A vegetation study in the walnut and fruit-tree forests of Southern Kyrgyzstan
The vegetation of the so-called walnut-fruit forests of Southern Kyrgyzstan has been analyzed using the Braun-Blanquet approach. Field work was carried out in two exemplary study areas in the forest area Kugart-Arslanbob. The spatial distribution of vegetation types, land-use and soil conditions in the area is delineated. Three plant communities are described with regard to their floristic composition, structure and ecology. The influence of grazing stock on the communities is discussed. The syntaxonomic relationship of walnut-fruit forests to the class Querco-Fagetea is shown to be relatively low. On the basis of field data, water supply is considered to be the most important environmental factor for the differentiation of plant communities. In an ecological series along the gradient of humidity, the Conioselinum tataricum-Juglans regia-community is found on the moistest sites, particularly slopes with northern exposition. These sites offer the best growing conditions, as measured by tree heights. The Hesperis sibirica-Juglans regia-community is found on transitional sites, often with western, eastern or southern exposition, characterized also by higher light intensities. The Stachys betoniciflora-Acer turkestanicum-community was observed on the driest sites, i.e. the middle and upper parts of western, southern or eastern slopes. Grazing is shown to have a strong influence on species composition, and pastoral variants can be distinguished in all of the examined forest communities. Finally, the relationship of the proposed scheme to earlier classifications based on the dominance principle is discussed.