秸秆还田对耕作黑土中小型土壤动物群落的影响

为了考察秸秆还田对耕作黑土中土壤动物群落结构的影响,2009年到2011年在黑龙江省海伦市进行了定点实验,调查了样地A(17kg秸秆+含高浓度催腐剂还田)、样地B(8.5kg秸秆+含低浓度催腐剂还田)、样地C(对照样地),样地D(8.5kg秸秆还田),样地E(17kg秸秆还田)的中小型土壤动物群落结构。共获取中小型土壤动物21779只,分别隶属于58个类群。其中,甲螨亚目、姬跳虫科、棘跳虫科与驼跳科4个类群土壤动物在本地区是最适应环境变化的土壤动物类群。土壤动物群落结构分析表明,对照样地C中土壤动物密度最高(46591.67只/m~2),土壤动物类群最多(17.17),土壤动物优势度指数最大(0.37),样地D中土壤动物丰富度指数最多(2.63),样地A中土壤动物多样性指数最高(1.72),样地B中土壤动物均匀性最高(0.64)。同时,各样地土壤动物基本都具有表聚性,样地A中土壤动物更趋于生存于上层土壤。综合比较分析表明,样地A秸秆还田方式相对来说最利于土壤动物生存。主成分分析表明,不同秸秆还田方式对土壤动物密度、甲螨亚目动物类群、节跳虫科类群、前气门亚目类群影响较大,是耕作黑土中对秸秆还田方式反应敏感的土壤动物指标,今后可以作为考察耕作黑土秸秆还田肥力效应的评价指标。另外,CAA分析表明:受土壤环境因子影响较大的土壤动物类群多为研究区域内优势类群与常见类群,土壤动物的密度与土壤中有机质、有机碳、碳氮比与全磷的含量关系最为密切。

Effect of straw-returning management on meso-micro soil fauna in a cultivated black soil area

Crop straw is an important material basis for nutrient cycling in agro-ecosystems. Straw returning is a method in which straw is applied to the soil to improve soil properties, and is used for accelerating immature soil development in cultivated land and improving soil fertility. Soil fauna is an important component of the ecosystem, and is involved in the straw decomposition process, improving the decomposition of organic matter and promoting nutrient absorption by plants. Therefore, research on the ecology of soil fauna and sustainable utilization of cultivated soil, including black soil, has been widely conducted. Understanding the correlation between soil fauna and straw returning will provide a scientific basis for the protection of the soil fauna community and sustainable utilization management of tillage ecosystems in black soil areas. To investigate the effect of straw returning on meso-micro soil fauna communities in cultivated black soil, field experiments were carried out in Hai-lun, Heilongjiang Province from 2009 to 2011. The experiments were conducted in five selected plots:Plot A:17 kg corn straw returning and high concentrations of microbial inoculants; Plot B:8.5 kg corn straw returning and low concentrations of microbial inoculants; Plot C:control; Plot D:8.5 kg corn straw returning; and Plot E:17 kg corn straw returning. A total of 21,779 individuals, belonging to 58 groups, were extracted and identified in the plots. Among them, Oribatida, Hypogastruridae, Onychiuridae, and Cyphoderidae were most suitable to understand environmental changes in the study area. Analysis of the soil fauna community structure showed that the density, group number, and Simpson Dominance Index of soil fauna were highest in the control Plot C (46,591.67 ind/m², 17.17, 0.37, respectively). The soil fauna richness index was highest in Plot D (2.63); the diversity index was highest in Plot A (1.72); and the evenness index was highest in Plot B (0.64). Meanwhile, the soil fauna was characterized by surface accumulation in the experimental plots. The group numbers of dominant soil fauna in Plot A in all soil layers were lower than those in other plots, and soil fauna was more dominant in the upper layer of the soil. Together, the method of straw returning in Plot A was the most productive for soil fauna. In addition, the results of a Principal Component Analysis (PCA) indicated that different methods of straw returning had a considerable effect on soil fauna density. Oribatida, Isotomidae, and Prostigmata were sensitive soil fauna that responded to different methods of straw returning, and could therefore be considered as an evaluating index to investigate the fertility effect of straw returning in cultivated black soil in the future. The results of the Canonical Correspondence Analysis (CCA) indicated that the dominant and common groups of soil fauna were considerably influenced by the soil environment, and the density of soil fauna was closely associated with organic matter, organic carbon, the carbon to nitrogen ratio, and total phosphorus in the soil.