Mapping of biodiversity hubs and key ecosystem services as a tool for shaping optimal areas for conservation

(Karongi district). On the farthest west of Rwanda, the elevation drops to a low-lying depres- sion west of the Congo-Nile divide along the shores of Lake Kivu to create a distinct regional climate ‘Kivu lake climate’ characterized by rainfall of about 1200 mm and annual tempera- tures around 20˚C. The extreme south of this region is Bugarama plain, Rwanda’s lowest point at 900 m.a.s.l, which is part of the tectonic depression of the African Rift Valley. This region is home to more or less the same plant and animal species than in the ‘Temperate zone of the central highlands’. 3.1.2 Priority areas for securing threatened species habitat. The geographical distribu- tion of threatened species hotspots is linked to the geographical distribution of biodiversity- rich habitats, hence on the four peripheries of Rwanda at distances from the centroid of Rwanda that harbors the most important human activity centers of the country. Threatened species hotspots are mainly located in already existing PAs, that mainly extend on three peripheries of the country, with ANP on the extreme east, VNP and Rugezi wetland on the northern periphery and GMNP and NNP on the Western periphery of Rwanda. Moreover, part of threatened species is also located on the unprotected southern periphery of Rwanda. PAs have enormously contributed to save a large number of endangered species from extinc- tion: ANP accommodates various endangered species such as the Critically Endangered (CE) Osyris lanceolata (African sandalwood), the CE Balaeniceps rex (Shoebill stalk), the CE Giraffa

camelopardalis (Giraffe), the Endangered (E) Albizia amara (Bitter albizia), etc. the VNP offers habitat to the famous CE Gorilla beringei beringei (Mountain Gorilla), and protection to the Vulnerable (VU) Vaccinium stanleyi, etc. NNP is home to the CE Xyris vallida, the E Taber- naemontana odoratissima, the E Casearia runsorica, the VU Kupeornis rufocinctus (Red-col- lared Mountain Babbler), the E Cercopithecus ascanius (Redtail monkey), etc. GMNP protects the E Cercopithecus mitis kandti (Golden Monkey), The VU Cryptospiza shelleyi (Shelley’s Crim- son-wing), the E Casearia runsorica, etc. Rugezi wetland in Burera district harbors many endangered bird species such as the VU Calamonastides gracilirostris (Papyrus Yellow War- bler), the E Bradypterus graueri (Grauer’s Swamp warbler), the E Balearica regulorum (Grey Crowned Crane) and a considerable number of endemic amphibians such as the VU Hypero- lius castaneus (Brown reed frog). Neverthlesss, a portion of threatened species also exist or exclusively exist in non-protected less undisturbed zones so far, particularly on the country’s southern periphery. The waters and shores of lake Kivu (Rubavu, Rutsiro, Karongi, Nyamasheke and Rusizi districts) and its numerous islands harbor various thematic groups of biodiversity, though its fish biodiversity is low (only harbors 26 fish species of which 15 are endemic Haplochromine), its islands are particularly important for the survivorship of water birds species who use the islands for repro- duction, feeding and resting and are home to many registered endangered species on IUCN

red list such as the E Ardeola idea (Madagascar Pond Heron). Rweru-Mugesera wetland com- plex in Bugesera, Ngoma, and Rwamagana districts accommodates ecological highly important Cyperus papyrus marshes which harbors the Nearly threatened (NT) Laniarius mufumbiri (Papyrus gonolek), the CE Thalassornis leuconotus (White-backed Duck), the CE Netta ery- throphthalma (Southern Pochard), the CE Microparra capensis (Lesser Jacana), the E Serinus koliensis (Papyrus Canary), the E Necrosyrtes monachus (Hooded vulture), the VU Pitta ango- lensis (African Pitta), the VU Numida meleagris (Helmeted Guineafowl), etc. Buhanga natural forest in Musanze district contains the CE Terathopius Ecaudatus (Bateleur), the CE Polemae- tus bellicosus (Martial Eagle), etc. Shagasha natural forest in Rusizi district contains the VU species like Cercopithecus l’hoesti (L’hoest’s monkey) isolated from other groups found in NNP. Muvumba natural forest in Nyagatare District is mainly constituted by Acacia kirkii an endemic plant species to Rwanda and not occurring elsewhere in the region. The forest also shelters the E bird species Balerica regulorum (Grey crowned crane) and the Vulnerable species PLOS ONE How do old national parks cope with regenerating conservation mission? PLOS ONE | https://doi.org/10.1371/journal.pone.0253151 August 17, 2021 11 / 20