Changes in Vegetation and Soil During Succession Following Landslide Disturbance in the Central Himalaya

Recovery of soil properties, species sequence and changes in plant biomass following landslide damage were studied on 19 sites adjacent to oak (oak zone) and pine (pin zone) forests in the central Himalaya. Fine soil content, organic C and soil nutrients (N, P, Ca and K) increased with age in a non-linear manner. The changes in the soil properties were more rapid in early stages than in later stages. Annuals dominated the sites in early stages of succession. The herb species content and cover increased with age and were positively related with fine soil content and total soil nitrogen. In the oak zone site, seedlings of pioneer tree species appeared from 6 years, while seedlings of climax oak species appeared after 15 years. On the other hand, seedlings of Pinus roxburghii appeared soon after disturbance in the pine zone, and species persisted throughout the developmental stages. The process of succession corresponded to the tolerance model and the resource ratio hypothesis in the oak zone and to an inhibition model in the pine zone. Nomenclature follows Osmaston (1926) and Naithani (1985).