25 research outputs found

    Deep carbon storage potential of buried floodplain soils.

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    Soils account for the largest terrestrial pool of carbon and have the potential for even greater quantities of carbon sequestration. Typical soil carbon (C) stocks used in global carbon models only account for the upper 1 meter of soil. Previously unaccounted for deep carbon pools (>1 m) were generally considered to provide a negligible input to total C contents and represent less dynamic C pools. Here we assess deep soil C pools associated with an alluvial floodplain ecosystem transitioning from agricultural production to restoration of native vegetation. We analyzed the soil organic carbon (SOC) concentrations of 87 surface soil samples (0-15 cm) and 23 subsurface boreholes (0-3 m). We evaluated the quantitative importance of the burial process in the sequestration of subsurface C and found our subsurface soils (0-3 m) contained considerably more C than typical C stocks of 0-1 m. This deep unaccounted soil C could have considerable implications for global C accounting. We compared differences in surface soil C related to vegetation and land use history and determined that flooding restoration could promote greater C accumulation in surface soils. We conclude deep floodplain soils may store substantial quantities of C and floodplain restoration should promote active C sequestration

    Controls on Soil Organic Carbon Partitioning and Stabilization in the California Sierra Nevada

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    There is a critical need to quantify the role of soil mineral composition on organic carbon (C) stabilization in forest soils. Here, we address this need by studying a matrix of forest ecosystems and soil parent materials with the objective of quantifying controls on the physical partitioning and residence time of soil organic carbon. We sampled soil profiles across a climate gradient on the western slope of the California Sierra Nevada, focusing on three distinct forest ecosystems dominated by ponderosa pine, white fir, or red fir, on three igneous parent materials that included granite, andesite, and basalt. Results indicated that short-range order mineral phases were the dominant factors accounting for the variation in soil carbon content and residence time. The results further suggested an interaction between ecosystem fire regime and the degree of soil weathering on the partitioning, chemical composition, and residence time of C in density separated soil physical fractions. These results suggest a link between the degree of soil weathering and C storage capacity, with a greater divergence in storage capacity and residence time in the Inceptisols, Entisols, and Andisols of the white fir and red fir ecosystems relative to minimal variation in the highly weathered Ultisols and Alfisols of the ponderosa pine ecosystem
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