Based on sample-plot survey and data statistics of Toona ciliata population in Shengjiaba of Enshi City , the life table of Toona ciliata was made to analyze and research the dynamics of population quantity.The results showed that population dynamics value Vpi =27.84％>0 indicated a growth form of the population and Vpi'=1.74％>0 indicated the a stable form of the population with low risk -resist-ance capacity .The life table and the survival curve of the population proved the tendency of quantity dy-namics in accordance with that of Deevey -Ⅲ.The two peaks of death rates were 0.250 between 1 and 2 age classes, and 0.364 between 3 and 4 age classes, and the maximum loss index fell in 3rd age class with the maximum value 0.452 .The peak of survival rate function was 0.75 in 1 st age class , decreasing monotonically, while the accumulated mortality rate function approached 1 in 8th age class, increasing monotonically.The mortality density function f(t) reached 3 peaks, which remained 0.063 in 1st age class, 0.063 in 3rd age class, 0 in 6th and 7th classes and 0.078 in 8th age class.The hazard rate func-tionλ(t) reached 0.111 in 3rd classes, fell to 0 in 6th and 7th classes but climbed to 0.5 in 8th class. The results indicated that the loss of Toona ciliata population from environmental sieve and disturbances was heavy in seedling and sapling stages , which was one of the principal factors for Toona ciliata popula-tion's extinction .The adult population stayed temporarily stable , and then involved in a new round of competition .%通过对恩施盛家坝红椿群落的样地调查和数据统计,编制红椿种群生命表进行生存分析,探究种群数量动态变化.结果表明:红椿种群动态指数Vpi=27.84％>0,种群属于增长型;V'pi=1.74％>0,种群仍稳定,抗风险能力弱.种群生命表和生存曲线显示数量动态变化趋势符合De-evey-Ⅲ型.死亡率出现2个高峰,1～2龄级为0.250;第3～4龄级为0.364;龄级间最大损失度在第3龄级,为0.452.生存率函数最大值在1龄级,为0.75,呈单调下降趋势;累计死亡率在第8龄级,最大值为1,呈单调增加趋势.死亡密度函数f(t)波动出现3个高峰,在第1和第3龄级,分别为0.063和0.063;在6和7两个龄级均为0,第8龄级上升到最高,为0.078;危险率函数λ(t)在第3龄级时最高,达到0.111;到6和7两个龄级为0,第8级达到峰值0.5.在幼苗和中树阶段受限于环境筛和干扰损失较大,也是其濒危主要因素.红椿种群成树过渡阶段稳定,逐渐进入新一轮竞争.
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