濒危植物秦岭冷杉种群空间分布格局及动态

Pattern and Dynamics of the Spatial Population Distribution of Endangered Abies chensiensis

为阐明秦岭冷杉种群分布格局动态特征,达到有效保护和恢复的目的,通过野外调查,采用相邻格子样方法,离散分布拟合、扩散系数、Morisita指数、均方-曲线等方法,对不同生境和年龄阶段的秦岭冷杉种群的空间分布格局及其动态进行了系统研究.结果表明:(1)秦岭冷杉种群空间分布格局在不同发育阶段和不同生境条件下基本属于聚集型分布,在25 m2、150 m2和300 m2的面积上聚集强度较大.天然条件下,种群聚集强度最大取样尺度,可能是其种群更新的最佳面积.(2)秦岭冷杉种群空间分布格局随海拔上升,聚集强度降低;聚集强度在海拔1 300～1 700 m较小,在海拔1 700～2 100 m地区较大;阴坡种群分布聚集强度大于阳坡.(3)随着种群年龄增加,分布格局由聚集型向随机型过渡,聚集强度减弱;聚集性最强的尺度规模在幼、中龄期为50 m2,老龄期为300 m2.(4)种群的空间分布格局与生物生态学特性、生境条件关系密切.在未来森林经营和种群恢复中,应针对生境和种群年龄,森林抚育管理作业面积应该尽量接近聚集强度最大的尺度.低海拔和阴坡应该适度间伐非目的乔木树种,高海拔和阳坡地区,应适度清理灌木和草本层,为群落内团块状更新创造空间;实行就地保护,减少人为干扰,促进天然更新保护策略.

The pattern and dynamics of the spatial population distribution of Abies chensiensis in different habitats and age groups were studied by field surveying,quadrat-juxtaposing grid sampling,discrete distribution fitting,dispersion coefficient method,Morisita index method and mean-curve method to clarify the dynamic population distribution pattern of Abies chensiensis and thus to effectively protect and rehabilitate Abies chensiensis population. The results indicated that （1） Abies chensiensis presented an aggregating distribution in different habitats and at different growth stages with its high aggregating intensity occurring with the quadrats of 25 m^2,150 m^2 and 300 m^2. Under natural circumstances ,the sampling area at the highest aggregating intensity was very probably the optimal area for the population regeneration. （2） Abies chensiensis presented a spatial population distribution whose aggregating intensity declined with decreased altitude above sea level,low within 1 300～1 700 m above sea level and high within 1 700～2 100 m above sea level;The aggregating intensities of the populations standing on northward-facing slopes were higher than those of the populations standing on southward-facing slopes. （3） As Abies chensiensis populations became older,their distributions transformed from the aggregating type into a random type while their aggregating intensities came down ;the highest aggregating intensity appeared at the quadrat of 50 m2 in the middle-aged populations and at the quadrat of 300 m^2 in the old-age populations. （4） The spatial distribution of the populations closely related to their biological and ecological characteristics and habitat conditions. In future forest management and rehabilitation,the forest-tending area should be the one at which the highest aggregating intensity will appear depending on forest habitats and ages. On purpose of creating the conditions for patchy population regeneration ,non-target arbor species should be inter-felled in the populations on northward-facing slopes and at low altitudes,and shrub species and herbal species should be properly reduced in the populations on southward-facing slopes and at high altitudes ;in situ protection should be carried out and human interferences should be reduced ,so that the strategy of natural regeneration will be enhanced to come into true.