An analysis of vegetation and species diversity patterns in sand dune and gravel desert ecosystem

Abstract

This study provides an analysis of vegetation and environmental relationships as well as diversity patterns in sand dunes and gravel desert plains of northern Badrud, Iran. A total of 63 species representing 49 genera and 15 families were recorded. The largest families were Asteraceae (22.2 %) and Chenopodiaceae (19.0 %). Therophytes (66.67 %) were the dominant life form. Chronological analysis showed 57.14 % Irano-Turani elements. Data from 60 1.5 2 m² quadrats, selected systematically randomized along three transects, were collected. Both two-way indicator species analysis (TWINSPAN) and cluster analysis using Ward’s method resulted in the recognition of three communities: an Artemisia sieberi community in the center plain with a Shannon-Wiener diversity index of 0.3, a Stipagrostis plumosa - Schismus arabicus community on the lower sand dunes with a Shannon-Wiener diversity index of 0.7, and a Haloxylon ammodendron community on the higher sand dunes with a Shannon-Wiener diversity index of 0.2. Detrended correspondence analysis (DCA), non-metric multidimensional scaling (NMDS), and multi-response permutation procedure (MRPP), confirmed the separation of TWINSPAN groups as well as the heterogeneity of the Artemisia sieberi - Schismus arabicus community, suggesting a distinct group with Artemisia sieberi and Schismus arabicus as the dominant species. Vegetation environmental analysis by means of multivariate techniques of principal component analysis (PCA) and canonical correspondence analysis (CCA) indicated that very coarse gravel has a strong negative effect on diversity and a negative effect on species cover percentage. Bare ground showed a highly positive effect on diversity variables. Soil analysis suggests final seral stages of succession towards severe desertification.

Keywords

• desert vegetation
• floristic inventory
• ordination
• cluster analysis
• TWINSPAN