Characterizations of soil enzyme activities and stoichiometry in three subtropical forest stands
We conducted in a common garden experiment to explore the differences in soil enzyme activity,stoichi-ometry,and their influencing factors among a secondary Castanopsis carlesii forest,10-year-old C.carlesii planta-tion,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 NO3--N were the primary factors influencing soil enzyme activity and enzymic stoichiometry.Collectively,there were significant differences in soil enzyme activity and micro-bial nutrient demands among different forest stands.Compared to secondary forests,the establishment of C.lanceo-lata plantations would intensify nutrient competition between plants and microbes,and exacerbate the N and P limi-tations for microbes.