Age Structure And Ecological Vulnerability Assessment Of Key Species Populations In Western Tianshan Wild Fruit Forest

The wild fruit forest in the Western Tianshan Mountains of Xinjiang is one of the origins of the cultivation of deciduous fruit trees in the world.It has high ecological function and scientific research value.Malus sieversii,Armeniaca vulgaris,Prunus divaricata and Crataegus songarica are the key species of wild fruit forest community in Xinjiang,which play an active role in water conservation,climate regulation,soil and water conservation and air purification.In recent years,the distribution area of wild fruit forest has gradually decreased,and its wild fruit resources are seriously endangered.At present,there are few reports on the age structure and ecological vulnerability of key species populations in wild fruit forests.According to the distribution of wild fruit forest in the West Tianshan Mountain of Yili River Valley,Xinjiang,this study uses Huocheng,Yining,Gongliu,Xinyuan 4 The typical distribution area of wild fruit forest in the county area is used as the research area.Malus sieversii population,Armeniaca vulgaris population,Prunus divaricata population,and Crataegus songarica population are selected as the research objects.Through field investigation,the ecological vulnerability assessment of the age structure of key populations and their distribution areas is conducted,with a view to providing a theoretical basis for the tending management of wild fruit forests and the rational development and utilization of resources..The main findings are as follows:(1)The Malus sieversii population and Armeniaca vulgaris population in different distribution areas of wild fruit forests in the Western Tianshan Mountains are declining populations,and the number of individuals in the middle age stage.The decline of Malus sieversii population and Armeniaca vulgaris population in wild fruit forest due to the blocked natural regeneration.The main reasons for the difficulty of natural regeneration of Malus sieversii populations in wild fruit forest are overgrazing,artificial fruit picking,Agrilus mali and Valsa mali,etc.;the main reasons for the difficulty in natural regeneration of Armeniaca vulgaris populations are the "cold spring cold" phenomenon,overgrazing,apricot bud gall and bacterial shot hole.(2)The Prunus divaricata population and Crataegus songarica population in the wild fruit forest of Daxigou are both growing populations,and the population is the largest number of individual young seedlings;The number of Prunus divaricata seedlings accounts for 47.7%of the population.The number of seedlings of the Crataegus songarica population accounts for 38.38%of the total population.With the increase of the age level,the number of individuals of the Prunus divaricata population and the Crataegus songarica population gradually decreases;due to intra-and inter-competition competition,grazing,and trampled by tourists etc..The seedlings of Prunus divaricata population and Crataegus songarica population will has higher mortality when they reached the young tree stage.(3)The survival curves of Malus sieversii population,Armeniaca vulgari population,Prunus divaricata population,and Crataegus songarica population are all Deevey-II.At this stage,the population dynamics of key species in wild fruit forests are relatively stable;Malus sieversii population individuals will begin to decline gradually after entering the fifth age,the individuals of Armeniaca vulgari population will begin to decline after entering the sixth grade,individuals of the Prunus divaricata population wil 1 begin to decline after entering the fifth grade,and individuals of the Crataegus songarica population entering the fifth grade Then will begin to decline.(4)Evaluation of the ecological vulnerability of wild fruit forests in the Western Tianshan Mountains based on the analytic hierarchy process shows that according to the calculated ecological vulnerability index values,the ecological vulnerability of the wild fruit forests in the Western Tianshan mountains can be divided into slightly fragile,low-fragile,moderate-fragile,and highly four levels of vulnerability;the corresponding weights of each evaluation index are obtained through the judgment matrix,and the four evaluation indexes with a higher weight are the degree of pests and diseases,grazing,forest roads and stand canopy closure;the evaluation results show that the type of stand the ecological vulnerability of wild fruit forests in Kresenbulak,Turgen Township,and Gilglang Gully,with Armeniaca vulgari as the mainstay,is highly fragile,and in Damohe Township,Jiaowutuohai wild fruit forests,with Malus sieversii as the main The vulnerability is moderate to high,and the ecological vulnerability of wild fruit forests in Daxigou Village,which is dominated by Prunus divaricata,ranges from low to medium fragility,which is consistent with the results of field surveys.(5)For the future protection and management of wild fruit forests in the Western Tianshan Mountains,local protection should be the main focus.Natural reserves should be established in areas where wild fruit forests are concentrated,strictly control the grazing intensity,strengthen the protection of key species populations in wild fruit forests,and promote natural renewal of key species of wild fruit forests;establishment of germplasm resource nurseries for key species of wild fruit forests;artificial breeding of seedlings of key species of wild fruit forests;and expansion of the number of key species of wild fruit forests;organize scientific research personnel to carry out scientific research on diseases and insect pests related to wild fruit forest to prevent the spread of diseases and insect pests.