Fuzzy分布函数在研究杉木人工林林分直径结构上的应用

鉴于Fuzzy分布函数特性与林分直径累积百分比分布序列取值间的一致性,将Fuzzy分布函数引入到林分直径分布领域的研究.除Fuzzy-Γ1拟合精度较低外,Fuzzy-Γ2、Fuzzy-Γ3、Fuzzy-Γ4、Fuzzy-C等均表现出较好的拟合性能,其中Fuzzy-Γ3的参数与林分年龄、密度紧密相关;一种拓展型Fuzzy分布函数--Fuzzy-Γ5表现出最高的拟合精度,其形状参数c大部分的取值在3或4附近,表明直径分布主要表现为近似于Fuzzy-Γ3和Fuzzy-Γ4型的形式;通过对Fuzzy-Γ5分布参数与林分因子间相关性的分析,探讨了年龄、密度等林分因子对分布函数各参数的作用规律;由Fuzzy-Γ5、Logistic等9种分布函数数学解析性及拟合特性得出:林分直径累积分布的拐点的主要分布范围位于0.4～0.6之间,且存在一个分布中心点,该点在0.5左右,分布函数的拐点存在于这个主要分布范围之内时,其模拟精度较高,且越接近分布中心点0.5,其精度越高.

Application of Fuzzy Distribution Functions to Stand Diameter Distribution of Cunninghamia lanceolata Plantations

According to the correspondence of mathematical characteristics of Fuzzy functions and distribution interval of stand diameter cumulative percentage series, this paper introduced Fuzzy distribution functions to model diameter distribution of Chinese Fir ( Cunninghamia lancelata ) plantation, and discussed their adaptability and reasons for discrepancy of simulation properties, and the highest precision, the value of its parameter c was mostly distributed nearby 3 and 4, indicating that stand parameters were discussed. After analyzing the mathematical quality and simulation properties of nine kinds of distribution curve have a main flexible interval (0.4 ～ 0.6) and a central distribution point (0.5 or so), for average simulation precision,when the inflection point of distribution function lies in the main interval, its precision is relatively high, and the closer to the central point, the higher the precision is.