explanation for similar patterns of community structure between regions within a given continent.  Patterns of community structure in emydids arose through a variety of processes that can only be disentangled by considering the evolutionary history of emydid lineages.

42

Evolutionary Ecology of Egg Size and Number in a Desert Seed Beetle.  Mary Ellen Czesak*

In many organisms, large offspring have improved fitness over small offspring, and thus their size is under strong selection.  However, due to a trade-off between offspring size and number, females producing larger offspring necessarily must produce fewer unless the total amount of reproductive effort is unlimited.  Because differential gene expression among environments may affect genetic covariances among traits, it is important to consider environmental effects on the genetic relationships among traits.  The genetic relationships among egg size, lifetime fecundity and female adult body mass (a trait linked to reproductive effort) in the seed beetle, Stator limbatus, were compared between two environments (host plant species, Acacia greggii and Cercidium floridum).  Genetic correlations among these traits were estimated through half-sib analysis, followed with artificial selection on egg size to observe the correlated responses of lifetime fecundity and female body mass.  The magnitude of the genetic trade-off between egg size and lifetime fecundity differed between environments – a strong trade-off was estimated when females laid eggs on C. floridum seeds, yet this trade-off was weak when females laid eggs on A. greggii seeds.  Also differing between environments was the genetic correlation between egg size and female body mass – these traits were positively genetically correlated for egg size on A. greggii seeds, yet uncorrelated on C. floridum seeds.  On A. greggii seeds, the evolution of egg size and traits linked to reproductive effort (such as female body mass) are not independent from each other as commonly assumed in life history theory.

43

Predicting population response to climate change:  a non-linear modeling approach.  Alicia Ellis and Eric Post

The rapidly growing body of research on the ecological consequences of global climate change has elicited a growing interest in the use of time series analysis of long-term datasets to investigate population dynamics and stability in a changing climate.  Here, we use non-linear self-excitatory threshold autoregressive (SETAR) models to investigate the potential influence of climate change on the stability and persistence of an isolated, undisturbed wolf population on Isle Royale, Michigan, USA.  The SETAR model revealed that the population was influenced by climate only at low densities, possibly reflecting the overriding influence of density dependence on dynamics at high densities.  Stability analysis suggests that if the population remains above a certain threshold density, it may maintain equilibrium densities despite climatic change.  Conversely, if the population decreases below this threshold, climate change is likely to lead to population decline, possibly to extinction, in the next 100 years.  In the absence of climate change, the population may exhibit multiple stable states, switching between them when environmental perturbations are strong.  Our results indicate that non-linearity in the strength of density dependence can have substantial implications for the stability and persistence of populations in a changing climate.  Further investigations into the implications of climate change for population stability and changes in mean density may facilitate the formation of appropriate conservation and management policies.

44

Revegetation of Blackwoods Campground, Acadia National Park.  Cristin O,Brien and Manley Reeser

Blackwoods Campground in Acadia National Park is on the eastern coastline of Mount Desert Island, Maine.  The campground contains 313 campsites and sees roughly 100,000 visitors per year.  While the spruce and fir overstory is well developed, there is a distinct lack of understory vegetation both within campsites and in many areas between them, creating long-term problems with regeneration and camper privacy. One facet of this revegetation project is focused on evaluating native shrubs that will survive and thrive under the harsh conditions imposed in this heavily used space.  Twenty-two campsites were randomly chosen and 13 native shrub species were planted at each site in July 2002.  Species were selected based on known tolerance to soil compaction and drought.  When possible, plants with park provenance were selected.  Disease and insect problems, phenology, survival, and growth will all be monitored in the coming growing season (2003).  Soil samples were taken from the test sites at time of planting, and measurements of soil strength will be taken in summer 2003.  Light measurements will be collected and used in regression analysis with edaphic factors and plant growth to evaluate these native species and create a working palate of shrubs for future campsite plantings.

45

Isopod detritus processing is decreased in infected individuals.  Alexander D. Hernandez and Michael V.K. Sukhdeo

This study examines the amount of leaf litter consumed and processed by the isopod Caecidotea communis (Say), and the effect of its acanthocephalan parasite (Acanthocephalus sp.).  A total of 100 uninfected and naturally infected isopods were collected from a stream in the New Jersey Pinelands.  Consumption was measured as the rate of weight loss in pre-weighed Oak-leaf circles 7 mm diameter.  Isopods were starved for 48 h and their weight and length measured before placing in a glass jar with a single leaf circle.  Leaf circles were weighed on day 14 and each isopod was killed and examined for parasites.  Infected isopods consumed 11.4 ± 1.4 % (± SEM) less leaf than uninfected isopods (p<0.05).  There was no correlation between isopod length or weight and the amount of leaf consumed by either infected or uninfected individuals.  These results suggest that parasites have a direct effect on the feeding behavior of their host, and may have significant indirect effects on the rest of the aquatic community that depends on the fine particulate organic matter (FPOM) that isopods produce.

46

Spatio-temporal niche partitioning among three sympatric predators in a one prey system.  Danielle Garneau and Eric S. Post

Terrestrial investigations of multiple predators sharing one prey are rare in natural systems.  This study offers an explanation as to how sympatric black bears, grizzly bears and gray wolves coexist on a seasonally limiting prey item, specifically moose calves.  Spatial and temporal separation within a shared niche dimension has classically been offered as an explanation for sympatric species coexistence.  Niche partitioning, resulting from differential hunting behaviors among members of the predator guild, is often used as a means of capitalizing on a common resource.  Our findings suggest that black bears and grizzly bears temporally separate hunting during moose parturition, due to their spatial overlap in habitat.  Similarly during periods of increased inter-predatory competition, black bears and gray wolves exhibit temporal overlap in hunting bouts; therefore, they must spatially segregate within different hunting habitats.  Consequently, findings from this study indicate the need to consider each member of the predator guild individually, complete with its own suite of behavioral, physiological and foraging strategies.

