The Himalayas are Earth's greatest mountain range not only in terms of their highest peaks, but also in the extent of their high altitude area. They have profound effects on Asia's climate, biodiversity and human cultures, but in many ways are still poorly known. Fundamental questions which are still to be fully answered include the timing of the formation of the High Himalayas, how this has affected the evolution of biodiversity in the region, how severely the region has been impacted by humankind and what the future holds as global climates change. Nepal, lying in the centre of the Himalayan Arc, is a microcosm for the whole range and this companion volume to the Flora of Nepal addresses all aspects of the Himalayas' environment. It includes contributions from more than forty international experts covering the region's geology, geomorphology, hydrology, climate, soils, evolutionary biology, ecology, palynology, ethnobotany, anthropology and conservation. The discussion of the Himalayas' biodiversity is not limited to higher plants, but also includes the ferns, bryophytes and lichens, as well as considering fungi and recent research into the evolution of the fauna. This review is a statement of our current understanding of a region, and presents new data and new perspectives, but also highlights the gaps in our knowledge that require further research. It is heavily referenced throughout, and will act as a source book for all environmental researchers working within Nepal and in its neighbouring countries.