About a quarter of the world's forests are in mountain areas, providing a wide range of goods and services to mountain people, those living downstream, and domestic and foreign visitors. Wood is perhaps the most obvious product of mountain forests—a source of energy, construction materials, fencing and many other products for both mountain people and others—and scientific forestry has commonly focussed on ensuring sustainable yields of timber. However, mountain forests are important for many other reasons, as the research papers and development articles in this issue of Mountain Research and Development (MRD) make abundantly clear. At a global scale, perhaps the most important values of mountain forests are their roles in trapping, storing, and releasing water, and protecting slopes and soils from erosion. In these ways, mountain forests contribute to the well-being of billions of people worldwide in ensuring that rivers flowing from the mountains provide reliable and high-quality supplies of water, particularly in the summer seasons when rainfall in adjacent lowlands is often limited, and evaporation rates and agricultural demands are highest.
Mountain forests are also global centres of biological diversity, containing plants and animals that have value for human consumption and medication, provide possibilities for development of pharmaceuticals, and attract tourists. As a number of the contributions in this issue make clear, mountain people recognize these diverse values—and it is often difficult to distinguish ‘natural’ mountain forests from ‘anthropogenic’ ones. In line with the editorial policy of MRD, most of the contributions focus on the importance of mountain forests for the local people who depend most directly on them, and have often developed sophisticated institutions for managing limited resources. Such institutions have often been threatened, or even destroyed, by centralization and globalization; yet there is increasing recognition that community-based institutions are the best adapted to ensuring that mountain forests continue to supply their diverse goods and services to both mountain and other people over the long term.