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Processes affecting the response of sulfate concentrations to clearcutting in a northern hardwood forest, Catskill Mountains, New York, U.S.A.

Biogeochemistry

By:
, ,
DOI: 10.1023/B:BIOG.0000031034.48927.1e

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Abstract

The effects of disturbance on the biogeochemical processes that affect the sulfur (S) cycle in forested ecosystems are important, but have been studied in only a few locations. In this investigation, the mechanisms that caused large decreases in stream SO42- concentrations after clearcutting a small forested catchment in the Catskill Mountains of southeastern New York in 1997 were identified through an examination of pH and SO42- concentrations in soil solutions, bulk deposition of SO42- in throughfall collectors, adsorbed SO 42- concentrations in buried soil bags, and spatial variations in SO42- concentrations in shallow groundwater. The load of SO42- -S in stream water during the first 2 years after clearcutting was about 2 kg ha-1.year-1 less than the background value of 8-10 kg ha-1 year-1. The 10 and 19% decrease in net throughfall flux of SO42- -S during the 2nd and 3rd year after the clearcut, respectively, reflects reduced dry deposition of S after removal of the canopy, but this decrease accounts for 0 and 43%, respectively, of the decrease in SO42- load in streamflow for these 2 years. The pH of B-horizon soil water decreased from 4.5 to 4.0 within 8 months after the clearcut, and SO42- concentrations decreased from 45 ??mol L-1 to less than 20 ??mol L-1 during this time. A strong correlation between SO 42- concentrations and pH values (r2=0.71, p<0.01) in B-horizon soil water during the post-harvest period (1997-1999) reflects increased SO42- adsorption in response to soil acidification. Sulfate concentrations in groundwater from 21 spatially distributed wells were inversely related to a topographic index that served as a surrogate for soil wetness; thus, providing additional evidence that SO 42- adsorption was the dominant cause of the decreased SO42- concentrations in the stream after clearcutting. These results are consistent with those from a 1985 whole-tree harvest at the Hubbard Brook Experimental Forest in New Hampshire in which increased SO 42- adsorption resulting from decreased soil pH was the primary cause of decreased SO42- concentrations in stream water.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Processes affecting the response of sulfate concentrations to clearcutting in a northern hardwood forest, Catskill Mountains, New York, U.S.A.
Series title:
Biogeochemistry
DOI:
10.1023/B:BIOG.0000031034.48927.1e
Volume
68
Issue:
3
Year Published:
2004
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
337
Last page:
354
Number of Pages:
18