模拟升温和放牧对高寒草甸土壤有机碳氮组分和微生物生物量的影响  

Labile and recalcitrant carbon and nitrogen pools of an alpine meadow soil from the eastern Qinghai-Tibetan Plateau subjected to experimental warming and grazing

作　　者：王蓓[1,2] 孙庚[1] 罗鹏[1] 王萌[1,2] 吴宁[1] 

机构地区：[1]中国科学院成都生物研究所生态恢复重点实验室,四川成都610041 [2]中国科学院研究生院,北京100049

出　　处：《生态学报》2011年第6期1506-1514,共9页Acta Ecologica Sinica

基　　金：国家"十一五"科技支撑计划项目(2007BAC18B04和2006BAC01A11);中国科学院"西部之光"人才培养计划一般项目;中国科学院"西部之光"人才培养计划西部博士资助项目;中国科学院山地生态恢复与生物资源利用重点实验室开放课题

摘　　要：土壤活性、惰性有机质库和微生物生物量在数量和分配上的变化是陆地生态系统土壤有机质贮存和动态变化的决定性因素。采用OTCs(Open top chambers)升温以及刈割+粪便归还的方法,对青藏高原东部高寒草甸土壤有机碳氮组分和微生物生物量对气候变暖和放牧的响应进行了研究。结果表明,模拟升温在短期内显著降低土壤活性有机碳Ⅰ、活性有机氮Ⅰ和惰性有机碳的含量,而由于粪便归还作用,放牧明显增加土壤活性有机碳、氮Ⅰ的含量。模拟升温和放牧对有机碳、氮组分的作用效应相互抵消,两者共同作用下有机碳、氮组分仅略有降低。单一的模拟升温或放牧没有显著改变微生物生物量碳,但是两者共同作用却能够大大增加微生物生物量碳。放牧和取样时间存在着明显的交互作用,放牧效应随时间递减。本研究表明,气候变暖对放牧草甸有机碳、氮组分影响不大;放牧过程中的牲畜粪便归还作用不容忽视。In terrestrial soils,carbon（C） and nitrogen（N） fluxes are primarily controlled by small but highly bio-reactive labile pools,while long term C and N storage is determined by the long-lived recalcitrant fraction.Changes in the size of labile,recalcitrant,and microbial carbon and nitrogen pools as well as redistribution among them may considerably affect terrestrial soil C and N storage and turnover rates.Hence,analyzing the labile and recalcitrant fraction of soils may improve our ability to detect and predict changes in soil C and N dynamics.This study used OTCs（Open Top Chambers） and clipping plus dung application and sulfuric acid hydrolysis to quantify changes in the labile and recalcitrant C and N fractions in soils from alpine meadows in the eastern Qinghai-Tibetan Plateau.Further,the effects of warming and grazing on labile and recalcitrant C and N fractions and microbial biomass in these soils were investigated.Using OTCs to warm soils resulted in an increase of 2.25℃ in daily mean air temperature at 30 cm above the ground and an increase of 1.17℃ in soil temperature at 10 cm depth,yielding significantly decreased labile C and N pools along with diminished recalcitrant C pool in the short-term,indicating an increase in soil respiration.Grazing markedly increased labile C and N pools I due to dung application,resulting in increments of 567 mg C/kg dry soil（26.13%） and 28mg N/kg（11.21%）.The effects of warming and grazing on labile and recalcitrant pools counteracted each other,which led to non-significant changes in the combined treatments.Although warming or grazing alone did not alter the microbial biomass C pool,the combined treatments greatly increased it,by an increment of 147 mg C/kg dry soil（41.91%）.The interaction between grazing and sampling dates was significant and the effects of grazing decreased with time.For all measured pools,soil microbial biomass C and N showed significant interactions between warming,grazing,and sampling dates,indicating that microbial biomass C

关 键 词：气候变暖 放牧 活性有机碳组分 活性有机氮组分 牛粪 微生物生物量 

分 类 号：S812.2[农业科学—草业科学]