47

Costly daughters?  Sex-specific suckling behavior of newborn white-tailed deer and its implications for sex allocation.  Amy Dechen and Eric S. Post

Theories of sex allocation in sexually dimorphic species assume differential costs to mothers of producing sons vs. daughters.  For species of mammals in which males are larger than females at birth and weaning, sons are assumed to be the more expensive sex to produce.  We investigated maternal correlates of birth mass and suckling behavior of male and female neonatal white-tailed deer as indices of the costs of producing sons vs. daughters in this sexually dimorphic, polygynous species.  Mean birth mass of 49 sons and 21 daughters produced by 33 individually identified mothers did not differ significantly between the sexes, but males were heavier than females.  Despite this male-biased size dimorphism at weaning, female fawns suckled on average nearly twice as long as males per bout, while the average interval between suckling bouts did not differ between the sexes.  Sex differences were also apparent in the factors influencing birth mass and suckling duration.  Litter size significantly affected birth mass of males, but not females:  sons born as singletons were heavier at birth than those born as twins.  Additionally, male birth mass increased with mother's mass preceding parturition, while female birth mass was influenced by maternal age and pre-parturition mass.  For males, the duration of suckling bouts was related to fawn age and maternal age, while for females it was related primarily to the size of the litter a daughter was born into as well as maternal mass preceding parturition.  These results do not support the hypothesis that males are the more costly sex to rear in this dimorphic species, and accord with earlier experimental evidence of male-biased offspring production under nutritional stress in this species (Verme 1969).

48

Effects of nitrogen supply on the dynamics and control of Japanese barberry (Berberis thunbergii) and Japanese stiltgrass (Microstegium vimineum).  Kristen Ross and Joan G. Ehrenfeld

Exotic invasive plant species are threatening eastern deciduous forests through the alteration of plant communities.  The research focus of this forest restoration project is the management of two exotic, invasive species, Japanese barberry (Berberis thunbergii) and Japanese stiltgrass (Microstegium vimineum), often found growing together in forested ecosystems.  Previous research suggests that both species are associated with elevated pH and nitrate levels.  These soil conditions may facilitate invasion and promote higher rates of seed production and growth of these species.  There are three main objectives of this study.  First, restore native vegetation within these study plots.  Second, experimentally evaluate different methods of soil management to promote native species growth.  Third, educate park staff and local volunteers about feasible, low cost methods useful for forest restoration.  Three forested study sites have been established within two national parks in northern New Jersey to test the effects of soil treatments on soil pH, on the C:N, and on nitrification rates.  Four soil treatments and a control will be administered in the spring of 2003. Native vegetation will be planted within the plots.  Soil conditions such as pH, worm density, nitrification rates, and organic matter and moisture content will be monitored.  Native plant survivorship and growth will be measured as well as exotic dispersal and re-invasion.  A greenhouse component will be included to determine how the problem species respond to nitrogen nutrition.  Physiological evidence of nitrogen use (tissue N content, nitrogen reductase concentrations, N uptake by roots) will also be documented.  Results from this study should supply scientists and managers with feasible control methods and provide a better understanding of the biology of these understudied, problem species.

49

Examining fungal vs. bacterial growth yield efficiencies: does the myth hold up?  Rachel Thiet, Serita D. Frey and Johan Six

Soil communities dominated by fungi such as those of no-tillage (NT) agroecosystems have greater macroaggregation, which improves soil C storage by slowing SOM turnover.  This trend of greater C storage in fungal-dominated systems is often attributed in part to fungi having a higher growth yield efficiency (GYE) than bacteria, such that fungi invest a greater proportion of available substrate C into biomass production than into energy generation.  This hypothesis may be unfounded because results from studies measuring fungal and bacterial GYE are equivocal.  We measured growth yield efficiencies directly using 13C-labeled glucose additions to trace substrate utilization through mixed microbial communities manipulated to have different fungal:bacterial (F:B) biomass ratios.  13C-labeled glucose loss and 13C-CO2 respiration were measured at 2-4 hour intervals for up to 24 hours in two related experiments in which the fungal:bacterial biomass ratios were manipulated by different means.  When chemical biocides were used to manipulate microbial community structure, communities with high and low F:B biomass ratios had growth yield efficiencies of 0.57 ± 0.02 and 0.63 ± 0.01, respectively.  When communities were manipulated using low and high quality wheat residues, growth yield efficiencies of high and low F:B communities were 0.25 ± 0.03 and 0.28 ± 0.02, respectively.  These experiments do not support the widely held view that soil fungi have greater GYE than soil bacteria.  We conclude that claims of greater fungal GYE may ultimately be unsubstantiated and thus should be evoked cautiously when explaining the mechanisms underlying greater C storage and slower C turnover in fungal-dominated soil systems.

50

Sampling of moth faunae in three Maine communities indicates high community diversity and complementarity, low emergence-rate fluctuation, and mobility inversely related to temperature.  James Hayden, David Grimaldi and William Hahn

An ecosystem's diversity increases its potential resilience, while indices of its uniqueness suggest its worthiness for conservation.  Edaphically and floristically defined communities differ in the magnitude and composition of their insect faunae, but the temporal sequence of insect emergence complicates sampling.  Species composition of moths was sampled weekly in three Maine communities (salt marsh, pitch-pine/scrub-oak barren, and mixed forest).  Abundance data were taken for a subset for correlation with locally recorded climatic variables.  Faunal similarity was found to be least between marsh and barren and greatest between marsh and forest, partly due to vagrant individuals.  The total species richness S per site was large and varied little (mean, 166; std. dev., 13.3), as was the percent of apparent endemicity to site (mean, 38.5%; std. dev., 3.91%).  Considerable faunal overturn was discovered by treating the sampling series as a temporal gradient, but the mean S remained nearly constant across weeks.  The rate of adult emergence was found to be almost invariant, based on graphs of newly recorded, finally recorded, and total species through time.  Abundance did not correlate significantly with any climatic variables, but (contrary to expectation) air temperature was found to explain abundance best.  Recommendations for conservation, particularly for the barren, follow from the results.

51

Links in gourmet food webs: length and slope of links in food webs plotted on body mass versus numerical abundance coordinates.  Daniel Reuman and Joel E. Cohen

Some previously unnoticed patterns in the lengths and slopes of links in food webs emerge when the species are plotted on body mass versus numerical abundance log-log axes.  For instance, two-variable linear relationships appear when length is plotted against log prey body mass and log predator body mass, or against log prey numerical abundance and log predator numerical abundance.  These relationships give rise to one-variable linear relationships between length and log prey body mass or log prey numerical abundance when only certain subsets of links are considered.  Slope deviates much from its mean value (about –1) only for short links.  Certain subsets of links have normally distributed lengths and slopes.  Data come from Tuesday Lake, Michigan.  The observed patterns have implications for models of food webs with additional data on average body mass and numerical abundance for each species.

