广西大明山格木种群的空间分布格局与数量动态特征

Spatial Patterns and Quantitative Dynamics of Erythrophleum fordii Populations at Damingshan Mountain,Guangxi

在广西大明山保存较为完好的格木天然林内设置1块1 hm2固定样地,从种群空间格局、年龄结构、静态生命表和存活曲线4个方面研究种群的空间分布格局和数量动态特征。结果表明：大明山格木种群从幼龄和中幼龄到大树阶段,其空间分布格局由聚集分布逐渐变为随机分布,但总体上呈聚集分布格局;该格木种群年龄结构大致呈金字塔形,属于增长种群,考虑潜在干扰影响时种群仍处于稳定状态;种群内幼苗丰富,死亡率高,以3-4龄级种群数量变化最为剧烈,是种群动态变化的关键时期,后面龄级的个体比例较低,死亡率较早期明显下降;种群生存分析显示,死亡率、死亡密度和危险率均随龄级增加呈下降趋势,早期生存压力明显高于中后期,格木种群存活曲线为Deevey存活曲线Ⅲ型。

A one-hectare plot was set in a well-conserved forest of Erythrophleum fordii at Damingshan Nature Reserve,Guangxi Autonomous Region. The four aspects of population spatial pattern,age structure,static life table and survival curve were investigated to study the spatial distribution pattern,quantitative characteristics and dynamics of E. fordii populations. The results showed that the spatial distribution pattern tended to be cluster on the whole,but changed from cluster at young and middle-aged stages to random at mature age stage. The population age structure shaped like pyramid,indicating that the population of E. fordii was increasing,and the population was stable even taking potential artificial disturbance into account. Seedlings and saplings were abundant in the population with high mortality,and the individual number decreased severely from age class three to Age Class four,and this period was thus considered as milestone in E.fordii population dynamics. Thereafter the mortality rate in higher age classes was obviously lower with low rate of individuals. Population survival analysis showed that mortality rate,mortality density and hazard rate declined as age classes increased. Competition at young stage was stronger than that at middle and mature stages,and the survival curve of this tree species fitted the Deevey Type Ⅲ.