1999 Spotlight on Graduate and
Undergraduate Research at ESF
THE FATE OF NITROGEN IN GYPSY MOTH FRASS DEPOSITED TO AN OAK FOREST FLOOR. Lynn M. Christenson.
DENSITY AND SPAWNING OF THE ASIAN CLAM IN THE ROANOKE RIVER, NC. John E. Cooper.
CHARACTERIZATION OF THE LIPID TRANSFER PROTEIN GENE FAMILY IN ARABIDOPSIS THALIANA. Nicole M. Nall and Lawrence B. Smart.
GRADIENT ANALYSIS OF FOREST TREES IN THE ADIRONDACKS. Benjamin D. Rubin and Paul D. Manion.
CHANGES IN LOWER TROPHIC INTERACTIONS IN EASTERN LAKE ERIE DUE TO THE INVASION OF EXOTICS (DREISSENA), REDUCTION OF PHOSPHORUS LOADING, AND SUBSEQUENT OLIGOTROPHICATION. Stacy Vega and Myron Mitchell.
SPATIAL VARIABILITY AND RELATIONSHIP OF SOIL ORGANIC CARBON AND SOIL MOISTURE IN THE LUQUILLO EXPERIMENTAL FOREST, PUERTO RICO. Hongqing Wang, Charles A. S. Hall, Joseph D. Cornell and Myrna H. P. Hall.
EFFECTS OF EASTERN HEMLOCK MORTALITY ON SOIL WATER CHEMISTRY. Thad E. Yorks, Donald J. Leopold, and Dudley J. Raynal.
THE FATE OF NITROGEN IN GYPSY MOTH FRASS DEPOSITED TO AN OAK FOREST FLOOR. Lynn M. Christenson, Faculty of Environmental and Forest Biology, Illick Hall, SUNY College of Environmental Science and Forestry, Syracuse, NY 13210. Myron Mitchell and Gary Lovett (IES, Millbrook, NY.), Advisors
Research investigating the impacts of insect defoliation on nitrogen (N) loss from forest ecosystems has shown elevated NO3- levels in stream water output. These studies have measured the loss of N from the system, but have not shown the pathway of N movement within the system. To trace the movement of N, 15N-labeled gypsy moth frass or 15N-labeled oak leaf litter was added to field trenched plots over a three year period. Nitrogen movement from the frass or litter was measured in the available, mineralizable, microbial and total soil pools. Total plant N and leaching losses were also traced. No significant differences were found between the frass or leaf treatments for total N in any of the pools. Significant differences were found among the treatments in the distribution of the 15N tracer. Forty percent of the 15N added as frass became incorporated in the soils, with less than 1% found in oak seedlings. Almost 80% of 15N added as leaves remained in the undecomposed leaf material after 2 years. These data suggest that N in frass is more readily mineralizable than N in leaf litter and the N added as insect frass may be conserved in the system. However, the N is essentially unavailable to plants and organisms, because it is not in the extractable, microbial, or readily mineralizable pools.
The Asian freshwater clam Corbicula fluminea expanded its range from the west coast of the US in the 1920's to cover nearly all of the western and southern states up to New Jersey by 1986. It was found in the Great Lakes in 1984. Asian clams were first reported in North Carolina in the Catawba River in 1971 and in the Roanoke River in 1978. This study compares the density and spawning of Corbicula from surveys made in 1978 and 1992-93. Clam density was higher at stations with water depths greater than 3m than those station at less than 3m and was higher in the river than in western Albemarle Sound. Juvenile and immature clam density was positively correlated (Pearson = 0.73; P = 0.0002) with percent sand in the sediment but adult density was not. Body condition index was higher at upriver stations and decreased in a downstream direction. Clams in the western sound had the lowest condition indices. Body condition decreased from February through spring and summer, perhaps due to spawning. Spawning occurred primarily in spring and summer with some evidence of spawning in late fall. The majority of spawning occurred at upriver stations. The majority of clams measured in 1978 were less than 10mm (maximum of 24.5mm) indicating a young population. The population had matured at the 1992-93 survey with a majority of clams between 25 and 29mm with a maximum of 39.5mm. Corbicula seems to be well adapted to the conditions of the Roanoke River.
