Geo-forestry of landslide affected areas in a part of Central Himalaya

Abstract

Black-and-white aerial photographs were used to map the lithology, land-use/forest types, and landslide zones (namely old, active, or potential) in a part of Central Himalaya. The landslide and land-use/forest type maps were simultaneously studied, and the frequency distribution of the landslide zones in different land-uses and forest types was estimated. The correlation between the maps indicated the following: In old landslide-affected sites, agriculture was the predominant land-use, followed by Pinus roxburghii forest (≦ 40% crown cover), scrub vegetation, and wasteland (including grassland). The presence of other forests (e.g. forests dominated by climax species such as Shorea robusta at low elevations and Quercus spp. at higher elevations) indicates a high potentiality of recovery of the ecosystems involved, provided biotic (especially anthropic) factors are not too intensive. The active and potential landslide zones were concentrated along geologically active planes, namely thrusts and faults, and/or in the vicinity of toe-erosion of hil-slopes. These two were dominated by P.roxburghii forest (≦ 40% crown cover). The broadleaf forests showed minimal signs of active and potential landslides, perhaps because of their multistratal character which is conducive to minimizing soil-loss compared with the mostly single-storeyed Chir Pine forest. It is, therefore, suggested that the sites should be maintained under a multistratal broadleaf canopy to conserve the soil. Where, however, the Chir Pine forest is already developed, appropriate silvicultural measures may be taken to increase its crown cover to more than 40%.