Is the life-supporting capacity of forests in the lower Mid-Hills of Nepal threatened?

Lack of knowledge on forest structure, composition, and magnitude of human impact on various components of the ecosystem remain a major limitation for the development of appropriate participatory management programmes for conservation and sustainable utilisation of forests in Nepal. This study provides information on state of the resource base and effects of site characteristics and human activities on density, diversity and regeneration in Sal (Shorea robusta Gaertn.f.) and Mixed Broadleaved (MBL) forests in the central, lower Mid-Hills of Nepal. For trees with diameter ⩾10 cm the results are based on 72 square (20 × 20 m) plots; for shrubs and herbs the material included 144 plots, nested within the 72 larger plots. Apart from vegetation data the material included information on human impacts, such as tree cutting, livestock grazing and lopping. The proportion of trees felled in Sal forest was observed to be up to 41%. The pressure on the vegetation also affected the regeneration of trees, shrubs and herbs. The density and basal area were moderate for all vegetation types, whereas the species diversity was higher than previously observed in other forests of Nepal. Among the species used by the ethnic group living in the study area, the Chepangs, only half (49.7%) were represented within the plots and the regeneration of such species was poor. Effects of altitude, aspect, grazing, crown cover and other factors on basal area and density of different vegetation strata was examined using general linear models. The results indicated significant human impact on the forest vegetation, both with respect to species diversity, density, distribution, and composition. Reduction of the densities of key livelihood species will affect the social and economic welfare of local people. Thus an improvement of forest management is urgent, because the forests need immediate recovery.

► Density, diversity, frequency, basal area, coverage and utilisation effects were studied in two types of forests. ► Indicated significant human impact on species diversity, density, distribution, composition and regeneration. ► Reduction of the densities of key livelihood species affects the social and economic welfare of local people.