Abstract
The Loess Plateau of China has the highest soil erosion rate in the world where billion tons of soil is annually washed into Yellow River. In recent decades this region has experienced significant climate change and policy-driven land conversion. However, it has not yet been well investigated how these changes in climate and land use have affected soil organic carbon (SOC) storage on the Loess Plateau. By using the Dynamic Land Ecosystem Model (DLEM), we quantified the effects of climate and land use on SOC storage on the Loess Plateau in the context of multiple environmental factors during the period of 1961–2005. Our results show that SOC storage increased by 0.27 Pg C on the Loess Plateau as a result of multiple environmental factors during the study period. About 55% (0.14 Pg C) of the SOC increase was caused by land conversion from cropland to grassland/forest owing to the government efforts to reduce soil erosion and improve the ecological conditions in the region. Historical climate change reduced SOC by 0.05 Pg C (approximately 19% of the total change) primarily due to a significant climate warming and a slight reduction in precipitation. Our results imply that the implementation of “Grain for Green” policy may effectively enhance regional soil carbon storage and hence starve off further soil erosion on the Loess Plateau.
Highlights
Soil organic carbon (SOC), the major component of soil organic matter, plays a key role in the terrestrial carbon cycle and has drawn great attention from scientific community
{krhSOMCdocom{kLuccCsom{DOCloss, methane where ktr is the transfer rate of decomposed LIT to soil organic matter (SOM); kgppdoc is the fraction of gross primary production (GPP) converted to soil dissolved organic carbon (DOC); kprd is the returned rate of decomposed production decay (PRD) to SOM pools as manure; krh is the fraction of decomposed SOM that is converted to CO2 through heterotrophic respiration; kLucc is coefficient for quick carbon loss from SOM due to land use conversion; DOCloss,methane is DOC consumed for the growth of production of methane
The combination of all these environmental factors considered in this study caused a net increase of about 0.27 Pg C in SOC storage from 1961 to 2005
Summary
Soil organic carbon (SOC), the major component of soil organic matter, plays a key role in the terrestrial carbon cycle and has drawn great attention from scientific community. It is a dynamic component of terrestrial systems, affecting carbon exchange between terrestrial ecosystem and the atmosphere [1,2]. Changes in climate and land use, caused by both natural and anthropogenic processes, have greatly influenced the terrestrial carbon balance during the past decades [5,6,7,8]. The effects of conversions from cropland to grassland/forest on the SOC storage have not been fully understood and there still remains large uncertainty
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