Treesearch

Aluminum (Al) has been suggested to be an important stress factor in forest decline due to its mobilization in soil following atmospheric deposition of acidic pollutants. A major goal of our research is to develop physiological and biochemical markers of stress in trees using cell cultures and whole plants. Needles of red spruce (Picea rubens) collected from several sites in the northeastern United States and red spruce cells grown in suspension cultures were examined for polyamine and inorganic-ion content. The cells in culture were exposed to various concentrations of Al for different...

Climate change has the potential to alter detrital processing in headwater streams, which receive the majority of their nutrient input as terrestrial leaf litter. Early placement of experimental leaf packs in streams, one month prior to most abscission, was used as an experimental manipulation to increase stream temperature during leaf pack breakdown. We studied leaf litter processing in three second-order, mid-Appalachian streams along a pH gradient (mean pH = 4.2, 6.5, 7.5). Leaf pack processing rate coefficients (k) were calculated for single species leaf packs of red maple, white oak,...

To investigate the effects of elevated soil temperatures on a forest ecosystem, heating cables were buried at a depth of 5 cm within the forest floor of a northern hardwood forest at the Huntington Wildlife Forest (Adirondack Mountains, New York). Temperature was elevated 2.5, 5.0 and 7.5?C above ambient, during May - September in both 1993 and 1994. Various aspects of forest ecosystem dynamics were studied, including soil solution chemistry (lysimeters at 15 and 50 cm depths), trace gas flux (closed box technique), decomposition of maple and American beech litter, and tree seed germination...

We examined microbial respiration and carbon/nitrogen content of decomposing leaf material in microcosms used for growth studies of the treehole mosquito, Aedes triseriatus. Leaf material originated from birch and oak trees exposed to conditions of shade/sun and elevated/ambient levels of CO2. Microbial respiration as measured by CO2 production was generally greatest on birch leaves grown under shaded conditions, however, ANOVA indicated possible light X CO2 interactions. There were also strong interactions between species of leaf and CO2 levels, but oak leaves grown under elevated CO2...

Application of a variety of two-dimensional interpolation algorithms to precipitation chemistry data gathered at scattered monitoring sites for the purpose of estimating precipitation- born ionic inputs for specific points or regions have failed to produce accurate estimates. The accuracy of these estimates is particularly poor in areas of high topographic relief. Because wet deposition of pollutants is a function of both the ionic concentration of precipitation and precipitation volume and because the local distribution of precipitation can be strongly influenced by terrain, incorporation...

Globally, surface-level concentrations of both CO2 and ozone (O3) are increasing annually. Because many studies have shown beneficial effects of increasing CO2, predictions have been made that elevated levels of CO2 would compensate for growth decreases caused by O3. For the past two years, we have been examining the interaction of O3 and CO2 on trembling aspen (Populus tremuloides) and eastern white pine (Pinus strobus) in open-top chamber studies involving both plants in pots and plants growing in the ground.

Global climate change models predict decreased rainfall in association with elevated CO2 in the western Lakes States region. Currently, the western edge of northern red oak (Quercus rubra L.) distribution coincides with the most xeric conditions of its ecological range. Decreased rainfall and water availability could alter ecological fitness and distribution. To better understand how climate change may affect this species, we are examining the interaction of CO2 (400, 520, 700 ppm CO2) with water stress (well-watered and water-stressed) on growth, and carbon and nitrogen metabolism of...

Understanding the influence of ozone, CO2, and changing climatic regimes on basic plant physiological processes is essential for predicting the response of forest ecosystems. To understand the relationships among these interacting factors, in the face of genetic and other environmental variability, requires a means of synthesis. Physiological process modeling provides one such tool: it allows the integration of diverse information from research, reflects the interactions among variables, and provides a direction for future research.

The objective of this study was to determine the long-term effects of ozone (O3) and carbon dioxide (CO2) on the growth and physiology of eastern white pine (Pinus strobus) and yellow-poplar (Liriodendron tulipifera) under plantation conditions. Two separate plantations of each species were established in Delaware, Ohio, in 1991 and 1992.

Differences in exposure, uptake and relative sensitivity to ozone between seedling, sapling, and canopy black cherry (Prunus serotina Ehrh.) trees were characterized during two growing seasons in north central Pennsylvania. Open-grown trees of all sizes received a similar amount of ozone exposure. Seedlings had greater foliar ozone injury, expressed as adaxial stipple and early leaf senescence, than larger trees, which was correlated with their higher rates of stomatal conductance and greater rates of ozone uptake. The higher stomatal conductance and ozone uptake of seedlings was proportion...