Soil Carbon Change through 2 m during Forest Succession Alongside a 30-Year Agroecosystem Experiment
Abstract:Forest succession (FS) and no-till (NT) agriculture are generally assumed to have a beneficial effect on surficial soil organic C (SOC) stocks compared with conventional tillage (CT) management; however, land use effects to depths >30 cm remain uncertain. In this research we compared SOC contents and composition to 2 m under CT, NT, and FS at the 30-year Horseshoe Bend agroecosystem experiment in Athens, Georgia, USA. Soils from 0 to 2 m were fractionated into particulate organic C (POC) (53‐2000 m) and fine C (<53 m) fractions, and bulk soil 13C signatures were determined. Soils from 0 to 28 cm were dry- and wet-sieved to estimate aggregate stability. Soil solutions were also collected at 0, 15, and 100 cm for dissolved organic C (DOC) analysis. Full-profile (0‐2 m) SOC storage is 52 Mg ha−1 in CT, 60 Mg ha−1 in NT, and 62 Mg ha−1 in FS. Significant differences are limited to 0‐5 cm and are linked to enhanced aggregate stability under NT and FS. Increases in subsoil POC under FS and changes in soil 13C and C/N ratio indicate that substantial subsoil C cycling has occurred. DOC fluxes at 0 cm were significantly greater under NT (200 kg ha−1 year−1) and FS (210 kg ha−1 year−1) than under CT (80 kg ha−1 year−1). DOC fluxes at 15 cm are estimated to be 20 kg ha−1 year−1 under CT and NT and 40 kg ha−1 year−1 under FS. At 100 cm, DOC fluxes are 2 kg ha−1 year−1, regardless of land use. An increase in FS POC of 2 Mg ha−1 from 15 to 100 cm outweighs cumulative differences in DOC input to this layer, implicating deep forest rooting and bioturbation as active mechanisms in subsoil C change. Whereas differences in SOC content were concentrated near the surface, dynamic changes in C cycling extend well below the plow layer.
Document Type: Research Article
Publication date: February 1, 2011
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- Forest Science is a peer-reviewed journal publishing fundamental and applied research that explores all aspects of natural and social sciences as they apply to the function and management of the forested ecosystems of the world. Topics include silviculture, forest management, biometrics, economics, entomology & pathology, fire & fuels management, forest ecology, genetics & tree improvement, geospatial technologies, harvesting & utilization, landscape ecology, operations research, forest policy, physiology, recreation, social sciences, soils & hydrology, and wildlife management.
Forest Science is published bimonthly in February, April, June, August, October, and December.
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