外来入侵植物三裂叶豚草凋落叶分解对土壤线虫群落结构的影响

Impacts of leaf litter decomposition of invasive plant Ambrosia trifida on soil nematode community structure.

为了解入侵植物凋落叶对土壤线虫群落结构和多样性的改变,揭示外来植物入侵对土壤生态系统的影响,收集沈阳地区入侵严重的外来植物三裂叶豚草(Ambrosia trifida)和共生的本地植物水蒿(Artemisia selengensis)的凋落叶,通过微生态箱法,在土壤中分别添加这2种植物的凋落叶,对照土壤不添加任何凋落物,之后测定土壤线虫数量和群落结构的变化。结果表明,与本地种水蒿相比,入侵植物三裂叶豚草凋落物分解更快,可能与其具有较高氮含量有关。随着分解时间的延长,2种凋落叶处理的土壤中食细菌线虫密度、食真菌线虫密度和土壤总线虫密度的差异程度增大。分解45天时,添加三裂叶豚草凋落叶的土壤中线虫总密度、食真菌线虫密度显著高于添加水蒿凋落叶的土壤;分解90天时,三裂叶豚草处理土壤中食细菌线虫密度和食真菌线虫密度均显著高于水蒿处理土壤。土壤线虫富集指数随时间虽有上升的趋势,但90天时2种凋落叶添加的处理间并没有显著差异;同时,土壤线虫结构指数有下降趋势,90天时该指数在三裂叶豚草处理的土壤中显著高于水蒿处理的土壤。土壤线虫的多样性指数在分解90天后处理间差异不显著。本研究表明,入侵植物三裂叶豚草通过凋落物分解途径能够显著刺激土壤线虫的增殖,改变土壤线虫的群落结构,但对土壤线虫的多样性影响不显著。

To reveal the impacts of exotic plant invasions on soil ecosystem, we studied the effects of leaf litter decomposition of the invasive plant Ambrosia trifida on soil nematode community structure and diversity. Leaf litters of the invader and the co-occurring native Artemisia selengensiscollected in Shenyang were added on soils in micro-ecotrons, and decomposed for different periods. Then we collected the soils and analyzed nematodes. The results showed that the invader had a higher litter decomposition rate than the native species, which may be associated with the higher nitrogen concentration for the invader. With increasing treatment time the differences in the densities of bacterivores, fungivores, and total nematodes increased between treatments. After 45 days of leaf litter decomposition, the densities of total nematodes and fungivores were significantly higher in invasive plant litter treatment than in native plant litter treatment. After 90 days of treatments, the densities of bacterivores and fungivores were significantly higher in invasive litter treatment than in native plant litter treatment. There was an increasing trend in enrichment index but a declined trend in structure index with increasing treatment time. After 90 days of treatments, the structure index was significantly higher in the invasive plant litter treatment than in the native plant litter treatment, while the difference in soil nematode diversity index was not significant between treatments. Our results suggest that leaf litter decomposition of the invasive species facilitates soil nematode proliferation and alters its community structure, but has no effect on α diversity.