ABSTRACTS OF 2001 FUNDED STUDENT RESEARCH GRANTS
(10 award recipients; $13,015 total funding)

Student: Sharon M. Ashworth (doctoral student), Department of Ecology and Evolutionary Biology, 2045 Haworth, University of Kansas, Lawrence, KS 66045; ashworth@eagle.cc.ukans.edu

Proposal Title: Vegetative development of newly created saline basins at Cheyenne Bottoms, Kansas

Abstract:  A major question in ecology is the relative influence of species pools, initial conditions, and environmental variability on plant species diversity.  In an attempt to address this question, I investigate the effect of local species pools, seed banks, and environmental factors on initial plant diversity and succession in 60 wetlands created at the Cheyenne Bottoms Reserve in central Kansas.  Specifically, I question which biotic and abiotic factors determine the initial floristic composition of the wetlands and ask if initial floristic composition or environment determines subsequent assemblages of plant species.  To answer these questions, sixty basins were randomly excavated across a 150 acre site.  Thirty of the basins are classified as ‘small' and range in size from 28.42 m² to 129.21 m².  Thirty of the basins are classified as ‘large' and range in size from 193.32 m² to 602.64 m².  The basins also differ in depth are classified as shallow (12 cm to 24 cm), intermediate (26 cm to 32 cm), and deep (33 cm to 55 cm).  Two species, Distichlis spicata and Eleocharis xyridiformes, were transplanted into 30 of the 60 wetland basins in May, 1999.  Vegetation surveys are conducted in the spring and fall.  The species pool for each basin is defined as those plants within a 10 m radius around each basin.  Water level and soil conductivity are measured weekly in each basin during the growing seasons.  A seed bank assay for each basin was conducted in March, 2000.  Using an environmental sieve constructed from information gained through regression analysis and the life history characteristics of the available species pool, I will predict the vegetative composition and successional trajectory for each basin or group of basins.  The restoration or creation of ecosystems provides an opportunity to establish initial conditions and then make predictions about the development of an ecological community.  My research will provide practical information for the creation and restoration of wetlands in the Great Plains region, which serve to provide critical shorebird habitat and enhance biodiversity.

Student: Vanessa B. Beauchamp (doctoral student), Arizona State University, Department of Plant Biology, Box 871601, Tempe, AZ 85287-1601, vanessa.beauchamp@asu.edu

Proposal Title:  Impacts of flow regime alteration on successional proceses in cottonowood (Populus fremontii) and willow (Salix gooddingii) dominated riparian forests, Verde River, Arizona.

Abstract:  In the southwestern United States, riparian areas are important habitat for wildlife. Creation of dams and reservoirs to accommodate expanding agricultural and urban demands has altered the natural flood cycles experienced by riparian ecosystems.  This has impacted recruitment of riparian pioneer species, such as cottonwood and willow, resulting in the decline or disappearance of riparian forests downstream from dams.  Although there have been many studies on the impacts of flow diversion and regulation on the riparian pioneer trees, few studies have assessed the effects of altered hydrologic regime on understory vegetation, soil properties, or mycorrhizal populations, all of which are critical components of riparian ecosystems.  Previous studies have shown that flood plain aggradation, soil nutrient content, and the proportion of fine to coarse textured soil particles increase as cottonwood forests age.  Cover and diversity of understory herbs also tends to increase with stand age.  Shifts in understory composition from annuals to perennials and finally to late-successional trees and shrubs, occur as disturbance becomes less frequent in the older stands.  River regulation tends to reduce the magnitude and frequency of flood flows thereby disrupting several fluvial and biotic processes. These include reduction of the frequency of flood plain inundation, and reduction of rates of sediment deposition, flood plain aggradation, and nutrient deposition.  I hypothesize that the decrease in influx of fine sediments and nutrients will impede or stop some successional processes, while other aspects of succession, such as establishment of perennial herbs in young cottonwood stands, may be accelerated by flow regulation.  A space-for-time substitution approach will be used to investigate the changes in understory vegetation, soil texture, chemistry, and mycorrhizae populations along a chronosequence of cottonwood and willow stands ranging from saplings to senescent trees.  Successional trajectories at sites above and below two major dams will be compared to assess how flow regulation impacts succession.  Findings from this study will be used to develop restoration strategies and monitoring programs, to predict impacts of reductions in water flow and sediment input, and to develop dam operation scenarios that will enhance the quality of cottonwood forest ecosystems.

