濒危植物翠柏的个体生长动态及种群结构与种内竞争

Interspecific Competition,Population Structure and Growth Dynamics of Endangered Calocedrus macrolepis

在样地调查的基础上,对滇中高原地区翠柏个体生长状况以及不同郁闭度翠柏纯林的种群结构、种内竞争进行比较研究。结果表明:1)翠柏植株胸高断面积与树高之间存在着显著的指数函数关系,胸径和树高分别为31～40cm和19m左右时是其生长过程中较为明显的转折点,之前,树高生长占有明显的优势,随后,胸径增长迅速,树高生长速度减慢,直至停止;2)滇中地区翠柏天然林林地破碎化程度较高,径级结构的分布极不规律,呈现出明显的不连续状;3)现有零星分布的翠柏纯林中,植株密度和大小存在较大差异,以致种群中单株平均竞争强度压力差异较大;同时,林下幼小植株受到的种内竞争压力极为强烈,但随着胸径的增大,植株受到的竞争压力逐渐减小,并在胸径31～40cm时形成明显拐点。胸径小于31～40cm的植株受到的竞争压力较大,且随胸径的增大出现急剧下降;胸径大的植株,如大于37cm,受到的竞争压力较小,且随胸径的增大,竞争强度的变化较为平缓。在翠柏的保育管理过程中,加强对竞争压力较小的林缘、林隙等地区的管理有助于拓展翠柏生存范围。同时,在经营和利用翠柏植株资源时,可以参照其天然植株生长特征,对林分进行合理的经营和管理。

Calocedrus macrolepis is an ancient relict plant,and it is called an important ‘living fossil’that lived in quaternary glacial epoch. Nowadays the species is one of second-class protected rare and endangered plants in China,and distributes in dispersal state and rarely gathers in a small cluster. Knowledge about characters of population and individual growth state of C. macrolepis is very useful for us to understand its living state and population characters,so as to protect and use it better. In this paper,individual growth state,interspecific competition and population structure in different canopy densities of C. macrolepis forests in the plateau area of central Yunnan Province were comparatively studied based on plot investigation. The results showed that： 1） there was an obviously exponential functional relationship between basal area at breast height and tree height,and there was an apparent turning point in the growth when DBH and tree height were 31-40 cm and 19 m respectively. Before the point,tree height grows more fast than DBH,and after the point DBH increased rapidly,and tree height growth slowed down till stopped. 2） In the central Yunnan province,natural forest land fragmentation of C. macrolepis was very common,and diameter class structure was very irregular and incomplete. 3） In the dispersal natural C. macrolepis forests,plant density and size were very different,which led to different average individual competition indexes in different forest lands. The smaller trees,the stronger the interspecific competition pressure. There was an apparent turning point when DBH was 31-40 cm. When the DBH was smaller than the point,the competition pressure was high,but sharply dropped with DBH’increase;When the DBH was greater than the point,the competition pressure was low,and the change of competition pressure with DBH’increase was very small. Therefore,it isvery useful to expand its distributing areas by strengthening the administration of the forest edges and the forest gaps where there is small competition pressure. At the same time,according to the growth of natural trees,some suitable measures would be done during the management of man-made forests.