Science of The Total Environment · 2018
Fine resolution map of top- and subsoil carbon sequestration potential in France
Chen, S., Martin, M. P., Saby, N. P., Walter, C., Angers, D. A., Arrouays, D.
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Fine resolution map of top- and subsoil carbon sequestration…
Abstract
Although soils have a high potential to offset CO2 emissions through its conversion into soil organic carbon (SOC) with long turnover time, it iswidely accepted that there is an upper limit of soil stable C storage,which is referred to SOC saturation. In this study we estimate SOC saturation in French topsoil (0–30 cm) and subsoil (30–50 cm), using the Hassink equation and calculate the additional SOC sequestration potential (SOCsp) by the difference between SOC saturation and fine fraction C on an unbiased sampling set of sites covering whole mainland France. Wethen mapwith fine resolution the geographical distribution of SOCsp over the French territory using a regression Kriging approach with environmental covariates. Results show that the controlling factors of SOCsp differ fromtopsoil and subsoil. Themain controlling factor of SOCsp in topsoils is land use. Nearly half of forest topsoils are over-saturatedwith a SOCsp close to 0 (mean and standard error at 0.19±0.12) whereas cropland, vineyard and orchard soils are largely unsaturated with degrees of C saturation deficit at 36.45±0.68% and 57.10±1.64%, respectively. The determinant of C sequestration potential in subsoils is related to parentmaterial. There is a large additional SOCsp in subsoil for all land useswith degrees of C saturation deficit between 48.52±4.83% and 68.68 ±0.42%. Overall the SOCsp for French soils appears to be very large (1008Mt C for topsoil and 1360Mt C for subsoil) when compared to previous total SOC stocks estimates of about 3.5 Gt in French topsoil. Our results also show that overall, 176 Mt C exceed C saturation in French topsoil and might thus be very sensitive to land use change.
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Although soils have a high potential to offset CO2 emissions through its conversion into soil organic carbon (SOC) with long turnover time, it iswidely accepted that there is an upper limit of soil stable C storage,which is referred to SOC saturation. In this study we estimate SOC saturation in French topsoil (0–30 cm) and subsoil (30–50 cm), using the Hassink equation and calculate the additional SOC sequestration potential (SOCsp) by the difference between SOC saturation and fine fraction C on an unbiased sampling set of sites covering whole mainland France. Wethen mapwith fine resolution the geographical distribution of SOCsp over the French territory using a regression Kriging approach with environmental covariates. Results show that the controlling factors of SOCsp differ fromtopsoil and subsoil. Themain controlling factor of SOCsp in topsoils is land use. Nearly half of forest topsoils are over-saturatedwith a SOCsp close to 0 (mean and standard error at 0.19±0.12) whereas cropland, vineyard and orchard soils are largely unsaturated with degrees of C saturation deficit at 36.45±0.68% and 57.10±1.64%, respectively. The determinant of C sequestration potential in subsoils is related to parentmaterial. There is a large additional SOCsp in subsoil for all land useswith degrees of C saturation deficit between 48.52±4.83% and 68.68 ±0.42%. Overall the SOCsp for French soils appears to be very large (1008Mt C for topsoil and 1360Mt C for subsoil) when compared to previous total SOC stocks estimates of about 3.5 Gt in French topsoil. Our results also show that overall, 176 Mt C exceed C saturation in French topsoil and might thus be very sensitive to land use change.
Although soils have a high potential to offset CO2 emissions through its conversion into soil organic carbon (SOC) with long turnover time, it iswidely accepted that there is an upper limit of soil stable C storage,which is referred to SOC saturation. In this study we estimate SOC saturation in French topsoil (0–30 cm) and subsoil (30–50 cm), using the Hassink equation and calculate the additional SOC sequestration potential (SOCsp) by the difference between SOC saturation and fine fraction C on an unbiased sampling set of sites covering whole mainland France. Wethen mapwith fine resolution the geographical distribution of SOCsp over the French territory using a regression Kriging approach with environmental covariates. Results show that the controlling factors of SOCsp differ fromtopsoil and subsoil. Themain controlling factor of SOCsp in topsoils is land use. Nearly half of forest topsoils are over-saturatedwith a SOCsp close to 0 (mean and standard error at 0.19±0.12) whereas cropland, vineyard and orchard soils are largely unsaturated with degrees of C saturation deficit at 36.45±0.68% and 57.10±1.64%, respectively. The determinant of C sequestration potential in subsoils is related to parentmaterial. There is a large additional SOCsp in subsoil for all land useswith degrees of C saturation deficit between 48.52±4.83% and 68.68 ±0.42%. Overall the SOCsp for French soils appears to be very large (1008Mt C for topsoil and 1360Mt C for subsoil) when compared to previous total SOC stocks estimates of about 3.5 Gt in French topsoil. Our results also show that overall, 176 Mt C exceed C saturation in French topsoil and might thus be very sensitive to land use change.
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