Nature conservation, outdoor recreation and research. The site is ideally placed to monitor changes in: * Tree colonisation - Mature trees (principally Scots pine, Pinus sylvestris) at the site are confined to a relatively small part of the lower ground and there had been no significant regeneration over the last two centuries due to heavy grazing by deer, and burning. However, a reduction in deer grazing began around 20 years ago and colonisation by saplings is now widespread; *Climate change - The site straddles the zones of increasing winter precipitation and decreasing summer precipitation whilst there is also evidence of increasing windiness. The specialised arctic-alpine plant communities found at the site can be used to provide an interesting early warning system for possible effects of climate change on habitats located further north in the arctic. * Hydrology - This is one of the longest recorded snow sites in the UK and is also a complete gauged catchment; * Pollution - Levels of air, water and soil pollution at the site are relatively low compared to other parts of the UK, and the site therefore provides a good control area; * Vegetation change - There is an excellent altitudinal sequence of communities, from Caledonian pine woodland at 300m up to arctic-alpine vegetation at 1100m which have been repeatedly surveyed over the past 20 years.