The Impact of Sample Area and Sample Amount on the Results of Community Species Diversity Measure——A Case Study with the Shrub Community in the West Region of Yanshan Mountain

In order to understand the impact of different sampling ways on the result of investigation on commmunity species diversity,an analysis was performed on how sample area and sample amount impacted the results of community species diversity measure based on the investigation of herbaceous plants in the shrub community in the west region of Yanshan Mountain.The results showed that sample area influences the community species richness,species diversity index and evenness markebly.Both species richness and α-diversityindexes increased with the sample area,and the evenness decreased with the sample area.They abruptly changed at the beginning and then kept steady while sampling area enlarged,indicating the strong influence of scale on diversity in some scale ranges.The sample area of 1 m2 which is used generally led to a lower value of species richness and α-diversity indexes and a higher value of evenness.Comparatively,the measure of species richness needs a bigger sample area than the measurement of α-diversity indexes.The sample area has a distinct influence on the degree of variation of species diversity,and enlarging the sample area properly would decrease the oversize variation between different parallel sample due to the small sample area.