The Study Of The Stand Spatial Structure Based On ArcGIS

By choosing the trees in the researched plots in Da’anyuan of Wuyi mountain as theresearched objects, generate the Voronoi polygon distribution map with ArcGIS Tyson polygongeneration tool, and get the species of dominant trees: Symplocosanomala, gurgeon stopper,Lithocarpusharlandii, Ilex fukienensis S. Y. Hu, Symplocosfukienensis Ling and Holly, thenanalysis the corresponding spatial structure of the dominant tree species. According to theparameters of forest stand from the calculation, obtain6parameters of the forest spatial structurebased on V-graph, namely the mixed degree of diversity, size ratio, open degree, angle scale,degree of aggregation and the degree of competition. Because there are more than4trees arearound the object tree and the adjacent trees locate in all directions. Then compared with the oneswith4adjacent trees, only the mixed degree of diversity and the size ratio of the dominantspecies of the both are in high consistency, and the angle scale and the open degree of the formerrelative to the latter is higher. The open degree, the degree of aggregation and the degree ofcompetition are linearily correlated with the size ratio after analyzing the correlation betweeneach parameter of the spatial structure. And the other parameters are concentrated to reflect onthe degree of competition. Analysis of the6parameters based on V-graphs respectively showsthe stand conditions as follows:(1) Size ratio: the situation of the DBH size of the dominant tree species in training sets isbetween bad state and optimal state, the growth of Symplocosanomalain DBH is at adisadvantage obviously, consistent with growth in vertical direction.(2) Degree of mixed diversity: degree of mixed diversity is superior to the traditional one,the majority of the dominant trees are the small trees in the lower layer of the forest, and thedegree of isolation mainly concentrate on the state moderate mixture and above it, and theintensivemixture account for the majority, in which Holly have reached the most intensivemixture.(3) Open degree: dominant trees in the research area focused on the insufficient conditionand basic sufficient condition, with less in extremely sufficient condition, and there are more Ilexfukienensis S. Y. Hus in sufficient condition than the others.(4) Angle scale: majority of the dominant trees is in clumped distribution in their owncompetitive unit, less in uniform distribution, while minimum in random distribution. In uniformdistribution, Holly accounts for the highest proportion.(5) Degree of aggregation: the whole species in training set and all dominant trees are inclustered distribution, each dominant species is also in a cluster distribution pattern. The degreeof aggregation increased with the decreasing of the number s.(6) Degree of competition: with the highest average competition index, Holly is in the most suitable niche while the competition is the fiercest in its sphere of influence, and the adjacentwoods also interfere the objects most strongly. Ilex fukienensis S. Y. Hu has the lowercompetition index, while Symplocosanomala has the least competition index.The causes of each parameter owning to the advantage existence conditions for the growthof plants in such suitable natural environment as Wuyi mountain, there are a variety of plants inthe protection area, the similar living conditions and needs of survival intensifies the competitionin the forest. And the dominant trees in mature are small trees in a larger proportion, thebiological and ecological characteristics of the dominant trees are obvious, many of which areinclined to wet and often gather under large trees, forming the lower canopy mixed with otherplants. The dynamic update of the gaps in forest of the whole district also contributes to theformation of certain characteristics in spatial pattern.