[Changes of total phenols and condensed tannins during the decomposition of mixed leaf litter of Pinus massoniana and broad-leaved trees.]

A field litterbag experiment was conducted to investigate dynamics of total phenols and condensed tannin in the mixed leaf litter of Pinus massoniana (P) with other three broad-leaved species, i.e., Sassafras trumu (S), Cinnamomum camphora (C), Toona sinensis (T) during decomposition in low hilly lands, Sichuan Province, China. The mass ratio of P. massoniana : S. trumu (PS) was 6:4, 7:3, 8:2, P. massoniana : C. camphora (PC) was 6:4, 7:3, 8:2 and P. massoniana : T. sinensis (PT) was 6:4, 7:3, 8:2, respectively. The results showed that the degradation rate of condensed tannin in pure P. massoniana litter was 84.4%, being significantly lower than that in the mixed litters after 180 d. The degradation rate of condensed tannin and total phenols were the highest in PC 6:4, with 90.3% and 68.6%, respectively. The mixed litters promoted the decomposition of condensed tannin and total phenols in the P. massoniana litter. With decomposition time, the degradation rate of condensed tannin in mixed litters between P. massoniana and broad-leaved species initial increased, and then remained stable. The degradation rate of total phenols in pure P. massoniana litter, PT 7:3 and all the PC treatments increased significantly and then decreased during the 90 d decomposition. The degradation rate of total phenols in all the PS, PT 6:4 and 8:2 treatments increased with the decomposition time. The dynamics of total phenols and condensed tannin were closely related to litter quality, and the enzyme activities of polyphenol oxidase, peroxidase and leucine aminopeptidase.