Land use/land cover change-induced greenhouse gas emissions in the global biosphere reserve of tropical Afromontane forest

Abstract

Land use/land cover (LULC) change is a prominent problem and source of greenhouse gas (GHG) emissions in tropical forests. However, little to no evidence is available on the contribution of biosphere reserves to reversing LULC change trajectories and reducing GHG emissions, particularly in tropical Afromontane forests. The objective of this study was to quantify the LULC change-induced GHG emissions from 1999 to 2020 in tropical Afromontane forests that were designated the Sheka Forest Biosphere Reserve (SFBR) by the MAB program of UNESCO in 2012. The IPCC Tier 1 approach was used to estimate GHG emissions. The results showed that the aggregated GHG emissions were 0.4 tonnes of CO2e ha−1 yr−1 in 1999, while they climbed to 1.46 tonnes of CO2e ha−1 yr−1 in 2010 and 5.2 tonnes of CO2e ha−1 yr−1 in 2020. Deforestation and forest degradation, the expansion of cropland, the development of tea plantations, settlement expansion, and the forest degradation of wetlands contributed to increased emissions by 40.4%, 32.2%, 17.6%, 8.3%, and 1.5% in 2010 and by 60%, 20%, 5.2%, 14.4%, and 0.33% in 2020, respectively. As a result, compared to 9.03 tonnes of CO2e ha−1 yr−1 in 1999, the overall GHG mitigation potential of the SFBR decreased by 12.6% in 2010 and 40.2% in 2020. The findings suggest that the SFBR's capacity to reduce GHG emissions was neither enhanced nor maintained by its designation as a forest biosphere reserve. Therefore, regularly monitoring the effectiveness of interventions and reconciling conflicting land use priorities would be essential for maintaining Afromontane forests and reducing GHG emissions. Promoting tree planting, afforestation, reforestation, and restoring degraded forest landscapes would play a vital role to minimize GHG emissions and enhance the mitigation potential of the ecosystem.