52

Habitat selection of a declining warbler population: the Canada Warbler in Vermont.  Z. Liu, Abraham Chacko, Jameson F. Chace and Steven D. Faccio

The Canada Warbler, Wilsonia canadensis, is a long distance Neotropical migrant that breeds in northeastern United States.  This is a Partner's-in-Flight listed "priority bird population" because of the steady declines detected by road-side surveys of the USGS Breeding Bird Survey and the long-term Forest Bird Monitoring Project of the Vermont Institute of Natural Science (VINS).  In 2001-2002, we measured and analyzed the vegetation at 134 of the VINS long-term monitoring point-count stations.  All stations were within large tracts of protected forest stands.  Habitats with Canada Warblers included cedar-fir swamps, red maple swamps, northern hardwood forest, and low-elevation spruce-fir forests.  The 30 vegetation variables measured were analyzed using Bonferroni-adjusted, Wilcoxon two-sample tests to determine which aspects of the forest vegetative structure Canada Warblers prefer.  We found that Canada Warblers prefer sites with greater total ground cover, greater shrub, fern and moss cover, lower canopy height, and a greater number of large (> 2.5 cm diameter) stems.  Within preferred habitat type of Canada Warblers, logistic regression of factors with highest significance (total ground cover, fern cover, and canopy height) accurately modeled (X^2 = 11.8047, df = 3, P = 0.008) Canada Warblers presence and absence.  These vegetative components are useful indices for predicting the occurrence of this sensitive species in the forests of Vermont.

53

Response of the Canada Warbler to the 1998 ice storm in Vermont.  Abraham  Chacko, Jameson F. Chace and Steven D. Faccio

The Canada Warbler, Wilsonia canadensis, is a long distance Neotropical migrant that breeds in northeastern United States.  Breeding habitat selection is correlated with low, semi-open canopy, with a dense understory (Liu et al. NEEC 2003), conditions of small forest canopy gaps created by wind throw and ice storm damage.  Faccio (in review, Forest Ecol. Manag.) documented the numerical response of a number of northern hardwood breeding birds at 60 locations at six sites in the Green Mountains of Vermont that were damaged by the 1998 ice storm.  We returned to these six sites in 2002 to measure the vegetation at 10 locations where Canada Warblers were present and 10 locations where absent following the 1998 ice storm.  We compared these sites with controls, selected at 15 locations across three sites that were not damaged by the 1998 ice storm, to determine which of 30 forest vegetation attributes Canada Warblers choose among northern hardwood forests in the Green Mountains using Bonferroni-adjusted, Wilcoxon two-sample tests.  Control sites had significantly lower total ground cover, lower shrub cover, fewer downed logs, and fewer large shrubs than ice-damaged sites.  Canada Warblers were found in ice-damaged sites or similarly structured control sites with more shrub cover, downed logs, large shrubs and young trees (dbh 8- 23 cm).  Logistic regression of these highly significant univariate factors accurately modeled (X^2 = 55.51, df = 12, P < 0.0001) Canada Warbler presence and absence.  The response of Canada Warblers to ice storm damaged site is consistent with components of habitat selection in other regions of Vermont.  Canada Warblers select breeding sites in northern hardwoods with a dense understory created by forest canopy disturbances such as ice storms.  Forest management plans for the Green Mountains should maintain such ecosystem disturbance processes and forest structural components to ameliorate the population decline of this, Partner,s-in-Flight listed, "priority bird species." 

54

Genetic Architecture of Herbivore Resistance in a Hybrid System of Willows.  Mary Ellen Czesak, R. Glenn Gale, Margaux J. Knee and Sara D. Bodach,

Resistance to herbivores is an important component of plant fitness, and hybrids often differ in resistance compared to their parental species.  The abundance and/or diversity of herbivores may be high on hybrids relative to parental species, thereby reducing hybrid fitness.  Conversely, herbivore abundance and/or diversity may be low on hybrids compared to one parent or both parental species.  Several quantitative genetic hypotheses have been proposed to explain hybrid resistance relative to the parental species, including the additive, dominance, partial dominance, hybrid resistance and hybrid susceptibility hypotheses.  Support for each of these hypotheses is varied.  Resistance to a particular herbivore may also carry costs, some which may be direct, such as allocation costs, or may involve interactions with other species.  We examined the genetic architecture of herbivore resistance in a hybrid system of willows, Salix eriocephala or S. sericea, and their interspecific hybrids.  Because high levels resistance to herbivores may carry a cost of reduced growth, we estimated the relationship between resistance and measures of plant vigor.  An ecological cost of resistance was also examined by comparing resistance to a willow leaf aphid species (Chaitophorus spp.) and resistance to an eriophyoid mite (Aculops tetanothrix). 

55

Comparative seedling demography of invasive Norway maple and native sugar maple.  Lucy Rubino, Sara L. Webb and Steven Passafaro

Norway maple (Acer platanoides) is a diversity-supressing invasive tree that does not depend on disturbance or edges to invade intact forests.  We compared Norway maple seedling demography with that of the native sugar maple (Acer saccharum) that is very similar in shade tolerance and morphology.  We studied annual changes in 40 4 x 4m plots in a New Jersey sugar maple/Norway maple forest with an extensive carpet of sugar maple and Norway maple seedlings.  We examined recruitment and mortality over a five-year period (1997-2002), and distinguished first-year seedlings in all censuses except the first.  After the first census in 1997, canopy Norway maple trees were removed from the area surrounding half of the plots.  This removal appeared to influence the first pulse of new recruitment during the first 2-year interval (1997-1999), but effects were not seen thereafter when recruitment levels were very low for both species.  Both species had 31 % mortality between 1999 and 2002 following the initial pulse of recruitment.  Differences between the species were most visible in their patterns of mortality over time (time x species interaction, p< 0.0005).  A comparison of populations in fall 2001, spring 2002 and fall 2002 showed that mortality for Norway maple is highest over the winter while sugar maple mortality is heaviest in the summer.  These data suggest that Norway maple and sugar maple may be masting together and experiencing mortalities of similar rates but at different seasons.

