黄土高原森林带植被群落下土壤活性有机碳研究

Soil Active Organic Carbon with Different Plant Communities on the Loess Plateau

为了探讨植被类型对土壤活性有机碳的影响以及活性有机碳对植被类型的敏感程度,在黄土高原沟壑区安塞县洞子沟流域,选择森林带不同植被类型下0—10cm和10—20cm土壤为研究对象,测定了四种表征土壤活性有机碳的指标,并对活性有机碳与植被群落中优势植物的特征指标进行逐步回归分析。结果表明,土壤有机碳以及活性有机碳含量均随土层深度的增加而降低,且含量都以乔灌草群落最大,草本群落最小。微生物生物量碳和溶解性有机碳占有机碳的比例不随植被类型和土层深度的变化而变化,保持在一个比较稳定的水平上。易氧化有机碳和轻组有机碳占有机碳的比例则随不同植被而变化。轻组有机碳占有机碳的比例在上下两层也有明显差异。活性有机碳对优势植物生物量和碳含量的响应,均敏感于总有机碳。而在四种活性有机碳中,微生物生物量碳的响应最为敏感,其次分别为溶解性有机碳,易氧化有机碳,轻组有机碳。

In order to discuss the effects of vegetation type on soil active organic carbon and analyze sensitive degree of active organic carbon to vegetation type.Four indicators regarded as representations of soil active organic carbon were analyzed.In the Dongzigou Basin,Ansai of hilly and gully region of the Loess Plateau,soil samples were collected under different forest vegetation types in the depth of 0—10 cm and 10—20 cm.Then the correlation between soil active organic carbon and indicators of dominant plants among vegetation community were analyzed by stepwise regression analysis.The results show that the contents of both soil organic carbon（SOC） and active organic carbon decrease with the increase of soil depth.The contents in tree-shrub-herb community are the highest among the three vegetation community,while they are the lowest in herbs community.Although soil samples differ in vegetation type and soil depth,the proportion of SOC in microbial biomass carbon（MBC） and dissolved organic carbon（DOC） remain stable.On the other hand,the proportion of SOC in light fraction organic carbon（LFOC） are found varies with vegetation types and soil depth,and the proportion of SOC in the easily oxidized carbon（EOC） were found varies with vegetation types.There is a closer relationship between soil active organic carbon and indicators of dominant plants（biomass and total C） and among these four indicators,MBC has the closest relationship,DOC,EOC and LFOC are followed.