Semi-arid rangeland vegetation of the Greater Caucasus foothills in Azerbaijan and its driving environmental conditions

We present the plant communities of two semi-arid rangelands at the foothills of the Greater Caucasus Mountains in Azerbaijan and describe their relationships to site conditions and grazing impact. We sampled a total of 313 vegetation releves containing 272 vascular plant species with a stratified random design and along ten transects in the Gobustan and Jeiranchel regions, covering 1500 km(2) and 1300 km(2) respectively. To classify the rangeland communities we applied agglomerative hierarchical clustering, while the influence of site parameters was obtained by Nonmetric Multidimensional Scaling (NMDS) ordination. A total of 16 plant communities were classified, ranging from deserts with annual herbs, semi-deserts dominated by various chenopod shrubs, Artemisia lerchiana semi-deserts to steppes with perennial forbs and bunchgrasses. The strongest gradients in vegetation composition can be explained by a combination of salinity and acidity along an altitudinal gradient, by differences in soil texture, and by slope inclination. Whereas we detected only small alterations in the response to grazing impact on the whole pastures, vegetation in the close vicinity of farms differs strongly. The involvement of annual species in the analyses gives a more detailed picture compared to previous vegetation classifications based on dominant species.