亚热带三种林分土壤酶活性和酶化学计量比特征

Characterizations of soil enzyme activities and stoichiometry in three subtropical forest stands

本研究依托同质园观测样地,选择次生林(主要树种为米槠)、10年生的米槠人工林和杉木人工林为研究对象,分析亚热带不同林分土壤酶活性和计量比特征的差异及其影响因素。结果表明:与次生林相比,米槠人工林土壤有机碳、总氮和可溶性有机碳含量分别显著降低42.6%、47.4%和60.9%,杉木人工林显著降低了42.9%、36.7%和61.1%。相比于次生林,米槠人工林土壤微生物生物量碳、微生物生物量氮(MBN)以及微生物生物量磷分别显著降低40.6%、35.5%和45.9%,杉木人工林显著降低了53.7%、56.4%和61.7%。与次生林相比,米槠人工林土壤酶活性变化不显著,但杉木人工林的碳获取酶(β-1,4-葡萄糖苷酶和纤维二糖水解酶)活性显著降低51.2%和59.8%,氮和磷获取酶活性分别显著降低41.0%和29.8%,碳获取酶/氮获取酶以及碳获取酶/磷获取酶分别显著降低11.3%和7.7%。冗余分析表明,MBN和硝态氮是驱动土壤酶活性及酶化学计量比变化的主要因素。不同林分的土壤酶活性和微生物养分需求存在显著差异,与次生林相比,营造杉木人工林会刺激植物与微生物的养分竞争,加剧微生物的氮、磷养分限制。

We conducted in a common garden experiment to explore the differences in soil enzyme activity,stoichiometry,and their influencing factors among a secondary Castanopsis carlesii forest,10-year-old C.carlesii plantation,and Cunninghamia lanceolata plantation.The results showed that compared to the secondary forest,the soil organic carbon,total nitrogen,and dissolved organic carbon significantly decreased by 42.6%,47.4%,and 60.9% in C.carlesii plantation,and by 42.9%,36.7%,and 61.1% in C.lanceolata plantation.Soil microbial biomass C,microbial biomass N(MBN),and microbial biomass phosphorus decreased significantly by 40.6%,35.5%,and 45.9%in C.carlesii plantation,and by 53.7%、56.4%,and 61.7% in C.lanceolata plantation.Compared to the secondary forest,soil enzymes activities in C.carlesii plantation did not change significantly,but in C.lanceolata plantation,the activities of β-1,4-glucosidase and cellobiohydrolase significantly decreased by 51.2%and 59.8%,β-N-acetyl glucosaminidase and acid phosphatase decreased significantly by 41.0% and 29.8%,and enzymatic C:N acquisition ratio and enzymatic C:P acquisition ratio significantly decreased by 11.3%and 7.7%,respectively.Results of redundancy analysis indicated that MBN and NO_(3)^(-)-N were the primary factors influencing soil enzyme activity and enzymic stoichiometry.Collectively,there were significant differences in soil enzyme activity and microbial nutrient demands among different forest stands.Compared to secondary forests,the establishment of C.lanceolata plantations would intensify nutrient competition between plants and microbes,and exacerbate the N and P limitations for microbes.