Rehabilitation of old river bed lands by an intensively managed silvi-pastoral system in the north-west Himalayas

Abstract

Coarse sediments deposited as gravel bars along seasonal rivers, which often overflow, deposit them on arable lands rendering them unproductive. Rehabilitation of such areas was attempted by a silvi-pastoral system with Grewia optiva (J.R. Drummond ex Burret), Chrysopogon fulvus (Spreng.) and Panicum maximum (Jacq.), which belong to this region. Three tree canopy management practices-coppicing, lopping and pollarding were imposed on G. optiva trees at the age of 5 years, and tree leaf fodder and woody biomass production were estimated, with and without grasses as understorey components. Results of the study indicate that among the systems evaluated, pollarding system was the most productive method for obtaining higher leaf and woody biomass on a regular basis. Averaged over 9 years, leaf biomass (kg ha-1) from tree only plots recorded was 803.4, 920.0 and 355.4 in the coppiced, pollarded and lopped treatments, respectively. Woody biomass in the same sequence was 3.24 Mg ha-1, 2.81 Mg ha-1 and, 1.08 Mg ha-1, respectively. There was an average decline of 37 and 35% in leaf and woody biomass production, respectively, over 9 years as a result of incorporation of the two fodder grasses under different canopy management practices. This long term study indicates that old river bed lands can be rehabilitated by raising G. optiva trees alongwith fodder grasses viz., C. fulvus and P. maximum and managing the tree canopy by pollarding for obtaining fodder and woody biomass on a regular basis.