春大豆长期连作对土壤线虫群落结构和食物网的影响

Effect of Spring Soybean Long-term Monoculture on Soil Nematode Community Structure and Food web

以土壤线虫为指示生物,研究了大豆不同耕作系统土壤线虫群落结构、生态指数和食物网指数的变化特征,以期明确大豆长期连作对土壤生物多样性和土壤食物网结构的影响。结果表明:大豆轮作土壤线虫属最丰富,大豆长期连作25年后土壤线虫属水平种类最少。大豆轮作和大豆短期连作3年土壤线虫群落组成Jaccard相似性最高(0.81),大豆轮作和大豆长期连作25年Jaccard相似性最低(0.66)。大豆短期连作3年土壤中植物寄生线虫的数量最高,显著高于大豆轮作和大豆长期连作25年。食真菌线虫在大豆长期连作25年土壤中较丰富,显著高于大豆轮作和大豆短期连作3年。大豆长期连作25年植物寄生线虫成熟度指数(PPI)高于大豆短期连作3年和大豆轮作。土壤线虫的通路指数(CI)在3个处理中均小于50,土壤腐蚀食物网的降解以细菌降解通路为主。大豆短期连作3年处理位于富集指数(EI)和结构指数(SI)食物网特征图的A象限,大豆轮作和长期连作25年位于食物网特征图的B象限。结果表明,大豆长期连作改变了土壤线虫的群落结构,降低了属的多样性,食物网结构向成熟稳定的方向恢复。

Soil nematode community structure, ecological index and food web index were investigated under different soybean planting system, aiming to determine the effects of soybean long-term monocuhure on soil biological diversity and food web. The results showed that nematode genera were most diverse in wheat/maize/soybean rotation system（ SR）, flowed by soybean monoculture for 3 years（SS） , and were lowest in soybean monoculture for 25 years（SL）. Jaccard index was highest between SR and SS, with value of 0. 81, and it was lowest between SR and SL, with value of 0. 66. The abundant of plant parasites was higher in SS than in SR and SL. Fungivores were most abundant in SL, and were higher than SR and SS. Maturity index of plant parasites was higher in SL than in SS and SR. The value of channel index was lower than 50 in all treatments, indicating bacterial decomposition pathway was dominant in soil food web. Treatment SS was located at the A quadrant of plot of enrichment index vs structure index, and SR and SL were located at B quadrant of the plot. These results indicated that soybean long-term monocuhure vary soil nematode community structure and degrade nematode genus diversity, and soybean long-term monocuhure drive food web structure towards relative maturity and stability.