稀有濒危植物长柱红山茶种群特征及数量动态研究

长柱红山茶(Camellia longistyla Chang ex F.A.Zeng et H.Zhou)是贵州特有经济植物,分布于贵州省金沙沟桫椤自然保护区和雷公山自然保护区海拔950~1400 m的常绿阔叶落叶混交林中,为我国珍稀濒危物种。通过对长柱红山茶密集分布的两个典型样地(望乡坡A和方山B)采样调查,采用径级代替龄级的方法绘制种群生命表、存活曲线(ln(ln))、生存率函数(Sn)进行生存分析研究,用动态指数(Vn、Vpi)和时间序列模型预测种群发展动向。结果表明:长柱红山茶种群的年龄结构总体上呈衰退型早期阶段,即中龄个体数量多、幼龄个体数量少,其生存曲线基本属于Deevey-Ⅰ型;生命表及其相关曲线分析显示,长柱红山茶种群有早期锐减、中期稳定、后期逐步衰退的特征;种群数量动态分析发现,幼苗不足,自然更新困难,但仍有一定的恢复潜力,且A种群受环境影响较大,对环境变化较敏感;时间序列分析表明,A、B两个种群的衰退现象是在最近的1~2个龄级时间内开始的,如果不采取有效保护措施,在未来4个龄级时间后,该物种原生种群将进入典型的衰退型年龄结构。因此,系统研究其种群特征及繁殖规律,并在加强就地保护的同时,采取人工繁育幼苗并种植回归原生境或引入相似生境中,通过栽培增加其种群数量和扩散能力,对其种质资源的有效保护和开发利用具有重要意义。

Population Structure and Dynamic Analysis of the Rare and Endangered Plant Camellia longistyla

Camellia longistyla Chang ex F.A. Zeng et H. Zhou is a rare, endangered and endemic economic plant in Guizhou Province, China. This species is distributed narrowly from 950 to 1400 m elevation in mixed evergreen and broad-leaf deciduous forests in the Jinshagou Alsophila spinulosa Natural Reserve and Leigongshan Natural Reserve. We surveyed naturally-occurring C. longistyla by establishing sampling plots in two typical densely-covered areas (Wangxiangpo A and Fangshan B). Time-specific life tables and survival function curves were established and drawn based on diameter class. We analyzed the survival curve (ln(l_n)) and survival function curve (S_n), and predicted population development trends by population quantity dynamics (V_n, V_pi) and time-sequence models. Results showed that: On the whole, the age structure of the C. longistyla population was declining type in the early stages, indicating more middle-aged trees and fewer young individuals. The survival curve was Deevey-Ⅰ type. Time-specific life table analysis and correlation curves revealed that the population structure of C. longistyla exhibited a slump in the early stage, stability in the middle stage and gradual decline in the late stage. According to the population dynamic analysis results, seedling supplementation was insufficient in both populations and natural regeneration was difficult, although there was a certain recovery potential. Furthermore, population A was sensitive to changes in the environment. Time-sequence analysis indicated that the decline in the two populations began in the last 1-2 age-class time. If effective protective measures are not taken, after four age-classes, the native populations will become typical declining type. With systematic study on population characteristics and propagation, together with strengthened in-situ conservation, artificially-cultivated seedlings can be returned to original habitat or introduced to similar habitat so as to increase population and dispersal ability. Such measures will be of great significance for the effective protection, development and utilization of C. longistyla germplasm resources.