中亚热带马尾松林凋落物分解过程中的微生物与酶活性动态

采用凋落物原位分解法,研究了中亚热带马尾松林中马尾松、槲栎凋落叶单独及混合(自然质量比8∶2)分解过程中的微生物数量与酶活性动态.结果表明:①3类凋落物的年分解常数K的大小为:混合凋落物(0.94)>槲栎凋落物(0.86)>马尾松凋落物(0.67);②3类凋落物真菌数量和微生物数量均在夏季(135 d时)达到最大值,而此时细菌和放线菌数量最低;③3类凋落物纤维素酶活性、酸性磷酸酶活性均与凋落物干重剩余率呈显著正相关(P<0.05),而马尾松与混合型凋落物中的多酚氧化酶活性同凋落物干重剩余率呈极显著负相关(P<0.01);④微生物数量和多酚氧化酶活性均总体表现为槲栎凋落物>混合凋落物>马尾松凋落物,酸性磷酸酶活性多表现为槲栎凋落物最低,与分解常数K排列有一定的差异,说明凋落物分解是微生物和多种酶共同作用的结果.整体研究表明,凋落物质量和季节气候的差异显著影响微生物群落及其调控的生态过程,与纯马尾松凋落叶相比,针阔混合使微生物数量和多酚氧化酶活性显著提高,这可能是导致分解加快的重要原因.

Dynamics of Microbes and Enzyme Activities During Litter Decomposition of Pinus massoniana Forest in Mid-subtropical Area

The dynamics of microbial quantity and enzyme activities during decomposition process of masson pine (Pinus massoniana) leaf litter, oak (Quercus aliena) leaf litter and their mixture (at natural mass ratio, 8:2) were studied with litterbag method in the pinus forest typical vegetations of mid-subtropical Jinyun Mountain nature reserve. The results showed that the decomposition constant K of leaf litter ranked as follows: mixture (0.94)>oak (0.86)>masson pine (0.67). Microbial groups and enzyme activity exhibited some similar responses to the litter decomposition process. After 135 days, fungal and microbial quantities reached the maximum while bacterial and actinomycetic number reached the minimum, presumably due to the high-temperature environment. The correlative analysis showed that the cellulase and acid phosphatase activity had significant positive relationship with the dry weight remaining rate (P<0.05), which played a key role for microbes in utilizing the substrates at early stages. Meanwhile, the polyphenol oxidase activity showed highly significant negative correlation with the dry weight remaining rate (P<0.01) in pine litter and the mixed litter, which worked on further decay of recalcitrant compound at late stages. Through the whole process, the microbial quantity and polyphenol oxidase activity were generally in the order of oak litter> mixed litter> pine litter, while in most cases the oak litter showed the lowest acid phosphatase activity, the ranking of which had some differences with the order of the decomposition constant K, indicating that litter decomposition was the result of integrated action by microbe and many kinds of enzymes. The results suggested that differences in litter composition and seasonal climate strongly influenced the microbial communities and the ecosystem processes they mediate. When mixed with oak leaves in given stand, the pine litter had an accelerating decomposition rate, which might depend on the higher microbial quantity and polyphenol oxidase activity in the mixed litter.