Landscape restoration with agroforestry system in West Africa: Carbon storage dynamics and soil carbon dioxide efflux

The event “Landscape restoration with agroforestry system in West Africa: Carbon storage dynamics and soil carbon dioxide efflux” is scheduled for May 26, 2025, at Aula Talento All'Opera (Palazzo Boyl, Pisa) or online (link here) featuring the following the following visiting speakers from the :

•  Stephen Adu-Bredu is a Chief Research Scientist of the Forestry Research Institute of Ghana (FORIG) of the Council for Scientific and Industrial Research (CSIR), a Professor at the CSIR College of Science and Technology, and was the Deputy Director of FORIG from January 2013 to June 2015. He also lectures at the Climate Change and Land Use Doctoral programme (WASCAL) of the Civil Engineering Department of the Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
• Emmanuel Amponsah Manu holds MPhil. Climate Change and Integrated Natural Resources Management from the CSIR College of Science and Technology.  He also holds BSc. in Natural Resources Management from the Kwame Nkrumah University of Science and Technology (KNUST), Ghana, with specialty in Forest Resources Technology in land Reclamation He has been with the CSIR-Forestry Research Institute of Ghana since 1998, assigned to Biodiversity conservation and Ecosystems services Division. He became Assistant Research Scientist in 2023. He has been actively involved in many Research project such as Establishment of Permanent sample plots at different ecological zones in Ghana, Lightning Project: Establishment of 50 hectares plots in Ankasa Conservation Area in the wet evergreen forest, The effects of trees in cocoa agroforest landscape in Ghana, Assessment of trees in cocoa agroforest landscape etc.
• Eunice Okyere-Agyapong is an Assistant Research Scientist at the CSIR-Forestry Research Institute of Ghana (CSIR-FORIG), assigned to the Forest and Climate Change (FCCD). Currently, she is a postgraduate student at the Kwame Nkrumah University of Science and Technology pursuing PhD in Silviculture and Forest Management. She holds MPhil. Climate Change and Integrated Natural Resources Management from the CSIR College of Science and Technology. She also holds BSc. in Natural Resources Management from the Kwame Nkrumah University of Science and Technology (KNUST), Ghana, with specialty in Silviculture and Forest Management. For the past ten years, she has been actively involved in bamboo and tree seedling production, training interested people in bamboo seedlings and plantlet production, livelihood improvement, forest landscape restoration and land use change, climate change mitigation and adaptation. In this regard, she has acquired experience in nursery establishment and management, bamboo seedling/ plantlet production, climate change and land-use interactions. Her broad scope in the forestry discipline makes her open for collaborations and partnerships into forestry programmes and research.

Abstract

The highlands of Kwahu Plateau in Ghana, which used to have a luxurious moist semi-deciduous forest environment, has lost substantial forest cover over the decades. This has resulted in decline in cocoa agroforestry farming. Some of the driving factors of the drastic changes in the natural environment are urban expansion, logging, exotic plantation development in forest reserves, expansion of market-oriented food crops, wildfires, erratic rainfall and increasing temperature. The aim of the restoration project is to re-establish the degraded landscape to an ecological integrity that will generate economically productive agroecological system for the enhancement of the livelihood of the people. This is being implemented through three interventions: i) enrichment of various shaded agroforestry systems on 34200 ha of degraded land, ii. Reforestation of 15000 degraded forest reserves with Modified Taungya System, and iii) rewilding of over 4050 ha of degraded land by allowing natural regeneration and enrichment planting of indigenous forest species, and subsequent reintroduction of wildlife. These interventions will consequently achieve climatic, biodiversity and community objectives. 

Using cross-space-for-time substitution along the West Africa aridity gradient biomass carbon stock for protected area (near natural forest) was estimated as 188.63, 33.31, 35.51 and 33.85, for fallow as 24.1, 12.68, 14.18 and 12.72, and for cropland as 5.89, 4.48, 8.70 and 15.10 Mg C ha-1, for the moist forest, guinea savannah, Sudanian savannah and Sudano-Sahelian ecological zones, respectively. The soil carbon stock was estimated as 68.2, 33.5, 59.4 and 60.4 for protected area, 53.3, 31.03, 51.10 and 49.40 for fallow, and for cropland it was 50.6, 39.00, 43.30 and 41.7 Mg C ha-1, for the moist forest, guinea savannah, Sudanian savannah and Sudano Sahelian ecological zone, respectively.

Soil carbon dioxide flux studies were carried out in a moist evergreen forest zone of Ghana, over a one-year period. There was a distinct seasonal variation in soil respiration rate in both instances. High respiration rate was exhibited in the dry season. The annual mean soil respiration rate for the forest, and two cocoa agroforestry sites, one with high basal area (19.16 m2 ha-1) and the other with low basal area (6.59 m2 ha-1) of shade trees, was estimated to be 181.10 ±84.71 (SD), 171.06 ±77.07 and 170.80 ±59.44 Mg CO2 ha-1 d-1, respectively.