Global change impacts on alpine habitats: climate and nitrogen deposition

Abstract

Abstract Global change may be considered to encompass recent (post-1960s) changes in land use and climate, and largely human-induced impacts in atmospheric chemistry (especially inorganic nutrients such as nitrogen compounds and carbon dioxide) and biotic interactions, such as invasions by alien species. The relative importance according to the severity and extent of impact of each of these factors, or drivers of global change on alpine biodiversity has been estimated to follow the order of: land use ≈ climate change > nitrogen deposition > carbon dioxide enrichment > biotic interactions (Walker et al. 2001a). We consider the three most important of these. Climate change is the focus of this chapter, together with briefly discussing the potential impacts of nitrogen deposition; land use is dealt with in the following chapter. We start with an outline of past climate changes and their perceived changes in the extent and quality of alpine habitats and vegetation. This is followed by characterizing climatic drivers and enlisting climate change scenarios and observed changes attributed to climate warming. Considerations are given to factors that couple or decouple climate and plant growth at the landscape scale. Finally, the reader is directed to the chapter on land use and conservation.