荒漠-绿洲土壤微生物群落组成与其活性对比

Comparative on microbial community composition and microbial activities in desert and oasis soils

结合野外观测与实验室研究方法,对比研究了准葛尔盆地南缘盐生荒漠与绿洲农田土壤微生物活性与其群落组成的变化特征,并分析了土壤温度与湿度对荒漠-绿洲土壤微生物活性的影响。结果表明:荒漠开垦为绿洲后,土壤细菌明显增加,真菌无明显变化,放线菌显著减少。细菌在绿洲农田土壤矿化作用中占主导,真菌则在荒漠中占优势,绿洲农田土壤微生物活性(包括真菌与细菌活性)明显高于荒漠。温度对荒漠-绿洲土壤微生物活性的影响只在一定土壤湿度范围内作用显著,绿洲农田受其影响较大;荒漠有机质含量明显高于绿洲农田,但水分与盐分因素抑制了微生物对其的分解和矿化。不同土地利用方式导致了荒漠绿洲间土壤湿度及盐份的较大差异,加之与土壤温度极显著的交互作用,使得开垦后土壤有机碳的易得性增强,微生物群落结构发生显著改变,进而有机碳的矿化速率加快,土壤碳库随之消减。

Desert grey soil is one of the typical soil types in were selected to represent the desert grey soil. The microbial arid zone. Soils at Fu-Kang oasis and the surrounding desert community composition and microbial activities were compared between saline desert and oasis farmland at south periphery of Gurbantonggut desert. The eukaryote （fungi） and prokaryote （bacteria） contribution to microbial activity were determined with selective inhibition techniques applied to soils. The gradients of soil temperature （17 --37 ℃ ） and moisture （8%--30%） were applied in treatments to understand the effects of temperature and moisture on soil microbial activities. Significant differences were found in microbial activities and community composition between desert and oasis. After the desert land was cultivated and became oasis, the number of bacteria increased, actinomyces decreased significantly, and fungi didn＇t change that significant. There was a bacterial higher than that in desert. Microbial activities both in oasis field and in desert were exponentially correlated with soil temperature, but the effect of temperature on the former was more significant. Temperature had significant effect on microbial activity in desert and oasis, but only for a given range of soil moisture. Meanwhile, the content of soil organic matter in desert was higher than that in oasis field, but had not resulted in high microbial activity in desert, which was likely caused by low soil moisture and high salt content. Namely, when desert became oasis after cultivation of the land,contrasting difference existed in soil moisture and salt content, which increased availability of soil organic carbon , and resulted in a significant difference in soil microbial composition and activities, and at the end, decreases of the soil carbon storage.