哈尼梯田生态系统土壤微生物量碳的影响因素

Abstract

土壤微生物量碳（MBC，Microbial Biomass Carbon）是土壤微生物量的重要组成部分，也是土壤肥力变化的重要指标之一。哈尼梯田肥沃的土壤对哈尼梯田生态系统的维持与循环起到重要作用。以哈尼梯田水源区（乔木林、灌木林、荒草地）和梯田为研究对象，采用氯仿熏蒸法测定了4种不同土地利用类型0-20、20-40、40-60 cm 3个土层的土壤MBC，并分析了其与季节变化、地上植被及土壤理化性质之间的关系。结果表明：4种土地利用类型土壤MBC 3个土层皆以乔木林最高，其次是灌木林、荒草地、梯田，且4种土地利用类型土壤MBC含量都随土层深度的增加而减少，其中乔木林0-20 cm土层土壤MBC含量是40-60 cm土层的3.19倍。4种土地利用类型土壤MBC含量均具有明显的季节变化，总体呈夏季偏高冬季偏低的变化模式。相关分析表明，不同土地利用类型地上植被的多样性指数、盖度、优势种高度、枯落物层厚度与每一土层土壤MBC都具有很强的相互关系。土壤MBC与土壤有机碳和土壤孔隙度呈正相关性，与土壤容重呈负相关性。植被生长情况、土壤有机碳和孔隙度含量及季节变化是导致不同土地利用类型土壤微生物量碳差异的主要因素。;Soil microbial biomass carbon (MBC,Microbial Biomass Carbon) is an important component of soil microbial biomass and one of the important indicators of soil fertility changes. The fertile soil of the Hani terraces plays an important role in the maintenance and circulation of the Hani terrace ecosystem. Taking Hani terraced water source area (arbor forest, shrub forest, grassland) and terraced fields as research objects, four different land use types of 0-20, 20-40 and 40-60 cm were determined by chloroform fumigation method. The soil MBC was analyzed and its relationship with seasonal changes, aboveground vegetation and soil physical and chemical properties was analyzed. The results showed that the three soil layers of the four types of land use type MBC were the highest in the arbor forest, followed by the shrub forest, grassland and terraced fields, and the soil MBC content of the four land use types decreased with the increase of the soil depth. The MBC content of 0-20 cm soil layer in arbor forest is 3.19 times that of 40-60 cm soil layer. The soil MBC content of the four land use types had obvious seasonal changes, and the overall pattern was high in summer and low in winter. The correlation analysis showed that the diversity index, coverage, dominant species height, litter layer thickness and the soil MBC of each soil layer had strong correlations with different land use types. The soil MBC was positively correlated with soil organic carbon and soil porosity, and negatively correlated with soil bulk density. The vegetation growth, soil organic carbon and porosity content and seasonal variation are the main factors leading to differences in soil microbial biomass carbon in different land use types.