Grantee Research Project Results

Multiple Stressors Affecting Nitrogen Cycling in Forests: Effects of Forest Harvesting and Atmospheric Deposition on Multiscale Watersheds

EPA Grant Number: MA916289
Title: Multiple Stressors Affecting Nitrogen Cycling in Forests: Effects of Forest Harvesting and Atmospheric Deposition on Multiscale Watersheds
Investigators: Golden, Heather E.
Institution: The State University of New York
EPA Project Officer: Hahn, Intaek
Project Period: January 1, 2004 through December 31, 2006
Project Amount: $81,396
RFA: GRO Fellowships for Graduate Environmental Study (2004) RFA Text | Recipients Lists
Research Category: Biology/Life Sciences , Fellowship - Natural and Life Sciences , Academic Fellowships

Objective:

The objective of this research is to measure: (1) the effects of forest harvesting on nitrogen (N) sinks and interwatershed transfers of N stored in harvested woody biomass within watersheds covering a range of areas; and (2) the effects of plot-scale harvests and atmospheric N deposition on soil C:N ratio recovery across a forest harvest chronosequence.

Approach:

Objective 1 will be tested using the U.S. Department of Agriculture Forest Service Forest Inventory Analysis (FIA) data and data on wood harvest export, import, and consumption through time within each of the 17 major watersheds of New York. Two sinks of N in harvested woody biomass will be calculated using an ArcGIS-based model. The net change of N in standing stock (live wood) will be calculated for each watershed as:

Net change of N in standing stock = N in net growth – N in harvest.

The net N exported in harvested wood will be estimated by:

Net N harvest export = N in harvested wood + N in imported wood – N in wood consumed within watershed – N in logging debris.

Objective 2 will be tested by measuring aboveground and shallow subsurface C, N, and organic matter pools across a forest harvesting chronosequence. A harvesting chronosequence will be used to evaluate recovery of soil C:N through several decades. In addition to C:N ratio recovery, testable variables include nitrification potential, onsite tree species, soil mass, bulk density, and soil moisture at each sampling location.

Losses of N in harvested wood should be highest in forested watersheds with stands averaging 80-120 years. Because of the increased availability of N in systems with extreme atmospheric N deposition, N assimilation in woody biomass should be higher in these watersheds. C:N ratio recovery should occur within one decade as a result of the system’s high N status. Because C:N ratios typically recover (increase) through time, rates of potential soil nitrification should decrease (an inverse correlation).

Supplemental Keywords:

fellowship, forested ecosystems, forest harvest, nitrogen cycling, regional watersheds, soil C:N ratios, harvesting chronosequence,, RFA, Scientific Discipline, Water, Forestry, Watersheds, Water & Watershed, Ecology and Ecosystems, Environmental Monitoring, multiple stressors, forest decomposition, watershed assessment, nitrogen inputs, ecosystem stress, nitrogen loading, anthropogenic processes, atmospheric processes

Relevant Websites:

2004 STAR Graduate Fellowship Conference Poster (PDF, 1p., 637KB, about PDF)

Progress and Final Reports:

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.