湖南八面山保护区银杉的种群数量和生长特征

Characteristics in quantity and growth pattern of Cathaya argyrophylla population in Bamianshan Reserve of Hunan

银杉(Cathaya argyrophylla)是我国特有的珍稀濒危植物,在森林生态系统生物多样性保护中起着关键作用。为分析湖南八面山银杉种群的数量特征和生长规律,给银杉种群的保护管理提供科学依据,通过全面系统调查和分析保护区银杉种群现状及其数量特征,利用标准主轴回归(SMA)方法研究了银杉树高和胸径之间的相对生长规律。结果为,八面山保护区银杉主要分布在苁光漏、脚盆寮、下黄、正江里、坳背里、大山里和田坳里等地段,存活个体共计406株,其中胸径6cm以下的幼苗、幼树有271株,占比为2/3;胸径6cm以上的银杉中,健康个体、枝干受损伤的个体、倾倒多年或死亡的个体分别为116株、8株和17株,2008年南方冰雪灾害造成保护区内7株银杉倾倒死亡;径级较大的银杉主要分布在脚盆寮和下黄,最大胸径分别为63.9cm和53.0cm,最大株高分别为21.0m和23.0m;苁光漏、脚盆寮和下黄的立地条件较好,银杉株高和胸径之间为等速生长,正江里的立地条件较差,株高和胸径之间的相对生长关系不显著。八面山保护区银杉种群数量较为稳定,但损伤、倾倒和死亡个体所占比例较大;银杉株高和胸径之间为等速生长,符合几何自相似理论;保护区较差的立地条件限制了银杉株高生长,但增强树体抵抗大风和冰雪积压的能力,有利于提高银杉的存活率。

Cathaya argyrophylla is a rare and endangered plant endemic to China and plays a key role in biodiversity conservation in forest ecosystems.This study aims to analyze the quantitative characteristics and growth patterns of the population.Firstly,we analyzed the quantitative characteristics of the population through a comprehensive and systematic survey of the status of C.argyrophylla in Hunan Bamianshan Reserve.Then the relative growth relationships between total height(H)and diameter at breast height(DBH)was quantified.A total of 406 living trees of C.argyrophylla were mainly distributed in Congguanglou,Jiaopenliao,Xiahuang,Zhengjiangli,Aobeili,Dashanli and Tianaoli,of which 271 were seedlings and saplings with DBH less than 6 cm and made up 2/3 of the population.For trees with DBH more than 6 cm,the number of healthy trees,damaged trees and trees fallen or dead were 116,8 and 17,respectively.Seven mature trees were dumped and dead during a snow disaster in southern China in 2008.Large trees were mainly distributed in Jiaopenliao and Xiahuang,the largest DBH were 63.9 cm and 53.0 cm and the largest H were 21.0 cm and 23.0 cm,respectively.Congguanglou,Jiaopenliao and Xiahuang were of good site condition,within which the relative growth relationships between H and DBH were isometric.While in Zhengjiangli,the site condition was relatively poorer,and the relative growth relationship between H and DBH was not significant.It is therefore concluded that the population state of C.argyrophylla in Bamianshan Reserve was stable;however,there were large proportions of damaged,dumped and dead trees.The relative growth relationships between H and DBH of C.argyrophylla were isometric and conformed to the geometricself-similarity theory.Although poor site condition restrained the height growth,it enhanced the ability to resist strong winds and heavy snows,and helped improve the survival rate of C.argyrophylla.