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Evolution of defense chemistry in Alliaria petiolata since introduction into North America.  Kristin Lewis and Fakhri A. Bazzaz

Invasive species threaten the integrity and function of ecosystems across the globe.  However, prevention of invasion has proved elusive because of the few commonalities among invasive species that might help predict invasiveness.  One characteristic common among invasive plant species is escape from specialist herbivores in their new range.  It has been predicted that plants released from herbivory will adjust their resource allocation to reduce investment in defense, particularly when defenses are costly.  Such adjustment could increase resources available for activities such as growth and reproduction, which might in turn contribute to competitive ability and rapid spread.   Alternatively, release from specialists and continued pressure from generalists in the new range could increase investment in defenses if these mainly deter generalists.  Using an invasive crucifer, Alliaria petiolata, with costly defenses (glucosinolates), we are investigating whether and how this species has shifted resource allocation between chemical defenses and other fitness-related traits.  We have compared growth, herbivory, defense chemistry, and reproduction in field populations in New England and in Hungary to determine whether invasive US populations differ significantly from native-range European populations.  Using herbivore exclusions, we can also distinguish between constitutive (inflexible) defenses and herbivore-induced defenses.  These data will provide insight into the changes that have occurred since introduction of these plants and the role of defense chemistry in competitive ability and invasiveness.  The potential for herbivory in the new range and flexibility in resource allocation could become useful screening tools to predict which species may become invasive when introduced outside their home range.

57

Body shape divergence of threespine stickleback Gasterosteus aculeatus L. in Loberg Lake, Alaska.  Windsor Aguirre

Loberg Lake, Alaska was poisoned in 1982, and the native threespine stickleback population was eliminated.  Anadromous threespine stickleback colonized the lake sometime between 1983 and 1989.  Annual sampling carried out since 1990 indicates a rapid decrease in body armor and gill raker number, which is consistent with rapid evolution towards the phenotype of the population originally inhabiting the lake.  Geometric morphometric methods were used to explore the possibility that body shape is changing as well, that it is converging with nearby freshwater benthic or planktonic feeding populations, and that it differs between lateral plate morphs.  Body shape has changed significantly over time and differences in body shape between low and complete plate morphs within years were much less than differences among years.  Loberg Lake stickleback appear to be diverging from the ancestral anadromous population in the general direction of local benthic feeding populations.

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Multitrophic interactions on the common milkweed (Asclepias syriaca): Does predator-free space exist on the common milkweed?  Colleen Hitchcock

This research examines if predator-free space exists for cryptic and aposematic species encountered on the common milkweed (Asclepias syriaca.)  Milkweeds are host to a relatively small number of primarily aposematic specialists.  The specialist herbivores of the of milkweeds have been models for the study of aposematic coloration of prey and research investigating usurpation of plant toxic compounds by herbivores for herbivore defense from predators.  Specialist herbivores clearly benefit from their association with toxic-host plants and visually-orienting predators (both vertebrate and invertebrate) have been shown in the field to avoid the aposematic specialists that sequester cardenolides from milkweeds. Predators have also been shown in laboratory experiments to avoid or learn to avoid aposematic specialists upon repeat exposure. Clay caterpillar models were used to estimate predation from avian predators for cryptic versus aposematic species found on milkweed plants and non-milkweed plants in old fields in eastern Massachusetts.  Bird beak marks are clearly visible on clay models and serve as a means to score attacks on models.  Predation rates on clay models suggest that predator-free space may exist on milkweed plants for both aposematic and cryptic species suggesting that milkweeds are not productive foraging grounds for birds.

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The Evolutionary Ecology of Methylbutenol Emission from Pines.  Dennis Gray*

Methylbutenol is a five-carbon alcohol produced enzymatically from dimethylallyl diphospate derived from the chloroplastic DOXP/MEP pathway of isoprenoid biosynthesis.  Although all plants posses this biochemical pathway, only those containing the enzyme methylbutenol synthase manufacture and emit methylbutenol from their leaves.  Methylbutenol emission appears to be restricted to the genus Pinus where its production is both an energetically costly and tightly regulated aspect of plant secondary metabolism.  Since the regulation of methylbutenol production is driven by the ambient thermal environment over the timescale of days, it has been suggested that methylbutenol may play a role in protecting the emitting foliage from damage at high temperatures.  However, this hypothesis has been difficult to test directly.  In order to understand the origin and possible function of methylbutenol emission I examine the phylogenetic, biogeographic, and ecological patterns surrounding its emission within the genus Pinus.  Mapping methylbutenol emission onto a phylogenetic supertree of pines shows that methylbutenol emission must have evolved and/or been lost multiple times.  Methylbutenol emission also exhibits a strong biogeographic pattern with emitting taxa restricted to western North America.  Yet oddly, species inhabiting areas with consistently warm summer temperatures were rarely methylbutenol emitters.  It is suggested that rather than protecting foliage from consistently high temperatures methylbutenol emission provides protection from large diurnal fluctuations in temperature that might be experienced by species living in dry mountainous habitats.

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Photosynthesis and competition between two co-ocurring invasive forest plants.  Heather McMahon and Janet A. Morrison

Alliaria petiolata and Microstegium vimineum are two non-native plant species that invade New Jersey forests.  Both grow in a wide range of light environments and colonize together in mixed stands.  Study plots with both species present were established at Washington Crossing State Park.  Light levels, percent cover, and photosynthesis rate were measured in each plot for each species.  Cover of M. vimineum was greater per plot than cover of A. petiolata, and increased with light level, while A. petiolata percent cover was unrelated to light levels.  In July and September, M. vimineum had greater mean photosynthesis rates than A. petiolata.  However, A. petiolata matched those higher rates during its rapid spring growth, measured in April before M. vimineum had germinated.  In a greenhouse experiment, M. vimineum exhibited an overall higher photosynthesis rate, as well as the ability to increase photosynthesis at a greater rate when exposed to increased light levels, suggesting that M. vimineum may have an advantage over A. petiolata in the forest by more readily utilizing high light patches.  However, in greenhouse competition, A. petiolata seedlings had greater overall mass than M. vimineum due to root growth in both light and shaded treatments.  Each species appeared to utilize a different strategy to promote invasion.  Understanding how each non-native species specifically acts within the ecosystem can be helpful for creating management strategies in areas where simultaneous invasions threaten native biodiversity.

