土地覆被变化与管理对土壤动物群落演变的耦合效应

The Combined Effects of Land-cover Change and Management Practices on Soil Microfauna Communities

以黑河中游人工绿洲边缘天然草地及其转变的人工梭梭灌木林(21a)、人工杨树林(28a)、人工樟子松林(33a)和农田(开垦27a和100a)为研究对象,基于6种研究样地中小型土壤动物群落的调查数据,采用多变量排序和通径分析等方法,研究了土地利用/覆被变化与管理措施对中小型土壤动物群落及其主要类群演变的耦合效应。主要结果是:①将天然草地转变为未实施管理措施的人工梭梭灌木林后并未引起土壤动物群落组成、数量和物种多样性的显著变化,而转变为实施管理措施的杨树和樟子松人工林及农田后,导致了土壤动物群落组成、数量和物种多样性的变异,证实了土地覆被变化对中小型土壤动物群落的作用及其效应受管理措施的强烈调控。②土壤动物群落的演变过程受土地覆被变化与灌溉和施肥管理的共同影响,其中灌溉的贡献率最大,是关键驱动因子。③不同土壤动物类群对土地覆被变化和管理耦合作用的响应不同。灌溉对跳虫、甲螨和革螨的个体数量和物种丰富度的直接影响和总效应最大;施肥对辐螨的个体数量和物种丰富度的直接影响和总效应最大;灌溉和施肥对稀有类群的个体数量和物种丰富度的直接影响和总效应均较大,具同等重要的作用。结论是,土地覆被变化与管理耦合作用通过改变土壤水文和生态环境条件驱动了中小型土壤动物群落的演变过程。

In this study,we investigated soil microfauna communities across six major land-use/cover types of natural grassland and 5 differently managed artificial systems(21-year-old planted shrubland,28-year-old Poplar and 33-year-old Pinus plantations,and 27-and 100-year-old croplands) converted from natural grassland in an arid region of northwest China.The data were used to quantify the combined effects of land-cover change and management disturbances on the dynamics of soil microfauna communities.The conversion of natural grassland to unmanaged planted shrubland did not cause a significant change in the structure of the microfauna community,while the conversion of natural shrubland to managed Poplar and Pinus plantations and croplands significantly increased abundance,richness and diversity of the microfauna community.Multivariate and path analyses showed that the assembly of soil microfauna communities was significantly affected by the combination of land-cover change(indicated by vegetation cover),irrigation and fertilization,but the irrigation disturbance was the most important driver.The response of soil microfauna to irrigation,fertilization and vegetation cover varied among different components of the assemblages.Overall,irrigation had the greatest contribution to observed variation in the abundance and species richness of Collembola,Oribatida and Gamasida,while fertilization was more important than irrigation and vegetation cover to variation in the abundance and species richness of Actinetidida,and both irrigation and fertilization contributed to variation in the abundance and species richness of the rare group.Our results suggest that land-cover change and management disturbances interact in shaping soil microfauna community dynamics,but irrigation was identified to be the most important structuring force in soil fauna communities in this arid environment.