Effect of Polyphenol of leaf litter on the leaf breakdown in a subtropical Stream
GUAN Zhao-ying1, ZHAO Ying2, TONG Xiao-li1
1. College of Nature Resources and Environment, South China Agricultural University, Guangzhou 510642, China; 2. College of Science, South China Agricultural University, Guangzhou 510642, China
We used a spectrophotometry method with 1, 10-phenanthroline-Fe (Ⅲ) to determine the contents of total polyphenol in two species of leaf litter, Dracontomelon duperreanum and Syzygium jambos. The effects of remaining polyphenolics concentration on decomposition rates, colonization of macroinvertibrates and microbial respiration in a subtropical stream were examined. Results showed that total polyphenol was significantly higher in S. jambos (19%) when compared to D. duperreanum (6%), and breakdown rate of S. jambos (k=0.01 day–1) was slower than that of D. duperreanum (k=0.04 day–1). The results also indicated that the average microbial respiration rates (0.2 mg O2 h-1 g DM-1) of S. jambos litters was significantly lower than those of D. duperreanum ( 0.4 mg O2 h-1 g DM-1), and its taxa richness and total density in shredders of macroinvertebrate was significantly less than in those of D. duperreanum (P<0.05). The low breakdown rate of S. jambos leaves in the early period is mainly as a result of inhibition of microbial activity as well as less palatable to shredders of macroinvertebrates due to high contents of polyphenols, which showed that the leaf polyphenol had a strong negative effect on leaf litter decomposition.