Land degradation and soil and water conservation in tropical highlands

Land degradation is not uniform, even in the same landscape, but nevertheless an overall consensus seems to grow on the fact that many areas are under way of rehabilitation. It is a debateable question whether the improving areas are improving because of interventions—or whether this has more to do with processes of innovation and adaptation. The international symposium ‘HighLand2006’ on land degradation and land rehabilitation, held in Mekelle (Ethiopia), from 21 to 25 September 2006, created a forum for those conducting research in East African Highlands as well as in similar regions around the globe to discuss findings. Tropical highlands (>1000 m a.s.l.) cover 4.5 million km² with an average population density of 33 inhabitants km⁻². Nearly all tropical highlands suffer from land degradation, especially medium to very high water erosion. Exchange of experiences during in-door sessions and excursions led to results which are condensed in this special issue. Studies presented tend to invalidate hypotheses on irreversibility of land degradation in tropical mountain areas. Circumstances are that in highly degraded environments, with high pressure on the land, no other alternatives are left open but to improve land husbandry; and that this is particularly successful in places where decision making processes at different levels in society give the highest priority to the implementation of soil and water conservation and other land rehabilitation, in situ and at catchment level.