Abstract: Bursaphelenchus xylophilusinfected Pinus massoniana forest soils were employed to investigate the effects of different infection rates of P. massoniana by pine wood nematode on soil physicochemical properties, microbial biomass and enzyme activities. The results showed that the contents of total carbon (TC), total phosphorus (TP), total potassium (TK), dissolved organic carbon (DOC), ammonium nitrogen (AN), nitrate nitrogen (NN) and available phosphorus (AP), and soil water content (SWC) increased with the aggravation of B. xylophilus infection in the forest soils. However, pH values, the contents of calcium (Ca), magnesium (Mg) and dissolved organic nitrogen (DON), microbial biomass carbon (MBC) or microbial biomass nitrogen (MBN) significantly decreased. Meanwhile, soil sucrase (SA), urease (UA), cellulose (CEA), and phenol oxidase (POA) activities tended to decline, whereas soil acid phosphatase (APA) and protease (PRA) activities were significantly elevated with the deterioration of B. xylophilus infection in the soils. In addition, the UA, SA, CEA and POA activities were negatively correlated with the soil physicochemical indicator of SWC, AN, NN, DOC, TP, TK, AP or TC, but were positively correlated with the soil pH, DON, Mg or Ca content, respectively. The APA and PRA activities were positively correlated with the indicator of SWC, AN, NN, DOC or TK, but negatively with the DON, pH, Mg or Ca content, respectively. The MBC and MBN were negatively correlated with the APA or PRA activity, but positively with the SA, CEA or POA activity, respectively. It was suggested that the B. xylophilus infection caused the changes of soil physicochemical properties as well as soil microbial community, microbial biomass and enzyme activities, which may be used to assess the soil quality in B. xylophilusinfected P. massoniana forest soils.

Key words: rice, melatonin, Cd, chemical form