Changes in soil carbon pools and microbial activity along land-use gradients in grassland and forest ecosystems

微生物是土壤中的主要分解者，其活动强烈影响土壤碳储量。胞外酶在土壤有机质矿化过程中起着重要作用。虽然土壤中几乎所有的碳都有可能降解，但土壤中相当一部分碳不易被微生物获得，它们的生长往往受到可用能量或营养来源的限制。特别是吸附基质的土壤颗粒的粘土部分似乎减少其对微生物的可用性。土地利用和环境变化影响进入土壤的新基质的数量和组成，以及碳在游离和矿物相关部分之间的分布。这也会影响微生物活性和酶的产生，进而影响土壤碳储量。虽然在实地研究中很难确定土壤碳的微小变化，但特定酶活性的变化可以是变化的早期指标。该项目的目的是将微生物组成和活动与受勘探站主要地点土地利用影响的土壤碳储存联系起来。我们的目的是分析碳储存在不同年龄和土地利用变化的敏感性，以及在这些馏分中的一系列胞外酶的活性的颗粒大小的部分。酶活性是功能土壤生物多样性的一个指标，与物种多样性和酶编码基因分析结果相关。

Microorganisms are the main decomposers in the soil and their activity strongly affects soil carbon storage. Extracellular enzymes play an important role in the mineralization of soil organic matter. While almost all carbon in soils is potentially degradable, a considerable part of carbon in soils is not easily accessible to microbes and their growth is often limited by available energy or nutrient sources. Especially the sorption of substrates to soil particles of the clay fraction seems to reduce their availability to microorganisms. Land use and environmental changes affect the amount and composition of new substrates entering the soil as well as the distribution of carbon between free and mineral associated fractions. This also influences microbial activity and enzyme production, which in turn affects soil carbon storage. While small changes in soil carbon are hard to identify in field studies, shifts in the activities of specific enzymes can be early indicators for changes. The aim of this project is to link microbial composition and activity to soil carbon storage as affected by land use on the main sites of the exploratories. We intent to analyse carbon storage in particle size fractions of different age and sensitivity to land use changes as well as the activities of a range of extracellular enzymes in those fractions. Enzyme activities are an indicator for functional soil biodiversity and will be related to results about species diversity and enzyme encoding gene analyses.