This book is unique in providing a global overview of alpine (high mountain) habitats that occur above the natural (cold-limited) tree line, describing the factors that have shaped them over both ecological and evolutionary timescales. The broad geographic coverage helps synthesise common features whilst revealing differences in the world's major alpine systems from the Arctic to the Tropics. The words barren and wasteland have often been applied to describe landscapes beyond the treeline. However, a closer look reveals a large diversity of habitats, assemblages and individual taxa, largely connected to topographic diversity within individual alpine regions. The book considers habitat-forming factors (landforms, energy and climate, hydrology, soils, and vegetation) individually, as well as their composite impacts on habitat characteristics. Evolution and population processes are examined in the context of the responsiveness / resilience of alpine habitats to global change. Finally, a critical assessment of the potential impacts of climate change, atmospheric pollutants and land use is made and related to the management and conservation options available for these unique habitats.