| Complex network is a new comprehensive discipline which is very strong.More and more scholars pay attention to the use of the principle and methods of complexity science to study the problem of evolution and ecology.So far,research on the network are mostly based on unweighted network,but in fact in most network,the network nodes are connected by different weights,and there are different coupling strength between the nodes.Therefore,it is more suitable to describe the real network by using weighted network model with different edge weights.This paper takes West Dongting Lake region as the research object,classified the landscape types in this area,and the landscape is regarded as a node,edge effect between patches as edge weight that between nodes.The weighted forest landscape plaques coupling network has been built,and heterogeneity,connectivity and landscape characteristics of forest landscape patches weighted coupling network node has been analyzed.Furthermore,this paper proposed measures to improve the node which can increase the efficiency of information dissemination between patches.The main research contents and conclusions are as follows:(1)The construction of weighted forest landscape plaques coupling network.Based on the study of forest landscape distribution pattern and the existing research methods and results of the project team,the forest landscape types are divided into 11 categories:Pine class landscape(young,middle-aged,mature),Chinese fir landscape(young,middle-aged,mature),broadleaf class landscape(young,middle-aged,mature),bamboo landscape,and shrub landscape.Ten weighted forest landscape coupling networks were constructed and screened.The results of edge effect and network model shows that the edge effect among forest landscape patches is mostly positive,it indicated that the adjacent two different types of landscape patches mostly contributed to the growth of arbor trees in the adjacent patch border zone,as well as the improvement of shrub and herbaceous species diversity.(2)Heterogeneity analysis of nodes.Through the Cubic model and Logistic model to describe and simulate the network node degree,patch shape index and strength distribution relationship,when the node degree and shape index changes within a certain range,the point strength distribution changes in a region,when the node degree,shape index reaches a certain threshold,the point intensity distribution shows strong discreteness,very few nodes have a larger point intensity distribution and become the core of the network,which is the core of the coupling.(3)Analysis of landscape characteristics of node heterogeneity.Through statisticed and analyzed the distribution of the strength and heterogeneity of the ten network nodes,we can know that heterogeneity of nodes is related to the shape index and node degree.The larger the area,the more irregular the shape of patches or the greater the degree of the node,the stronger the node strength,the heterogeneity of the corresponding nodes is also greater;On the contrary,the smaller the area,the shape is closer to the circular patch or the smaller the degree of the node,the smaller the node strength,the smaller the heterogeneity;The dominant tree species with the greatest intensity and heterogeneity of the nodes were the young broad-leaved forest,and the smallest was the landscape type of the middle age forest and the shrub forest and bamboo forest.(4)Analysis of connectivity between nodes that are directly connected and landscape characteristics.Through the statistical analysis of the node pairs of the maximum and minimum efficiency values of the connected nodes,the results showed that when the middle age forest of Chinese fir is connected with two nodes of broad-leaved young forest,the maximum efficiency is the best among nodes,and the connectivity is the best,and the edge effect of the patch is the biggest.The better the mutual growth of grass and shrub between patches,the more the type of this kind of landscape,the better the growth of stand in the whole coupling.And two node landscape types of middle aged broad-leaved forest and mature forest of broad-leaved,middle aged broad-leaved forest and shrub forest,middle aged pine forest and middle aged Chinese fir plantation,middle aged broad-leaved forest and Cunninghamia lanceolata mature forest is among the nodes in the maximum efficiency,the connectivity is the worst,the node of the edge effect between the patches is minimum,the plaque between the trees,shrubs and herbs growth inhibition effect is the largest.The more the four kinds of landscape types,the more unfavorable for the growth of the standing forest in the whole coupling.(5)Analysis of connectivity and landscape characteristics of indirectly connected nodes.This paper studies the connectivity of nodes indirectly connected between the nodes,the two nodes in the middle of the node are studied through the nodes of the 1 and 2 nodes,based on the statistical analysis of the node pairs of the maximum and minimum efficiency values of indirectly connected nodes,the results showed that the efficiency value of the indirectly connected node pair is equal to the sum of the value of the pair of nodes that are directly connected to the node,the more the landscape types of the nodes connected to the nodes are the middle age and the middle age forest,the lower the efficiency of the node pairs,the worse the connectivity,the lower the efficiency of the information transmission between the corresponding patches,and through the middle patch of the dominant tree species reforestation to improve the connectivity between patches,increase the efficiency of information dissemination between the patches,and improve the growth of the standing forest in the whole coupling. |
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