Recommendations on Tree CLs: 2024 Fall NADP Meeting

Atmospheric deposition of nitrogen (N) and sulfur (S) continue to impact natural ecosystems, including individual tree species.  Over the past few years, researchers have developed several different approaches for estimating thresholds of impacts - termed critical loads - using a variety of techniques.  This presentation gives an overview of the literature in this area and provides recommendations for the Critical Loads of Atmospheric Deposition (CLAD) working group under the National Atmospheric Deposition Program (NADP). CLAD is the coordinating body that hosts the National Critical Loads Database (NCLD), and this presentation is intended to inform discussions of which critical loads to recommend for decision support versus for research purposes. 

Impact/Purpose

The purpose of this presentation is to provide recommendations to the Critical Loads of Atmospheric Deposition (CLAD) working group under the National Atmospheric Deposition Program (NADP).  Over the past few years researchers have developed several ways to estimate thresholds - termed critical loads - above which there are negative impacts to tree species.  This presentation provides an overview of that research, finding that the critical loads from different methods are all robust, but that those based on maximum likelihood are likely more robust for decision making purposes.  This presentation will provide the starting point for CLAD discussions, which will end with a decision on which critical loads to recommend as "decision-ready" in the National Critical Loads Database.  This CLAD recommendation will be helpful for various air quality and natural resource decision makers across the U.S., in the EPA, US Forest Service, and the National Park Service. 

Citation

Clark, C. AND J. Coughlin. Recommendations on Tree CLs: 2024 Fall NADP Meeting. National Atmospheric Deposition Program Fall Meeting 2024, Duluth, MN, November 04 - 08, 2024.