土地利用方式对土壤碳库影响的敏感性评价指标

The sensitive evaluation indicators of effects of land-use change on soil carbon pool

综述了目前国内外在监测土地利用方式对土壤有机碳动态的影响时所采用的一些敏感性指标:微生物量碳和微生物商、CO2通量和qCO2、轻组有机质和颗粒态有机质、溶解态有机碳(DOC).大量的研究表明,与土壤有机碳相比,微生物量碳库的周转率更大,周转时间更短,在土壤总有机碳变化可检测之前,土壤微生物部分的变化可能被检测到,是土壤碳动态的敏感性指标.轻组和颗粒态有机质是自然土壤肥力的决定因素,也是土地管理方式影响最明显的部分,对于准确评价土地利用变化对土壤碳过程的影响具有重要意义.CO2通量和qCO2可以综合反映土壤微生物的活性、利用土壤有机碳的效率及土壤中碳的代谢作用等,也是土壤碳动态的敏感性指标.DOC通量比全球植物和大气间碳交换量小1～2个数量级,所以生物圈碳平衡的很小变化会导致DOC的巨大变化,DOC浓度和通量是土壤温度和湿度变化的敏感指标.

In this article, we reviewed the latest studies of the sensitive evaluation indicator of effects of land-use change on the soil carbon pool, including the microbial biomass carbon and microbial quotient, CO2 flux and qCO2, light fraction organic matter and particulate organic matter, and dissolved organic carbon. A lot of studies showed that the microbial biomass carbon pool, comparing to the total soil organic carbon, had greater turnover rate and shorter turnover time, and could be inspected before the total soil organic carbon could. Light fraction organic matter and particulate organic matter are determinants to nature soil fertility and more influenced by management practices than total SOM. So light fraction organic matter and particulate organic matter are sensitive evaluation indicators accurately evaluating effects of land-use change on the soil carbon pool. CO2 flux and qCO2 could synthetically show the microbial activity, efficiency of carbon availability and metabolize carbon of soil microorganism, and are sensitive indicators of soil carbon dynamic. DOC fluxes are 1~2 orders of magnitude smaller than the global transfer of the carbon between vegetation and atmosphere, so small changes in the carbon balance of the biosphere could result in large changes in DOC export. DOC concentrations and flux are sensitive to changes in temperature and moisture conditions in soil.