土地利用与反季节水位波动影响下土壤活性有机碳的组分特征

为了研究消落带不同土地利用类型和水淹强度下土壤活性有机碳组分特征及其主要的影响因子,选取不同海拔高程(水淹强度)与不同土地利用类型的消落带土壤为研究对象,定量解析土地利用方式与水淹强度对三峡水库消落带土壤活性有机碳组分的影响,并分析土壤活性有机碳与土壤理化性质之间的关系。结果表明,消落带土壤活性有机碳含量总体上随着水淹强度的增强而减小。土地利用、水淹强度及其交互作用对土壤活性有机碳影响的解释度分别为22.1%,13.7%,9.3%;土壤微生物生物量碳主要受土地利用、土地利用与淹水强度交互作用的影响,对土壤微生物生物量碳影响对应的解释度分别为3.9%,0.6%;土壤可溶性有机碳与土壤颗粒有机碳主要受淹水强度的影响,其方差解释度分别为65.1%,5.5%。多元因子分析(MFA)结果表明,土壤活性有机碳组分MBC含量主要与EC具有显著的负相关关系,而不同水淹强度可能影响土壤理化性质中TN和C∶N,进而影响土壤活性有机碳组分DOC分布。土壤POC含量与SOC含量呈显著正相关,POC可被用来衡量消落带不同水淹强度下有机碳库变化的敏感性指标。

Effects of Land-use Types and Off-season Water-level Fluctuation on Component Characteristics of Soil Active Organic Carbon

In order to determine the effects of land-use types and dam-triggered flooding intensity on soil active organic carbon fractions and identify the main influencing factor in the riparian zone of the Three Gorges Reservoir, soils from different flood intensities and land-use types were collected as study objects and were used to quantitatively analyze soil active organic carbon fractions, while the relationships between soil active organic carbon fractions and soil physical and chemical properties were analyzed. The results showed that the content of soil active organic carbon decreased with the increase of flooding intensity. The land-use types, flooding intensity, and their interaction explained by 22.1%, 13.7%, and 9.3% respectively, on soil organic carbon variation. Soil microbial biomass carbon was mainly affected by land-use types and the interaction between land-use types and flooding intensity, and their variation partitioning for the effects on soil microbial biomass carbon were 3.9% and 0.6%, respectively. Soil dissolved organic carbon and soil particulate organic carbon were mainly affected by the dam-triggered flooding intensity, and the explanations for their variation partitioning were 65.1% and 5.5%, respectively. Multiple factor analysis showed that significant correlations between the MBC content of soil active organic carbon and soil electrical. However, Water flooding intensity might affect TN and C:N in soil properties, and further affect the distribution of DOC. Soil POC content was significantly positively correlated with SOC content, and POC can be used as an indicator to measure the flooding intensity changes of organic carbon pool in the riparian zone of the Three Gorges Reservoir.