2004 SWS Student Research Grant Awards
EVALUATING CLIMATIC CONTROLS ON SOIL ORGANIC MATTER DEVELOPMENT IN NEW YORK RESTORED WETLANDS
Investigator: Kate Ballantine
Cornell University
Wetland restoration is increasingly used as a strategy to address both historic wetland losses and to mitigate, even justify, new wetland destruction. However, limited research suggests that few restored wetlands achieve the biophysical properties or provide the ecological benefits of their native counterparts. The disparity may be due in part to the current "one size fits all" strategy for restoration methodologies. Information is needed showing how restoration success is affected by climate as well as wetland location, soil or landscape position.
This project will examine the influence of climatic conditions on wetland restoration success in New York State. It will take advantage of a unique set of 1,179 wetland restoration projects conducted since 1990 by the New York Fish & Wildlife Service. The approach will be to compare restored wetland sites between the cooler wetter counties of the Tug Hill Plateau and western Adirondack regions with warmer drier sites just south of Oneida Lake. The focus of this evaluation will be on soil organic matter as an indicator of soil development processes that influence water quality functions.
A complement of field techniques and a short-term experiment will be used to quantify and compare the wetland restoration projects between the two regions. A field inventory of soil cores will be conducted and litter bags will be used to compare rates of decomposition. The results of this research should provide useful insights into the factors controlling restoration success in New York and nationally.
TEMPORAL AND SPATIAL VARIABILITY OF PEAT ACCUMULATION AND VEGETATION OF POST-FIRE BOREAL BOGS
Investigator: Brian Benscoter
Southern Illinois University - Carbondale
Peatlands are landforms where production exceeds decomposition, resulting in the accumulation of stored organic matter, or peat. Globally, peatlands sequester 76 Tg of atmospheric carbon annually and comprise a terrestrial carbon pool of 455 Pg, with 42 Pg in western Canadian peatlands alone. Fire severely compromises peatland functional capacity, consuming approximately 1470 km2 of peatland annually in western Canada, directly releasing 3.1 Tg C through combustion. However, the indirect effects of fire may be even more pronounced. Combustion removes surface vegetation, resetting the successional process and stopping photosynthetic production as well as possibly increasing decomposition rates, resulting in the net release of carbon for many years post-fire.
To assess temporal and spatial variability in post-fire peat accumulation, I will determine vegetation successional pathways, rates of production and decomposition, and their combined affect on bog peat accumulation by comparing these processes between burned and unburned bog peatlands in Alberta, Canada, to develop functional post-fire recovery trajectories. Five sites with various fire recovery times (1-63 years) possessing burned and unburned portions of the same landform were chosen. Vegetation composition will be determined spatially, by conducting vegetation surveys, and temporally through macrofossil analysis of peat soil cores to determine the successional patterns of each site.
Re-establishment of moss on burned peat will be experimentally induced by seeding with combinations of moss species fragments and compared to control treatments to determine the importance of competition and the mechanism(s) of re-establishment. Production will be measured (using the cranked wire method) for the moss layer and litter traps for vascular input to the soil carbon pool. Peat cores sectioned at 3-cm intervals and placed into decomposition bags will be used to determine decomposition rates temporally post-fire and with depth, and all studies will be referenced to distance from water table for functional comparisons.
The results of all studies will be integrated to determine the temporal trajectory of peatland recovery, both physically and functionally. Preliminary conceptual modeling suggests a 5-10 year lag post-fire before positive peat accumulation returns, with an even greater time period (>20 yrs) before the peat carbon pool returns to its pre-fire magnitude.
A SPATIOTEMPORAL ASSESSMENT OF LENGTH-MASS RELATIONSHIPS USING ADULT ODONATA
Investigator: Jason Bried
Mississippi State University
Rapid and reliable tools are needed to measure functional integrity of wetland ecosystems. Aquatic insect production provides powerful endpoint signals of perturbation to streams. Production estimates for wetlands, however, are difficult because of logistical drawbacks to sampling aquatic forms of wetland insects.
One approach for accelerating measurement of secondary production without compromising accuracy is to predict mass from closely correlated linear dimension parameters (e.g., length of body or wing). Mass is an approximate cubic function of length for insects in general, but nothing is known as to whether length-mass correlations of wetland insects are upheld across spatial or temporal scales. Therefore, I will execute a spatiotemporal gradient survey of length-mass relationships that will help determine whether mass predictive equations are feasible for making broadly applicable estimates of biomass and secondary production.
