随机与系统取样的生态学信息量比较

COMPARISON OF ECOLOGICAL ENTROPY WITH RANDOM AND SYSTEMATIC SAMPLING

系统取样与随机取样是两种常用的取样方法。植被取样，也即是一有关植被数据的收集过程，通常采用系统取样的方法，其具有简便快捷易于操作的特点，但所获得的数据常是不甚妥当地应用于一些要求取样必须为随机的统计检验分析。随机取样从理论上来讲则是最理想的，但在植被实际调查过程中，真正达到随机取样的可能性较小。两者除了各自的统计学特点以及实际操作的可行性之外，在相同取样面积等条件下，所收集的数据所包含的生态学信息量是否显著不同，迄今鲜有报道。本文借助地理信息系统（ＧＩＳ）技术，以在海南霸王岭自然保护区所建立的永久样地为例，进行了计算机模拟的随机与系统取样。结果表明，在取样面积小于最小取样面积的范围内，随机取样在物种丰富度、种群密度、物种重要值等指标的测度上，在相同取样面积的条件下，所含信息量一般高于系统取样下所含信息；当取样面积较大时，两种取样方法所含的信息量则未有明显差异。

Permanent plots of the tropical montane rain forest located at Bawangling nature reserve,Hainan island,were established.With the aids of geographic information system,various random and systematic sampling schemes within the permanent plots were simulated.Variation of species richness,species density and species importance value with sampling area were used to compare the ecological entropy between random and systematic sampling.The results indicate that ecological entropy with random sampling was higher than that with systematic sampling while sampling area was less than the minimum sampling area of the community.