CHARACTERIZATION OF THE LIPID TRANSFER PROTEIN GENE FAMILY IN ARABIDOPSIS THALIANA. Nicole M. Nall and Lawrence B. Smart, Faculty of Environmental Forest Biology, State University of New York College of Environmental Science and Forestry, 6 Illick Hall, Syracuse, NY 13210.
In Arabidopsis thaliana, a multigene family encodes lipid transfer protein (LTP), as is the case in several other species of plants. It has been proposed that LTP participates in the movement of fatty acids to the cuticle layer. To date there are published reports of three genes of the LTP family from Arabidopsis which have been cloned and characterized. We have identified six additional LTP genes in A. thaliana and will present their DNA sequences. The genes were identified by BLAST searches of Arabidopsis expressed sequence tags (EST) and genomic sequences in GenBank using LTP1 and LTP2 as query sequences. Sequences were compared to each other and a classification scheme was devised based on sequence similarity and dissimilarity. Representative EST cDNA clones were obtained from the Arabidopsis Biological Resource Center and the full sequences were determined utilizing automated sequencing. Cross hybridization of the genes was observed upon genomic Southern analysis and banding patterns were compared to previously published work. Our results include the full cDNA sequence of LTP3, which is linked to LTP8, in the sequence of chromosome 5. LTP1 and LTP2 are also linked, but on chromosome 2. Sequence and phylogenetic analysis of the LTP genes from Arabidposis and other plants has revealed subfamilies that may have evolved to serve specific functions during development or in response to stress.
GRADIENT ANALYSIS OF FOREST TREES IN THE ADIRONDACKS. Benjamin D. Rubin and Paul D. Manion, Faculty of Environmental and Forest Biology, 8 Illick Hall, SUNY College of Environmental Science and Forestry, Syracuse, NY 13210.
Environmental gradients that affect a tree do so by modifying its energy profit, or the difference between its gross photosynthesis and gross respiration. Therefore, environmental gradients should explain variation in a measure of species success that is a surrogate for energy profit. Two forest inventories of the Adirondack State Park provide, the importance value (IV) of 12 common tree species on state owned and privately owned land and the radial growth rate of the same species on privately owned land. Patterns of IV and growth rates were analyzed along 6 environmental gradients: air temperature, soil moisture, solar radiation, site productivity, stand age and stand basal area. Air temperature was the best predictor of IV for most species and air temperature, soil moisture, stand age and stand basal area were the best predictors of growth rate. On private land, significant trends were more common for growth rate than IV. Significant patterns of IV were more common on protected state land than on private land. From a third inventory it is also shown that tree diseases have significant negative effects on growth rates. Future work will test the hypotheses that environmental gradients can explain 1) the distribution of forest communities, 2) patterns of diameter distribution within a forest and 3) the distribution of tree diseases.
CHANGES IN LOWER TROPHIC INTERACTIONS IN EASTERN LAKE ERIE DUE TO THE INVASION OF EXOTICS (DREISSENA), REDUCTION OF PHOSPHORUS LOADING, AND SUBSEQUENT OLIGOTROPHICATION. Stacy Vega and Myron Mitchell, Department of Environmental and Forest Biology, 209 Illick Hall, SUNY-College of Environmental Science and Forestry, Syracuse, NY 13210.
