黄土高原典型流域“自然-人工”植被对土壤表层碳分布的影响

Effects of “nature-artificial” vegetation on surface soil carbon distribution in typical watershed of the Loess Plateau

黄土高原大规模退耕还林(草)对土壤有机碳会产生显著影响。相比总有机碳,土壤活性有机碳对区域微环境变化响应敏感,且能灵敏地反映土壤质量变化情况。为了探讨黄土高原不同植被恢复类型对土壤有机碳(SOC)及土壤活性有机碳的主要组分土壤颗粒态有机碳(POC)、微生物量碳(MBC)和易氧化有机碳(EOC)的影响,本研究以王茂沟流域3种主要植被类型0~10cm和10~20cm土层土壤为研究对象,对其活性有机碳组分进行研究。结果表明:(1)土壤有机碳密度由高到低依次为杏树、油松、玉米;(2)同种植被类型下,0~10cm土层POC含量均高于10~20cm土层;微生物活动集中分布在10~20cm土层;杏树与坝地玉米10~20cm土层EOC含量高于0~10cm土层,油松0~10cm土层EOC含量高于10~20cm土层;(3)坝地玉米SOC含量低于油松与杏树SOC含量,土壤活性有机碳中的EOC含量对土壤SOC含量的高低起到了重要的作用。

The large scale Grain for Green Project has a significant effect on soil organic carbon in the Loess Plateau. Compared with soil organic carbon, soil active organic carbon is highly sensi- tive to changes of microenvironment and could be cited as a sensitive indicator for changes in soil quality. In order to investigate the effects of different vegetation restoration types on soil organic carbon （SOC） and the main soil active organic carbon components POC, MBC and EOC in the- Loess Plateau, and three vegetation types in the Wangmaogou watershed are selected as research subjects. Soil samples in 0~10 cm and 10~20 cm layers are collected to measure SOC and active organic carbon components. The results show that：① The SOC densities from large to small in turn are：Apricot, Chinese pine, Dam land corn. ② The POC content in 0~10 cm are higher than that in 10~20 cm layer with the same vegetation type; the microbial activities are mainly distrib- uted in soil layer of 10~20 cm; the soil EOC contents of 10~20 cm layer in dam land corn and a- pricot land are higher than that of 0~ 10 cm layer. In Chinese pine land, on the contrary, the EOC content in 0~10 cm layer is higher than that in 10420 cm layer. ③ The SOC content in dam land corn is much less than that in Chinese pine and apricot land, with the EOC contents having significant influences on the SOC pool.