Defining ecological hotspots
Several approaches have been developed by conservation organisations to define ecological or biodiversity hotspots, like Key Biodiversity Areas, Important Bird Areas, Critical Sites, Freshwater Ecoregions, etc. Many of these concepts are based on roughly similar criteria for delineating ecological hotspots:
- A hotspot should contain a minimal proportion of the global, regional or flyway population;
- Attention for areas where (groups of) species aggregate during stages of their lifecycles;
- Additional focus on range-restricted species;
- The incorporation of threats for identification of hotspots, for example on a species level or a threat to the area as resulting from conversion of land, urbanisation or for example mining.
All approaches mentioned assume a reasonable amount of detailed information on the distribution and abundance of species. Important Bird Ares and Critical Sites Networks focus on bird species, but the other approaches also consider other taxa. Key Biodiversity Areas look at all relevant taxa.
The assessment of ecological hotspots for the Upper Niger Basin and the Inner Niger Delta is limited through scarce data and the lack of recent data. In the framework of the BAMGIRE-project a study was done on best applicable methods (Wymenga et al. 2017a) and available information (Wymenga et al. 2017b). In addition a field mission was carried out to parts of the Upper Niger Basin, in particular the headwaters of the Niger River, to do a quickscan of river habitats and protected areas in Guinea (Klop et al. 2019). On the basis of the collected available information and these field studies, a preliminary map of ecological hotspots is presented on this website.
Ecological hotspots in the Upper Niger Basin
In contrast to the Inner Niger Delta (see below), detailed ecological data for the Upper Niger Basin are scarce. The starting point for delineating hotspots in the UNB is the work of Brugiere & Kormos (2008) on Key Biodiversity Areas (KBAs) in Guinea. In addition, several other categories of ecological hotspots are used, including Important Bird Areas from BirdLife International and Critical Sites from Wings over Wetlands. The classification of ecological hotspots within the UNB is based on four main criteria:
- Identifying Key Biodiversity Areas
Starting point is the analysis of Bugiere & Kormos (2008) and the KBAs they identified in Guinea within the boundaries of the UNB. As far is relevant, these areas are completed with the KBAs delineated by IUCN (2016) and Important Bird Areas.
- Critical sites (WOW)
Based on other bird surveys (Critical Sites, Wings over Wetlands) the list of key areas is completed with data for threatened and endemic birds species, as well as known bird concentrations within the UNB.
- Important Biodiversity areas for fish communities/species
Fish data are poorly available, as most surveys cover only small parts of the area. Some information can be used from the (proposed) Ramsar sites (delineation unclear).
- Areas with a high biodiversity based on Protected Areas
Where appropriate the list of key areas is expanded with data from the Protected Area network in Mali and Guinea. These areas may harbour high biodiversity values (for example, breeding colonies or populations of vulnerable species).
The preliminary ecological hotspots in the Upper Niger Basin are presented in the map below, and the interactive viewer with information on protected areas and biodiversity. It shows the network of protected areas, including the Haut Niger N.P., as well as the Niger and Bani tributaries and surroundings. The delineation of proposed Ramsar sites in Guinea is unclear (see Klop et al. 2019 and the viewer). Many of the riverine areas host (temporal) wetland habitats and Gallery forest along the rivers. In the northern parts this is often no more than a thin strip of a few trees bordering the water, but in the southern sections some well-developed gallery forests are present. These patches of gallery forest provide important habitat to several forest species in a matrix of open savanna and agricultural fields. There is hardly any information on the ecosystems and biodiversity of the headwaters of the Bani tributaries, expect some scarce information on protected areas.
Preliminary ecological hotspots in the Upper Niger Basin, see the text for explanation.
The site with probably the highest biodiversity value in the Upper Niger Basin is Mafou Forest, which is one of the core areas of the Haut Niger National Park. Mafou Forest might represent one of the last remnants of mature dry forest in the wider region, providing habitat to species such as the critically endangered West African Chimpanzee (Pan troglodytes verus). Many parts of Haut Niger N.P., including the buffer zones and Amana classified forest, consist of degraded woodland savanna with an impoverished fauna. The field visits to these parts of the park indicated high levels of human activity, including hunting, logging, savanna burning, fishing, gold mining, cattle grazing, slash-and-burn agriculture, beekeeping, collection of grass and firewood, etc. No wild mammals like duikers or primates were observed in the park, indicating high hunting pressure. Several large mammals have already been extirpated from the area, including African savanna elephant and (most likely) Lion. Given the lack of staff and resources, effective conservation and protected area management in Guinea is a major challenge.
