Assessing risk to forest ecosystems from nitrogen and sulfur deposition across the continental US
Linda Pardo1, Kevin J. Horn2, Christopher M. Clark3, R. Quinn Thomas4, Robert Sabo5, Jeremy Ash6, Michael D. Bell7, Justin Coughlin8 and Jennifer James9
The consequences of atmospheric nitrogen and sulfur deposition continue to affect the growth and survival of trees in forest ecosystems across the US. We found that the majority of the 94 tree species we evaluated had detrimental responses to N and or S deposition. Based on analysis of US Forest Service Forest Inventory and Analysis (FIA) data and US-EPA CMAQ model deposition estimates, we set critical loads for N and S deposition for 73 tree species in the conterminous United States. Growth and survival estimates were made from repeated measurements of more than 1.4 million individual trees measured between 2000 and 2016.
We examine tree CLs and exceedances for example ecosystem types in the eastern and western US to demonstrate how resource managers could use this information to assess likely impacts from atmospheric N and S deposition under various management scenarios.
1USDA Forest Service, lpardo@fs.fed.us
2Forest Resources and Environmental Conservation, Virginia Tech, Blacksburg, VA,, 3horns@gmail.com
3National Center for Environmental Assessment, US Environmental Protection Agency, Washington, DC, Clark.Christopher@epa.gov
4Forest Resources and Environmental Conservation, Virginia Tech, Blacksburg, VA,, rqthomas@vt.edu
5National Center for Environmental Assessment, US Environmental Protection Agency, Washington, DC, Sabo.Robert@epa.gov
6USDA Forest Service, jash@fs.fed.us
7Nation Park Service, michael_d_bell@nps.gov
8National Center for Environmental Assessment, US Environmental Protection Agency, Washington, DC, michael_d_bell@nps.gov
9National Center for Environmental Assessment, US Environmental Protection Agency, Washington, DC, michael_d_bell@nps.gov