Spatial Autocorrelation and Fractal Dimension of Alga Species Assemblage in a Gravel Stream of Central Europe

Abstract

AbstractThe relationship of benthic diatom species to sampling scale was studied in two Moravian rivers that differ in substrate and discharge. Number of cells per mm2 of each species was used for statistical analysis. The distribution of abundance of benthic algae follows a fractal pattern, because it exhibits the same detail over a continuum of scales. DCA first axis score, variogram and fractal dimension were used for spatial autocorrelation estimation. The fractal dimensions obtained are generally close to 2, implying weak spatial dependence. The fractal dimension was not a constant function of scale, implying that patterns of spatial variation at one scale cannot be extrapolated to other scales. The results suggest that appropriate distances among samples of benthic algae must be considered.