Climate Threats and Human Activities on the Population Dynamics Of Detarium Microcarpum Guill. & Perr. In Burkina Faso

Abstract

Tropical savanna species influence ecosystem multifunctionality through the ecological mechanisms underlying the provision of multiple ecosystem services. Despite this functionality, anthropogenic factors such as deforestation, overexploitation of natural resources, extension of agricultural lands, overgrazing, and bushfires, coupled with the adverse effects of climate change, contribute to the loss of Detarium microcarpum. Within this context, this study aimed to contribute to the sustainable management and conservation of D. microcarpum in Burkina Faso. To achieve these goals, the methods have consisted of semistructured and focus group surveys of 465 people, 165 plots for forest inventories, tree rings and wood anatomy analysis, allometric equation and species modelling. The local population highlights the multipurpose uses of Detarium species and reveals the threats of the species are linked to the type of uses and the status of the site. A total of 102 woody species belonging to 79 genera rang in 28 families, were found in the natural habitats of D. microcarpum. The structure analysis reveals the unstable population of the species and the lack of regeneration. D. microcarpum showed distinct growth ring boundaries, the annual radial growth is positively related to precipitation during the end of the rainy for the current years but negatively to the previous years. Tree ring analysis revealed annual growth ring boundaries were 1.034 ± 0.425 mm. year-1. The above-ground biomass and above-ground carbon allocation are greater in the Sudano-Sahelian than in the Sudanian climatic zone. The allometric models established to predict D. microcarpum biomass were TAGB = e4.4002 (dbh*dbh*h) 0.9456 + e-3.5219 (dbh)2.4007 + e- 2.8845(dbh)1.3465 in the Sudanian zone and TAGB = e-4.1053 (dbh)2.4222 + e-5.2567(dbh)2.9539 + e- 2.9894(dbh)1.5285 for the Sudano-Sahelian climatic zone. The current suitability area for the species covers 65.6 % of the country area with respectively high suitability (36.73%) and low suitability (29.16%). Models projections indicate that highly suitable areas for Detarium microcarpum conservation are expected to decline under future climate change scenarios, regardless of the models used. The only exception is the MIROC6 model under the SSP5-8.5 scenario, which predicts a slight expansion of suitable habitats. The shift was observed from both unsuitable and highly suitable areas to the low-suitability areas in the model results across all climatic zones, with a notable progression in the Sahelian zone. Overall, this study provides important information for the sustainable use of D. microcarpum and the conservation guide for forest practices.