61

Age and growth of pitch pines (Pinus rigida) in the context of frequent disturbance.  Susan Natali, R. Matt Landis, Jessica Gurevitch and Gordon A. Fox

Fire is an integral factor in the maintenance of pine barrens along the Atlantic coastal plains.  Pitch pine (Pinus rigida) is the characteristic and dominant species in the Pine Barrens of Long Island, NY, which cover approximately 100,000 acres in south-central/southeastern Long Island.  Historically, pine barren stands on Long Island burned frequently with severe enough fires to result in partial or full stand regeneration about every 10-30 years.  Since the enormous population increase on Long Island following WW II and the rise of suburbanization, it is believed that fire frequency has decreased due to fire-suppression and increased fragmentation.  In this study we used a dendrochronological analysis of living and dead trees to determine age distribution, mortality, and recruitment of P.rigida in 15 sites known to have burned at different dates, from before 1938 to 1990.  Five sites were located in the globally rare Dwarf Pine Plains and ten sites were located in normal-statured pine stands.  We also looked at changes in community composition in full-statured and dwarf pine stands after fire.  Age distribution was variable among sites, ranging from single-aged stands with recruitment immediately following fire to mixed aged stands, with a long tail of recruitment continuing for many years following fire.  These results are surprising because it is believed that fire or other major disturbance is necessary for pitch pine seedling recruitment.  Growth rates and mortality rates also differed greatly among sites.  Patchiness in demographic parameters is an important factor in determining population and community characteristics in these sites.

62

Seasonal Correlates of Avian Hematozoa in the Neo-Tropical Clay-colored Robin (Turdus grayi).  Nicole Basta,  Andrea B. Gager and Martin Wikelski

The Clay-colored Robin presents an advantageous study system in which to examine the factors contributing to the seasonal dynamics of the prevalence of blood parasites in the tropics.  Studies have shown that the population breeds synchronously during the dry season (February-April), in Gamboa, Panama (9°06,N, 79°42,W), the research site where individuals were sampled, and that males experiences an increase in testosterone during this time.  The rainy season begins in May and continues through mid-December.  Many studies have shown a rise in the prevalence of avian blood parasites in the temperate zone during the springtime, when both breeding occurs and vector densities increase.  Yet, because of the compounding influences of the simultaneous breeding activity and increase in vector densities, it has not been possible to examine the potential contribution of each separately.  This study aims to determine if there is a significant seasonality in the prevalence of blood parasites in the Clay-colored Robin, and, second, to determine if the observed seasonality is correlated to either a rise in testosterone levels or an increase in vector densities.  The former was deduced by examining correlations between the 129 individuals for whom data on both infection status and testosterone level were collected.  The latter was obtained by researching historical data for this region given the vector species transmitting parasites locally.  Preliminary results indicate that there is indeed a significant seasonality of hematozoa infections with a great increase in the number of infected individuals seen during the breeding season, prior to the onset of the rainy season.

63

A Study on the Behavioral Effects of Competition Between Zebras (Equus burchelli) and Cattle, and Among the African Wildlife.  Melinda Rostal, Dan Rubenstein and Ilya Fischhoff

As ranching is becoming more prominent in Kenya, it is important to look at the effects it has on the wildlife.  This study focuses on the interactions of zebra and cattle, primarily looking at their behavior and food selection.  Because it is impossible to see which species of grass a zebra is eating we looked at plant species selection using donkeys. We made the substitution because the analysis of equine and bovine dung with Near Infrared Spectrophotometry has shown that donkeys and zebras process their food very differently than bovines do.  My study recorded the plant species of every plant eaten by donkeys during the trials across three experimental plots one of which cattle had been excluded and two of which cattle were allowed to graze.  When donkeys and cattle were together we compared the plant species eaten each.  Grass selection was analyzed to compare whether there is competition for specific plants between zebra and cattle.   The study also focused on how the behavior of zebras changed from a control with no cows, to when there were cows nearby, to after the cows left.  The behavior was analyzed by comparing time budgets during the treatments.  This study also examined the behavior of wildlife when given access to a limited resource: phosphorous enriched salt.  We examined whether animals return specifically because they remember the resource is there, or if they are randomly discovering the resource again.  We also looked at the dominance hierarchy among the African wildlife to compare competition among the wildlife itself.

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Delayed reproductive senscence and maturational trade-offs: testing evolutionary predictions and investigating a cellular mechanism.  Yaniv Brandvain, Simon Klebanov, Kevin Flurkey and David E. Harrison

The phenomenon of senescence presents a problem for the adaptationist program.  If Darwinian selection favors maximization of reproductive success, how could selection produce individuals that “die of old age,” rather than individuals that live until killed by an extrinsic factor?  Williams (1957) argued that trade-offs due to pleiotropic effects of genes regulating life history traits indirectly selects for senescence.  Williams, theory predicts that decreased ecological mortality selects for delayed senescence, that slow individual development correlates with slowed senescence, and that selection for increased longevity results in less vigorous youth.  To test these predictions we compared life history characteristics of mice from an environment with diminished predation (the Micronesean island of Pohn-Pei), which should reduce ecological mortality, to a robust hybrid population derived from 4 diverse inbred strains.  Compared to controls, Pohn-Pei mice weighed less at 30 days of age, began breeding later, had longer female reproductive lifespans, and had smaller litter sizes when young, but sustained litter size as they aged, resulting in larger litters in late adulthood.  Each result supports predictions of the theory.  Because female reproductive life span in mice is regulated by oocyte number, as well as neuroendocrine factors, we investigated mid-life oocyte number as a proximate explanation for the extended female reproductive life span of Pohn-Pei mice.  As predicted, Pohn-Pei mice had more oocytes at 200 days of age than controls (C57BL/6J, a long-lived laboratory strain).  Regulation of oocyte number over time may be a cellular mechanism that coordinates life history trade-offs.