Ecological hotspots in the Inner Niger Delta
From several studies it is clear that the entire IND can be regarded as an ecological hotspot harbouring outstanding biodiversity and significant parts of globally threatened water bird populations (Zwarts et al. 2009). The floodplain area has been designated as a Ramsar site in 2004. Using information on vulnerable sites and species, key areas within the delta have been identified to prioritise and stimulate an effective management of the area. The classification is based on four criteria:
- Key Habitats in the floodplain ecosystem
Some habitats in the IND play a key role in the ecosystem. This applies for instance to flood forests, moist forest around the delta, bourgou fields, mares, permanent deep water, shallow lakes etc.
- Water Bird Concentrations
Based on data from monitoring of water birds, areas and sites are selected that hold large concentrations of water birds. This applies to roosts of water birds, large concentrations of foraging water birds and sites with a high densities of rare species.
- Breeding Colonies
The IND holds a number of major breeding colonies of herons, ibises and cormorants, which are amongst the largest in Africa. In addition, there are sites where rare species come to breed, such as the vulnerable Black Crowned Crane.
- Areas with a high biodiversity of threatened species
Areas that harbour threatened or range-restricted species like Hippos, Manatees etc, or which are vital for these species during certain stages in their life cycle.
The preliminary ecological key structures in the IND are presented in the map below, and the interactive viewer with information on protected areas and biodiversity. The maps present the flood forests, foraging zones of colonial breeding water birds, and bourgou fields at four different flood levels (300, 400, 500 and 600 cm at Akka). The latter is done to express the strong relationship with the flood extent and maximum flood level.
The dry and moist forests – very important as habitat for resident biodiversity and migratory land birds - are not included in this stage. Next to these habitats, the northern lakes are included and east of the delta the Reserve des Élephants. The plain de Seri is part of the delta as a whole, for its significance as breeding area for Black-crowned Crane. The distribution of these breeding birds is however not known.
Ecological key structure in the Upper Niger Basin, see the text for explanation.
Sources and more information
- Beintema, A.J., J. van der Kamp & B. Kone (éds.). 2007. Les forêts inondées : trésors du Delta Intérieur du Niger au Mali. A&W-report 964. Altenburg & Wymenga conseillers écologiques, Veenwouden. Wetlands International, Sévaré. Pays-Bas / Mali.
- Brugiere, D. & R. Kormos 2009. Review of the protected area network in Guinea, West Africa, and recommendations for new sites for biodiversity conservation. Biodiversity and Conservation 18: 847-868.
- CILSS 2016. Les Paysages de l'Afrique de l'Ouest : Une Fenêtre sur un Monde en Pleine Évolution / Landscapes of West Africa. U.S. Geological Survey EROS, 47914 252nd St, Garretson, SD 57030, UNITED STATES. https://eros.usgs.gov/westafrica/sites/default/files/ebook-English/index.html#p=30.
- Klop, E., M. Sikkema, M. Diawara, A. Gado 2019. Ecological hotspots and land use patterns in the Upper Niger Basin, Guinea. A&W-report 2501. Altenburg & Wymenga ecologisch onderzoek, Feanwâlden / Wetlands International, Bamako.
- Wymenga, E., M.L. Diawara, F. Hoekema & W. Bijkerk 2017a. Ecological hotspots in the Upper Niger Basin and Inner Niger Delta. A&W-report 2253a. Altenburg & Wymenga ecological consultants, Feanwâlden.
- Wymenga, E., M.L. Diawara, W. Bijkerk, F. Hoekema & J. van der Kamp 2017b. Ecological hotspots in the Upper Niger Basin and Inner Niger Delta. II. Existing data and information. A&W-report 2253b. Altenburg & Wymenga ecological consultants, Feanwâlden.
- Zwarts, L, Bijlsma RJ, van der Kamp J, Wymenga, E 2009. Living on the Edge. Wetlands and birds in a changing Sahel. KNNV Publishing, Zeist. p. 1-564. http://www.altwym.nl/uploads/file/540_1433753005.pdf