The Population Structure And Dynamic Characteristics Of Picea Purpurea In The Taohe River Upstream

Picea purpurea is endemic in China,young forest growth strong resistance to negative,It is an important advantage of forest tree species and constructive species subalpine areas of Gansu province.The forest area of Taohe river basin is vast,the ecosystem is complex and diverse,and its forest resources played great ecological efficiency in stabilizing Taohe river and even the Yellow river water quantity,controlled water quality,flooding,prevented soil erosion and so on,but there were still more serious damaged to the forest resource protection in some remote areas.Therefore,to strengthen the protection of the ecosystem and forest resources in this area was of great significance to stabilize the Yellow river water volume and maintain the ecological security in the middle and lower reaches of the Yellow river.P.purpurea as the protective plants in Gansu province,based on the Taohe river upstream of Gahai-zecha nature reserve Zecha ravine,the Kache village of the Kache forest,Yeliguan national forest park of P.purpurea natural forest as the research objects,through the sample survey and statistics,drawn the population structure,made the static life table,analysis of survival curves,used the theory of survival analysis and quantitative analysis method to study the population structure and dynamic spectrum method,population dynamics,and the application of time series model to predict population dynamics,to analyze the population structure and dynamics of P.purpurea under different habitats revealed.The characteristics of population structure and survival status,clarified the population regeneration and maintenance mechanism,provided scientific basis for the protection and management of the species resources,and supported theoretical basis for the restoration of the study area of P.purpurea population regeneration and structure.The results of the study as followed:?1?The population structure analysis showed that the age-class structure,height structure and crown breadth structure of the P.purpurea population with Gahai-zecha,the Kache forest area and the Yeliguan forest area were all inverted"J"type,which was the growth type population.The proportion of seedling and saplings stage was:Gahai-zecha?62.23%?>Kache forest area?52.92%?>Yeliguan forest area?46.9%?.Under the combined action of biological characteristics,environmental conditions and man-made factors,the height of diameter and tree in three regions accords with the two function relation of y=ax²+bx+c,x?(0,-b/2a].?2?The analysis of Life table showed that the population of P.purpurea in different areas of Taohe had a large proportion of seedlings and young trees storage,but the survival rate was generally low.The death rate and disappearance rate of population were the largest in seedling and saplings stage,and the whole life process was accompanied by large fluctuation of death and disappearance rate.The death rate of seedling and saplings stage from high to low was:Yeliguan?83.33%?%>Kache forest area?74.49%?>Gahai-zecha?72.36%?.?3?The survival curve of the P.purpurea population of Gahai-zecha tended to be Deevey-?type,Kache P.purpurea forest population survival curves met B₁ subtype Deevey-?type survival curves;Yeliguan forest area of P.purpurea population survival curves before 6 age class closed to Deevey-III type,after the age class of 6level approached to Deevey-?type.?4?The P.purpurea in three regions can be updated under natural conditions and the forest was well updated.The low survival rate of seedlings and young trees caused by competition and self-thinning was the key factor affected the natural regeneration success and the population structure of P.purpurea population.Because of the small external disturbance of the Gahai-zecha,the population structure of the Kache forest area was seriously damaged,and the P.purpurea in the Yeliguan forest area affected the whole survival status mainly because of the distribution of the population.?5?The population dynamic analysis and time series prediction showed that the growth potential of P.purpurea in three regions was:Gahai-zecha area>Kache forest area>Yeliguan.In the next 2,4,6,8 age classes of P.purpurea population increased.The number of individuals in each age class increased proportion of the overall population trends and seedlings,saplings,the higher the proportion of seedlings,saplings,the greater the population growth.?6?The results of spectral analysis showed that the dynamic change of the population of P.purpurea was influenced by the fundamental wave,and the quantity fluctuation in different regions varied.Gahai-zecha P.purpurea pure forest closer to the natural state,the population was the most complete,can reflect the natural cycle of the population dynamics of the P.purpurea,the human disturbance affected the small cycle phenomenon of the P.purpurea population in the Kache forest area,and the population distribution and composition condition affected the quantity dynamics of the P.purpurea in the Yeliguan forest area.?7?The survival rate of seedlings and saplings was too low,which can be increased through artificial measures so as to promote the steady growth of population structure and recovery.In Gahai zecha area,strengthen the environmental protection of the survival of seedlings and saplings and improved seedling quality and survival rate were the key to keep the population growth;based on the Kache forest seedlings and strengthen the protection of the environment to focus on strengthening supervision,prohibition of man-made destruction;Yeliguan forest areas while reducing the impact of the visitors had to go through artificial replanting,plant and other measures to make the seedlings,saplings formed a certain scale,promoted structural recovery.The relevant forestry policy supported was also essential.