濒危植物杜鹃红山茶种群结构和动态变化

Population structure and dynamic change of endangered plant Camellia azalea

通过样地调查和数据统计,以基径(BD)5 mm为径阶距划分径级,对分布于广东阳春鹅凰嶂省级自然保护区内的杜鹃红山茶(Camellia azalea Wei)种群的径级结构和静态生命表进行了分析,通过个体标准化存活曲线、个体死亡率曲线和个体损失度曲线探讨该种群的生命过程,并对种群的时间序列进行了预测。结果表明:该种群径级结构表现出小径级和大径级的个体存活数较少而中间径级的个体存活数较多的特征,其中,Ⅳ级(15 mm≤BD<20mm)至Ⅵ级(25 mm≤BD<30 mm)以及Ⅰ级(BD<5 mm)和Ⅱ级(5 mm≤BD<10 mm)的个体存活数分别占个体总存活数的52.0%和3.3%。从静态生命表看,个体存活数和个体标准化存活数的变化趋势与种群径级结构的变化趋势基本一致;个体标准化死亡数、个体死亡率和个体损失度在Ⅰ级至Ⅲ级(10 mm≤BD<15 mm)均为负值,Ⅳ级后随径级增大呈波动增加的趋势,Ⅸ级(40 mm≤BD<45 mm)后随径级增大呈波动减少的趋势;个体区间寿命在Ⅳ级和Ⅴ级(20 mm≤BD<25 mm)达到峰值,此后随径级增大而减少;个体总寿命、个体期望寿命和个体存活率总体上随径级增大而减少。该种群的个体标准化存活曲线属于DeeveyⅠ型曲线,显示该种群为下降型种群;个体死亡率曲线和个体损失度曲线的变化趋势基本一致,均从Ⅲ级开始波动增加,无明显峰值。时间序列预测结果表明:与现存个体存活数相比,在未来2和5年后,Ⅷ级(35 mm≤BD<40 mm)至ⅩⅣ级(65 mm≤BD<70 mm)的个体存活数均呈增加趋势;在未来10年后,Ⅹ级(45 mm≤BD<50 mm)至ⅩⅤ级(BD≥70 mm)的个体存活数增加,且径级越大增加趋势越明显。总体上看,该种群幼苗缺乏,呈衰退趋势,为下降型种群;生境恶劣和人为干扰是主要致危因子。根据研究结果,对该种群的保护提出了一些建议。

Taking basal diameter（ BD） of 5 mm as diameter class,diameter class structure and static life table of Camellia azalea Wei population in Ehuangzhang Provincial Nature Reserve in Yangchun of Guangdong Province were analyzed by using plot investigation and data statistics. Life process of this population was discussed by using standardized survival curve,mortality rate curve,and loss degree curve of individual,and time sequence of this population was predicted. The results show that structure of diameter class of population exhibits relatively small survival number of individual in small and large diameter classes while relatively large survival number in medium diameter class,in which,survival number of individual from Ⅳ class（ 15 mm≤BD〈20 mm） to Ⅵ class（ 25 mm≤BD〈30 mm）,and Ⅰ class（ BD〈5 mm） and Ⅱ class（ 5 mm≤BD 〈 10 mm） account for 52. 0% and 3. 3% of total survival number of individual,respectively. According to static life table,variation tendency of survival number and standardized survival number of individual is generally consistent with that of diameter class structure of population. Standardized death number,mortality rate and loss degree of individual are negative values from Ⅰ class to Ⅲ class（ 10 mm≤BD〈15 mm）,and those show a fluctuation tendency to increase afterⅣ class and a fluctuation tendency to decrease after Ⅸ class（ 40 mm≤BD〈45 mm） with the increasing of diameter class. Span life of individual reaches the summit value in Ⅳ class and Ⅴ class（ 20 mm≤BD〈25 mm）,then decrease with the increasing of diameter class. Total life,life expectancy,and survival rate of individual generally decrease with the increasing of diameter class. Standardized survival curve of individual of this population belongs to Deevey Ⅰ type curve,suggesting this population is a diminishing population. Variation tendency of mortality rate curve and vanish rate curve of individual is basically consistent,both show a fluctuation tendency to increase from Ⅲ class and have no evident summit value. The time sequence prediction result shows that survival number of individual from Ⅷ class（ 35 mm≤BD〈40 mm） to ⅩⅣ class（ 65 mm≤BD〈70 mm） all shows a tendency to increase after two and five years compared with present survival number of individual. After ten years,survival number of individual from Ⅹ class（ 45 mm≤BD 〈 50 mm） to ⅩⅤ class（ BD≥70 mm） increases,and the larger the diameter class,the more obvious the tendency to increase. In general,this population lacks seedlings and shows a declining tendency,indicating it is a diminishing population. Horrible habitat and human interference are major threatening factors. Based on these results,some suggestions are proposed for protection of this population.