Projects

Category	Plant Sciences
Project	43-07 - Nutrient deposition at oak canopies: potential consequences for plant community dynamics and ecosystem processes
Project Leader	Cadenasso
Affiliation	UC Davis Dept. Plant Sciences
Objective	Atmospheric nitrogen (N) deposition has become a pollutant of concern in ecosystems worldwide. In California oak savannas, the difference between N deposition at the oak canopy compared to the surrounding open grassland may be significant and lead to system-wide changes in community structure and dynamics. This study also addresses the impacts of N deposition in adjacent rangelands due to urbanization. The global hypothesis of this study is: Enhanced N deposition occurs heterogeneously within a landscape at multiple scales and is altering species interactions and ecosystem functioning. Specific objectives of the proposed research are to 1) verify that oak canopies receive greater N deposition than the surrounding open grassland, 2) examine the impacts of enhanced N deposition on community dynamics and ecosystem processes, and 3) determine the effect of enhanced N deposition at oak canopies on the spatial patterns of exotic and native species dynamics in California oak savannas. Study sites will be located along a regional N deposition gradient. At each site, the effect of the oak canopy on N interception and deposition will be determined using atmospheric deposition data. Plant community structure and composition and plant and soil nutrient concentrations under various N deposition levels will be compared. A field experiment will be performed to determine the effect of N fertilization on species performance with regard to the form of N and other potentially limiting factors. The proposed research addresses fundamental questions of pollution effects and invasion biology in heterogeneous landscapes and as such, has implications for rangeland management.