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| Hydrological Effects of CWD in Sub-alpine Dark Coniferous Ecosystem of Upper Reaches of Yangtze River |
| Yu Xinxiao,Chen Lihua,Niu Jianzhi,Zhao Yutao |
| Key Laboratory of Soil and Water Conservation & Desertification Combating (Beijing Forestry University), Ministry of Education of China, College of Soil and Water Conservation, Beijing Forestry University, Beijing 100083 |
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Abstract The volume of coarse woody debris (CWD) in dark coniferous ecosystem of upper reaches of Yangtze river amounts to 101 74?m 3/hm 2. There are remarkable differences among different succession community of the fallen tree and snag in terms of their volume and decay degree and decay degree of the fallen. The distribution trend generally abides by the rule of increasing with the succession. The decay degree obeys normal distribution. The second, the third and the fourth degree of fallen tree snag, and CWD account for 86.12%, 78.40% and 79.65% wlume of the total volumes of fallen tree, snag and CWD respectively. The water-absorption and water-losing process is the exponential function of the time. With the decay degree's decreasing, the capacity of CWD water-holding decreases. The natural and saturated water-holding capacities of the first degree of CWD amount to 100%, while those of the fifth can attain to three and a half times to seven and a half times of dry-weight itself respectively. The water-holding function of fallen tree almost amounts to 10 times of that of snag. Totally, 7.41mm of precipitation can be hold by CWD under the natural conditions in the dark coniferous ecosystem whereas 9.91mm of precipitation can be hold if all the CWD are saturated, which is an important contribution to the water regulation role of dark coniferous ecosystem of upper reaches of Yangtze river.
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Received: 21 April 2004
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