Impacts of Climatic Variables and Anthropogenic Disturbances on the Dynamics of Net Primary (…)

ABSTRACT

Protected areas (PAs) in Togo play a crucial role in biodiversity conservation: however, in recent decades, they have been increasingly affected by climate change and anthropogenic pressures. This study analyses the spatiotemporal trends of net primary productivity (NPP) between 1984 and 2021. Validated 30 m land-cover maps for the Sahel–Sudano-Guinean region of Africa was used to derive NPP values for different land-cover units through spatial intersection with NPP maps using ArcMap. Statistical significance tests of the NPP time series were subsequently performed with the R software environment. The Residual Trend (RESTREND) method was applied to assess the relative influence of climate factors and human activities on NPP variations. This study reveals that the average NPP of the analysed PAs (Oti-Kéran National Park, Sadji Classified Forest, Fazao-Malfakassa National Park, Abdoulaye Wildlife Reserve, Togodo South Wildlife Reserve and Missahoé Classified Forest) was estimated at 3143 kg C·ha⁻¹·year⁻¹, with an annual accumulation of 2.18 Pg.C out of the total area of 420,403 ha. Overall, NPP exhibits a fluctuating but increasing trend, although its spatial distribution remains highly variable, suggesting that the various changes induced by climatic factors and human activities have not yet affected the carbon sequestration capacity of ecosystems within PAs. Intense human pressure on these areas has led to the predominance of shrubs and crops, while forests exhibit the highest NPP, reaching 4698 kg C·ha⁻¹·year⁻¹. The impact of climate factors on NPP increase has significantly declined: it contributed 68% to its improvement between 1990 and 2000, but only 28% between 2010 and 2020. Conversely, the influence of human activities has risen to 72%, highlighting their growing role in the transformation of these PAs. These findings emphasize the urgent need for sustainable management of PAs and the implementation of ecological restoration measures to preserve their carbon sequestration capacity.