Cao Jixin, Wang Xiaoping, Sun Xiangyang, Zhang Lin, Tian Yun
Key Lab. Soil and Water Conservation and Desertification Combating, Ministry of Education, College of Soil and Water Conservation, Beijing Forestry University, Beijing, China.
Key Lab. Soil and Water Conservation and Desertification Combating, Ministry of Education, College of Soil and Water Conservation, Beijing Forestry University, Beijing, China ; Beijing Forestry Carbon Administration (Beijing Forestry and Parks Department of International Cooperation), Beijing, China.
Springerplus. 2013 Dec 11;2(Suppl 1):S1. doi: 10.1186/2193-1801-2-S1-S1. eCollection 2013.
Grazing can cause changes in soil carbon (C) level. This study aimed to elucidate the response of soil labile organic carbon (SLOC) under four different grazing intensities: non grazing (NG), 0 sheep·ha(-1); light grazing (LG), 0.91 sheep·ha(-1); moderate grazing (MG), 1.82 sheep·ha(-1), and heavy grazing (HG), 2.73 sheep·ha(-1). Results showed that there was no significant difference in total soil organic carbon (TOC) and soil inorganic carbon (SIC) content from three soil depths (0-15 cm, 15-30 cm, and 30-45 cm) under different grazing intensities. However, the SLOC including particulate organic carbon (POC), light fraction organic carbon (LFOC), and readily oxidizable carbon (ROC) content at a depth of 0-15 cm decreased with the increasing grazing intensity among LG, MG and HG. The SLOC content at depths of 15-30 cm under the NG and LG were significantly higher than that under the MG and the HG. The TOC and SLOC content decreased with increasing depths of soil horizons, but SIC content increased. The variation trend of the density of different soil carbon fractions and the ratio of individual SLOC fractions to TOC were similar to that of the soil carbon content of corresponding fractions. These results indicated that MG and HG treatments caused C loss at 0-30 cm; and SLOC was more sensitive than TOC in response to different grazing intensities.
放牧会导致土壤碳（C）水平发生变化。本研究旨在阐明在四种不同放牧强度下土壤活性有机碳（SLOC）的响应情况：不放牧（NG），0只羊·公顷⁻¹；轻度放牧（LG），0.91只羊·公顷⁻¹；中度放牧（MG），1.82只羊·公顷⁻¹；重度放牧（HG），2.73只羊·公顷⁻¹。结果表明，不同放牧强度下三个土壤深度（0 - 15厘米、15 - 30厘米和30 - 45厘米）的土壤总有机碳（TOC）和土壤无机碳（SIC）含量没有显著差异。然而，在0 - 15厘米深度处，包括颗粒有机碳（POC）、轻组有机碳（LFOC）和易氧化碳（ROC）在内的SLOC含量在LG、MG和HG中随放牧强度增加而降低。NG和LG处理下15 - 30厘米深度处的SLOC含量显著高于MG和HG处理下的含量。TOC和SLOC含量随土壤层深度增加而降低，但SIC含量增加。不同土壤碳组分密度以及单个SLOC组分与TOC的比值的变化趋势与相应组分的土壤碳含量相似。这些结果表明，MG和HG处理导致0 - 30厘米深度处碳损失；并且SLOC对不同放牧强度的响应比TOC更敏感。