Student:  Julia A. Cherry (doctoral student), Department of Biological Sciences Box 870206 Tuscaloosa, AL 35487-0206, julia.cherry@ua.edu

Proposal Title: The effects of semi-terrestrial invertebrate herbivores on the growth, production and reproductive fitness of Nymphaea odorata

Abstract:  Within the field of ecology, the effects of herbivory on plant production and fitness are debated among those who contend that the impacts of herbivores on plants are negative (undercompensation) and those who contend that herbivory can result in positive responses (overcompensation or grazing optimization).  Within aquatic ecosystems, generalizations concerning the effects of herbivores on macrophytes are lacking.  Through the combination of field and laboratory experiments, I am investigating the interaction between Nymphaea odorata and its invertebrate herbivores in an attempt to ascertain if compensatory growth is one of the defensive mechanisms employed by the plant to offset the loss of biomass due to grazing.  I hypothesize that herbivory will cause a decrease in leaf longevity with a corresponding increase in turnover rates resulting in an increase of aboveground net primary production (ANPP), and that herbivory will cause a decrease in the number of flowers and seeds produced.  Eighteen plots consisting of six controls, six shade-controls, and six exclosures at Lake Ponderosa, Bibb County, AL will be monitored weekly for two years to determine if Nymphaea odorata compensates for herbivory with increased leaf biomass, flower, or seed production.  In addition, 40 microcosms, each containing one specimen of Nymphaea, will be monitored in a controlled environment for two years to ascertain if clipping results in compensatory responses such as resource allocation to the roots.  By studying plant-herbivore interactions in an aquatic ecosystem, my goal is to understand the general relationship that exists within a specific interaction and how it compares to other interactions in aquatic ecosystems, while simultaneously addressing the debate of compensation that still prevails among plant ecologists.

Student:  Edward Gage (Masters degree student), Colorado State University, Department of Earth Resources, 322 Natural Resources Building, Fort Collins, CO 80523-1482, edgage@lamar.colostate.edu

Proposal Title:  Patterns of willow (Salix spp.) seed dispersal, seed entrapment, seedling emergence and survivorship in montane riparian communities of Rocky Mountain National Park

Abstract:  Willows (Salix spp.) are the dominant woody plants in montane riparian wetlands on the east side of Rocky Mountain National Park (RMNP).  There is concern among park managers and members of the scientific community regarding a documented decline in the extent and condition of willow communities in the RMNP elk winter range.  Understanding the implications of potential management strategies and the successful development of restoration activities in RMNP requires specific information on willow life history characteristics, and the biotic and abiotic factors that affect willow establishment.  Data from the 2000 field season indicate that seed rain may be a factor limiting establishment in portions of the elk winter range. T he proposed research will attempt to more clearly identify patterns of aerial seed rain and to develop a model of seed dispersal.  Hydrochory will also be examined as a potential mode of dispersal for both sexual and asexual propagules.  Post-dispersal processes that may strongly affect patterns of willow recruitment include seed entrapment and germination.  Seed entrapment is likely influenced by the amount of microtopographic relief present in a specific location, whereas successful seed germination may be influenced by soil moisture; a function, in part, of soil texture.  How specific soil surface and textural characteristics influence these two processes is unknown.  The proposed research will attempt to: (1) characterize the patterns and processes of willow seed dispersal, (2) identify the importance of soil surface conditions on willow seed entrapment, (3) identify the role soil texture plays in germination and initial seedling survival, and (4) describe the interactions of seed entrapment, germination and seedling survival in relation to fluvial landforms.  These studies will clarify basic processes of willow recruitment and can help scientists and managers develop more realistic models of montane riparian vegetation, and management strategies to promote natural or assisted plant establishment.

Student: Prairie Rose Hyde (Masters degree student), International Agricultural Development, University of California-Davis, One Shields Ave., Davis, CA 95616, abdulrose@hotmail.com

Proposal Title:  Wetlands at the Village Level: Role in Village Economy and Water Quality Improvement

Abstract:  Wetlands are productive ecosystems with unique properties and functions that are valuable to humans.  This is clearly seen in Africa, where the continent’s many wetlands support large numbers of people.  In addition to large, well-studied floodplain and lake systems, there are also smaller, localized wetlands that are tightly linked to the communities around them.  I propose to study the links between Kambolé, in Central Togo (West Africa), and the many wetlands surrounding the village.  I chose this village because I am interested in the relationship between the wetlands and the village.  The wetlands are large and seem to play a significant role in the agricultural economy of the village.  Also, these wetlands may also play a vital role in filtering village runoff, thereby improving the quality of water leaving the area.  I intend to explore the uses and functions of this natural resource at the village level by testing two hypotheses: 1) villagers with greater access to wetland areas will use the wetlands directly more so than those with less access; 2) these wetlands improve the quality of polluted village runoff passing through them by accumulating sediments and metabolizing nutrients, specifically nitrogen and phosphorous.  In order to test my hypotheses, I need to fulfill the following objectives: 1) determine the size and location of the wetland areas, and identify the dominant plant species and communities within the wetlands; 2) identify main uses and current management of wetland areas and their economic and social significance, and 3) assess the nutrient status of water, sediment, and plant samples along impacted and non-impacted, and outlet transects before and after the rains begin.  This study is important for three reasons.  First, it will provide a comprehensive account of one village and its links with the surrounding wetlands.  This information will be invaluable when and if management changes or development projects are proposed in this area.  Second, the plant information I collect could be used to design constructed wetland water treatment systems in similar areas.  Third, the idea is novel, and will contribute to the understanding of wetland systems and our reliance on them.