Lake Erie is currently undergoing major changes that could have a serious effect on production and trophic relationships. In the mid-1970's, eutrophication was reversed by an international agreement calling for the reduction of phosphorus loading. More recent years have brought the introduction of zebra (Dreissena polymorpha) and quagga mussels (Dreissena bugensis). Both of these events have brought about changes in the trophic interactions. The lower trophic levels of eastern Lake Erie are necessary to sustain the populations of rainbow smelt (Osmerus mordax), the primary food source for predatory sport fish. Any change in primary producers or the organisms they directly support could shift Lake Erie to an ecosystem unable to support higher trophic levels. To investigate the structure of the lower trophic levels, two parameters will be measured. Primary productivity will be measured using a Fee incubator and the 14C uptake method. Energy flow through consumer and predator trophic levels will be determined using analysis of C and N stable isotopes. Elemental and biochemical compositions of animals reflect their diets. Carbon isotope ratios aid in ascertaining the sources of carbon fixed in primary production as well as the flow of energy through limnetic systems. The nitrogen isotope ratio will be used to identify the trophic level of the organisms. Analysis of the primary production, combined with the stable isotope analysis, will indicate changes in the lower trophic structure of Lake Erie, as well as its ability to support predatory game fish and other higher trophic levels.
SPATIAL VARIABILITY AND RELATIONSHIP OF SOIL ORGANIC CARBON AND SOIL MOISTURE IN THE LUQUILLO EXPERIMENTAL FOREST, PUERTO RICO. Hongqing Wang, Charles A. S. Hall, Joseph D. Cornell and Myrna H. P. Hall, Faculty of Environmental and Forest Biology, 301 Illick Hall, SUNY College of Environmental Science and Forestry, Syracuse, NY 13210.
The spatial relationships between soil and topographic properties in the Luquillo Experimental Forest (LEF), Puerto Rico, were quantified using geostatiscal analysis. Soil samples (n = 100) were collected from the LEF and analyzed for soil organic content (SOC), soil moisture (SM), and bulk density (BD). Data on elevation, slope, and aspect were also collected at each site. GPS data was used to locate and georeference sample sites. Isotropic and anisotropic semi-variograms and cross-variograms were calculated for the selected soil and topographic properties using a geostatistical software package (GS+, Gamma Design, Michigan). Kriging, (Block and Punctual) was used to create a continuous GIS coverage of the entire LEF for parameters from the sample data. Spatially structured variance (the variance due to the location of sampling sites)accounted for a large proportion of the sample variance for SM (90%), BD (82%), elevation (96%) and slope (86%). Aspect and SOC were moderately spatial dependent( spatially structured variance 74% and 56%, respectively). The range of spatial dependence (the distance within which parameters are spatially dependent) for SOC, SM, BD, elevation and slope were 3680 m, 660 m, 220 m, 5590 m, and 310 m respectively, while aspect was found to be spatially dependent over the entire LEF. Cross-correlograms showed that there was positive correlation between SOC and elevation, and SOC and SM over separation distances less than 6000 m. The degree to which these parameters were correlated decreased as separation distance increased. Similarities of the ranges of spatial dependence for SOC and elevation suggest that the distribution of SOC in the LEF is determined by a combination of biotic and abiotic gradients related to elevation. However, most of the variation of SOC might be caused by the high spatial heterogeneity of microtopographic features rather than variations in biotic factors, such as differences in litterfall. This indicates the importance of both the rainfall/elevation and the soil moisture/topographic gradients in controlling biogeochemical processes in the LEF.
Our objectives are to determine if, and how long, hemlock mortality causes increased nutrient losses in soil water. We have been monitoring soil water chemistry in four eastern hemlock stands each month since October 1996 using tension lysimeters. Hemlock trees in two of the stands were killed by girdling (i.e. severing bark and cambium around the base of the bole) in July 1997 to simulate mortality due to the hemlock woolly adelgid, an insect currently causing hemlock mortality from North Carolina to Massachusetts. Initial effects of girdling were elevated concentrations of nitrate, ammonium, aluminum, calcium, magnesium, and sodium in soil water in the fall of 1997. These increases in ion concentrations were attributed to fine root mortality and decomposition. Concentrations returned to baseline levels during the winter of 1997-1998 when low temperatures restricted biological transformations and nutrient turnover in soil. Very high leaching losses were observed in the summer, fall, and early winter of 1998, presumably due to the elimination of nutrient uptake by hemlock trees and continued root mortality and decomposition. It is unknown how long these elevated concentrations will last, but the magnitude of 1998 ion concentrations from girdled stands indicates that elevated leaching losses could persist several additional years.
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