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CLIMATE CONTROLS ON FOREST SOIL C ISOTOPE RATIOS IN THE SOUTHERN APPALACHIAN MOUNTAINS
Author(s) -
Garten C. T.,
Cooper L. W.,
Post W. M.,
Hanson P. J.
Publication year - 2000
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.1890/0012-9658(2000)081[1108:ccofsc]2.0.co;2
Subject(s) - environmental science , soil carbon , temperate forest , litter , soil organic matter , temperate rainforest , forest ecology , ecology , plant litter , soil water , ecosystem , soil science , biology
A large portion of terrestrial carbon (C) resides in soil organic carbon (SOC). The dynamics of this large reservoir depend on many factors, including climate. Measurements of 13 C: 12 C ratios, C concentrations, and C:N ratios at six forest sites in the Southern Appalachian Mountains (USA) were used to explore several hypotheses concerning the relative importance of factors that control soil organic matter (SOM) decomposition and SOC turnover. Mean δ 13 C values increased with soil depth and decreasing C concentrations along a continuum from fresh litter inputs to more decomposed soil constituents. Data from the six forest sites, in combination with data from a literature review, indicate that the extent of change in δ 13 C values from forest litter inputs to mineral soil (∼20 cm deep) is significantly associated with mean annual temperature. The findings support a conceptual model of vertical changes in forest soil δ 13 C values, C concentrations, and C:N ratios that are interrelated through climate controls on decomposition. We hypothesize that, if other environmental factors (like soil moisture) are not limiting, then temperature and litter quality indirectly control the extent of isotopic fractionation during SOM decomposition in temperate forest ecosystems.