Altitudinal variation of woody vegetation in Tirthan valley of great Himalayan national park at Kullu, Himachal Pradesh

Abstract

The present investigation entitled "Altitudinal variation of woody vegetation in Tirthan valley of Great Himalayan National Park at Kullu, Himachal Pradesh" was carried out in three different elevation i.e. lower zone (1500-2000 m.), mid zone (2000-2500 m.) and upper zone (2500-3000 m.) of Tirthan valley at Great Himalayan National Park. In every elevational zone, 12 quadrats of 30 m X 30 m (900 sq m) size determined by species area curve method were randomly laid to study tree species. In each quadrat, a sub-quadrat of 5m X 5m (25 sq m) size for study of shrubs was laid. The generic spectrum of vegetation in Tirthan valley of Great Himalayan National Park comprised of 113 woody elements which included 58 tree species and 98 shrub species. In Tirthan valley, number of forest species decreased periodically from lower elevation to upper elevation and mean density (Individual/ha.) of tree vegetation increased along elevation. Tree density (Individual/ha.) in Tirthan valley was 683.33, 758.34 and 816.67 for lower zone, mid zone and upper zone respectively. Whereas, shrub density (Individual/ha.) in valley was 2866.67, 1900, 1233.33 for lower, mid and upper zone respectively. In valley, Pinus wallichiana at lower zone (IVI 58.7), Picea smithiana at mid zone (IVI 50.43), Quercus semecarpifolia at upper zone (IVI 70.79) were the dominant tree species. In shrub layer of Tirthan forest, dominant species at lower zone was Desmodium triflorum, at mid zone was Indigofera heterantha while at upper zone it was Rosa sericea.