Biomass production and carbon stock potential of natural vegetation, agroforestry and cultivated land use systems along altitudinal gradient in north western Himalaya

The present study was undertaken in two altitudinal ranges 365-635 m and 636-914 m above mean sea level covering sub-montane, low hills and sub-tropical regions of Himachal Pradesh, India. The two altitudinal ranges were selected because of having common eight land use systems viz., agriculture (T-1), horticulture (T-2), agrisilvicultural (T-3), silvopastoral (T-4), agrihorticulture (T-5), agrihortisilvicultural (T-6), forest (T-7) and grassland (T-8). The experiment was carried out to identify variation in different land use systems in terms of biomass production and carbon stock potentials. The maximum value of aboveground biomass (184.75 t ha(-1)), belowground biomass (47.84 t ha(-1)) and total biomass (232.59 t ha(-1)) was recorded in forest land use system. All traits of biomass followed the order of T-6>T-2>T-5>T-3>T-4 >T-1>T-8 Among the agroforestry systems maximum aboveground (66.46 t ha(-1)), belowground (20.84 t ha(-1)) and total biomass (86.48 t ha(-1)) were accumulated in agrihortisilviculture system. The values of above, below and total biomass showed declining trend with increase in altitude. Vegetation carbon density also decreased with increasing altitudinal range. Among agroforestry systems, maximum (90.10 t ha(-1)) total carbon stock was observed in agrihortisilviculture, which was 2.45, 4.42, 10.67 and 44.80% higher than agrihorticulture, silvopastoral, agrisilviculture and agriculture land use system.