季节变化对沙漠生态系统土壤中自由生活线虫和原生动物间营养关系的影响

选择沙漠常绿灌木丛枝霸王(Zygophyllum dumosum)群落及群落间的开阔地带采样,研究土壤线虫和原生动物的种群大小、物种组成及营养结构.本研究共获线虫29属,裸变形虫33属90种;在所获各类原生动物中,鞭毛虫和纤毛虫均为食细菌类群,而鞭毛虫个体数量最多;在沙漠生态系统中,土壤湿度被认为是影响生物活性的最重要因素之一.然而,本研究显示:土壤湿度对线虫和原生动物是否重要取决于这些动物对土壤湿度的生理生态适应能力;土壤线虫和原生动物的体型大小、生活史策略和活动能力与土壤湿度的有效性相关不显著,但它们对微生物和微小土壤动物区系间的相互作用有重要影响,在干旱生态系统中,这种影响能够显著改变土壤生态系统短期的养分循环.本研究还表明,土壤线虫和原生动物种群间的关系主要取决于两者营养类群组成的变化.

Seasonal effect on trophical relationship between soil free-living nematode and protozoan populations in a desert ecosystem

The population, taxa composition and trophic structure of microfaunal(nematode and protozoan) communities were studied in soil samples collected under perennial Zygophyllum dumosum shrubs and from intershrub open spaces in a desert soil system. Soil moisture is known to be one of the most important and unpredictable triggers initiating biological activity in desert systems. However, the responses of the nematode and protozoan populations to this leading factor were found to be different due to differences in their ecophysiological adaptation. The main factor found to control nematode/protozoan interactions was the trophic group composition in the soil habitat. The nematode and gymnamoeba populations were represented by 29 and 90 taxa, respectively. Furthermore, the absolute number of flagellates tended to be greater than that of the ciliates and gymnamoeba, where both groups(flagellates and ciliates) are known to be bacterial feeders. The differences in size, life strategies, mobility, and the response of the nematode and protozoan populations to soil moisture availability were not found to be strongly related. However, they can have a significant effect on microbial-microfaunal interactions, which can, in turn, significantly affect short-term nutrient cycling in arid systems.