Scale Effects and Fractal Analysis of Species Diversity in Typical Steppe of Inner Mongolia

The variations of the Shannon diversity index and Patrick richness index with different sampling scale were analyzed to study the effect of special scale on species diversity in Inner Mongolia typical steppe using the transect line survey method.The study educed the fractal dimensions(D) of two α-diversity indexes using fractal theory combining with fractal methods.Results showed that Shannon diversity index first increased rapidly then decreased with a sampling scale increasing,while Patrick richness index held the line after reaching a peak value.Five square meters was an optimal scale to study α-diversity in this area.Two α-diversity indexes had significant correlation with sampling scale in bi-logarithm coordinates of five-meter sampling range(P0.01),and the correlation coefficients(R) were more than 0.99,but there was no obvious linear regularity beyond five-meters.D value indicated that the species composition in the researched region was not complicated.Therefore,smaller single sampling squares or more sampling squares should be applied carefully to study community diversity.The sampling scale should be introduced basing on study purpose and the characteristics of diversity indices.