| Wild fruit forest is one of the important origins of deciduous fruit trees in the world,and it is also a rare natural gene bank of biodiversity in the world.Among them,the dominant species of Malus sieversii is not only a national endangered second-class key protected plant,but also a priority protected species of biodiversity.However,in recent years,the distribution area of Malus sieversii has decreased sharply,and the survival number has decreased significantly.Previous studies in this area mostly focused on the wild fruit forest in the Western Tianshan Mountains of Xinjiang,and there were few studies on the distribution characteristics and survival status of wild fruit forest and Malus sieversii in other regions.This study takes the wild fruit forest distributed in the talbahetai mountain area east of horjit Township,Emin County,Tacheng area as the research object,adopts the typical sample plot survey method,obtains the basic data of wild fruit forest community through the sample zones and quadrats established at different altitudes,and studies and analyzes the characteristics of wild fruit forest community composition and species diversity The relationship between niche characteristics and advantages of main tree species,and the population structure and spatial distribution characteristics of Malus sieversii,the main established species,are aimed at further understanding the survival status of Emin wild fruit forest and Malus sieversii at the population and community level,so as to provide corresponding theoretical basis and technical support for its scientific management,protection and utilization.The main results are as follows:1、The average density of wild fruit forest community in Emin county is 885.83 plants/hm2 in tree layer,1625.83 plants/hm2 in shrub layer,4811.66 plants/hm2 in herb layer,and the average canopy density of stand is 0.54.A total of 68 species of plants belonging to 53 genera and 26 families were investigated in the community,all of which were seed plants,of which single family and single genus accounted for 57.7%;The floristic components of seed plants in the community are mainly world distribution type and north temperate distribution type,accounting for 53.85%and 18.87%of the whole,respectively;Malus sieversii has the highest important value in the tree layer,accounting for 32.17%of all trees;Spiraea media Schmidt has highest important value in the shrub layer,accounting for 28.38%of all shrubs;Geum aleppicum Jacq.has the highest important value in the herb layer It accounted for28.27%of all herbs.The species diversity of the community is herb layer>shrub layer>tree layer,and the species diversity index and evenness index are low2、Among the 7 main tree species in the wild fruit forest group in Emin County,the horizontal niche width of the dominant species Malus sieversii is 5.297 and the vertical niche width is 1.872,all ranking first;In terms of niche overlap,the horizontal niche and vertical niche of wild apple in Xinjiang and other main tree species in the community are 0<NO<0.25,showing partial overlap;By testing the overall correlation of the community,VR=1.88,W=24.53,02.95（16）<(2<02.05（16）,the overall community showed no significant positive connection.In all 105 species pairs,the positive connection species pair was 1.79 times that of the negative connection species pair,and the non significant species pair was 1.67 times that of the significant species pair,indicating that the connection between species pairs was weak and the community structure of wild fruit forest was unstable.3、The height class structure of Malus sieversii is generally"single peak",with an average height of6.88 metres;The age structure of the population presents an atypical pyramid like a spindle.Although the population belongs to the growth structure,it is very sensitive to external interference,and the survival curve tends to Deevey–Ⅱ.In the next 2,3 and 4 age classes,young individuals will decline,and the number of middle-aged and elderly individuals will be supplemented;The seedlings under the forest are mainly sprouted seedlings,and the regeneration of seedlings is in a bad state;Most of the individuals of Malus sieversii at different age stages show random distribution in a small scale,while most of them show no correlation in terms of spatial correlation.To sum up,the wild fruit forest and Malus sieversii show an unstable state at the community and population level,and it is difficult to maintain the population for a long time.Therefore,in the future,it is necessary to strengthen the tending management and artificial remediation of the seedlings and existing individuals of the dominant species of Malus sieversii,so as to promote the stable growth and resource recovery of Malus sieversii population and wild fruit forest in Xinjiang. |
