彭州市不同土地利用方式土壤小型分解者群落结构和功能

分解作用是农业生态系统养分循环的重要环节,也是影响 农田土壤肥力和生产力的关键过程。土地利用方式不仅显著影响了农田中的土壤微生物和线虫等小型分解者群落的结构特征,还可能改变其生态功能,进而影响分解作用。但是,农业生态系统中的生境变化如何影响了分解作用速率仍不明确,不同土地利用方式下环境因子、土壤生物群落和分解作用之间的动态关系如何也不清楚。利用"茶包指数"量化了彭州市典型农区内农田、撂荒地、经济林和杂木林四种生境下的分解速率,并调查比较了各生境下的环境因子和土壤小型分解者群落结构和功能的差异。研究结果发现杂木林和撂荒地的分解速率最快,其次为经济林和农田。有乔木覆盖的生境中土壤小型分解者的丰度相对更高,食物网趋于成熟稳定。在人为管理更频繁的农田和经济林,共生和腐生真菌的丰度显著下降,地下食物网的连通性也弱于受干扰程度低的半自然生境,但病原菌的丰度也较低。土壤细菌是调控分解速率最重要的分解者类群;生境中地上植物丰富度的增加、土壤pH、容重和含碳量的升高均有助于加快分解速率。在彭州市推行农林间作模式,增加地上生境复杂度并合理进行人为管理能够更好地维持地下食物网复杂度和连通性,促进分解作用快速、彻底地进行,对维持土壤养分和健康,提高生产力具有重要意义。

The community structure and function of soil micro-decomposers under different land use types in Pengzhou City

Decomposition is an important process in the nutrient cycling of agricultural ecosystems, and it is also crucial in affecting soil fertility and productivity o f farmland. Land use not only significantly affects the structure of micro-decomposer, including soil microorganisms and nematodes in farmland, but may also change their ecological functions, which affects decomposition consequently. However, it is still unclear how habitat changes in agroecosystems affect the decomposition rate, nor are the dynamic relationships between environmental factors, soil biota, and decomposition under different land use types. In this study, the ''tea bag index'' was used to quantify the decomposition rate of farmland, fallow land, economic woodland and mixed woodland in the typical agricultural areas of Pengzhou City. The differences in environmental factors as well as the community structure and functions of soil micro-decomposers between habitat types were compared. The results showed that the decomposition rate was the highest in mixed woodland and fallow land, followed by economic woodland and farmland. The abundance of soil micro-decomposers was relatively higher, and the food web tended to be more mature and stabilized in the woodland. In farmland and economic woodland where agricultural management is more frequent, the abundances of symbiotic and saprophytic fungi were significantly lower, and the connectivity of decomposer food web was weaker, but the abundance of pathogenic bacteria was also lower than those in less disturbed semi-natural habitats. Soil bacteria was the most important biotic factors to regulate the decomposition rate. The increased aboveground plant richness, soil pH, bulk density and carbon content contributed to accelerating decomposition. The implementation of agroforestry and intercropping in Pengzhou, improvement of habitat complexity and rational human management can better maintain the complexity and connectivity of decomposer food webs, which can promote rapid and thorough decomposition. This is of great significance in maintaining soil nutrients and health, and promoting productivity.