Intermediate levels of socio-ecological disturbance drive higher biodiversity in naturally regenerating forests: A case study from Nepal

Abstract

Farmers in the middle hills of Nepal have been abandoning agricultural land over the last three decades due to complex socio-ecological drivers and dynamics. A consequence of this shift is the succession of forest. Naturally regenerating tree species, and farmers’ opinions of species benefits, were assessed with field measurements and interviews to guide an analysis of the socio-ecological factors that influence forest succession. Non-linear patterns of species abundance and diversity suggest that intermediate levels of disturbance lead to higher rates of biodiversity than either high or low management interventions within regenerating forest patches. Farmers that practice no or low levels of disturbance exhibit little investment or perceived benefits from their land beyond occasional fodder collection, while high forest disturbance is motivated primarily by activities within the succeeding forest that generate income. Intermediate disturbance patterns in succeeding forests mimic traditional farming practices in Nepal, utilising trees within the mosaic landscape for livelihood purposes. The local heterogenic agro-ecosystems are also associated with higher species diversity. Policy to support the maintenance or enhancement of forest succession on formerly cultivated cropland could contribute to higher species diversity and build adaptive capacity of rural households during landscape transitions.