样方大小对苔藓植物生态学指标的影响

Influence of sample size on bryophyte ecological indices

关键词:  苔藓植物  样方大小  生态位  多样性  最小面积

Key words:  bryophyte  sample size  niche width  diversity  minimum area

摘要:

为了分析样方大小对苔藓植物生态指标的影响,在环境相对一致的条件下,在各样点以巢式取样法调查苔藓植物盖度,取样的大小分别为20 cm×20 cm,30 cm×30 cm,40 cm×40 cm,50 cm×50 cm,60 cm×60 cm。通过统计发现,随着取样面积的增加,目测法所获得的优势种、总的苔藓植物的盖度呈现下降趋势,但是非优势种和偶见种的盖度却有上升趋势; 随着样方大小之间差异的扩大,所得调查数据间的差异也在扩大; 随着取样面积的增加,样方中苔藓植物的多样性指数、生态位宽度和重叠值、苔藓植物的平均种数均符合饱和曲线的增加规律; 取样面积大小对环境因子与苔藓植物分布之间关系的分析结果也有明显影响; 在生境相对一致的土生环境下,苔藓植物的取样面积可考虑在40 cm×40 cm～50 cm×50 cm的范围内。

Abstract:

In order to analyze the influences of sample sizes on byophyte ecological indices,plots were located using systematic sampling method under the similar ecological conditions,and the coverage of bryophytes were investigated by nested sampling method,the size of samples were 20 cm×20 cm,30 cm×30 cm,40 cm×40 cm,50 cm×50 cm and 60 cm×60 cm,respectively. A total of 73 plots including 365 samples were surveyed in the present study. Bryophyte coverages at each quadrat were recorded by vision estimation. Data analyses showed that the diversity indices,niche width and overlap,average species number of bryophyte per sample increased with the enlargement of sample size. Sampling size also affected the relationship between enviornmental varialbes and bryophyte distribution. In sites with relatively homogeneous habitats,sampling area for bryophyte communities could be considered from 40 cm×40 cm to 50 cm×50 cm.