Assessment of Carbon Stock and Its Relationships with Forest Conditions in the Leasehold Forest User Groups (A Case Study from Nawalpur District)

Abstract

The introduction and implementation of the REDD+ (Reduced emission from the deforestation and forest degradation) program has resulted in an investigation of forest carbon from a local to global scale. Due to being the most productive terrestrial ecosystem, forests play an important role in mitigating climate change as they act as major carbon stores. Leasehold forestry (LF) is a participatory model of forest management whereby patches of degraded forest are handed over to groups from low-income households to improve forest conditions and reduce poverty. The planting of grasses in the forest floor and the introduction of fodder species, and promotion of natural regeneration by the removal of shrubs have contributed towards increased plant diversity and higher economic return in leasehold forests. The improved condition of the forest might significantly increase the environmental services provided by the forest, including carbon sequestration. However, studies on the quantification of carbon stock in leasehold forestry are lacking. We estimated the forest carbon stock of leasehold forests in three carbon pools namely Above Ground Tree Biomass (AGTB), Below Ground Tree Biomass (BGTB) and Above Ground Sapling Biomass (AGSB) in Nawalpur district in Nepal and assessed its variations with respect to restoration activities. Furthermore, we analyzed trade-off and synergies between carbon stock and tree diversity. Concentric sample plots with sub plots of 8.92, 5.64 and 1 m radius for trees, sapling and regeneration respectively were systematically laid out using 1% sampling intensity in three Leasehold Forest User Group (LFUG) clusters. Over these circles we collected information about trees (height, diameter at breast height (dbh) and species name), sapling (species name and dbh) and regeneration (species name and count) were collected from respective sub-plots. Average carbon stock was found to be 11.40 t/ha and the carbon stock in the tree-based restoration plot (14.49 t/ha) was significantly higher than in the non-tree-based restoration plot (3.81 t/ha). In contrast to majority of previous findings, we found synergy between carbon stock and tree diversity. Poor forest condition and restoration activities were the major reasons for such synergy. We recommend restoration of leasehold forests through protection and management of existing natural forests and planting of diverse trees.