增温对高寒灌丛根际和非根际土壤微生物生物量碳氮的影响

Effects of warming on microbial biomass carbon and nitrogen in the rhizosphere and bulk soil in an alpine scrub ecosystem

本文对青藏高原东缘窄叶鲜卑花高寒灌丛生长季根际和非根际土壤微生物生物量碳和氮对增温的响应进行研究.结果表明:窄叶鲜卑花灌丛生长季初期根际和非根际土壤微生物生物量碳和氮均显著高于生长季中期和末期.在多数时期,增温对根际土壤微生物生物量碳和氮的影响不显著.在非根际土壤中,增温对土壤微生物生物量碳和氮的影响因不同生长季节而不同:增温使生长季初期土壤微生物生物量碳显著降低,而使土壤微生物生物量氮显著提高;生长季中期增温使土壤微生物生物量碳和氮显著提高;而在生长季末期增温对土壤微生物生物量碳和氮的影响不显著.土壤微生物生物量碳和氮的根际效应也因不同生长季节而不同:土壤微生物生物量碳和氮在生长季初期表现为负根际效应,而在生长季中期表现为正根际效应;在生长季末期,土壤微生物生物量碳表现为负根际效应,土壤微生物生物量氮则表现为正根际效应.增温在生长季初期使土壤微生物生物量碳和氮的根际效应显著提高,而在生长季中期和末期使土壤微生物生物量碳和氮的根际效应降低.本研究初步阐明了气候变暖背景下高寒灌丛根际和非根际土壤生物学过程变化机理.

To understand the effects of climate warming on the rhizosphere ecological process in the alpine scrub ecosystem,the responses of microbial biomass carbon and nitrogen in the rhizosphere and bulk soil to experimental warming were examined in a Sibiraea angustata scrubland on the eas-tern Qinghai-Tibetan Plateau,China.The results showed that the concentrations of microbial biomass carbon and nitrogen in the rhizosphere and bulk soil in the early growing season were significantly higher than those in the middle and late growing seasons.Experimental warming did not significantly affect the concentrations of microbial biomass carbon and nitrogen of the rhizosphere soil in the most growing seasons.In the bulk soil,however,the effects of experimental warming on the microbial biomass carbon and nitrogen differed among the growing season.Experimental warming significantly decreased microbial biomass carbon but increased microbial biomass nitrogen in the early growing season.In the middle growing season,warming significantly increased both microbial biomass carbon and nitrogen.In the late growing season,there was no significant effect.The rhizosphere effects of soil microbial biomass carbon and nitrogen also differed with the growing season.The rhizosphere effects of microbial biomass carbon and nitrogen were negative in the early growing season but positive in the middle growing season.In the late growing season,there were negative rhizosphere effects of soil microbial biomass carbon and positive rhizosphere effects of soil microbial biomass nitrogen.Furthermore,experimental warming significantly increased the rhizosphere effects of soil microbial biomass carbon and nitrogen in the early growing season,but decreased those in the middle and late growing seasons.These results uncovered the changing mechanism of the biologi-cal process in the rhizosphere and bulk soil in the alpine scrub ecosystems under the background of climate warming.