PROCEEDINGS: Index of Abstracts

SOIL RESPIRATION AND NET N MINERALIZATION ALONG A CLIMATE GRADIENT IN MAINE

Jeffrey A. Simmons, Ivan J. Fernandez, and Russell D. Briggs

Department of Applied Ecology and Environmental Sciences, University of Maine, Orono, ME 04469-5722.

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 (r²) 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 net N mineralization within climate zones, but additional environmental factors become important at a larger landscape scale. The slope of the relationship between respiration and temperature was significantly greater in the Northern and Central regions than in the Southern and Coastal regions, suggesting that soil biota are more sensitive to temperature in the former. Soil moisture was a poor predictor, probably because moisture is infrequently and transiently limiting in these forests.