典型黑土区农田土壤线虫群落的纬度分布格局及其驱动机制

东北黑土区是保障我国粮食安全的重要土壤资源, 了解该区域内农田土壤线虫的群落组成及其对环境驱动因子的响应机制, 对于研究黑土区农田土壤生态系统的生物多样性分布格局具有重要意义。2018年9月, 我们在42°50°‒49°08° N的典型黑土区采集了93个农田土壤样品, 利用形态学鉴定技术分析了土壤线虫群落的组成与结构。共鉴定出47个线虫属(相对丰度 > 1%), 其中食细菌线虫中的拟丽突属(Acrobeloides)是典型黑土区农田土壤中的优势属(相对丰度 > 5%)。土壤线虫总丰富度和总多度均随纬度增加而显著增加, 然而类似的变化趋势只出现在食细菌和杂食/捕食线虫中。土壤有机碳是影响土壤线虫丰富度和多度最为重要的环境因子, 其次是月平均温度。典型黑土区农田土壤线虫群落结构以47° N为分界线分为南部和北部两类, 主要归因于线虫群落中植物寄生和杂食/捕食线虫的相对多度在南、北特征属中存在差异。土壤pH值和容重分别是影响南部与北部黑土区线虫群落最重要的环境因子。本研究明确了典型黑土区农田土壤线虫群落的纬度分布格局及其与环境因素的关系, 可为揭示农业活动干扰下土壤生物对环境因子的响应机制提供基础数据和理论参考。

Latitude distribution and associated environmental factors of soil nematodes in a typical black soil region

Aims: Northeast black soil is one of the most important agricultural resources in China. Understanding the spatial distribution of nematode communities as well as their influcing factors is of great importance for ensuring food security in China.Methods: In September 2018, 31 farmland sampling sites were selected across the black soil region within the bounds of 42°50°-49°08° N, and 93 soil samples were collected. Soil nematode communities were identified by morphological identification. Results: A total of 47 nematode genera (relative abundance > 1%) were identified. Across all samples, the bacterivores nematode Acrobloides was the most abundant (relative abundance > 5%). Species richness and abundance of nematode communities increased with latitude, but only among bacterivores and omnivores/predators nematodes. Soil organic carbon was the most important environmental factor affecting richness and abundance of soil nematodes in a typical black soil region, followed by monthly mean temperature. Soil nematode community structure in this region was divided into two categories: south and north, with a boundary at 47° N separating the two groups. This division was attributed mainly to the differences in the relative abundance of plant parasitic and omnivorous/predatory nematodes between the two areas. Soil pH value and bulk density were the most important factors influencing community structure in the south and north, respectively.Conclusion: This study clarifies the relationship between environmental factors and nematode community structure, as well the geographical distribution of nematode communities in a typical black soil region. As such, it provides basic data and reference for the mechanism driving the character of soil biota under agricultural interference.