利用浙西天目山常绿阔叶林样地调查数据,在随机样方点格局分析基础上,提出样方形状对点格局分析性能影响差异性问题。结果表明:(1)在最优样方面积相同条件下,通过配对t检验得出圆形与正方形、圆形与正六边形和正方形与正六边形样方性能对比的配对t检验概率P分别为0.249、0.043和0.023,表明样方形状对点格局分析性能影响具有差异性,圆形样方和正方形样方之间没有显著差异,正六边形样方与圆形样方、正方形样方之间差异显著;(2)圆形～正六边形和正方形～正六边形样方间VMR差值的95%置信区间分别为[-0.429,-0.010]和[-0.196,-0.021],其区间值上界均小于0,表明正六边形样方分析性能为最优,其性能高于圆形样方和正方形样方;(3)随机样方法在样本量较小时,点格局分析结果不稳定,但随着采样数目逐步增大到90以上时,其VMR值和P值趋于稳定。
陈永刚, 汤孟平, 施拥军, 葛宏立, 胡芸
. 样方形状对空间点格局的性能影响分析——以天目山阔叶林为例[J]. 地理研究, 2012
, 31(4)
: 665
-671
.
DOI: 10.11821/yj2012040009
Based on spatial point pattern and survey data of the evergreen broad-leaved forest in Tianmu Mountain,West Zhejiang Province,we come up with a question about how quadrat shape affects performance efficiency of spatial point pattern.The research results are shown as follows.(1) In the same area of optimal quadrat,the probabilities are 0.249,0.043,and 0.023 between round quadrat and square quadrat,between round quadrat and hexagon quadrat,and between square quadrat and hexagon quadrat with paired-T test.It is indicated that quadrat shape significantly affects performance efficiency of spatial point pattern,and there is no significant difference between round quadrat and square quadrat,and there is significant difference between hexagon quadrat and round quadrat or square quadrat.(2) The 95% confidence intervals of the VMR difference between round quadrat and hexagon quadrat,square quadrat and hexagon are[-0.429,-0.010] and[-0.196,-0.021],the ceiling of the intervals is less than 0,indicating that hexagon quadrat is the best performance quadrat,and that its performance is much higher compared with round quadrat and square quadrat.(3) When the sample size is small in random quadrat analysis methods,random quadrat analysis results are unstable,but with the sampling number exceeding 90,the VMR(Variance-Mean Ratio) and P value remain stable.