Close length-mass correlations in fresh ("wet") adult dragonflies were found previously. Adult stages of Odonata (damselflies, dragonflies) are easy to identify, are intrinsicly important for aerial trophic interactions in wetlands, and are known to be ecologically sensitive to physical perturbations of aquatic and terrestrial habitat. Adult Odonata will be collected early, mid, and late summer from three disparate locations in north Mississippi, USA. Fresh mass (0.01 mg) and total body length (1.0 mm) of target species (abundant, asynchronous breeders) will be measured on samples collected from various wetland habitats (e.g., cypress-tupelo sloughs, beaver marsh, moist-soil marsh, bottomland microhabitats) at each location. All individuals will be dried and reweighed for determination of water:tissue mass ratios and for assessing variance in internal water content.
Length-mass regression slopes of target species will be compared across the space and time gradients using analysis of covariance. Similarity in these length-mass relationships would suggest that mass predictive equations for target odonate species are not necessary for every level of the given spatiotemporal gradient. However, if the correlations are dissimilar for one or more taxa then broad usage of equations may not be appropriate, thus making the length-mass approach less practical for conservation protocols (e.g., wetland bioassessment).
FACTORS INFLUENCING INVASION OF ARUNDO DONAX IN RIPARIAN ECOSYSTEMS OF SOUTHERN CALIFORNIA: AN EXPERIMENTAL APPROACH
Investigator: Gretchen Coffman
University of California, Los Angeles
The alien plant giant reed (Arundo donax) is rapidly invading riparian ecosystems along rivers in mediterranean climate regions, forming extensive stands or monocultures. Due to natural and anthropogenic disturbances characteristic of rivers of mediterranean climates, weedy species like giant reed have established within these systems. Giant reed is known to increase the risk of flooding, create fire hazards, outcompete indigenous species for scarce water resources, and reduce the value of riparian habitat for wildlife.
Factors such as quantity of water, nutrients, and light abundant in riparian ecosystems of mediterranean climate regions are thought to increase the competitive ability of giant reed. Recent field studies conducted in rivers of mediterranean Southern California indicate that giant reed grows in soils and groundwater with higher nutrient levels than in which native riparian plants are found. However, there is little scientific evidence to fully explain the cause of giant reed invasion in riparian ecosystems of mediterranean climates.
Without knowledge of all factors influencing giant reed invasion, solutions to this problem may not be fully addressed. The aim of the current study is to investigate several factors thought to contribute most to the giant reed invasion process using a more-controlled experimental approach. Between November 2002 and June 2003, a field experiment was established on a riparian terrace located on the south bank of the Santa Clara River in Ventura County, California. The experiment is designed to measure the effects of various nutrient, water, and light treatments on establishment, growth and competition of giant reed with three other dominant native riparian species.
Preliminary data collected in 2003 suggests that giant reed outcompetes several native species under several specific environmental conditions tested. In addition, over 98 percent of the cuttings planted in the experiment survived the first year and have become well established. The proposed research will be conducted at the established field experiment during the second and final growing season (May – October 2004). Data collection during this period is essential to the success of the experiment, since only limited data was collected during the first year when the plants were not yet fully mature.
INFLUENCE OF FLOATING MACROPHYTES ON THE PHYTOPLANKTON COMMUNITY IN A WETLAND FROM THE LOW PARANÁ FLOODPLAIN (OTAMENDI NATIONAL RESERVE, ARGENTINA): AN EXPERIMENTAL APPROACH
Investigator: Paula de Tezanos Pinto
University of Buenos Aires
I will carry out an experimental study in the main shallow lake of the Natural Ecological Reserve of Otamendi (Buenos Aires, Argentina) at mesocosms scale. This natural wetland presents extense areas with stressed environmental conditions characterized by extreme low light intensities and anoxia due to abundant floating macrophytes and high reductive conditions respectively. In an area densely covered with floating macrophytes, I will address the species composition and emergent characteristics of the phytoplankton functional groups in response to light attenuation produced by floating macrophytes.
The experiment will consist of three treatments, being each treatment carried out by triplicate: T1: dense intact macrophyte cover, corresponding to the natural system; T2: removal of floating vegetation and addition of a dark mesh to assess the light attenuation (abiotic effect) produced by floating macrophytes; T3: removal of vegetation cover to study the effects of light limitation (abiotic effect) as well as the biological effects produced by floating macrophytes. The experience will last approximately 20 days, starting with the removal of the macrophyte cover and the installation of the mesh when corresponding.
