Figure 1
Nitrogen-fixing Nepalese alder (Alnus nepalensis D. Don.) is a fast-growing early successional species which often forms pure stands in areas affected by landslides and sometimes it occurs mixed with other species in the central Himalayas. In this study, we assessed the distribution of ecosystem carbon storage in plants and soil in a chronosequence of A. nepalensis forest stands in central Himalaya. We examined six forest stands: (1) A. nepalensis-early regeneration (AER) forest, (2) A. nepalensis-late regeneration (ALR) forest, (3) A. nepalensis- mature oak mixed (AMOM) forest, (4) A. nepalensis- mix with rhododendron (AMR) forest, (5) A. nepalensis –mix with old oak (AMOO) forest and (6) A. nepalensis-planted by the forest department in the degraded forest (APDF). The ecosystem C stock increased with an increase in stand total basal area (TBA). C storage in A. nepalensis tree biomass in different stand AER, APDF, ALR, AMOM, and AMR, AMOO, was 8.97, 51.41, 16.07, 53.74, 144.77, and 101.14 Mg ha-1, respectively. Soil organic C (SOC) in different soil depths in successional stages AER (0-10 cm), APDF (0-30 cm), ALR (0-100 cm), AMOM (0-100 cm), AMR (0-100 cm), and AMOO (0-100 cm) was 3.31, 31.21, 75.47, 157.04, 159.43 and 210.13 Mg ha-1, respectively, with decrease in SOC concentration with increasing soil depth. The ecosystem C storage averaged 15.85, 183, 216.26, 390.32, 403.66, and 500.08 Mg ha-1 in AER, APDF, ALR, AMOM, AMR, and AMOO sites, respectively. Overall, in A. nepalensis forest development markedly ameliorated both vegetation and soil succession in central Himalaya.