天宝岩猴头杜鹃林粗死木质残体数量特征

对天宝岩国家级自然保护区不同天然猴头杜鹃林粗死木质残体(coarse woody debris,CWD)的形态、贮量、直径分布规律以及腐烂等级分布特征等方面进行对比研究。结果表明,CWD输入形式多样,主要是以倒木、枯立木和树桩的形式存在;从树种组成看,CWD以猴头杜鹃和长苞铁杉为主;随着海拔上升,CWD总贮量、各类CWD现存量均呈递增趋势,各个腐烂等级CWD也基本呈递增趋势;猴头杜鹃林CWD现存量呈正态分布,数量顺序为Ⅱ>Ⅲ>Ⅴ>Ⅳ>Ⅰ,此外,CWD总现存量为45.266 4 t.hm-2,且倒木>枯立木>树桩;各海拔猴头杜鹃林主要是由小径级木组成,直径为0-20 cm的CWD所占比例随着海拔增加呈现递减趋势,此外,CWD的数量大小顺序为小径级木>中径级木>大径级木,即随着径级的增大,倒木和枯立木数量均呈减少趋势;无论是倒木、枯立木还是树桩,其腐烂等级分布呈增—减—增趋势,出现2个高峰,即Ⅱ和Ⅴ级。

Quantitative characteristics of coarse woody debris in natural Rhododendron simiarum forests in Tianbaoyan National Nature Reserve

The comparative study on the input ways,storage,diameter distribution and decay rank characteristics of coarse woody debris in different elevations in Tianbaoyan national nature reserve was conducted.The results showed that: the means of CWD input were different,mainly in the forms of fallen trees,snags and stumps,there-into,the fallen trees were composed of the uprooted blown down,the breakage at trunk and the blown down.In view of the composition of tree species,CWD was mainly made up of Rhododendron simiarum and Tsuga longibracteata.With the increase of the elevation,the storage of total CWD,and each type of CWD displayed the ever-increasing trend,and each rank of decay class almost had the same trend,and Ⅱ and Ⅲ dominated.The storage of CWD in Rhododendron simiarum forests displayed Normal Distribution,namely,the storage within the range of II and Ⅲ was relatively much,while within the other decay ranks was relatively little,the order was like this: Ⅱ>Ⅲ>Ⅴ>Ⅳ>Ⅰ,in addition,the total storage was 45.266 4 t·hm-2,and the storage of fallen trees was far more than that of snags or stumps,followed by that of the snags,and the storage of stumps was second to the snags′.Rhododendron simiarum forests were mainly composed of CWD of small-diameter-class at the three elevations,and the percentage of 0-20 cm was becoming smaller and smaller with the increase of the elevation,besides,the number of small-diameter trees was the most,and the middle-diameter trees more than the big-diameter ones,in other words,the number of fallen trees and snags decreased with the increase of diameter.The decay-class distribution of each type of CWD was turned out to be increase-decrease-increase.