In each sampling date and in each experimental unit, water samples will be collected in order to analyse the influence of light penetration on changes in phytoplankton functional groups, species composition, nutrition and mobility strategies. Several physical and chemical variables such as underwater irradiance, pH, dissolved oxygen, temperature and conductivity will be measured in situ and phytoplanktonic chlorophyll a, nutrients, suspended solids and humic acids will be determined in laboratory. In order to assess possible enclosure effects on the treatments, water surrounding the enclosures will be analysed with the same periodicity for all studied variables. The results to be obtained will contribute to further develop the phytoplankton functional groups classification sensu Reynolds and to examine processes at small scale that could be extrapolated to the whole system.
FOOD-CHAIN LENGTH AND THE RELATIVE IMPORTANCE OF CARBON SOURCES IN NATURAL AND MODIFIED AQUATIC HABITATS OF THE UPPER PARANA RIVER BASIN, BRAZIL
Investigator: David Hoeinghaus
Texas A&M University
A significant portion of the world’s total wetland area is comprised by tropical floodplains. Neotropical floodplain systems are some of the most biologically diverse habitats on the planet. Predictable seasonal flood-pulses are essential to the life-history strategies of many terrestrial and aquatic species occurring in these systems. Modification of the natural hydrologic regime in these systems by damming eliminates or decreases the extent of seasonal flooding, and results in longitudinally and laterally disconnected systems. Common effects of damming include: lower floodplain productivity, slower nutrient cycling, decreased inputs of detritus to aquatic habitats, lower recruitment of fisheries stocks, and blockage of fish migration routes.
The increasing rate of dam construction on tropical floodplain rivers necessitates improved understanding of anthropogenic impacts on these systems. I will use the stable isotopes of carbon and nitrogen to address what effects dam construction has on trophic structure (i.e. food-chain length, and primary carbon sources) of aquatic communities of tropical floodplain river systems. This study will be conducted at a large spatial scale, including the last natural stretch of the Paraná River. Comparative food web studies of diverse tropical ecosystems are rare, and the proposed study will describe essential features of ecosystem structure and potential impacts of hydrological modifications.
My research will be an important contribution to on-going work by Brazilian ecologists studying floodplain communities and ecosystem dynamics of the upper Paraná River basin, and should describe essential features of ecosystem structure and potential impacts of hydrological modifications useful to floodplain ecology in general. This research will be conducted in collaboration with Brazilian ecologists, and will foster continued collaboration. Results of this study will be applicable to natural resource managers, conservation professionals and policy makers, and will promote educated decision making by these individuals.
DECOMPOSITION DYNAMICS IN RIPARIAN DEPRESSION AND SLOPE WETLANDS OF CENTRAL PENNSYLVANIA: ARE THERE FUNCTIONAL DIFFERENCES?
Investigator: Zaneta Hough
Pennsylvania State University
A significant portion of the world’s total wetland area is comprised by tropical floodplains. Neotropical floodplain systems are some of the most biologically diverse habitats on the planet. Predictable seasonal flood-pulses are essential to the life-history strategies of many terrestrial and aquatic species occurring in these systems. Modification of the natural hydrologic regime in these systems by damming eliminates or decreases the extent of seasonal flooding, and results in longitudinally and laterally disconnected systems. Common effects of damming include: lower floodplain productivity, slower nutrient cycling, decreased inputs of detritus to aquatic habitats, lower recruitment of fisheries stocks, and blockage of fish migration routes.
The increasing rate of dam construction on tropical floodplain rivers necessitates improved understanding of anthropogenic impacts on these systems. I will use the stable isotopes of carbon and nitrogen to address what effects dam construction has on trophic structure (i.e. food-chain length, and primary carbon sources) of aquatic communities of tropical floodplain river systems. This study will be conducted at a large spatial scale, including the last natural stretch of the Paraná River. Comparative food web studies of diverse tropical ecosystems are rare, and the proposed study will describe essential features of ecosystem structure and potential impacts of hydrological modifications.
My research will be an important contribution to on-going work by Brazilian ecologists studying floodplain communities and ecosystem dynamics of the upper Paraná River basin, and should describe essential features of ecosystem structure and potential impacts of hydrological modifications useful to floodplain ecology in general. This research will be conducted in collaboration with Brazilian ecologists, and will foster continued collaboration. Results of this study will be applicable to natural resource managers, conservation professionals and policy makers, and will promote educated decision making by these individuals.
