Treesearch

Available methods for analyzing migration of forest species are evaluated, including simulation models, remeasured plots, resurveys, pollen/vegetation analysis, and age/distance trends. Simulation models have provided some of the most drastic estimates of species changes due to predicted changes in global climate. However, these models require additional testing against field data to ensure their reliability. Remeasured plots would provide a basis for model testing, but the number of plots required to detect short term trends might be excessive. Remeasurement data from forested areas where...

Our objective was to determine the influence of temperature and moisture on soil respiration and net N mineralization in northeastern forests. The study consisted of sixteen deciduous stands located along a regional climate gradient within Maine. A significant portion of the variance in net N mineralization (41 percent) and respiration (33 percent) was predicted by temperature. The fraction of explained variance (r?) was much higher when data were partitioned by region or by individual sites (as high as 80 percent). This suggests that temperature is a strong predictor of respiration and...

Forest soil acidification has been reported to result in reduced forest productivity and forest decline. Soil acidification and forest decline may trigger changes in nutrient cycling in forest ecosystems with important consequences for drainage water chemistry and aquatic biota.

The effect of global warming on north temperate and boreal forest soils has been the subject of much recent debate. These soils serve as major reservoirs for C, N, and other nutrients necessary for forest growth and productivity. Given the uncertainties in estimates of organic matter turnover rates and storage, it is unclear whether these soils will serve as short or longer-term net sources or sinks for C and N if mean air and soil temperatures increase over time.

We tested the hypothesis that growth, survival, and reproductive capacity of treehole mosquitoes can be affected by alterations of forest sunlight and CO2 levels. Larval Aedes triseriatus were fed naturally senesced , abscised foliage from red oak (Quercus rubra) and paper birch (Betula papyrifera) seedlings grown in ambient and elevated CO2 atmospheres. Oak seedlings were grown in full sunlight. Birch were grown in full sun and partial shade. Females fed birch leaves grown in elevated CO2 were larger than those fed birch grown in ambient CO2. However, fewer females emerged from microcosms...

Preliminary results are presented from a case study designed to evaluate the potential for cation depletion in low-elevation forest soils of northern New England and New York.

Litter temperature and moisture may be altered due to changes in global climate. We investigated the effect of small changes in litter temperature and moisture on forest-floor communities in West Virginia.

The Howland Integrated Forest Study (HIFS) was developed in a low elevation, commercial spruce-fir forest in east-central Maine, USA at approximately 60 m elevation on level topography.

A nitric acid gas analysis system was designed, tested, and calibrated to measure nitric acid deposition to forest tree species.

The Michigan gradient study was established in 1987 to examine the effects of climate and atmospheric deposition on forest productivity and ecosystem processes in the Great Lakes region. Four intensively-monitored northern hardwood study sites are located along a climatic and pollutant gradient extending from southern lower Michigan to northwestern upper Michigan. The project continues today, with the following overall objectives: (1) to continue measuring key ecosystem variables at four sites; (2) to understand how carbon allocation, nutrient cycling, and forest productivity respond to...