The influence of quadrat size on spatial heterogeneity of meadow grassland, Northern China

The objective of this study was to determine influence of survey quadrats size on spatial heterogeneity of meadow grassland in north China. An integrative approach was used based on field survey method that the sample line combined with sample quadrat to analyze the vegetation heterogeneity characteristics of Stipa + Leymus Mss. steppe in Hulunbeier grassland. Results showed that: perennial plants, C₃ plants, and cluster grass plants were dominant communities in Hulunbeier grassland under different functional classification. And species richness of them were accounted for the total species richness of more than 86%, 90% and 23.4%, respectively. Despite the species richness of bunch grass plants was little in the functional composition classification, the above ground biomass was accounted for a larger proportion of 50.2%. From the spatial heterogeneity characteristics of Stipa+Leymus Mss. steppe, 6m² is the turning point of the spatial heterogeneity of total species richness, species richness of perennial plant, cluster plant and C₃ plant. That's because when the quadrat size is less than 6m², the spatial heterogeneity of the total species richness, species richness of perennial plant, cluster plant and C₃ plant were changed significantly with the quadrat size changed, and when the quadrat size is larger than that of 6m², its spatial heterogeneity becomes small. The above analysis shows that in the field survey of Stipa+Leymus Mss. steppe, the quadrat size used in the survey should be not less than 6m², for the summary vegetation information of quadrat size with 6m² can describe the general characteristics of vegetation investigation well.