Carbon Sequestration Potential in community managed Forests in Mahottari District of Central Nepal

Abstract

Forest carbon sequestration plays a significant role in mitigation and adaptation to the impacts of the climate change. The carbon sequestration is accounted as carbon credit for reducing emission from deforestation and forest degradation (REDD+) programme. On the other hand, increasing concentration of CO2 emission contributes to green house gases (GHGs), which are mainly responsible for global warming and consequence is impacts of climate change. These, both need intensive scientific records to assess them, the former needs the records of carbon stock change while the latter one needs the record of sources of GHGs emission particularly the CO2 and CH4 emission. Such researches are very limited in Nepal. Thus, this study is objectively carried out to assess the specieswise Importance value index (IVI) and carbon stock; to assess the carbon stock in community managed forests; to identify the carbon sequestration potential and confrontation for carbon trade; to evaluate the carbon stocks for sustainable management of forests; to appraise the plant biodiversity status and its relationship with the forest carbon stock; to identify drivers of deforestation and forest degradation and its effects on carbon stocks in community managed forests and to quantify the CO2 and CH4 emission from domestic fuel and livestock keeping of household living near to forest and distant from the forests. For this study, two types of data specifically biophysical and socio-economic data were collected. The biophysical data were collected from community managed forests like three from each collaborative and community forests as well as public plantations and community planted forests of Mahottari district. In addition, socio-economic data collection was focused on drivers of deforestation and forest degradation, which were collected from workshop with key informants. Meanwhile, Sahodawa and Maisthan villages were selected for assessing the CO2 and CH4 emission from fuel consumption and cattle keeping respectively, which are sources of climate change process drivers. The maps of forest areas were prepared and stratified using GPS coordinates. Latter, altogether 96, 80, 28 and 24 permanent sample plots were distributed randomly on the maps of collaborative forests, community forests, public plantations and community planted forests respectively. The randomized block design (RBD) was set so the data were collected using stratified random sampling from collaborative and community forests. Meanwhile, the complete random design (CRD) was set to gather data applying simple random sampling from public and community planted forests. Similarly, altogether 138 households were sampled randomly after well-being ranking such as rich, medium and poor, then the quantity of fuel consumption was recorded in the morning and evening for seven days during summer and winter seasons setting RBD. Next, the record of cattle keeping was noted in order to determine the CH4 and CO2 emissions. At the same time list of drivers of deforestation and forest degradation were also gathered. The biophysical data were analyzed using the biomass equation of Chave et al. The species wise IVI was also calculated and their ranking was evaluated to know the effect of carbon on IVI. Same biophysical data were used to find out the relationship between biodiversity and forest carbon. Moreover, soil carbon was calculated applying Walkley and Black Method. Meanwhile, the carbon stocks of community forests and collaborative forests were checked applying Biolley's "Check Method" - Method du-Control and Biolley's sustainable principle. Additionally, the relationships were evaluated between carbon stocks and species richness and between carbon stocks and Simpson's evenness. The socio-economic data were analyzed using descriptive analysis. It showed that, IVI of Shorea robusta was the highest about 68.59 in Tuteshwarnath CFM while this value of Gmelina arborea was the lowest 0.4 in Gadhanta- Bardibash CFM. Meanwhile, the carbon stock of Shorea robusta was the highest 50.43±0.43 t ha-1 and this of Desmodium oojeinense was the lowest 0.01 t ha-1 in Gadhanta- Bardibash CFM. In addition, there was effect of carbon stock in species ranking. It was found that the estimated carbon stock was the highest 274.67 t ha-1 in Gadhanta- Bardibash CFM while it was the lowest in 30.34 t ha-1 in Bisbitty public plantation. The estimated current annual carbon increment (CACI) was found to be highest 2.85 t ha-1 at third year in Chyandanda community forest. However, annual carbon loss (ACL) was recorded as leakage -1.68 t ha-1 from Banke- Maraha CFM. The net value of carbon sequestration potential was US$ 5967.62. Therefore, these community managed forests can be avenue for carbon trade under the REDD+ programme. Neither community forests nor collaborative forest showed sustainability performance based on Biolley's "Check Method" - Method du-Control and Biolley's sustainable principle. Here, the issues of sustainable forest management and biodiversity should be balanced equally. The estimated R2 values indicated that there is very weak relationship between species richness and carbon stock, however, the hump- shaped relationship was exist between them. The over exploitation, grazing and forest fire were major drivers of deforestation and forest degradation, which are affecting the carbon stock. Total quantities of CO2 emission were 4792.25 t and 9235.68 t in Maisthan and Sahodawa villages respectively from firewood consumption. The CH4 emissions were 160.58 and 157.66 t yr-1 in Maisthan and in Sahodawa villages respectively from the livestock keeping, which together may emit 7367.59 t CO2 equivalents but managing the CH4 emission through biogas can offer US$ 47568.35 certified emission reduction. Therefore, it can be concluded that community managed forests are potential for carbon trade. On the other it is essential to determine the drivers of deforestation and forest degradation to address them for REDD+ programme in Nepal as well as to determine the sources of CO2 and CH4 clearly to reduce them as measures of climate change adaptation and mitigation. Keywords: Carbon sequestration, CO2 and CH4 emission, REDD+, biodiversity, community forests, collaborative forests, public plantation, community planted forest.