Dynamics of ecosystem carbon in different forest types in the central
Himalaya: Role of nitrogen-fixing Nepalese alder (Alnus nepalensis D.
Don.)
Abstract
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.