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Forest Management Effects on Surface Soil Carbon and Nitrogen
Author(s) -
Knoepp Jennifer D.,
Swank Wayne T.
Publication year - 1997
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1997.03615995006100030031x
Subject(s) - environmental science , soil water , watershed , productivity , forestry , forest management , soil carbon , agronomy , agroforestry , hardwood , hydrology (agriculture) , geography , ecology , soil science , biology , geology , geotechnical engineering , machine learning , computer science , economics , macroeconomics
Changes in surface soil C and N can result from forest management practices and may provide an index of impacts on long‐term site productivity. Soil C and N were measured over time for five watersheds in the southern Appalachians: two aggrading hardwood forests, one south‐ and one north‐facing, undisturbed since the 1920s; a white pine ( Pinus strobus L.) plantation planted in 1956; and two regenerating hardwood forests, a whole‐tree harvest in 1980, and a commercial sawlog harvest in 1977. Soils on harvested watersheds were sampled before and for ≈15 yr after harvest. Surface soil C concentration on the undisturbed watersheds varied significantly among sample years. Concentrations fluctuated on the south‐facing and decreased on the north‐facing watershed. The pattern for total N was similar. Total N decreased significantly on the north‐facing but was stable on the south‐facing watershed. In the white pine plantation, C increased while N concentrations decreased during the 20‐yr period. Soil C and N concentrations generally declined the first year following whole‐tree harvest. Fourteen years after cutting, C remained stable, while N was greater compared with reference watershed soils. The commercial sawlog harvest resulted in large increases in surface soil C and N concentrations immediately after cutting. Carbon levels remained elevated 17 yr following cutting. Our data suggest that the forest management practices examined do not result in long‐term decreases in soil C and N. However, the high interannual variation on all watersheds suggests that care must be taken in selecting control sites to determine long‐term treatment impacts.