Student: Virginia L. Jin (doctoral student), University of Georgia, Department of Botany, 2502 Miller Plant Sciences, Athens, GA 30605, vjin@dogwood.botany.uga.edu

Proposal Title: Plant organic nitrogen uptake in temperate wetland ecosystems

Abstract:  In temperate wetland ecosystems, the mineralization of organic matter and subsequent availability of mineral nitrogen (N) are limited by anoxic conditions imposed by water tables close to the surface and periodic flooding.  The availability of mineral nitrogen in these ecosystems is further restricted by microbial immobilization and adsorption of predominantly ammonium ions onto organic molecules.  Because levels of mineral N relative to organic N in these ecosystems are very low, plants may turn to alternative N sources to supply growth demands.  Since temperate wetland plant species are among the most likely to experience the environmental conditions under which the use of alternative nitrogen sources may function as a possible adaptive mechanism, I propose that various wetland plant species may use organic N forms, particularly low molecular-weight free amino acids (AA).  Specifically, I hypothesize that plant uptake of AA may depend upon the availability of both mineral and organic N, and that AA uptake may vary with species and/or life-history characteristics.  Because little data have been published to date on AA uptake by plants growing in situ in temperate wetland ecosystems and on the ecological implications of AA uptake in these ecosystems, I will measure several soil chemical properties, including concentrations of soil amino acids and inorganic N, and use stable isotope labeling techniques in field and greenhouse experiments to investigate the occurrence of plant AA uptake.  I plan to use these data to quantify the contribution of directly acquired external AA to plant productivity and explore the implications for nitrogen cycling in three floodplain forest ecosystems in the southeastern USA.  The purpose of this proposal is to obtain funding to purchase the supplies necessary for conducting chemical analyses that address the soil aspects of my research, including the determination of soil amino acids and inorganic N.

Student: Karin M. Kettenring (doctoral student), University of Minnesota, Department of Applied Plant Sciences, 375 Alderman Hall, 1970 Folwell Ave., St. Paul, MN 55108,  karin_kettenring@hotmail.com

Proposal Title:  Factors limiting the natural recolonization of restored prairie pothole wetlands

Abstract:  Over the past 15 years, recognition of the role wetlands play in a healthy environment has increased markedly.  Wetland restoration activity has begun to counteract 130 years of wetland loss when nearly half of all naturally occurring wetlands were drained throughout the United States.  In prairie pothole restorations, hydrology can be restored to drained wetlands through clogging drainage ditches and breaking drainage tiles.  However, little effort has focused on actively revegetating restored wetlands because it has been assumed that the native vegetation will quickly return to restored wetlands.  Recent study of the vegetation of restored wetlands has shown that many species, and in particular sedge meadow plants, are slow to recolonize restored wetlands.  Possible limitations to natural recolonization include seed availability limitations due to low seed production in natural wetlands and seed dispersal limitations due to landscape fragmentation.  This research will focus on seed production and seed dispersal limitations in 6 Carex species that have different rates of recolonization of restored wetlands.  This summer I will initiate a 3 year study of seed production in natural wetlands southwest of the Twin Cities, MN, where I will determine total viable seed output per unit area of species coverage.  Furthermore, an experiment with 2 of the Carex species will explore possible seed production limitations due to herbivory and fungal damage through comparisons between controls and insecticide or fungicide treated plants.  This summer I will develop techniques with which I can investigate seed dispersal limitations.  I will explore the use of fluorescent microspheres as a technique for marking seeds.  Also, I will develop and test different seed traps to determine a design best suited for this system.  These techniques will allow me to mark seeds in natural wetlands and determine whether they arrive in seed traps in restored wetlands.  Then I’ll be ready to investigate seed dispersal limitations next summer.  Results from my production and dispersal studies will form the basis of a spatially explicit computer model that will explore seed production and dispersal limitations to natural recolonization and simulate recovery trajectories for vegetation in restored wetlands.

