Changes in the West African forest-savanna mosaic, insights from central Togo

Abstract

The West African forest-savanna mosaic, an important habitat for biodiversity and humans, is severely degraded, fragmented and modified by human activities. However, few studies have quantified the land cover changes observed over time and/or analysed the drivers of change. This study focused on Fazao-Malfakassa National Park, the largest in Togo, uses a combination of remote sensing, ground surveys and questionnaires to: (i) quantify vegetation changes, (ii) determine the drivers of change, (iii) compare results with findings elsewhere in the region and (iv) suggest management interventions. The images used were Landsat 5 TM, Landsat 7 ETM and Sentinel-2. Different vegetation indices were computed including: number of fragments, index of dominance, mean area of a vegetation type and mean annual expansion rate. In total, 300 people (including park staff and local populations) were interviewed using a semi-structured questionnaire. Results indicate that between 1987 and 2015 closed-canopy forest and tree-savanna became severely degraded and fragmented, following trends in other parts of the West African forest-savanna mosaic. The main drivers of change were agricultural expansion, bush fires and timber extraction. Observed changes and drivers altered with time: e.g. agricultural expansion was greatest during 1987–2001 (linked with political instability) while illegal timber extraction augmented during 2001–2015 (following increased timber value). Park staff and local populations’ perceptions on drivers of change did not differ. Our study highlights that action is urgently needed if we are to preserve this important habitat, the biodiversity it hosts and the services it provides to humans. We suggest several management interventions, learning from successful interventions elsewhere in the region.

Land Use and Land Cover Dynamics Analysis of the Togodo Protected Area and Its Surroundings in Southeastern Togo, West Africa

“…In an area as complex as ours, with small parcel sizes, the overall accuracies of 76.79% and 82.46% (less than the 85% target value) seem quite relevant for LULC change analysis [49,50]. In Togo, in similar contexts, accuracies of the same order of magnitude have been obtained by several studies [13,17,22]. Similar accuracies were also obtained on historical images of the Amazon [24].…”

“…We chose the Sentinel 2 image for the last time point because of its availability and high spatial resolution (10 m). Studies showed the high potential of Sentinel 2 images for improving the monitoring of tropical forests and savannahs [22,23]. For the selected years, we favoured acquisitions from the late rainy season and early dry season to obtain the maximum contrast between the different elements of the landscape [24].…”

Impact of the Accuracy of Land Cover Data Sets on the Accuracy of Land Cover Change Scenarios in the Mono River Basin, Togo, West Africa

“…The results of Badjana et al (2017); Koglo et al (2018) revealed that deforestation and savanna changed to cropland and settlements in south and north of Togo. In Fazao-Malfacassa National Park, in the northern part of the MRB, Atsri et al (2018) found that forest and savanna are degraded, which could be explained by agriculture expansion, bush fire, timber extraction and linked by population growth. By assessing the land use change process in the Kéran protected area in the northern Togo, Polo-Polo-akpisso et al 2019confirmed that savanna and forest have decreased annually at the rate of more than 2%, whereas cropland and settlements have increased in the region.…”

“…LULC spatial trend direction and location are approximately situated in the locations of the main cities of the basin, therefore, LULC spatial trend can be explained by population activities and growth as mentioned by Koglo et al (2018) in the south district of MRB. Because of its fine resolution, the Nangbéto dam area and some protected forests such as Malafacassa (Amoussou et al, 2017;Atsri et al, 2018) are well delimited. The excellent reclassification of these land cover is due to low and high albedo factor of water and forest which plays a role during data collection by satellite's sensors.…”

“…Land use and land cover (LULC) change in West Africa is mostly caused by population growth, although locally other drivers may be of importance (Atsri et al, 2018). With increasing population demand for food, energy, and water is also increasing (Lambin et al, 2003), which causes land use and land cover changes (LULCC).…”