稀有濒危植物贵州红山茶种群结构及数量动态变化的研究

Population structure and dynamics analysis of rare and endangered plant Camellia kweichowensis

关键词:  贵州红山茶, 种群结构特征, 种群数量变化, 时间序列预测, 物种濒危机制

Key words:  Camellia kweichowensis, population structure characteristics, population quantity change, time series prediction, species endangered mechanism

摘要:

贵州红山茶(Camellia kweichowensis)是红山茶组中稀有5室蒴果代表种之一,具有重要物种生物学意义和经济利用价值。为探索贵州红山茶物种稀有濒危原因,该文采用样方法与实测法调查,通过种群年龄结构和生存力分析,开展种群结构动态量化特征和未来发展趋势的研究。结果表明:(1)贵州红山茶原生植被具有亚热带湿润性常绿阔叶林典型特征,常绿落叶阔叶混交林占主体林分,华山松(Pinus armandii)+桦木(Betula luminifera)+枫香(Liquidambar formosana)+蓝果树(Nyssa sinensis)+山茶(Camellia sp.)+铃木(Eurya sp.)+木荷(Schima sp.)等针叶阔叶混交林常见。(2)贵州红山茶植物种群结构为增长型,以小树和中树龄级阶段植株为主体,占种群数量的73.02%; 种群存活曲线Deevey-Ⅱ型特征明显,种群生命期望值在幼苗期达到最大值,死亡率和消失率曲线的变化趋势基本一致; 种群幼苗库丰富但响应生境外的干扰敏感,幼苗存活至Ⅶ龄级植株概率陡降至36.17%,整体呈现“Ⅳ龄级前增长-Ⅳ龄级后衰退”的特点。(3)贵州红山茶在未来2、4、6、8、10个径级的生长期之后,种群动态趋于中树(Ⅴ～Ⅶ龄级)、大树(Ⅷ～Ⅹ龄级)和老树(Ⅺ～ⅩⅢ龄级)的态势。综上认为,贵州红山茶生境资源及空间有限性导致种群内部或不同物种间的竞争加剧,使种群幼苗存活率降低和低龄级植株数量减少,加上人类掠夺性采伐造成的成年植株死亡率增高,致使其种群的数量增加及种群扩散受阻,分布区狭窄,物种趋于濒危。

Abstract:

Camellia kweichowensis is a rare 5-locular capsule-bearing representative species of the section Camellia with biological importance and economic value. In order to explore the reasons for its endangered status, we studied the quantitative characteristics of population structure dynamics and future development trend by combining the sample investigation and actual measurement methods, the analysis of population age structure and survivability. The results were as follows:(1)The primary vegetation of C. kweichowensis had typical characteristics of subtropical humid evergreen broad-leaved forests. While the mixed evergreen and deciduous broad-leaved forest were the main stands, and the coniferous broad-leaved mixed forest of Pinus armandii + Betula luminifera + Liquidambar formosana + Nyssa sinensis + Camellia sp. + Eurya sp. + Schima sp. was common.(2)The growth population of C. kweichowensis dominated the growth structure. The points were mainly concentrated in the small and medium tree stages, and the sum of the proportion constituted 73.02% of the overall population. Deevey-Ⅱ type characteristic of the population survival curve was obvious, the life expectancy of C. kweichowensis was the maximum at the seedling stage. The change trend of mortality and the vanishing curves of the same plot were approximately the same. The quantitative dynamic analysis indicated that the three plots had abundant seedling pools, but were sensitive to the disturbance outside the habitat. The probability of surviving to Ⅶ age-class dropped significantly to 36.17%. On the whole, the population structure showed the characteristics of “growth in the early stage and decline in the late stage of Ⅳ age-class”.(3)After the growth period of 2, 4, 6, 8, and 10 diameter scales, the C. kweichowensis population dynamics tilted toward the succession of middle trees(Ⅴ-Ⅶ age-class), big trees(Ⅷ-Ⅹ age-class), and aged trees(Ⅺ-ⅩⅢ age-class). In conclusion, due to the limited habitat resources and space, intraspecific and interspecific competition intensifies, which reduces the survival rate of population seedlings and the number of young, and increased the mortality of adult plants caused by human predatory logging. As a result, the population renewal and diffusion are hindered, the distribution area is narrow, and the species tend to be endangered.