Study On Picea Crassifolia Dynamics And Regeneration In The Eastern Slope Of Helan Mountain

Inorder to study and explore the population dynamics and regeneration characteristics ofP. crassifolia in the eastern slope of Helan mountain, forest investigation has been done,typical sample plots has been measureed, and the method of “space instead of time” has beenused to analysis the population age structure, distribution pattern, natural regeneration andbiodiversity of P. crassifolia. The results as follows:(1) Pure forest population age structure of P. crassifolia in Helan mountain can be dividedinto three categories: growth type, stable type and nearly stable type. A succession of linearchange of population size shows that P. crassifolia has driving stability of self-organizationand self-development. Age structure standardization of P. crassifolia population is of growthtype, tending to be stable, and also harbor a certain growth. Survival curve is tending toDeevey-II, showing that the population has some fluctuation in the process of development. Ifthere won’t any artificial interference, it could remain stable for a long time.(2) Stand structure has certain influence on the spatial distribution pattern of P. crassifolia,along with the succession process of dynamic change: respectively secondary shrub (highcongregation)�'theropencedrymion of P. crassifolia+Populus davidiana (high congregation)�'pure forest stage of P. crassifolia (general congregation). Nowmatter how the age structuremade of, the seedlings and young trees are characterized by cluster distribution, whilemedium sized trees and big trees are in the form of cluster distribution or approximatelyrandom distribution. Congregation index shows that in the process of seedlings to the youngtrees, environmental screening did not cause obvious transformation of spatial pattern.(3) Natural regeneration ability of P. crassifolia population is different under differentstand structure: theropencedrymion of P. crassifolia+Populus davidiana(high congregation)> secondary shrub (high congregation)>>pure forest stage of P. crassifolia(generalcongregation). And population density, per plant height and crown breadth, all show the samecharacteristics. Population density is closely related to the main stem and canopy density, andthis correlation may be mainly caused by the changes of light environment. Plant speciescomposition and diversity index of different forest types of P. crassifolia has similarities andcomplexities.26species (including trees, shrubs, herbal) were found in sample plot,belonging to15families,20genera;17of the species were repeatedly found. Secondary shrub has high richness and Shannon-Winner index; theropencedrymion of P. crassifolia+Populusdavidiana forest has higher herbaceous richness and Shannon-Winner index; pure forest hashigh arbor richness, shrub and herb evenness index. The cause of this complex character isrelated to the phototaxis and shade endurance of seed germination and seedling growth of P.crassifolia, and the main stem environment.