Discussion on the Analysis Method of Uniform Angle Index Based on Voronoi Diagram-Take Fushou Forest Farm as an example
The uniform angle index was a new parameter for describing the distribution pattern of tree po-sitions.It described the degree of spatial regularity of the neighboring trees around a given reference tree.This parameter,accepted by more and more researchers,can be used to analyze complicated forest spatial structures.In order to put forward standards for uniform angle index,based on Voronoi diagram,in this paper,1000 randomly distributed plots with 1hm2 (100m ×100m)each one,were simulated and ana-lyzed.And the standard angle of the uniform angle index based on Voronoi diagram was formulated by 360°/(n +1 ).The critical value for the identification of tree random distribution pattern was discussed within the interval μ±3σ.The mean value of the uniform angle index for the random case was defined by the bounds[0.327,0.357].It can be inferred by the definition of the uniform angle index that a Wv value of less than 0.327 was most likely from a regular distribution,values exceeding 0.357 were most likely from a clumped distribution.Finally,the tree spatial distribution pattern of six plots in Cunninghamia lan-ceolata non-commercial forest were analyzed by two different methods,i.e.aggregation index and uniform angle index,and they were same.This new judgment criterion to analyze the type of tree spatial distribu-tion represented an important improvement of the uniform angle index theory.
standard anglethe judgment criterionspatial structure parameterspatial structure unitcom-putation geometry
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