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Soil Carbon Dynamics Following Reforestation of Tropical Pastures
Author(s) -
Cook Rachel L.,
Stape Jose Luiz,
Binkley Dan
Publication year - 2013
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/sssaj2012.0439
Subject(s) - reforestation , pasture , soil water , environmental science , agronomy , soil carbon , carbon fibers , tropics , forestry , agroforestry , soil science , ecology , biology , geography , mathematics , algorithm , composite number
Soil carbon changes following reforestation of tropical pasture soils have been variable and the mechanisms poorly understood. This limits predictive capabilities and therefore management decisions. Photosynthetic pathways of C4 grasses and C3 trees create unique stable carbon isotopic signatures that can be used to determine soil carbon dynamics. In this study, mineral soils were sampled to 45 cm from paired land cover types consisting of an unmanaged forest and pasture, pastures paired with broadleaf plantations, and broadleaf paired with conifer plantations. Soil δ 13 C values were determined from pastures (SOC 4 ) and forests (SOC 3 ), allowing the calculation of turnover time of SOC 4 following reforestation. Reforested pasture soils became dominated by SOC 3 in 10 years at 0 to 15 cm and in 8 yr at 15 to 30 cm, but remained dominated by SOC 3 from original forest cover from 30 to 45 cm. From 0 to 15 cm, the rate of SOC 3 accumulation (0.21 Mg C ha ‐1 yr ‐1 ) matched the rate of SOC 4 disappearance (‐0.21 Mg C ha ‐1 yr ‐1 ). Soil carbon decreased slightly in the 15‐ to 30‐cm (‐0.17 Mg C ha ‐1 yr ‐1 ) and 30‐ to 45‐cm (‐0.08 Mg C ha ‐1 yr ‐1 ) soil layers from a loss of SOC 4 and no gain of SOC 3 . Overall, reforestation led to relatively small net losses of mineral soil C (‐0.20 Mg C ha ‐1 yr ‐1 , 0–45 cm). Turnover time for SOC 4 increased with depth from 30 to 73 yr. The results from this analysis contribute to a better understanding of soil carbon dynamics following reforestation of tropical pastures.