木炭の持続可能なエネルギー転換における生物多様性の役割

Unofficial AI-generated summary based on the public title and abstract. Not an official translation.

🔬研究者:Provides biome-specific carbon dynamics data and modeling approaches for land-use and climate research.

🏢実務担当者:Offers insights for sustainable charcoal sourcing and land management in African operations.

🏛政策担当者:Informs land-use governance and energy transition policies in Sub-Saharan Africa.

Charcoal remains an important energy source for millions of people in Sub-Saharan Africa (SSA) because no viable alternatives exist, yet its production contributes to land-use and land-cover change (LULCC), forest degradation, and long-term shifts in the regional and potentially global carbon balance. As SSA faces rapid population growth, increasing energy demand and associated deforestation, and increasing vulnerability to climate change, there is a need to understand how charcoal production impacts carbon dynamics across SSA’s diverse biomes and how these impacts interact with LULCC and climate change. Despite the growing knowledge on charcoal’s carbon footprint, how the magnitude and direction of carbon fluxes vary by biome, and how future carbon dynamics in SSA’s biomes will respond to accelerating LULCC and climate change remain poorly understood. This thesis addresses this gap by investigating how charcoal production, LULCC, and climate change collectively shape carbon dynamics across SSA biomes. It is grounded in the hypothesis that ongoing charcoal production disrupts the carbon balance in biomes of SSA, undermining their resilience to future land-use and climate pressures. To test this, we designed three independent but complementary studies focusing on six major SSA biomes: tropical rainforest, montane forest, moist savanna, dry savanna, temperate grassland, and semi-desert. The first study aimed at examining the responses of biomes to varying charcoal production intensities (i.e. harvest amounts and rotation period) through quantifying impacts on carbon stocks, Net Ecosystem Exchange, and recovery times. We used a dynamic global vegetation model, LPJ-GUESS-Fire, to simulate the different biomes, parameterized for the different biomes, and their responses to charcoal production regimes. We find that high-biomass biomes, tropical rainforests and montane forests, experience the strongest carbon losses from charcoal harvesting and require the longest recovery periods, often shifting from net carbon sinks to net sources even under low harvesting intensity. Although above-ground carbon in moist and dry savannas recovered relatively quickly at all harvesting intensities, soil organic carbon showed the slowest response, with recovery times approaching 100 years. Similarly, in semi-deserts and temperate grasslands, charcoal production primarily affected soil carbon, with recovery times ranging from 30 to 75 years. The second study aimed to indentify the key drivers of forest loss, disturbance, and gain by zooming in into the national level in Mozambique, testing for effects of climatic, demographic, physical, and land-use variables on forest dynamics. Using a Random forest model, we find that land use and management, particularly cropland expansion, are the dominant drivers of forest dynamics, strongly predicting both forest loss and disturbance. Climate variables, especially rainfall and temperature, emerge as secondary but important modifiers, mediating forest degradation and loss under drought and extreme weather conditions. Spatial probability mapping indicates that over 60% of Mozambique’s forested area is at moderate to high risk of deforestation, with forest gains insufficient to offset widespread losses. These patterns point to a trajectory of net forest decline, implying sustained carbon emissions from biomass loss and a reduced capacity for forest recovery and long-term carbon sequestration at the national scale. The third study assessed how future LULCC and climate change, under the five Shared Socioeconomic Pathways (SSPs), will shape carbon dynamics across SSA’s biomes through to 2100. Again, using LPJ-GUESS-Fire, we find that regionally, scenario simulations show that LULCC will remain the leading driver of future carbon losses across SSA, overriding climate-driven carbon gains in all biomes. Under combined LULCC and climate change simulations, most biomes transition toward persistent net carbon sources, with moist and dry savannas contributing the largest cumulative emissions due to their spatial extent and high exposure to cropland and pasture expansion. Although climate change alone enhances NPP in some biomes through CO₂ fertilisation, these gains are insufficient to offset land-use–induced carbon losses. Intensified LULCC further shortens biome carbon turnover times by up to 50%, particularly in tropical rainforests, indicating accelerated carbon cycling, reduced long-term storage, and declining biome resilience under future socioeconomic pressures. Overall, the findings from the different studies show that charcoal production is a significant but biome-dependent driver of carbon loss, and that future trajectories in SSA will be shaped by land-use decisions rather than by climate change. Sustainable pathways, therefore, require linking energy access, land-use governance, and nature conservation and protection to avoid carbon losses while supporting livelihoods. A sustainable energy transition in SSA requires biome-specific strategies, with tropical rainforest and montane forest needing strong protection, savannas benefiting from regulated harvesting and livelihood support, and temperate grasslands and semi-deserts relying on soil-focused restoration and improved grazing. This work demonstrates that while socioeconomic and LULCC pressures are growing, the pathways to sustainability should consider strengthening energy alternatives, implementing biome-specific management, improving land-use governance, and fostering regional cooperation in SSA.

• openalex https://doi.org/10.5167/uzh-435300first seen 2026-08-20 04:37:30