Abstract:

Coarse woody debris (CWD) plays important roles in forest structure and biogeochemical element fluxes between different parts within forest ecosystem, and affects the abundance and distribution of many organisms. Compared with the similar studies in temperate and tropical rain forest, CWD storage, annual increment, its structure and ecological functions are poorly documented in monsoon evergreen broad-leaved forests (MEBF) near the treaved forencer. In this paper, the amount of storage, annual increment of CWD was quantified in an old-growth MEBF at the Dinghushan Nature Reserve, South China. Based on inventory of all trees in a 1-ha permanent plot carried out in 1992, 1994, and 1999, we calculated CWD storage of this community. For sound standing and fallen dead tree, their stocks were separately calculated for bole, branch, leaf, and root using respective regression equations. For stumps, the stocks were calculated based on their volume and average density. Annual increment of CWD for MBEF in the duration from 1992 to 1999 was approximately estimated by calculating the average value of CWD storage increment between two close inventories correspondingly. We also analyzed soil nutrient conditions in a gap to discuss CWD roles in the forest nutrient cycling. Soil samples were collected in 5 subplots (20 m×20 m for each) in the gap area, numbered as No.7, 11, 12, 13, and 17, respectively, analyzing soil organic matter, available N, P, K and total N. The results showed as follows: 1) standing CWD storage in MBEF amounted to 25.278 t·hm-2, of which standing dead boles (snags), fallen boles, large branches were 8.094 t·hm-2, 12.544 t·hm-2, and 4.64 t·hm-2, respectively; 2) Castanopsis chinensis was the main contributor to CWD pool, which accounted for 29.95% of the total CWD storage in MBEF, then followed by Cryptocarya concinna, Aporosa yunnanensis, and Acmena acucminatissma, with the percentage of 26.39%, 3.87%, and 2.80%, respectively; 3) the average annual mortality rate during 1994-1999 was 2.4%, and the average annual increment of CWD in MBEF was 4.128 t·hm-2, and 4) soil organic matter and available K in sub-plot 12 were the highest of all the 5 subplots, while the highest available N and P and total N occurred in sub-plot 11.