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

human activities in Rwanda [54], this paper argues that the existing PAs system in Rwanda dis- proportionately privileges the protection of certain taxonomic groups and species over others, which leaves many species of some taxonomic groups out of the protection shield. Mammals and birds are respectively the most privileged and fish, reptiles and amphibians are respectively the least fortunate. Although the work of caring for the existing PAs is challenging and requires a lot of financial efforts, it is totally incomplete to think that nature preservation mission can achieve total success if it is only restricted with the sole conservation of biodiversity inside the PAs even for the most privileged taxonomic groups. Some unprotected key ecosystems are still scattered all over the country creating a reasonable porosity for biodiversity conservation in Rwanda [55]. Once they collapse, some species will go extinct and others very negatively affected especially those with limited dispersal mechanisms, small populations or restricted species. The creation of more reserves, setting up a conservation status to unprotected ecosys- tems to support the existing PA is of utmost importance to ensure the functionality and suc- cess of Rwanda’s protection network. A multilevel collaboration of stakeholders at national and international level, in which the public plays a strong role is crucial for the long-term con- servation success in Rwanda. Beyond its heavily reliant on gorilla trekking and big five tour-

ism, Rwanda needs to expand and diversify its tourism industry through the development of other forms of tourism, such as bird-related tourism and others [16]. The inclusion of unpro- tected habitats and other taxonomic groups into the protection scheme would undoubtedly set the foundation for Rwanda to better its environment, enrich its biodiversity and diversify its tourism. Well protected wetlands can play a particular role at enhancing the biodiversity of dif- ferent taxonomical or functional groups, such as vegetation, amphibians, reptiles, fish, and birds. It is also recommended to enlarge that they can be ecologically viable. 4.2 The delineation of PA vs priority area for ES provision Originally conceived to conserve iconic landscapes and wildlife, PAs are now expected to achieve an increasingly diverse set of conservation, social and economic objectives. Rwanda is a country with globally significant biodiversity and a high level of human dependence on eco- systems. We assessed key regulating ES (Carbon storage, Water balance, Human footprint on water quality/ diarrheal diseases and Human footprint on water quality/annual). PAs perform multiple roles that go beyond their intended conservation purposes, many of which go unno- ticed and thus are seldom targeted for improvement. Such are the contribution to water bal- ance, water quality, and carbon storage. Mapping PA and ES do not only provide spatial information about their state to help target- ing areas where it is necessary to implement and monitor environmental policies, but also

facilitate understanding of the real impact of current environmental policies on ecosystems and the services they provide [21]. Rich biodiversity in protected wetlands can improve their treatment efficiency by enhanc- ing their biogeochemical cycling [73] hence, enormously contributing to boost carbon seques- tration hence, the reduction of carbon emissions. By contrast, urban areas are generally characterized by high concentration of nitrate, ammonia, and phosphate levels and are respon- sible for high concentrations of Ca, alkalinity, and T-hardness in the downstream rural area waters through erosions, surface and subsurface flow, and agricultural runoff. Higher nutrient levels and low concentrations of chemicals in the urban areas reveal a clear human footprint on water quality of their upstream river [74]. The widespread of human footprint on water quality shown is emphasized by the fact that Diarrhoea is a leading cause of childhood mortal- ity in developing countries including Rwanda despite its simple protection measures, recent surveys indicate that 12% of children <5 years old nationally had caregiver-reported diarrhoea 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 14 / 20