65

Variation in photosynthesis among populations of Andropogon virginicus.  Theodore Sabelnik and Janet A. Morrison

Andropogon virginicus is a native perennial grass often dominating successional fields throughout the eastern United States.  In southern New Jersey it is found in the pine barrens on very sandy acidic soils, and it is also grows on more mesic soils in central New Jersey.  It is host to a parasitic smut fungus pathogen, Sorosporium ellisi, but populations vary in the presence and frequency of disease.  With a common garden experiment we are investigating physiological and environmental factors that may influence the probability and severity of smut fungus infection.  Experimental plants were raised from seed collected from three plants (families) in each of five populations ranging from the pine barrens to Morris County, New Jersey, and propagated into replicated clones in a greenhouse.  Replicate transplants were placed into four blocks in a garden in August and allowed to establish for a month with frequent watering.  Soil treatments were then applied, including enhanced watering, enhanced fertility, and ambient.  Each plant was inoculated with smut teliospores, and using a Li-Cor 6400 photosynthesis system, photosynthesis was measured on all plants during the fall. Infection outcomes will be assessed in fall 2003.  Photosynthesis was so far unaffected by soil treatments. We found significant variation in photosynthesis among families, and among block/population-source combinations.  These results illustrate genetic variation for photosynthesis rates that is influenced in part by environmental (block) conditions.  Combining these results with infection outcomes in Fall 2003 will allow us to connect the genetic and environmental components of grass physiology with resistance to infection.

66

Exploring the Adaptive Landscape of Dispersal Evolution in Fragmented Habitats.  Roman Yukilevich

I identify the genetic and ecological conditions under which dispersal will either evolve or be lost in fragmented habitats.  Under different parameters, the form of dispersal evolution changes from additive to epistatic.  I then explore novel evolutionary predictions of the model.

67

Temporal Autocorrelation of Pollen Variation in Albizia julibrissin.  Lisa Bono, Peter E. Smouse, Andrew J. Irwin, James L. Hamrick and Mary Jo W. Godt

Genetic variation is extremely important in maintaining the evolutionary future of any species.  There is growing concern that current trends in forest fragmentation can be expected to reduce the genetic variation in tree populations.  Much of the variation in question results from gene flow, primarily pollen flow.  Most pollen flow studies use data collected from a single year, but we (Irwin et al., 2003: Heredity, in press) have shown that this leads to an underestimate of the pollen variation among mothers.  Here, we use data from a multiyear study of Albizia julibrissin to perform an autocorrelation analysis on the temporal variation of male gametes.  We collected 40 seedlings from each of 15 mother trees for each of four consecutive years.  Using eight allozyme loci, we measured the genetic distance between each pair of male gametes, from which we extracted the correlation measures (r) for both the pooled data and for each mother individually.  Our pooled results indicate that male gametes within a single year are positively correlated, r ~ + 0.022, but the correlation is negative for those that are one-, two-, and three-years apart, r ~ - 0.008, - 0.005, and - 0.009, respectively.  These values are small but highly significant (p < 0.001).  Although the r-values for the individual mothers vary somewhat, they show the same overall trend.  Our results show the necessity for the introduction of a temporal factor into assessments of pollen flow.

68

Systematics of Strychnos (Loganiaceae) using morphology and internal transcribed spacer (ITS) sequences.  Cynthia Frasier and Lena Struwe

Strychnos, a genus of tribe Strychneae of the plant family Loganiaceae, consists of an estimated 190 species that are spread throughout the tropics of Africa, Asia, and the Americas.  The plants are often small trees or lianas with characteristic Melastomataceae-like leaves that have three major veins splitting at the base of the leaf; the flowers are small and sometimes hairy.  Some species have leaves that have been modified into tendrils.  Strychnos has been used by indigenous cultures as a component of curare, a dart poison, and to treat numerous ailments from snakebites to gastrointestinal disorders.  The pharmaceutical properties of this genus have been linked to alkaloids, such as the well-known toxin strychnine, and iridoids.  Past work on Strychnos has been focused primarily on morphology, which has resulted in its division into 12 sections.  DNA sequences of the internal transcribed spacer (ITS) regions of Strychnos species are being collected and analyzed together with morphological data to determine the phylogenetic relationships between species.  Parsimony analysis on preliminary data suggests that the American species of Strychnos are the most derived and that the current classification into sections is not supported.  Future work will also be focused on the biogeographic patterns and chemistry of Strychnos and determining the genus, relationship to other genera of Loganiaceae, e.g. Neuburgia, Gardneria, and Spigelia.

69

Analysis of the Diversity of Ammonia Oxidizing Bacteria Based on a Comparison of 16S rRNA and amoA Genes in Monterey Bay, CA.  Gregory O'Mullan and Bess B. Ward

The diversity of ammonia oxidizing bacterial communities was investigated in a time series of depth profiles in comparison to the rates of nitrification in Monterey Bay, California.  Nitrification rates varied by a factor of 2.5 over the two year period.  Sequence analysis of 16S rRNA and ammonia monooxygenase (amoA) genes of beta- and gamma- subdivision ammonia oxidizing bacteria displayed differing patterns of both diversity and structure.  16S rRNA sequences indicated limited diversity and very little temporal or vertical community structure.  Most of the beta-subdivision 16S rRNA sequences were distinct from, but most similar to, cultivated Nitrosospira strains, and were almost identical to environmental sequences from two geographically distinct marine environments.  Gamma-subdivision 16S rRNA sequences were closely related to cultivated Nitrosococcus oceani and are among the first environmental N. oceani–like clones obtained from the ocean.  In contrast to 16S rRNA results, amoA sequences displayed much greater diversity but also formed distinct clusters with depth and time.  Many of the cloned amoA sequences grouped with recently obtained environmental clones from Chesapeake Bay sediments but did not group with cultivated strains.  Quantitative diversity estimators showed greater similarity in a pair of temporally and seasonally isolated samples than in pairs of samples collected from a single vertical profile.  Diversity estimators did not correlate with the rate of nitrification. The two genes displayed different levels of diversity and the functional gene allowed greater resolution for the analysis of community structure.  In conclusion, over a depth range of less than 100 meters in a well mixed upwelling regime both temporal and vertical structure was observed in nitrifier assemblages.

70

Invasion success and the impact of microorganisms on a resident community.  Jennifer Price, Robert Hamilton and Elizabeth Ravit

We conducted an experiment monitoring the invasion success of nine protozoan species into established communities of protozoans and bacteria.  We also studied their effect on the resident community.  Three invading species represented each of three trophic levels: bacterivores, omnivores, and predators.  All of the invaders successfully invaded the resident community, although one species, the predator Didinium nasutum, was rapidly declining by the conclusion of the experiment.  Invader success, measured by total biomass of the invading species, was not related to the trophic level of the invader.  Predators, however, had the greatest effect on the resident community.  By the end of the experiment, only predators had significantly affected any of the resident species in comparison with the control community, which contained no invaders.  There was also more variation in the way that predators affected the resident community.  Each predator eliminated at least one resident species, but the species driven to extinction differed with the identity of the predator.  In contrast, final densities of resident species were similar in treatments with bacterivorous and omnivorous invaders.  The biomass of an invading species was not related to its effect on the resident community.  Stentor coeruleus, a predator, had consistently low biomass throughout the experiment, but had the strongest effect upon the resident community.  Therefore, we conclude that the biomass of a species was a poor predictor of its effect upon other species in this community. 

