贵州大沙河国家级自然保护区野生银杉种群结构和动态分析

Population Structure and Dynamic Analysis of Wild Cathaya argyrophylla in Dashahe National Nature Reserve, Guizhou, China

摘要:

银杉(Cathaya argyrophylla)是我国特有重点保护珍稀濒危极小种群野生植物之一，也是贵州大沙河国家级自然保护区重点保护对象和旗舰种。该研究基于2022年对贵州大沙河国家级自然保护区野生银杉的调查数据，计算数量动态指数、编制静态生命表、绘制存活曲线并引入生存函数和谱分析描绘其结构动态。结果表明，保护区内野生银杉种群年龄结构为倒J型，种群的动态变化指数V_pi为39.43%，大于V_pi'且两值都大于0，可以看出银杉种群为增长型，但增长缓慢，对外部干扰非常敏感。银杉的存活曲线属于Deevey-II型，生存率、累计死亡率、死亡密度及危险率在I~III龄级变化较大，后趋于稳定。谱分析表明第III龄级是影响银杉种群数量的主要阶段。保护区内银杉幼龄个体数多但死亡率高，是导致种群野外更新困难的主要原因，建议保护区加强银杉幼苗抚育工作，改善生存环境，从而推动银杉种群的自然更新与恢复。

Abstract:

Cathaya argyrophylla is one of the endemic rare and endangered wild plant with extremely small population in China, and is also the key protected object and flagship species in Guizhou Dashahe National Nature Reserve. Based on survey data of wild C. argyrophylla in the reserve in 2022, the quantitative dynamic index was calculated, static life table was compiled, survival curve was drawn, and survival function and spectral analysis were introduced to describe its structural dynamics. The results showed that the age structure of wild C. argyrophylla population was inverted J-type, and the dynamic change index of population (V_pi) was 39.43%, which was greater than V_pi' and both of them were greater than 0, indicating that the C. argyrophylla population was a growth type, but the growth was slow, and it was sensitive to external disturbance. The survival curve of the population belonged to Deevey-II type, and the survival rate, cumulative mortality rate, mortality density and risk rate changed greatly in age class from I to III stage, and then tended to be stable. The life spectral analysis showed that the III age class was the main stage affecting C. argyrophylla population. Therefore, the large number of young individuals and high mortality rates of C. argyrophylla in the reserve was the main reason leading to the difficulties of regeneration. It was suggested that the reserve should strengthen the care of C. argyrophylla seedlings and improve the living environment, so as to promote the natural regeneration and recovery of C. argyrophylla population.