Effects of climate, site and soil characteristics on critical loads and exceedance in forests in the northeastern U.S.

Linda Pardo1, Jason A. Coombs2, Molly Robin-Abbott3, Jennifer Pontius4 and Claire B. O’Dea5

Assessing the impacts of the multiple threats impacting ecosystem health and sustainability over the long term, in particular climate change and nitrogen (N) deposition, remains a critical challenge for resources managers and policy makers. To facilitate such assessments, we developed a GIS-based tool, Nitrogen Critical Loads Assessment by Site (N-CLAS), which calculates critical loads and exceedances for N deposition to forests in the northeastern US. It provides high resolution outputs (maps, graphs, and tables) for multiple areas and accounts for the influence of site, climate, and topographic conditions on 23 key tree species in the region. N-CLAS evaluates the impact of multiple stressors (N deposition and climate change) simultaneously for species of management concern on forest lands in the Northeast and Upper Midwest. In addition to calculating species-specific critical loads, N-CLAS is designed to take into account the impact of site abiotic factors on the response of trees to N deposition.  The abiotic modifying factors include, precipitation, temperature (e.g., January T, July T, May-September T), and soil characteristics. This tool is designed N-CLAS facilitates assessment of risk to forest ecosystems for resource managers and policy makers.

In this hands-on demo session, we will demonstrate how to use the tool, the types of outputs it produces, and the ways that it can be utilized to assess extent and magnitude of risk to forest ecosystems and to evaluate the susceptibility of individual tree species.


1USDA Forest Service, lpardo@fs.fed.us
2USDA Forest Service, jcoombs@cns.umass.edu
3USDA Forest Service, mjrobina@gmail.com
4UVM/USDA Forest Service, japontiu@uvm.edu
5USDA Forest Service, cbodea@fs.fed.us