Response of soil fauna to land use intensification in a global meta-analysis

土地利用集约化，特别是从粗放(低投入)管理的农业生态系统向集约(高投入)管理的农业生态系统的转变，往往被视为全球生物多样性下降的主要驱动因素之一，被认为是对土壤生物多样性施加压力的主要因素。面对未来土地利用的变化，了解土壤生物多样性对不同强度的土地利用方式的响应对于合理的土地管理是至关重要的。然而，对于不同的分类群体如何一致地对土地利用集约化做出反应，仍然存在很大的不确定性。该项目的主要目标是通过网络荟萃分析系统地评估和量化全球农业生态系统中土地利用集约化对土壤生物的影响，并分析这些影响对土壤属性(有机质、pH、养分和水的有效性、质地)、气候变量和土地利用历史等非生物因素的依赖性。全球荟萃分析将有助于理解某些生物分类或功能类群是否更受土地利用集约化的影响，或者居住在土地利用历史较长地区的生物是否表现出与生活在较短历史地区的生物相似的反应。土地利用集约化对土壤生物的影响(大小和方向)与所研究的集约化类型、气候和土壤属性(pH、N、质地、有机质)的相关性也可以通过全球荟萃分析来量化。网络荟萃分析特别适合于这一目的，因为它利用了所有可用的直接和间接证据，并消除了在所有研究中采用传统的基于成对比较的荟萃分析(即干预：耕地与参考：未受干扰的生态系统、干预：牧场与参考：未受干扰的生态系统)的共同参考土地利用的需要。这使得可以纳入更多的研究进行分析，比较至少两种不同强度的土地利用制度对土壤生物的影响(即干预：耕地与参照：牧场；干预：牧场与参照：未受干扰的生态系统)。

Land use intensification, particularly a shift from extensively (low-input) to intensively (high-input) managed agroecosystems is often seen as one of the main drivers of global biodiversity decline and is considered the main factor applying pressure on soil biodiversity. When confronted with future land use change, understanding the responses of soil biodiversity to different land use regimes of varying intensity is decisive for adequate land management. However, there is still substantial uncertainty about how consistently different taxonomic groups respond to land use intensification. The main objective of this project is to systematically assess and quantify through network meta-analysis the effects of land-use intensification on soil organisms in global agroecosystems, and to analyze the dependence of these effects on abiotic factors such as soil properties (organic matter, pH, nutrient and water availability, texture), climatic variables and land use history. A global meta-analysis will help to understand whether certain taxonomic or functional groups of organisms are more affected by land use intensification, or whether organisms inhabiting areas with a longer history of land use show similar responses to those living in areas with shorter history. The dependance of the effects (size and direction) of land use intensification on soil organisms on the type of intensification studied, climate, and soil properties (pH, N, texture, organic matter) can also be quantified through a global meta-analysis. A network meta-analysis is especially appropriate for this purpose as it exploits all available direct and indirect evidence, and eliminates the need to have a common reference land use in all studies as occurs with traditional meta-analyses based on pairwise comparisons (i.e. intervention: arable vs. reference: undisturbed ecosystems, intervention: pasture vs. reference: undisturbed ecosystems). This allows to include more studies for analysis, that compare the effects of at least two land use regimes of different intensity on soil organisms (i.e. intervention: arable vs reference: pasture; intervention: pasture vs reference: undisturbed ecosystems).