北方土石山区水蚀及水保措施对土壤有机碳的影响

Effect of water erosion and soil conservation measures on soil organic carbon content in rocky mountainous areas of northern China

土壤侵蚀是土壤有机碳退化的主要因素。为探究水蚀对土壤有机碳的影响及寻求有效的水土保持措施对土壤有机碳进行保护,在北京周边选取4处典型样地,进行土壤有机碳调查及野外人工模拟降雨实验,分析了水蚀及水土保持措施对土壤有机碳的影响。结果表明:①不同样地土壤有机碳质量分数大小顺序为:土壤堆积区、轻微溅蚀区、细沟侵蚀区、强烈冲刷侵蚀区。水蚀对浅层土壤有机碳质量分数影响较大,程度剧烈的侵蚀,会造成深层土壤有机碳流失;②土壤平均有机碳质量分数随降雨历时的增加(土壤侵蚀量增长)呈减少趋势,并且减少趋势随降雨历时增加(土壤侵蚀量增长)逐渐变缓而趋于稳定;③不同鱼鳞坑配置对土壤有机碳的累积规律为:乔木枯枝落叶覆盖(32.7g·kg^-1)>乔木低矮植被覆盖(27.9g·kg^-1)>乔木种植(23.5g·kg^-1)>无措施(21.9g·kg^-1)>灌木(21.5g·kg^-1)。其中地表覆盖(枯枝落叶及低矮植被)能有效增加土壤有机碳;④不同植被措施对土壤有机碳恢复作用从大到小依次为人工林、苗圃、果园和农田,因此要选取适合的水土保持措施进行土壤有机碳的保护。

Soil erosion is the main factor contributing to soil organic carbon (SOC) degradation. To explore the effect of water erosion on SOC and to seek effective soil and water conservation measures to protect SOC, four typical sample plots around Beijing were studied and manual simulation rainfall experiments were carried out. The results showed that (1) The order of soil organic carbon content in different plots was: soil accumulation zone, slight splash zone, rill erosion zone and strong erosion zone, water erosion had a great influence on the content of organic carbon in surface soil, and soil organic carbon loss in deep soil caused by severe erosion.(2) The average soil organic carbon content decreased with the increase of rainfall duration (soil erosion amount), and these decreases gradually diminished with the increase of rainfall duration (soil erosion amount).(3) For the accumulative regularity of soil organic carbon with different fish scale pit configurations, dry branches and fallen leaves coverage (32.7 g·kg^-1) shows the highest content, followed by trees and low vegetation coverage (27.9 g·kg^-1), trees only (23.5 g·kg^-1), no measures (21.9 g·kg^-1) and shrubs (21.5 g·kg^-1). Among them, the surface coverage of dry branches, fallen leaves and low vegetation can effectively increase soil organic carbon.(4) The effects of different vegetation measures on soil organic carbon restoration from large to small were plantation, nursery, orchard and farmland, thus, suitable soil and water conservation measures should be taken to restore soil organic carbon.