贵州茂兰珍稀濒危植物四药门花种群特征

Population characteristics of rare and endangered Loropetalum subcordatum in Maolan Natural Reserve of Guizhou

关键词:  珍稀濒危植物, 径级结构, 静态生命表, 存活曲线, 茂兰国家自然保护区

Key words:  rare and endangered plants, diameter structure, static life table, survival curve, Maolan National Natural Reserve

摘要:

四药门花是我国特有的珍稀濒危植物,其种群特征是制定切实有效保护策略的重要依据。该研究根据四药门花在贵州茂兰的分布特征,设置了5个40 m × 10 m样带对其种群进行调查,从种群径级结构[Ⅲ级开始,胸径(DBH)2.5 cm 为一个径级]、静态生命表、存活曲线等方面分析其种群结构。结果表明:(1)贵州茂兰四药门花个体数比例最大的为IV级(2.5 cm≤DBH<5 cm),占27.0%,幼苗库的个体数比例占24.7%,为稳定型种群。(2)I级(h<1.3 m)、Ⅱ级(h>1.3 m且DBH<1 cm)的生命期望值最大; 在V龄级(5 cm≤DBH<7.5 cm)前的预期生命值随着年龄增加而降低,V龄级后预期寿命先升后降。(3)死亡率曲线和消失度曲线趋势一致,大致表现为先上升后下降但降幅较小; 龄级V的死亡率和消失度最高,其主要影响因素可能为环境筛尤其是水分胁迫。(4)存活曲线除Ⅱ级到Ⅲ级(1 cm≤DBH<2.5 cm)有小幅上升外,基本单调递减。(5)四药门花种群的就地保护,除延续现在的封禁模式外,需要对中树加强抚育。

Abstract:

Loropetalum subcordatum(Hamamelidaceae)is one of rare and endangered species, and endemic species to China. The population structure is an element issue for its protection. The innovation of this paper was to analyzed population characteristics of L. subcordatum in Maolan Karst Natural Reserve, Guizhou Province and to provide countermeasure for protecting L. subcordatum. We investigated the population diameter structure, static life table and studied survival curve of L. subcordatum based on the survey. The results showed were as follows:(1)Proportion of the individual number of L. subcordatum was diameter Class Ⅳ(2.5 cm≤DBH<5 cm), which accounted for 27.0%, and the seedling bank accounted for 24.7%. Therefore, the population was stable with lots of seedling and young trees pool.(2)Diameter class Ⅱ(h>1.3 m, DBH<1 cm)and Class I(h<1.3 m)has the highest life expectancy. At Class V(5 cm≤DBH<7.5 cm), there was an inflection point of life expectancy. In Class I, Class Ⅱ, Class Ⅲ and Class IV, the life expectancy of L. subcordatum decreased with the age increasing. In Class VI, Class Ⅶ, Class Ⅷ and Class IX, the life expectancy of L. subcordatum was increased firstly and then decreased with the age increasing.(3)Class V had the highest mortality and disappeared rate, because of the environmental sieve especially water stress. The trend of mortality curve was consistent with disappeared rate curve and the curve was up and then slightly down with aging.(4)The survival curve was monotone decreased except for Class Ⅱ to Class Ⅲ(1 cm≤DBH<2.5 cm).(5)To protect the species more effectively, the best way is in-situ conservation(on-site maintenance). The medium diameter class of L. subcordatum needs more attention to tending. The L. subcordatum population in Maolan can have a better recovery potential, as long as continue to maintain the reforestation politics.