Research On The Spatial Structure Of The Broad-leaved Forest Of Lingyan Mountain In Dujiangyan

Broad-leaved forest is a fairly stable forest community formed by long-term succession,which is widely distributed,diverse in types and rich in flora composition.It is of great significance to the construction of water conservation and ecological environment protection in the whole region.Based on the analysis of tree species composition,distribution characteristics and spatial structure characteristics of broad-leaved forest in Lingyan mountain,this study found the change rule of population spatial distribution in the process of community succession,which provided a theoretical reference for the scientific and reasonable protection of broad-leaved forest resources in Sichuan and how to develop and manage them.The results are as follows:(1)In this study,there are 18 species of trees in the broad-leaved forest of Lingyan mountain.The proportion of tree species is: 7 Camptotheca acuminata,5Padus wilsonii Schneid,1 Cunninghamia lanceolata,1Cryptomeria fortunei and1 Machilus pingii Cheng ex Yang.Camptotheca acuminata and Padus wilsonii Schneid have the largest number of tree species in the community,and Camptotheca acuminata(0.490)and Padus wilsonii Schneid(0.152)have the highest proportion of DBH sectional area in the community,which shows that Camptotheca acuminata and Padus wilsonii Schneid are the dominant tree species in Lingyan mountain.(2)Based on the analysis of three parameters of spatial structure of broad-leaved forest in Lingyan mountain,it can be seen that the distribution of Camptotheca acuminata and Padus wilsonii Schneid is relatively concentrated and has a greater advantage in the forest,while Cunninghamia lanceolata,Cryptomeria fortunei and Machilus pingii Cheng ex Yang are in the middle and inferior position and the distribution is relatively random.The whole forest is in a medium mixed state,and the distribution is random,and the distribution of trees is more scattered and average.(3)In the broad-leaved forest of Lingyan mountain,the trees in the lower forest layer(H<10m)show obvious aggregation distribution,while the trees in the higher forest layer(H ≥ 10m)show random distribution in most spatial scales,which conforms to the law that the aggregation degree of species decreases with the increase of forest layer height.(4)The spatial point pattern of different tree species is regular distribution and tends to random distribution;the main tree species in the evergreen broad-leaved forest sample plot of Lingyan mountain,with the increase of spatial scale,appear the spatial pattern of aggregation distribution gradually weakened,and finally tend to random distribution.(5)In this study,9 pairs showed positive correlation in a certain spatial scale,but there was no correlation in the whole spatial scale.The spatial correlation between Camptotheca acuminata and all tree species increased with the spatial scale,showing a change from positive correlation to no correlation,while that between Padus wilsonii Schneid and main tree species was the opposite,showing a change from no correlation to positive correlation with the increase of the spatial scale.