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Soil Carbon and Nitrogen Changes in Forests of Walker Branch Watershed, 1972 to 2004
Author(s) -
Johnson D. W.,
Todd D. E.,
Trettin C. F.,
Sedinger J. S.
Publication year - 2007
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/sssaj2006.0365
Subject(s) - watershed , environmental science , soil water , hydrology (agriculture) , leaching (pedology) , vegetation (pathology) , plant litter , litter , soil test , soil science , ecosystem , ecology , geology , biology , medicine , geotechnical engineering , pathology , machine learning , computer science
Changes in soil C and N concentrations and contents in four samplings during a 32‐yr period on Walker Branch watershed in Tennessee were determined and compared with previously measured C and N fluxes and with changes in ecosystem C and N pools during this period. Soils showed significant increases in C and N concentrations in surface horizons from 1972 to 2004, and most of this increase occurred between 1972 and 1982. A previously observed decline in soil C and N contents between 1982 and 1993 was reversed in 2004 such that the latter increased to near 1982 values. The changes in soil C content could be approximately accounted for by previously measured litterfall and soil CO 2 –C fluxes. Changes in soil N could not be accounted for by leaching, increments in vegetation, or by laboratory bias, changes during sample storage, or reasonable estimates of field sampling errors. We conclude that, although vegetation C and N pools increased steadily during the sampling period in most cases, changes in soil C and N pools on Walker Branch watershed are highly variable in both space and time, and there has been no unidirectional trend during the time period of this study.