Effects of litter thickness on leaf litter decomposition and enzyme activity of three trees in the subtropical forests
亚热带3种树种凋落叶厚度对其分解速率及酶活性的影响

The effect of leaf litter thickness on its decomposition and enzyme activity of Cunninghamia lanceolata, Cinnamomum camphora and Ginkgo biloba were investigated through the experiments.Based on the Zhejiang province average level of acid rain, set up the pH 4.0 values, because the pH4.0 is common distribution in this region and affected the litter decomposition by changes of critical value. Three kinds of litter thickness were set up for the experiments through up the litter weight in same size bag as one indicator, including 40g, 20g and 10g. To simulate nature decomposition conditions, we enclosed leaf litters in the net bags and laid them on the ground follow up the popular method. The results showed litter thickness increased can promote leaf litter decomposition of the three species, and with the thickness increase, the litter decomposition is more quickly. Litter decomposition rate of C. lanceolata in weight 10g,20g and 40g were 0.24,0.27 and,0.34,specifically 40g is much higher than 10g and 20g,but 10g and 20g were no significant difference. C. camphora was 0.25,0.3 and 0.32, specifically 10g is much lower than 20g and 40g,20g and 40g were no significant difference. G. biloba was 0.42,0.5 and 0.58,there are significant differences. While between different species, have different mode in the decomposition rate. For the three kinds of tree species, decomposition rate of G. biloba is the fastest, C. lanceolata is the second, C. camphora is the slowest, they were associate with tree species properties. Also, the effect of litter thickness on urease activity was expressed as:40g>20g >10g, in early stage, urease activity increased slowly,then fell slowly. As to urease activity of C. lanceolata, had significant differences among the three, C. camphora had no significant differences at the preliminary stage, over time, among the three species have significant differences in early stage. G. biloba leaf litter thickness 40g and 20g significantly above 10g. Cellulose activity was expressed as:40g,20g>10g,specifically 10g is much lower than 20g and 40g,this kind of situation in three tree species can exist, litter thickness 20g of C. camphora even above 40g, G. biloba 20g and 40g had no difference. Sucrose activity at the last stage was expressed as:40g>20g >10g, C. lanceolata in early stage had no marked differences between three kinds of litter thickness, in the later period, gradually showed 40g>20g >10g,C. camphora and G. biloba in the early stage performance for 10g>20g >40g results, in the later stage gradually evolved into 40g>20g >10g. Enzyme activity of litter decomposition was greatly influenced by season temperature, with the high temperature, the higher the enzyme activity. A singer enzyme activity changes can't accurate indicator litter decomposition specific conditions, litter decomposition is a complicate process, and it is the result of many kinds of enzymes integrated action.