降水量对川西北高寒草甸牦牛粪分解速率的影响  

Effect of rainfall regimes on the decomposition rate of yak dung in an alpine meadow of northwest Sichuan Province,China

作　　者：吴新卫[1] 李国勇[1] 孙书存[1,2] 

机构地区：[1]中国科学院成都生物研究所,成都610041 [2]南京大学生物系,南京210093

出　　处：《生态学报》2011年第23期7013-7021,共9页Acta Ecologica Sinica

基　　金：国家自然科学基金资助项目(31000232)

摘　　要：青藏高原高寒草甸的降水年际变化很大,而且在未来全球气候变化的背景下可能进一步增大。为了研究降水量变化对川西北高寒草甸牦牛粪分解的潜在影响,通过塑料膜覆盖(去除降水)、模拟额外增水(增水量为实际降水量的50%)和对照(野外无干扰情形)形成3种不同的水分处理。测定了牛粪的含水量、干重及氮磷含量,并统计了主要分解者(手捡法获取粪食性甲虫及其幼虫)的种类和数量。结果发现:覆盖处理显著地降低了牛粪含水量、牛粪中的粪食性甲虫数量与牛粪分解量,但增水处理并没有显著影响牛粪的分解进程,可能与实验期间降水量较高有关。在牛粪分解前期,粪食性甲虫数量与牛粪含水量之间正相关,而牛粪分解量与粪食性甲虫数量之间正相关,说明牛粪含水量的高低影响了粪食性甲虫数量,进而决定了牛粪分解量。但是,降水量的人为增加或减少均没有显著地改变牛粪中的全氮和全磷含量。总体上看,在高寒草甸的放牧生态系统中,降水量的减少将会降低牛粪的分解速率、延长牛粪分解过程,从而可能会降低生态系统的生产力水平。The alpine meadow of the Tibetan Plateau is the fifth largest rangeland of China. The estimated population density of yaks is about 10/hm2 ; the recorded dung density is about 3600 pats/hm2 on average and sometimes can reach 5900 pats per hm2, occupying about 24% of the total grassland area in summer grazing pastures. The decomposition rate of yak dung is therefore of great importance to ecosystem primary productivity and nutrient cycling of the alpine meadow. Previous studies have demonstrated that the decomposition rate is largely dependent upon both abiotic factors such as temperature and rainfall and biotic factors including microbial biomass and the abundance of beetles, flies, and many other decomposers. Changes of the abiotic factors may affect the dung physical properties and dung the decomposer abundances, collectively influencing the rate of the dung loss rate. However, the effect of the abiotic factors on the dung decomposition has scarcely been examined in relation to the decomposer abundances. The amount of rainfall fluctuates greatly between years and the magnitude of the interannual variation may become greater in the future warmed world of the Tibetan Plateau. In this study, in order to determine the potential effect of rainfall regimes on the decomposition rate of yak dung and associated underlying mechanisms, we artificially manipulated rainfall amount to conduct an experiment involving three treatments including yak dung pats covered by plastic than natural rainfall） , and exposed to natural rainfall sheet （rainfall exclusion） , sprayed with additional water （50% more （as control） in an alpine meadow of northwestern Siehuan Province.For each treatment, there were 30 replicates that were sampled for 6 times （ on the third, fifth, eighth, thirteenth, eighteenth, and twenty-fifth days after starting the experiment）, each having five replicates. Water content, the number of coprophagous beetle adults and larvae that were hand-collected, and the dung dry weight were surveyed for 6 ti

关 键 词：降水 牛粪分解 养分释放 高寒草甸 粪食性甲虫 

分 类 号：S812[农业科学—草业科学]