Sequential Pattern in the Stabilized Dunes of Donana Biological Reserve (SW Spain)

Abstract

There is a spatial pattern of shrub vegetation within the stabilized dunes of the Donana Biological Reserve consisting of a six dune-ridge/dune-slack sequence. A vegetation data set was subjected to a Split Moving Window Boundary Analysis along a 10.5 km transect. This method allows the identification of boundaries along transects and thereby different vegetation zones through the calculation of metric dissimilarities between adjacent groups of samples. The obtained dissimilarity profile shows twelve peaks, five of them corresponding to transitions to heathlands (mainly composed by Erica scoparia L.). Those patches of heathlands show a regular pattern, appearing at a distance of ca. 1,500 m away one from each other, and are related to the location of the slacks of the ancient dune systems, where the water availability is higher than in the dune ridges. The general dune field is composed of several episodes of dune development, with the younger dune forms partially transgressing inland over the older forms. Each of the dune building episodes has created dune forms with different topographic elevations and with different depths to groundwater, which is further manifested in different patterns of heathland composition.