| The forest ecosystem of Mountain Natural Forest in Xinjiang plays a leading role in water conservation,soil and water conservation and the formation and maintenance of forest ecosystem in Xinjiang.As the region with the most reasonable spatial structure and perfect ecological function in the forest ecosystem,the high accumulation forest area has an obvious impact on the whole forest ecosystem.Therefore,taking the state-owned forest administration in Western Tianshan,Xinjiang-West Tianshan National Nature Reserve and the state-owned forest administration in Altai mountain,Xinjiang-Fuyun branch as typical study areas,this paper sets up typical quadrats in the high accumulation forest area for investigation.The main tree species in the study area are Picea schrenkiana var.Tianschanica and Larix sibirica Ledeb.Based on the measured data of 13 quadrats,the distribution characteristics of stand DBH and tree height were analyzed by kurtosis coefficient and skewness coefficient;The angle scale and size ratio were used to study the horizontal distribution pattern and the degree of tree size differentiation;The species diversity of understory vegetation was analyzed by importance value,diversity index and evenness index;The physical and chemical properties of soil were discussed by using the indexes such as soil water content,soil p H value,soil organic matter content,nitrogen,phosphorus and potassium content and supply in soil,so as to study the non spatial structure characteristics,spatial structure characteristics,understory vegetation diversity and soil fertility of trees in the sample.The main findings are as follows:(1)In terms of non spatial structure characteristics of stands,the average DBH and average tree height of the high accumulation forest subarea quadrats in the West Tianshan Mountain Nature Reserve are 58.9cm～73.7 cm and 30.4 m～38.6 m respectively.The average DBH and average tree height of the high accumulation forest subarea quadrats in the study area of Fuyun sub bureau are 29.2 cm～42.1 cm and 21.5m～23.9 m respectively;The DBH structure of the quadrats in the two study areas is mainly inverted "J" type,and the tree height distribution has double peak distribution and single peak distribution;The skewness coefficient of DBH of the quadrats in the two study areas showed a left deviation trend as a whole,while the number of trees near the average DBH was relatively discrete,the distribution curve was relatively flat,and the overall distribution curve showed a low peak;The tree height distribution of the West Tianshan Mountain reserve quadrat has peak and low peak distribution,while the tree height distribution of the Fuyun branch quadrat is mainly peak distribution.(2)In terms of stand spatial structure characteristics,about 60% of the trees in the West Tianshan Mountain reserve quadrat and about 55% of the trees in the Fuyun sub Bureau quadrat are mainly randomly distributed,the overall degree of tree size differentiation is moderate,and the overall growth of the trees in the quadrat is good;From the angular scale size ratio binary distribution maps of the quadrats in the two study areas,it can be clearly seen that the two parameters of angular scale and size ratio are closely related,and the concentration and distribution of trees will significantly affect the growth of DBH of trees.(3)In terms of vegetation diversity,there are 26 species of understory plants in the West Tianshan Mountain reserve quadrat,and the dominant species are obvious,while there are 30 species of understory vegetation in the Fuyun branch quadrat,and the competition of understory vegetation in the forest area is fierce;The diversity index and evenness index show that the understory vegetation species in the West Tianshan Mountain reserve are less,but the distribution is more uniform,while the vegetation species in Fuyun branch are more abundant and more concentrated.(4)In terms of soil fertility,the sample soils in the two study areas are mainly acidic soils.Among them,the soil nutrient content in the West Tianshan Mountain reserve is high,and the soil moisture content is about 50%;The soil moisture content in the sample of Fuyun branch is about 60% ～ 70%,the soil leaching effect is strong,and the soil nutrient content is good. |
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