THE EFFECTS OF VARIOUS PRE-PLANTING TREATMENT METHODS ON THE ESTABLISHMENT SUCCESS OF NATIVE TREES AND SHRUBS IN A REED CANARY GRASS (Phalaris arundinacea) MONOCULTURE
Investigator: Stephen M. Hovick
University of Wisconsin, Milwaukee
Nonnative invasive species are extremely detrimental to restoration efforts, especially when the invaders limit safe site availability for the establishment of native vegetation. In some ecosystems grasses in particular have been shown to limit the invasion of woody species, partially due to these safe site limitations. One of the most problematic grasses that can limit the establishment of forested wetlands in the northern United States is reed canary grass (Phalaris arundinacea).
However, if safe sites could be established in Phalaris monocultures it is theoretically possible for those trees and shrubs, once established, to outcompete the Phalaris through shade – one of the few environmental conditions under which Phalaris does not thrive. The initial step in such a long-term goal must be to determine best pre-planting Phalaris treatment methods to ensure high survival of the woody species. This research tests twenty-two tree and shrub species in various treatments to determine which treatments and which species are most successful for establishment in Phalaris monocultures.
The primary questions addressed by this research are the following: 1) how does the survival of eleven tree and eleven shrub species compare when planted in a reed canary grass monoculture following various pre-planting treatments, 2) which treatments lead to the highest survival and establishment success of the woody species, and 3) what are the relative labor costs per acre for the various methods tested. If successful, in the long-term this research will have two major implications for wetland restoration. First is the development of a novel method for establishing swamp forests, a group of communities that have remained largely unstudied in the recent flood of wetland restoration literature. Second is the development of a novel and practical method for controlling reed canary grass, a species whose numerous negative community and ecosystem effects and difficulty of treatment make its control highly valuable.
ZONATION OF BENTHIC COMMUNITIES IN A TROPICAL MANGROVE FOREST AT GAZI BAY ON THE SOUTHERN COAST OF KENYA
Investigator: Masinde K. Kizito
Egerton University
The widespread loss of wetland habitats throughout the world has played a major role in the disappearance of many species both on a local and regional scale. In contrast to the obvious direct effects of wetland habitat loss we know relatively little about how bethic macroinvertebrate community composition of a particular wetland may respond to less dramatic disturbance.
The purpose of this study is to make an inventory and map the sea-land distribution of benthic macroinvertebrate communities in three mangrove sites in Gazi Bay at the Kenyan coast. Gazi Bay is a shallow, tropical coastal water system situated on the southern coast of Kenya. The bay is sheltered from strong waves by the presence of the Chale peninsula to the east and a fringing coral reef to the south.
Due to anthropogenic impacts, the bay has three distinct sections: a very disturbed, a replanted and a relatively natural site. In these sites, samples will be collected from a randomly selected transect in each site, running from the lowest to the highest tide mark. The upper sediments will be scooped then macroinvertebrates sorted from them in the laboratory and preserved in ethanol for identification. On each sample occasion, the temperature, pH, oxygen level and conductivity will be measured. Diversity will be calculated using the Shannon-Weiner diversity index while differences in species diversity and abundance between the sites and between the dry and wet seasons will be statistically tested using the Mann-Whitney U-test.
The results of the study will indicate the species composition, relative abundance, dominance and species associations in relation to seasonal and physical changes in the mangrove forest. The information from the study will provide a better understanding of the likely ecological consequences to benthic macroinvertebrates when mangrove ecosystems are modified. In addition, the habitat maps and inventories developed will provide managers with benchmarks against which to detect and monitor human impacts in mangrove forests.
LANDSCAPE GENETICS OF THE BOREAL TOAD (Bufo boreas boreas) AND THE CHORUS FROG (Pseudacris triseriata) POPULATIONS IN YELLOWSTONE NATIONAL PARK
Investigator: Melanie A. Murphy
Washington State University
Amphibians are sensitive species and thus good indicators of wetland health. Therefore, understanding restrictions in amphibian breeding locations and movement between those sites can demonstrate the importance of functioning wetland systems to amphibian persistence. Demographic studies can be used to address population movement but often require long-term studies or large sample sizes for significant results and are influenced by the frequent large fluctuations in amphibian population size. However, genetic fingerprinting techniques can be used to estimate migration between breeding populations (Berry et al. 2004) and identify dispersal limitations.
