A timeline study of the total biomass and the biodiversity per unit area at different sites is being carried out in order to assess the status of the vegetation, to improve understanding of the processes underlying degradation, and to assess the need for and impact of measures to rehabilitate natural species and support natural regeneration. The species composition and biomass production is measured in seven different locations at regular intervals. At most of these sites simple protection measures are being used to support rehabilitation of the ecologically-degraded land. The long-term study will also help determine whether areas infested with the weed species Lantana and Eupatorium will be able to become more productive through natural processes. There has been considerable improvement in the vegetation status of the site since it was taken over by ICIMOD in 1993. Initially 394 plant species were identified, by 1996 the number had risen to 405, and by 2002 to 694, including 3 endemic, 4 rare, 4 endangered, 22 threatened, 41 multi-purpose tree, and 87 medicinal and aromatic plant species. Between 1993 and 2002, the average biomass of the natural forest on steep slopes increased from 93 to 182 t/ha; that of shrubland on mixed slopes from 27 to 40 t/ha; and that of shrubland on the valley floor from 35 to 61 t/ha. Overall, the average biomass of the site nearly doubled from 51 t/ha in 1993 to 90 t/ha in 2002. This is still much less than the 247 t/ha that can be expected in a well-preserved natural forest area in a similar ecological zone, but the trend shows clearly that rehabilitation is possible and the approach successful.