濒危植物秦岭冷杉种群数量动态

为了对濒危植物秦岭冷杉种群数量动态评价和预测,通过样地调查和数据统计,研究了秦岭冷杉种群的年龄结构、静态生命表及其与环境因子关系,运用时间序列模型预测了种群数量动态.结果表明,多数秦岭冷杉种群幼龄级个体数较少,中老龄个体数量较大,呈衰退趋势.仅处于低海拔地区的秦岭冷杉-木蓝-苔草群丛中的种群(D种群)由于立地条件较好,幼龄级个体数量相对丰富,种群稳定.不同秦岭冷杉种群生命表和存活曲线的分析表明,尽管生境条件差异,但存活曲线基本接近DeeveyⅢ型;不同种群偏离典型存活曲线的程度与幼苗缺乏程度有关,一般Ⅲ～Ⅴ龄级死亡率较高.时间序列分析表明,在未来20、40和80年中,不同秦岭冷杉种群均会呈现老龄级株数先增后减的趋势,种群稳定性长期维持困难.对影响秦岭冷杉种群增长的10个环境因子通过主成分分析(PCA)发现,乔木层盖度、土壤有机质含量和空气湿度对种群发挥有利影响,而人为干扰和光照强度对秦岭冷杉种群增长发挥不利影响.应充分利用秦岭冷杉性喜荫、耐寒、种子活力较强的特点,加强现有林分就地保护,重点是具有结实能力的中老龄个体;在阴坡地带,对林下灌木比较密集的群丛,通过砍灌、清理林下活地被物等抚育措施,为幼苗发育创造良好的环境条件;就地采种育苗,扩大人工种群.

Population dynamics of endangered plant species Abies chensiensis

In order to know the endangered status and causes of Abies chensiensis in Qinlin Mountains, a field investigation on 18 plots was conducted on its age structure, life table and fecundity, and its population dynamics were predicted by time sequence model. The analysis on the age structure of Abies chensiensis populations showed that there were fewer young individuals, but middle-aged and old individuals were relatively rich. The population D in Abies chensiensis-Indigofera amblyantha-Carex lanceolata association showed a relatively stable development tendency, while other four populations (A, B, C and E) in Abies chensiensis-Pinus tabulaeformis-Sinarundinaria nitida-Carex lanceolata association, Abies chensiensis-Quercus aliena var. acutserrata-Litsea pungens-Carex lanceolata association, Abies chensiensis-Betula albo-sinensis-Sinarundinaria nitida-Duchesnea indica association, and Abies chensiensis-Pinus tabulaeformis-Smilax stans-Carex lanceolata association all showed an obviously declining tendency. The analysis on the life tables and survival curves showed that the survival curve of Abies chensiensis populations belonged to Deevey III, and the death peak of different populations was in the period of 60--100 years old. The number difference among populations reflected the population habitat. Time sequence prediction indicated the numbers of old individuals would be increased at the beginning, and decreased finally in 20, 40, and 80 years. It was difficult to maintain the population stability. Analysis on 10 ecological factors showed that tree coverage, soil organisms and air humidity influenced population positively, and human disturbance and sunlight influenced population negatively. In situ conservation should be taken as the most important management countermeasure, and natural regeneration should be promoted. At the same time, artificial population should be expanded.