The objective of this study is to identify ecological and anthropogenic landscape features influencing gene flow in two amphibian species within Yellowstone National Park, boreal toads (Bufo boreas boreas) and chorus frogs (Pseudacris triseriata). Breeding locations for each species will be identified and selected sites will be visited in 2004 and 2005. Individuals will be sampled by mouth swabbing without prior identification of populations and will be subjected to DNA fingerprinting.
Genetic analysis software (STRUCTURE) will be used to group individuals into populations based on genetic similarity. Membership probabilities from STRUCTURE will be used to create a genetic surface in a Geographic Information System (GIS). High points in the genetic surface will indicate areas of high gene flow (lots of movement) and low points will indicate areas of restricted gene flow (little movement). Spatial analysis will be used to correlate ecological and anthropogenic features with the genetic surface.
Once landscape features limiting amphibian populations such as wetland alteration identified, they can be incorporated into wetland conservation and management. In addition, the methods developed will provide the foundation for using genetic and landscape data to build empirical relationships between ecological factors (e.g. hydrological gradients), anthropogenic factors (e.g. wetland modification), and gene flow in any species.
AN INVESTIGATION OF WATER SOLUBLE CARBON QUALITY AND QUANTITY AS CONTROLLERS OF DENITRIFICATION AND ITS END PRODUCTS
Investigator: Steven Schaff
University of Georgia
Denitrification returns mineralized nitrogen (primarily nitrate) to the atmosphere (as dinitrogen gas (N2) or nitrous oxide (N2O)) and is a primary pathway in the ecological cycling of nitrogen. Nitrate and oxygen concentrations, soil pH, and organic matter content have all been suggested as controllers of both denitrification rate and the relative composition of its end products (N2 and N2O).
Most research has been conducted with the expectation of ample available soil carbon for the conversion of nitrate; however, this assumption may not always be met. For example, riparian forests are hotbed of denitrification activity and buffer aquatic systems from nitrogen fluxes from adjacent agricultural lands. Concerns over water quality have led to proposed large scale forest restoration to remediate nitrogen loading to waterways. Restored sites, especially previously cultivated lands, will likely have low soil carbon. Carbon availability will be dictated by both the species selected for the restoration plan and prescribed stocking rates.
This research will evaluate differences in water soluble carbon (WSC) quantity and quality as controllers of denitrification rate and subsequent gas composition. Mesocosms planted in 2002 with Salix nigra, Quercus lyrata, an equal combination of both species, or an unplanted control, will be leached of their available WSC for 24 hours. In the laboratory, an incubation experiment will be conducted using the leachate as the only metabolic carbon source for denitrification. This research will allow me to identify the kinetic relationship between WSC and denitrification, and provide kinetic parameters such as maximum denitrification rate and the half saturation constant to compare differences due to carbon quality.
I also plan to compare the effects of WSC quality and quantity on the C and N content of denitrifying bacteria and as a means to explore tree species differences in driving denitrification. Finally, I will explore WSC as a controller of gas emissions to determine if manipulating tree species limits N2O release. This research will provide needed information about the relationship between WSC and denitrification rate and the relative composition of its end products, and provide guidance in species selection and stocking rates for restoring riparian forests as nitrogen filters.
CALIFORNIA TIDAL MARSH VEGETATION CHANGE: A 30-YEAR RECORD OF CHANGES IN PLANT DISTRIBUTION AND ABUNDANCE IN TIDAL MARSHES OF THE SAN FRANCISCO ESTUARY
Investigator: Elizabeth Watson
University of California, Berkeley
San Francisco Estuary tidal marshes are unique along the Pacific Coast of North America in extent, in plant species assemblages, and in the attention now being given to policy and restoration. Resurvey of vegetation transects in six San Francisco Estuary tidal marshes will provide a record of how tidal marsh plant community structure has evolved with thirty years of environmental change in freshwater flow and sea level rise in the San Francisco Estuary. Topography, plant distribution, pore water salinity and soil organic matter will be assessed along historically surveyed transects in six intact tidal marsh ecosystems. We intend this study not only to provide a measure of how tidal marshes have responded to anthropogenic change, but also to inform policy decisions regarding marsh restoration, sea level rise, and water diversion from the Sacramento-San Joaquin Delta.
