濒危植物裂叶沙参种群生殖力表的研究

本文分别以当年产种子数量和一年生幼苗数量为基础,编制了裂叶沙参种群(总和)和海拔2300-2400m, 2700-2900m, 2900-3100m, 3100-3400m 4个不同海拔区域种群的生殖力表,分析了不同种群两种生殖表的种群内禀增长率(r_m),周限增殖率(λ),净增长率(R₀),毛增长率(G)等动态参数与种群动态的关系;比较了两种生殖力表的特点和利弊;讨论了裂叶沙参种群生殖生态学特性和种群发展趋势及其与环境因素的关系。以种子数量为基础编制的生殖力表的各种群动态参数表明,裂叶沙参具有较强的产生种子的能力,特别是在生境条件较好的海拔2700-3100m区域,种群个体结实量可达到很高的水平。以一年生幼苗数量为基础编制的生殖力表表明,裂叶沙参种群从整体上呈衰退趋势。但不同种群间存在差异:在海拔2300-2400m,水份条件较好的特殊生境和海拔2900-3100m的种群呈稳定特征;而海拔2700-2900m,3100-3400m的种群呈缓慢衰退特征。以种子数量为基础编制的生殖力表可以反映裂叶沙参种群产生种子的能力和生殖生态学特征;而以一年生幼苗数量为基础编制的生殖力表包含了种子库的生态学过程,能较好的反映种群动态特征。在实践中,两种生殖力表应配合使用,才能全面刻划种群生殖生态学和种群动态特征。

STUDY ON POPULATION FECUNDITY SCHEDULES OF ADENOPHORA LOBOPHYLLA, AN ENDANGERED SPECIES

The fecundity schedules of the whole population and 4 different populations at altitude 2300-2400m, 2700-2900m,2900-3100m,3100-3400m were compiled respectively based on the number of seeds and the number of seedlings at one year old.Two kinds of fecundity schedules and their population dynamic parameters, the intrinsic rate of natural increase (r_m),the finite rate of natural increase (λ), the net and gross reproductive rates (R_o, G) etc.were compared and analyzed.The population reproductive ecological characteristics and the population dynamics tendency have been discussed.The reproductive parameters of population,the net and gross reproductive rate(R_osd,G_sd)from the fecundity schedules on the number of seeds show that A.lobophylla population has the stronger ability to yield the seeds, especially in the favorable condition.However, the intrinsic rate of natural increase (r_msg),the finite rate of natural increase(λ_sg),the net and gross reproductive rate (R_osg, G_sg)from the fecundity schedule on the number of seedlings at one year old suggest that the whole A.lobophylla population is declining slowly.There are differences among the populations:the population at altitude 2300-2400m in the better water condition and the population at altitude 2900-3100m perform the stable characteristics (r_msg=0.0000,λ_sg=1.0000),while the populations at altitude 2700-2900m,3100-3400m perform the slowly declining characteristics(r_msg=-0.0001,λ_sg=0.9999).Comparing with 2 kinds of the fecundity schedules, the fecundity schedules on the number of seeds can show the population reproductive characteristics to produce the seeds.Whereas the fecundity schedules on the number of seedlings at one year old can be successful to explain the population dynamic tendency because it includes the information from the ecological process of seed bank in soil.Therefore, it is necessary that 2 kinds of the fecundity schedules should be used together when explaining the population dynamic and reproductive ecological characteristics.