The Hindu Kush/Afghanistan

Afghanistan is a mountainous country in C Asia with connections to S Asia. The main mountain ranges are the Hindu Kush with several partly isolated ranges, which diverge from NE to the W and SW. Deep valleys, basins and very high mountains form a complex mosaic of sites with contrasting climatic conditions. The Hindu Kush has significantly higher elevational belts than the Alps, the Caucasus, and the Iranian mountains. Thus, the ecological conditions are very diverse and are the reason for a high biodiversity and very diverse vegetation cover. The climate is high continental with hot summers and cold winters. Most regions are rather dry or even arid, having precipitation only during fall, winter or spring. However, the SE facing parts of the Hindu Kush in Nuristan, Nangarhar and Paktia (Safed Koh) receive additional summer-rains by monsoonal influence. Phytogeographically, those regions with their Himalayan influence had dense forests, whereas most other parts of the Hindu Kush have predominantly Irano-Turanian species with open woods, steppes or semi-deserts often with thorny cushion plants. The family Asteraceae has the most genera and species, and the genus Astragalus has the highest number of species. The upper elevational belts are home to some Siberian and boreal floristic elements. The most recent estimations of species numbers for Afghanistan are about 5000 species and 25% endemism.