71

Phylogeny of the Malagasy Ring-tailed mongoose (Galidia elegans) from mtDNA sequence analysis.  Chanda Bennett, William Hahn, Jennifer Pastorini, C. E. Bennett, W. Hahn, J. Pastorini and L. Dollar

The monotypic genus Galidia is one of four genera of the Malagasy subfamily Galiinae (Herpestidae, Carnivora).  The ring-tailed mongoose, G. elegans, is one of the most common and widely distribution mongooses in Madagascar with three geographically distinct subspecies G. e. elegans in the eastern part of the island, G. e. dambrensis in the north, and G. e. occidentalis in the west.  Subspecific delimitation has been based on morphological diversity between the distinct geographic locations, most notably by differences in pelage color.  We conducted a molecular phylogenetic study to test the monophyly of the described subspecies and to determine their phylogenetic relationships.  We analyzed approximately 500bp of mitochondrial DNA sequence data from a fragment of the d-loop region from twenty G. elegans specimens representing all three subspecies from across the species range.  Additional data from other outgroup taxa we re also included for comparison of patterns and to root our trees.  Examination of the sequences revealed three distinct genetic signatures in concordance with the geographical distributions of the subspecies.  A similar pattern was detected in one other widespread Malagasy carnivore, the fossa (Cryptoprocta ferox).

72

Chamaecyparis phylogeny inferred from molecular and morphological data.  Kristin Mylecraine and Lena Struwe

The genus Chamaecyparis (Cupressaceae) includes five species: C. formosensis in Taiwan, C. obtusa and C. pisifera in Japan, and C. lawsoniana and C. thyoides in North America.  A sixth species, Xanthocyparis nootkatensis, has recently been moved out of Chamaecyparis and placed in the new genus, Xanthocyparis, following the discovery of a new, related conifer, X. vietnamensis, in Vietnam.  We performed phylogenetic analyses on morphological data and DNA sequence data from three chloroplast regions: trnL intron, trnV intron, and petG-trnP intergenic spacer region.  The trnL intron region was sequenced for this study, while the trnV and petG-trnP sequences were obtained from GenBank.  The morphological matrix produced a phylogeny that was not as well supported with jackknife analysis, but displayed the same topology as the molecular phylogeny.  The combined molecular and morphological analysis indicates that Xanthocyparis nootkatensis is more closely related to Cupressus than to Chamaecyparis, and that Chamaecyparis forms a monophyletic group within the taxa analyzed.  This is supported by pistillate cone characteristics and the absence of cupressoflavone in Chamaecyparis species.  Three subclades are apparent within the genus: (1) the eastern North American species, Chamaecyparis thyoides, (2) the Asian C. obtusa and western North America C. lawsoniana, and (3) the Asian Chamaecyparis pisifera and C. formosensis.  Subclades (1) and (2) are sister to each other and Chamaecyparis thyoides is sister to the combined (1) and (2) clade.  These relationships within Chamaecyparis do not correspond with geographical distribution, and may reflect a wider distribution of the genus in the past.

73

A long-term study on the reproductive biology of the endangered dioecious shrub Corema conradii (Empetraceae).  Christopher Martine

Corema conradii (broom-crowberry) is a rare, dioecious, low-growing shrub with a disjunct distribution from Newfoundland to New Jersey.  In New Jersey, the plant is a characteristic component of an uncommon xeric habitat type known as the pine plains.  A hot fire burned through one of the most extensive populations of this state-endangered species during the spring of 2001 (near Warren Grove, NJ) and resulted in nearly complete mortality of C. conradii in the burn area. In the fall of 2002, new seedlings were observed in abundance.  Research plots are now established in the area as part of a long-term monitoring project with a focus on reproductive biology.  This research is intended to elucidate the significance of sexual dimorphism in this species (including the differential costs of reproduction according to gender) and the role played by ants in seed dispersal and seedling establishment.

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The Importance of Scale in Modeling and Managing Wildfires. Joshua Halofsky and Colleen Hatfield

With the ever-growing number of wildfires both nationally and globally, in combination with the increasing number of individuals now living in human-wildland interfaces, there is a rising outcry from the public and government for forest managers to better model wildfire occurrence and curb the affects of wildfires felt by individuals.  Because different scales of imagery connote different kinds of information however, two essential questions that forest managers must answer are: Will the resulting burn pattern change with scale leading to different post-fire management decisions?  What is the proper scale or scales to model a wildfire?  To help answer these questions, a unique set of multi-spectral and multi-resolution remotely sensed imagery was obtained before and after the 2000 Cerro Grande fire.  Coarsening 1 meter imagery to 5, 15, and 30 meters, and coarsening Thematic Mapper imagery from 30 to 120 meters allowed us to examine if and how the shape of the burn changed between 5 and 120 meters.  Additionally, the fire-modeling program FARSITE was run at different resolutions to determine how simulated wildfire burn patterns changed with scale. Using the perimeter-area fractal dimension, results of the Cerro Grande fire indicated that while little information was lost between sensor platforms, the burn patterns only remained statistically self similar between 30 and 120 meters. A visual assessment of the FARSITE simulated fire footprints indicated that from 30 to 120 meters, the overall shape remained fairly consistent.  Between 240 and 960 meters, however, the shape of the simulated fires changed

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Molecular support for the monophyly of the fungal plant pathogens Ustilaginoidea and Munkia and corroboration of their placement in the Clavicipitaceae.  Joe F. Bischoff, Jeffrey F. ^.White and Lena Struwe

