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THE ROLE OF GHANAIAN TROPICAL FOREST IN GREENHOUSE GAS EXCHANGE AND CARBON SEQUESTRATION
By Dr. Caleb Mensah, Researcher, UENR-Sunyani
African tropical forests represent specific forest biogeocenosis, differing both physiologically and ecologically from other tropical forests. The climatic function of a typical African tropical forest is also very important, as they affect the mesoclimate of the nearby area by increasing evapotranspiration and the cooling effect. However, few studies on greenhouse gas (GHG) measurements over forest ecosystems have been conducted in Africa, despite the significant role that African tropical forests play in global carbon sequestration. Thus, the establishment of an eddy covariance (EC) experimental station in the Bia Tano forest reserve within the Ahafo region of Ghana, will provide a direct and accurate means to measure carbon dioxide (CO2) and water vapour (H2O) exchange between a typical African tropical forest ecosystem and the atmosphere with its dynamic response to environmental variables. The Carbon Flux monitoring station is located at Longitude -2.622°, Latitude: 7.033° within the Bia Tano Forest reserve, compartment 152 at Gambia Number 1 in Mim, under the Goaso Forestry division. The location was chosen based on several requirements: the presence of a flat terrain, a homogenous canopy with no gaps and the absence of sources of anthropogenic CO2. The station comprises a 70-m flux tower that lies within the western part of Ghana between moist-evergreen and moist semi-deciduous forest types. Moreover, studies on the transfer of water and energy between the land surface and the lower atmosphere will also be assessed at the forest ecosystem site applying the EC technique. Basic meteorological parameters (air and soil temperature, humidity, photosynthetically active and global radiation) will be measured continuously above the tropical forest canopy and within the vertical profile at the station to derive the sensible and latent heat storage flux. Additionally, soil water content and groundwater level will be measured automatically in a representative position in four different depths (0, 5, 10, 20 and 30 cm). To also better understand the hydraulic function of different plant species found within such a humid mixed tropical forest ecosystem, sap flow measurements will also be carried out in 5 different tree species, through the application of a sap flow system that implores the heat pulse velocity and/or ratio method. Furthermore, for analysis of biomass allocation during the growing season, the stem diameter increment at the breast height (DBH) of 45 trees of 5 main tree species will be measured by mechanical dendrometer bands. Results from this project will also be crucial in the formulation and implementation of climate change mitigation and adaptative strategies/policies such as the REDD+ by both governmental and non-governmental institutions.