Abstract: We investigated the responses of soil extracellular enzyme activities and stoichiometric characteristics following the conversion of mixed conifer-broadleaf forest to Castanea henryi plantation in the subtropical region. The results showed that the conversion from natural forest to C. henryi plantation significantly reduced activities of cellulose hydrolase (CBH), β-D-glucosidase (βG), β-N-acetylglucosaminidase (NAG), acid phosphatase (AP) by 70.6%, 53.5%, 82.3%, and 76.2%, respectively. Redundancy analysis indicated that soil pH, soil water content, nitrate nitrogen and available phosphorus were the primary factors driving change in soil extracellular enzyme activities. Soil extracellular enzyme activities were positively correlated with microbial biomass carbon and negatively correlated with nitrate nitrogen. NAG and AP activities were significantly positively correlated with soil moisture, ammonium nitrogen, and total soil carbon. βG activities were significantly positively correlated with total carbon. Soil extracellular enzyme C:N and N:P activity ratios were significantly affected by soil pH, soil moisture, microbial biomass carbon, nitrate nitrogen, ammonium nitrogen, available phosphorus, and total soil carbon, while the C:P activity ratio was positively correlated with soil microbial biomass carbon, ammonium nitrogen, and total carbon. Soil extracellular enzyme C:N:P activity ratio increased from 1:1:1.66 to 1:1:2 following the conversion, with a vector angle greater than 45° and a decrease in the vector length. In summary, the conversion of natural forest to C. henryi plantation led to a significant reduction in soil extracellular enzyme activities and exacerbated phosphorus limitation in subtropical forest soils.

Key words: land use pattern; extracellular enzyme activity; enzyme stoichiometric; Castanea henryi plantation