藏东南暗针叶林粗木质残体的数量特征

Quantitative Characters of Coarse Woody Debris of Dark Coniferous Forest in Southeast Tibet,China

通过对藏东南暗针叶林粗木质残体进行调查研究,分析了林内粗木质残体的数量特征。研究表明:倒木是粗木质残体的主要输入形式;在粗木质残体平均数量上,阴坡为258.67株/hm2,多于阳坡(237.22株/hm2),但受生境影响,阴坡的1级腐烂、2级腐烂粗木质残体数量较阳坡少,而3级腐烂较阳坡多;在与海拔的关系上,阴坡粗木质残体数量随海拔高度变化呈双峰曲线,峰值分别在4 000m和4 200m处,其数量分别为511.11株/hm2、366.67株/hm2,阳坡粗木质残体随海拔高度的升高呈逐渐减少趋势,但规律不明显,且阳坡、阴坡粗木质残体均在海拔4 100m处存在一个相对低值,均为133.33株/hm2;在径级分布上,所有粗木质残体主要分布于小径级上,尤其是大凋落枝几乎只存在小径级粗木质残体。

Based on investigation of coarse woody debris （CWD）of dark coniferous forest in Southeast Tibet,quantitative characters of CWD under the forest were analyzed.The results showed that fallen wood was the main source of CWD;mean value of CWD of the forest on shady slop was 2 5 8.6 7 plants/ha,higher than that on the sunny slop（237.22 plants/ha）,which also depended on habitats,decay classⅠ＆amp;Ⅱof CWD of the forest on shady slop were less than that on sunny slope,but decay classⅢ of the former was more than that of the latter;the relationship between CWD on shady slope and elevation showed a double-peak curve,with the peak values of 5 1 1.1 1 plants/ha at an altitude of 4 000 m and 366.67 plants/ha at an altitude of 4 200 m,by contrast,the CWD on sunny slope showed an inconspicuously descending trend,and the lowest value（133.33 plants/ha）appeared at an altitude of 4 100 m for both CWD on shady slope and that on sunny slope;all the CWD were in small diameter classes,especially the big branch litter.