洮河上游紫果云杉种群结构特征

Population structure characteristics of Picea purpurea in the upstream of Taohe River

该研究以洮河上游尕海-则岔自然保护区、卡车林区和冶力关林区的紫果云杉(Picea purpurea)天然种群为研究对象,通过样地调查和数据统计,绘制种群结构图,编制静态生命表,拟合并分析存活曲线,运用数量化方法研究种群动态,揭示种群生存现状,预测种群发展趋势,以期为该物种的保护、管理及结构恢复提供理论依据。结果显示:3个林区紫果云杉种群自然更新能力强,幼苗、幼树储量丰富,幼小龄期死亡率普遍偏高;尕海-则岔种群存活曲线符合Deevey-III型,种群稳定结构完整,卡车林区和冶力关林区种群存活曲线均符合Deevey-II型,且均出现了局部衰退;3个林区种群动态指数均大于0,说明种群均属于增长型,增长潜力为尕海-则岔>卡车>冶力关;受随机干扰时卡车林区紫果云杉最敏感,冶力关次之,尕海-则岔种群最稳定。该研究表明:竞争和自疏作用是造成紫果云杉幼小龄级个体存活率偏低的普遍因素,3个林区不同的生存状况反映了紫果云杉种群在不同生境及生活史下生存能力的差异,保护幼苗生存环境并提高幼苗质量和存活率是种群更新和发展的关键。尕海-则岔紫果云杉生存良好,种群生存状况主要受自身生物学特性和环境因子的影响;卡车林区主要受人为影响,种群结构遭到破坏;冶力关林区受分布限制,造成种群结构不稳定,须采取一定的人工措施来促进种群更新与增长。

Aims Natural population of Picea purpurea in Gahai-Zecha Nature Reserve and Kache and Yeliguan forest regions in the Taohe River upstream was selected,to reveal the demographic status of P.purpurea populations.The results from the current study will provide theoretical basis for the protection,management and structural restoration of P.purpurea.Methods Based on field surveys and data analysis,population structure diagram was drawn,static life table was designed,and survival curve of P.purpurea was fitted and analyzed.Quantitative methods were used to study the population dynamics.The population development trend was predicted by time-sequence model.Important findings In the three forest regions,P.purpurea population showed signs of strong natural regeneration ability with abundant seedling and sapling reserves,yet the mortality rate of saplings was high.The population in Gahai-Zecha forest manifested a Deevey-III type survival curve representing a stable population with a complete population structure,and the population in Kache forest and Yeliguan forest manifested Deevey-II type survival curves with partial declines present in both forests.With population dynamics indexes(Vpi)>0,the populations of all three forests were in growth.The growth potentials ranking from highest to lowest were Gahai-Zecha>Kache>Yeliguan.The P.purpurea population in Kache forest showed the highest sensitivity to random interference followed by that in Yeliguan forest while Gahai-Zecha population was the most stable.This study showed that competition and self-thinning were the common causes of low survival rate of P.purpurea saplings and that different living situation in the three forests reflected the difference of survivability of P.purpurea populations in different habitats and life histories.The key to regeneration and development of P.purpurea populations was to protect the habitat of seedlings and to improve their quality and survival rate.The P.purpurea population in Gahai-Zecha forest grew well and the survivorship of that population was mainly affected by its own biological characteristics and environmental factors.The population structure of Kache forest was damaged under human interference.The population structure of Yeliguan forest was unstable due to its limited distribution.Appropriate anthropogenic interference measures should be adopted to promote population renewal and growth.