根系在凋落物层生长对凋落叶分解及酶活性的影响

Effects of root growth on leaf litter decomposition and enzyme activity in litter layer

根系向凋落物层生长是森林生态系统存在的普遍现象,研究根系存在对凋落物分解的影响对理解森林生态系统的养分物质循环具有重要意义。在福建三明市楠木和格氏栲林进行1年的凋落叶分解试验,设置有根处理和无根处理(对照),研究根系生长对凋落叶分解速率、养分释放和酶活性的影响。结果表明:在分解360 d后,有根处理楠木和格氏栲凋落叶干重残留率比对照分别降低8.4%和19.7%;根系在分解前期(90~180 d)对凋落叶分解影响最为显著。在分解360 d后,与对照相比,有根处理凋落叶碳、氮、磷残留率在楠木人工林分别降低6.0%、19.1%和20.6%,在格氏栲人工林分别降低21.3%、23.2%和20.5%。在整个分解过程中,根系生长对凋落叶水解酶活性无显著影响;在分解180 d时,楠木和格氏栲有根处理凋落叶过氧化物酶活性比对照显著升高111.4%和92.4%。碳、氮、磷残留率与纤维素水解酶、β-葡萄糖苷酶、酸性磷酸酶和过氧化物酶活性呈显著负相关。根系在凋落物层生长会通过养分吸收和刺激氧化酶活性来加速凋落叶分解和养分释放过程。

The growth of roots towards aboveground litter layer is a common phenomenon in forest ecosystems.It is of great significance to examine the effects of root presence on litter decomposition for understanding nutrient cycling in forest ecosystems.We explored the effects of root growth on leaf litter decomposition,nutrient release and enzyme activities by establishing treatments with and without root with a one year field decomposition experiment in Phoebe zhennan and Castanopsis kawada-mii forests at Sanming,Fujian.The results showed that after 360 days decomposition,leaf litter mass remaining ratio in the treatment with root was 8.4%and 19.7%lower than control,respectively.The presence of root exhibited significant effect on litter decomposition during the 90-180 days.Compared with the control,the remaining ratio of leaf litter carbon,nitrogen and phosphorus were 6.0%,19.1%and 20.6%lower in the treatment with root in the P.zhennan forest,and were 21.3%,23.2%and 20.5%lower in the C.kawadamii forest,respectively.During the whole decomposition process,root presence did not affect the hydrolytic enzyme activity.After 180 days decomposition,the peroxidase activities in the treatment with root were 111.4%and 92.4%higher than control in the P.zhennan and C.kawadamii forests,respectively.The remaining ratio of leaf litter carbon,nitrogen and phosphorus were negatively correlated with the activities of cellobiohydrolase,β-glucosidase,acid phosphatase,and peroxidase.Root presence in litter layer could accelerate litter decomposition and nutrient release through nutrient uptake and stimulation of oxidase activity.