Ustilaginoidea is a pantropical pathogen of many grass species and is typified by U. virens, the causal agent of false smut of rice.  After infecting the flower and replacing the seed it develops into a stromal mass producing yellow-brown, echinulate conidia pleurogenously along the hyphae.  Munkia martyris is a monotypic Neotropical pathogen that develops at the nodes of its bamboo host causing witches’ brooming.  Munkia martyris develops into a stromal mass and produces yellow-brown, smooth conidia pleurogenously from its hyphae.  Due to the similarity in conidial and stromal formation, Diehl (1950) believed that these genera were evolutionarily linked and members of Clavicipitaceae (Hypocreales, Ascomycota).  The relationship between the anamorphic (asexual) genera Munkia and Ustilaginoidea is evaluated using morphological comparisons and phylogenetic hypotheses using large subunit ribosomal DNA (LSU rDNA).  However, traditionally only teleomorphic (sexual) states are placed into taxonomic hierarchies (i.e. families, orders and phyla) while anamorphic genera are grouped phenetically in the phylogenetically uninformative Deuteromycota.  Parsimony and Log Determination analyses of the LSU rDNA support the monophyly of Ustilaginoidea and Munkia in the Clavicipitaceae.  In addition, the molecular data support the monophyly of taxa based on anamorphic states with greater regularity than teleomorphic, host, or microhabitat data for the other members of Clavicipitaceae.

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Effect of Forest Fragmentation on Lyme Disease Risk.  Brian F. Allan, Felicia Keesing and Rick Ostfeld

Forest destruction and fragmentation in the United States recently have been shown to reduce mammalian species diversity and to elevate population densities of white-footed mice (Peromyscus leucopus).  One potential consequence of reduced species diversity and high mouse density in small fragments is an increase in human exposure to Lyme disease.  Increased risk of exposure to this disease is expected be-cause of the role of the white-footed mouse as the principal natural reservoir of the Lyme bacterium, Borrelia burgdorferi.  Blacklegged ticks (Ixodes scapularis) feeding on mice have a higher probability of becoming in-fected with the bacterium than do ticks feeding on any other host species.  We hypothesized that small forest patches (2 ha) have a higher density of infected nymphal blacklegged ticks, which is the primary risk factor for Lyme disease, than larger patches (2–8 ha).  In the summer of 2000, we sampled tick density and B. burg-dorferi infection prevalence in 14 maple-dominated forest patches, ranging in size from 0.7 to 7.6 ha, in Dutchess County of southeastern New York State.  We found a significant linear decline in nymphal infection prevalence with increasing patch area and a significant exponential decline in nymphal density with increasing patch area.  The consequence was a dramatic increase in the density of infected nymphs, and therefore in Lyme disease risk, with decreasing forest patch size.  We did not observe a similar relationship between the density of larval ticks and patch size.  These results suggest that by influencing the community composition of vertebrate hosts for disease-bearing vectors, habitat fragmentation can influence human health.

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Community structure in an old field: Plant and insect responses to productivity and density gradients.  Matthew I. Palmer and Zachary T. Long.

To study the interactions between an old-field plant community and its insect herbivores, we established a factorial experiment of plant density and primary productivity gradients in an abandoned agricultural field.  The experimental design allows us to test two separate but related ideas.  Our first goal is to investigate how insect herbivory influences plant community structure under variable densities of the canopy dominant (Solidago altissima) and variable levels of primary productivity.  In particular, we are considering whether the density of Solidago influences rates of herbivory on subordinate species. Solidago is considered to be a superior competitor for resources, but it may also provide an associational benefit by masking subordinate species from their herbivores. The second goal is to test ideas about how insect communities assemble in response to the plant community. Specialist herbivores are expected to respond to the density of their host plant while generalist herbivores are expected to respond to productivity gradients.  We further intend to examine the reciprocal impact of these herbivores on plant community structure.  Preliminary results suggest that our experimental treatments - fertilization and clipping Solidago – have had a significant impact on the cover of some of the most frequent species.  The response of the herbivore community to the experimental treatments is expected to appear in the second year, since the insect response lags behind the changes in the plant community.  One interesting result of the initial vegetation data is that total plant cover is positively related to the diversity of the plant community in our unclipped plots, but negatively related to diversity in our clipped plots.  We consider some possible implications of this finding for the debate about diversity and ecosystem function.

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NEKTON USE OF DIFFERENT MARSH GRASS SPECIES.  Craig A. Woolcott and Judith S. Weis

In recent years there has been concern over the value of different marsh grasses as habitat for estuarine nekton, especially as Phragmites australis invades tidal marshes and estuaries along the eastern seaboard.  We studied the two dominant forms of tidal marsh vegetation (Phragmites australis and Spartina alterniflora) in the Meadowlands of Bergen and Hudson Counties, New Jersey, with regard to their respective use by estuarine nekton.  While there has been similar work done in Chesapeake Bay, Southeastern New Jersey and Connecticut, this study is unique in that the monotypic stands of P. australis and S. alterniflora that were sampled exist adjacent to each other, offering nekton a “choice” upon entering the marsh plain.  Field studies were conducted at two sites along the Sawmill Creek.  Site #1 consists of a small drainage creek running between the individual monotypic stands, and Site #2 consists of adjacent monotypic stands running along the northern bank of the main creek channel.  Marshes were sampled using 20’ long X 3’ Flume Nets and standard killifish traps.  Nets were sampled twice a month for six months (May-October 2001).  Fundulus heteroclitus (sub-adults to adults) were abundant in the collections and showed a strong preference for the S. alterniflora marshes compared to P. australis marshes.  Other species showed little to no preference for either marsh.  The grass shrimp, Palaemonetes pugio, was abundant in each collection, showing no preference for either habitat, while Callinectes sapidus was found occasionally, also showing no preference for either marsh type. Amphipods were present in all collections and were equivalent in both marshes.  The fishes Gobiosoma bosci, Menidia menidia, and Syngnathus fuscus, and the fiddler crab Uca pugnax were found sporadically, but provided inconsistent or insignificant results.

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The Return of Seabeach Amaranth (Amaranthus pumilus) to the Mid-Atlantic States.  Jay F. Kelly

Seabeach amaranth (Amaranthus pumilus), a threatened species occurring along the coastline of eastern North America, experienced significant declines throughout its range during the twentieth century until, by 1989, it was reduced to a few populations in North and South Carolina. In 1990, however, it was rediscovered in New York, where it had not been seen since the 1950’s, and the next decade saw its return to Maryland, Delaware, Virginia and New Jersey as well. This paper attempts to explain the return of the species to these states using what evidence is available from recent genetic analyses, botanical surveys, meteorological events, human ecological events, and other sources.