Student:  Kristi MacDonald (doctoral student), Ecology and Evolution Program, Rutgers University, 14 College Farm Road, New Brunswick, NJ 08901, kristim@eden.rutgers.edu

Proposal Title:  Characteristics of forested wetlands promoting species richness and nesting productivity of Neotropical migrant songbirds in urban areas of northeastern New Jersey

Abstract:  Declines in several species of Neotropical migrant birds have been noted on both their winter and summer ranges for at least three decades.  Habitat loss and fragmentation due to agriculture, urbanization, and forestry practices are most commonly offered as explanations for this decline.  Although change in habitat area has been shown to impact the richness and abundance of bird species, there has been little research done on the underlying habitat changes that result from fragmentation, the effects of fragmentation on population dynamics such as nesting productivity, and the effects of specific anthropogenic changes in land cover.  Because the breeding range of many Neotropical migrants fall within heavily urbanizing areas of North America, an understanding of the affect that this type of land use change has on breeding bird populations is needed.  The proposed research will study the effects of different levels of urbanization on habitat quality, colonization probability and nesting success of Neotropical migrant birds in 10-ha, forested wetlands of northeastern New Jersey.  Bird communities and nesting productivity will be measured using point count surveys and mist netting from mid-May to mid-August in 2001-03.  Habitat characteristics including insect abundance, presence of nest predators, vegetation structure, hydrology and level of human use will be measured.  In addition, landscape-level characteristics such as density of development and dispersion of open space will be quantified within the 1 km radius area of each forested wetland.  Comparing bird species richness and nesting success with local and landscape habitat variables will provide information on the factors, beyond habitat area, which either enhance or degrade the value of urban forested wetlands for breeding Neotropical migrants.  This information will be useful for the improvement of local and regional conservation planning, regulatory policies and management for these species in urbanized landscapes.  Furthermore, an understanding of the relationship of bird communities to other urban wetland characteristics has direct policy implications for ranking urban wetlands based on their context-dependent values and functions.

Student: Ian Roul (Masters degree student), Dept. de Phytologie, Universite Laval, Pavillion Paul-Comtois, Quebec, QC Canada G1K 7P4, Canada, rouli2@yahoo.com

Proposal Title:  A comparison of vegetative and hydrologic responses to surface modifications in block-cut peatlands

Abstract:  Peat in Canada is primarily extracted for horticultural products by one of two methods; mechanical vacuum harvesting (current) or hand block-cut mining (historical).  Twenty years after extraction, vacuum sites are often devoid of vegetation while post block-cut sites show high regeneration rates, with one particular absence - Sphagnum.  Sphagnum is responsible for many ecosystem functions in peatlands, particularly carbon sequestration.  Restoration efforts are concentrated on returning Sphagnum dominance to these ecosystems.  Three potential causes for the lack of Sphagnum in block-cut peatlands have been identified: 1) a lack of sufficient moisture (rewetting), 2) substrate barriers to plant establishment, and 3) a physical barrier to propagule transport.  Two experiments explore these potential limits to Sphagnum colonization. In one experiment, Sphagnum growth rate, community composition and hydrologic variables (soil moisture, tension and depth to the water table) are examined in four different water regimes, achieved by differential spacing of ditch blocking.  A second experiment examines the patterns of Sphagnum colonization after the removal of surface litter and the shrub barrier to dispersion. Results should provide a clear picture of the limiting factors to Sphagnum growth in block-cut peatlands and provides a guide to restoration with the particular aim of improving the carbon sequestration.

Student: Merritt R. Turetsky (doctoral student), Department of Biological Sciences, University of Alberta, Edmonton, Alberta. Canada T6G 2E9, turetsky@ualberta.ca

ProposalTitle: Permafrost thaw and carbon accumulation in boreal peatlands of central Siberia

Abstract: Permafrost in peatlands currently is melting at its southern limit across western Canada with no sign of recovery.  This thaw is in response to a recent warming across Canada’s boreal forest since the Little Ice Age and/or increasing fire frequencies in western Canada.  Permafrost melt increases carbon sequestration in peatlands and is an important factor in predicting the response of boreal systems to future climatic flux.  Little is known about the extent of permafrost thaw in the discontinuous permafrost regions of boreal Siberia.  Using aerial photographs to map the abundance of internal lawns, wet open sedge fens representing areas of recent permafrost melt, I hope to document the regional importance of permafrost thaw to peatlands in the Snejhnogorsk region of central Siberia.  This study also seeks to quantify rates of carbon accumulation over the past 200 years in internal lawns, frost mounds and ombrotrophic bogs (with no permafrost) in replicate peatland complexes in this area. ²¹⁰Pb-dated age chronologies from peatlands with permafrost, without permafrost, and with melted permafrost will document the influence of permafrost aggradation and degradation on rates of peat accumulation.  These data will extend our knowledge of peat accumulation and permafrost thaw from a regional perspective based almost entirely in western Canada to a more widespread understanding of boreal systems across the globe.