中文摘要：

对天宝岩国家级自然保护区长苞铁杉林不同海拔、不同腐烂等级枯倒木的径级结构、高度/长度分布,以及材积分布特征等进行了研究,结果表明：（1）天宝岩长苞铁杉林枯倒木主要由小径级木组成,且数量随着海拔的升高呈先降低后上升的趋势,中径级枯倒木所占比例呈现出先升高后降低的趋势,而大径级枯倒木数量最少;（2）枯倒木的高度/长度主要集中在1～6 m,随着高度/长度的增加,各海拔分布的枯倒木所占比例均减小;（3）不同腐烂等级枯倒木材积的变化趋势为Ⅲ〉Ⅳ〉Ⅱ〉Ⅴ〉Ⅰ;（4）不同径级枯倒木材积的分布呈现中径级较大,大径级次之,小径级较小的趋势。

英文摘要：

The dynamic changes of diameter distribution,decay class,height/length distribution and volume distribution were studied in this paper.The results showed that：（1）The Tsuga longibracteata forests in Tianbaoyan National Nature Reserve was mainly composed of small-diameter dead logs which showed a reduction trend in diameter with altitude increasing.While mid diameter logs showed a downward trend in diameter with altitude increasing after the first increase with altitude increasing.And the amount of large diameter dead logs was the least.（2）The height/length ratio of dead logs mainly distributed at the range of 1-6 m.And with the height / length ratio increase,the proportion of dead logs in various altitude reduced.（3）The volume of dead logs in order was ⅢⅣⅡⅤⅠ.（4）With the increase of diameter,the volume of dead logs was in order of mid diameterlarge diametersmall diameter.