Mu Lan, Liang Yinli, Han Ruilian
Institute of Soil and Water Conservation, Northwest A&F University, Yangling Shaanxi Province, China; Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi Province, China.
PLoS One. 2014 Apr 15;9(4):e94770. doi: 10.1371/journal.pone.0094770. eCollection 2014.
The conversion of farmland to forestland not only changes the ecological environment but also enriches the soil with organic matter and affects the global carbon cycle. This paper reviews the influence of land use changes on the soil organic carbon sink to determine whether the Chinese "Grain-for-Green" (conversion of farmland to forestland) project increased the rate of SOC content during its implementation between 1999 and 2010 in the hilly and gully areas of the Loess Plateau in north-central China. The carbon sink was quantified, and the effects of the main species were assessed. The carbon sink increased from 2.26×106 kg in 1999 to 8.32×106 kg in 2010 with the sustainable growth of the converted areas. The black locust (Robinia pseudoacacia L.) and alfalfa (Medicago sativa L.) soil increased SOC content in the top soil (0-100 cm) in the initial 7-yr period, while the sequestration occurred later (>7 yr) in the 100-120 cm layer after the "Grain-for-Green" project was implemented. The carbon sink function measured for the afforested land provides evidence that the Grain-for-Green project has successfully excavated the carbon sink potential of the Shaanxi province and served as an important milestone for establishing an effective organic carbon management program.
退耕还林不仅改变了生态环境，还使土壤富含了有机质，并影响了全球碳循环。本文回顾了土地利用变化对土壤有机碳汇的影响，以确定中国的“退耕还林”项目在1999年至2010年实施期间，是否提高了中国中北部黄土高原丘陵沟壑区土壤有机碳（SOC）含量的增加速率。对碳汇进行了量化，并评估了主要树种的影响。随着退耕面积的持续增长，碳汇从1999年的2.26×106千克增加到2010年的8.32×106千克。刺槐（Robinia pseudoacacia L.）和苜蓿（Medicago sativa L.）种植的土壤在最初7年里增加了表层土壤（0 - 100厘米）中的SOC含量，而在“退耕还林”项目实施后，100 - 120厘米土层中的碳固存发生在7年之后。对造林地测量的碳汇功能证明，退耕还林项目成功挖掘了陕西省的碳汇潜力，并成为建立有效的有机碳管理计划的一个重要里程碑。
