Abstract:Soil enzyme plays an important role in the biochemical processes of forest ecosystems, which can quickly reflect the changes of soil environment (such as nutrient content and availability). Harvest residue is an important source of forest soil nutrients, and its treatment methods will affect the nutrient content and availability of forest soil. In order to explore the effects of different harvest residue treatments on soil enzymes activities, harvest residue was managed in the following ways, i.e., residue retained (RR), residue removed (R) and residue burnt (RB) after cutting a 40-year-old mature Chinese fir forest in Sanming City, Fujian, and six soil extracellular enzymes activities in 0-10 and 10-20 cm soil layers were studied. The results showed that: (1) After 4 years of harvest residue treatment, compared with RR treatment, the contents of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), inorganic nitrogen (IN) and NO3--N in RB and R treatments decreased significantly. Further, the decrease of NO3--N content under RB treatment was significantly higher than that of R treatment, decreased by 88% and 51% for 0-10 and 10-20 cm soil layers respectively; (2) Compared with RR treatment, microbial biomass phosphorus (MBP) and carbon (MBC), and six soil enzymes activities, that were acid phosphatase (AP), β-1,4-glucosidase (βG), Cellobiohydrolase (CBH), β-1,4-N-acetylglucosaminidase (NAG), Poly-phenol oxidase (PHO), and Peroxidase (PEO) of RB and R treatments decreased significantly. Also MBC and MBP contents in two soil layers under RB treatment were significantly lower than those of R treatment; (3) Redundancy analysis showed that soil enzymes activities in the 0-10 cm layer were significantly correlated with soil MBP and MBC contents, and DON, NO3--N and MBC were the key factors affecting soil enzyme activities in the 10-20 cm layer. Therefore, the retention of harvest residues is beneficial to the improvement of soil nutrients and enzyme activity, and it is an effective management measure for the maintenance of soil fertility and the improvement of forest productivity.