贵州省喀斯特地区凋落物分解对气候变暖的响应

Litter Decomposition and Its Responses to Climate Warming in Karst Area of Guizhou Province

采用纬向温度梯度模拟研究了气候变暖对喀斯特地区凋落物分解的影响,以普定原生乔木林叶凋落物为研究对象,将装有普定原生乔木林叶凋落物的分解袋同时分别放置在普定原生乔木林(原地)、茂兰原生乔木林样地(异地模拟气候变暖)进行分解,每月月底回收1次。经过两年的分解,原地分解(CK)和异地模拟气候变暖分解(CM)的质量剩余率分别为28%和24%,异地模拟气候变暖分解的月均失重率总体上大于原地分解。异地模拟气候变暖3.2℃,凋落物分解50%、分解95%所需的时间变短,分解半衰期缩短11.8%。在分解的24个月里,随着分解时间的推进,叶凋落物中C含量呈递减的趋势,N含量呈递增的趋势;从群落水平来看,分解过程中C含量总体上表现为原地分解>异地模拟气候变暖分解,N含量总体上表现为异地模拟气候变暖分解>原地分解。在降水量基本不变、气候变暖3.2℃情景下,叶凋落物在分解过程中的N含量升高,C含量及C/N值降低,其分解速率加快了1.14倍。

The effect of climate warming on litter decomposition in Karst area was studied by using the method of latitudinal temperature gradient in this paper.Litter of Puding primeval arboreal forest was used as the research object.The decomposition bags containing the leaf litter of Puding primeval arboreal forest were separately placed in Puding primeval arboreal forest(in-situ,CK)and Maolan primeval arboreal forest(remote simulation of climate warming,CM)at the same time,and the bags were collected at the end of each month.After two years of decomposition,the mass residual rates of the CK and CM were 28%and 24%respectively,and the average monthly weight loss rate of the remote simulated climate warming decomposition was greater than that of the in-situ decomposition.In the CM,the climate warmed by 3.2℃,the decomposition time of litters by 50%and 95%was shortened,and the decomposition half-life reduced by 11.8%.During the 24 months of decomposition,the C content in leaf litter showed a decreasing trend and the N content showed an increasing trend with the advance of decomposition time.From the perspective of community level,during the decomposition process,the C content in Puding was higher than that in Maolan,while the N content was opposite.Under the condition that precipitation was basically unchanged and the climate warmed by 3.2℃,the N content of leaf litter increased during decomposition while the C content and C/N ratio decreased,and the decomposition rate of leaf litter accelerated by 1.14 times.