极小种群植物猪血木的种群现状及保护对策

猪血木(Euryodendron excelsum)是特产于中国的山茶科极危种, 但目前对导致猪血木种群结构改变的原因缺少相关的调查及研究, 保护策略不完善。该研究依据野外调查方法、编制标准生命表、存活曲线、致死力和寿命期望曲线, 利用德氏多度分析方法分析了广东省阳春市八甲镇极小种群野生植物猪血木种群的年龄结构和动态, 并与2007年的研究结果进行对比, 分析该种群近10年的变化情况及其原因。结果表明: (1)研究区域内野生猪血木种群的数量变化动态指数(V_pi和V′_pi)均小于0, 存活曲线趋于Deevey-III型, 种群结构属于衰退型, 幼树数量丰富, 但由于向小树发展过程受阻, 种群无法及时更新补充。(2)存活曲线、致死力和寿命期待曲线一致显示在幼树、小树2级、中龄树2级这3个阶段, 出现阻碍因素, 影响种群的自然更新。(3)三甲镇猪血木幼苗减少了39.3%, 八甲镇猪血木幼苗锐减了71.9%, 三甲镇幼苗转化率较八甲镇低了近1/2。人为干扰是导致猪血木野生种群衰退的主要驱动因素, 已实施的保护策略并不适合当前情况下的野生猪血木种群。

Population status and conservation of an extremely small population species Euryodendron excelsum

Aims Euryodendron excelsum, an extremely endangered species of Theaceae, is endemic to China. However, there are few studies on the cause of population structure change of E. excelsum, and its conservation strategy is not perfect. We studied the age structure and dynamics of the E. excelsum population, compared them with the research results in 2007, and analyzed the changes of the E. excelsum population in the last ten years, so as to provide scientific reference for the effective protection and management of the E. excelsum population.Methods Based on field investigation data, the values of parameters such as standard life table, survival curve, killing power and life expectancy curve were established, and the structure status of the E. excelsum population was analyzed as well. The community composition was analyzed using DET’s multiple analysis method.Important findings (1) The analysis of population dynamic indices showed that dynamic indices (V_pi and V′_pi) of the wild E. excelsum population were all less than 0. The survival curve of the whole population generally fit a Deevey-III type curve, suggesting a declining population. The number of young individuals was abundant, but impaired development, and hence cannot support the population growth in time. (2) The analysis of survival curve, killing power and life expectancy showed that the sapling, small tree II and middle tree II obstructed the natural population renewal. (3) The Sanjia and Bajia group seedlings of E. excelsum decreased by 39.3% and 71.9%, respectively. The seedling conversion rate of Sanjia group was nearly 1/2 times lower than the Bajia group of E. excelsum. Human interference was the main driver of population decline of E. excelsum. In addition, the conservation strategy that has been implemented is not suitable for the current situation.