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Management Intensification Impacts on Soil and Ecosystem Carbon Stocks in Subtropical Grasslands
Author(s) -
Adewopo J.B.,
Silveira M.L.,
Xu S.,
Gerber S.,
Sollenberger L.E.,
Martin T.A.
Publication year - 2014
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/sssaj2013.12.0523
Subject(s) - environmental science , rangeland , agronomy , pasture , grassland , biomass (ecology) , ecosystem , agroforestry , carbon sequestration , soil carbon , grazing , soil water , biology , ecology , soil science , carbon dioxide
Proper management of grassland ecosystems for improved pasture productivity can also enhance their potential to serve as sinks for anthropogenic carbon (C). We assessed the long‐term (>22 yr) effects of grassland intensification (conversion of native rangeland to slash pine‐bahiagrass silvopasture or bahiagrass‐sown pasture) on above‐ and belowground C stocks in a subtropical ecoregion. Soil cores (0‐ to 30‐cm depth) were collected from five equidistant quadrats (20 × 20 m) established along a diagonal transect within each of the experimental units. Root and aboveground biomass responses to grassland intensification were also evaluated. Management intensification resulted in increased soil organic C (SOC) stocks from 41 Mg ha ‐1 in the native rangeland to 62 and 69 Mg ha ‐1 in sown pasture and silvopasture, respectively. Additional C storage occurred in the live biomass of slash pine trees in silvopasture (58 Mg ha ‐1 ), while the C accruing to woody biomass in native rangeland (3 Mg ha ‐1 ) was lost after conversion to sown pasture. Conversion to tree‐integrated silvopastoral ecosystem favored the sequestration of a more stable mineral‐associated C fraction (41.8 Mg ha ‐1 ; ∼200% increase) compared with the native rangeland. Ecosystem C was greater in silvopasture (144 Mg ha ‐1 ) and in sown pasture (83 Mg ha ‐1 ) relative to the reference native rangeland (69 Mg ha ‐1 ). This research supports growing evidence that increasing intensity of grassland management is beneficial for soil and ecosystem C sequestration in the long term; however, shifts in the allocation of C into ecosystem pools will likely have implication for biochemical cycling within this subtropical ecoregion.