Using biodiversity features to promote an Ecosystem-Based Conservation framework in terrestrial ecosystems

PLOS One | https://doi.org/10.1371/journal.pone.0336705 November 21, 2025 12 / 18 Implications of PA approach on conservation and management of biodiversity Despite surpassing the global target for PAs as set by the CBD (2010), Tanzania ranks 11th globally and 2nd in Africa (behind Madagascar) for the highest number of threatened species on the IUCN Red List (2023). This includes nearly 200 native vertebrate species, 137 invertebrate species, and 1,031 plant species, which are classified as threatened, vulner- able, endangered, or critically endangered (IUCN, 2023). These figures highlight that broad PA coverage alone is not enough to prevent high levels of biodiversity loss. Consistent with this, our findings have shown that a significant propor- tion of most Tanzanian ecosystems remained unprotected, indicating that key biodiversity areas are potentially at risk. Furthermore, invertebrate taxa were reported in fewer studies compared with other taxonomic groups (see S2 Data). This aligns with broader evidence that biodiversity monitoring and conservation planning often show taxonomic bias, with PAs disproportionately focused on certain taxa, while neglecting others [71]. For instance, Casanelles‐Abella, Fontana [72] reported a spatial mismatch between invertebrate hotspots and PAs, while Wu, Yu [73] showed that the existing network of PAs in southwest China has less than a quarter of overlap with conservation hotspots, and only a fraction of these hotspots receive adequate protection. Taken together, these results emphasize that PAs as a conservation approach often

fail to address crucial ecological processes such as individual home ranges and propagule dispersal [74], suggesting that relying solely on PAs is inadequate for fully understanding biodiversity distribution and abundance patterns across taxa and ecosystems. Similar limitations have been documented across East Africa, where PAs cover just 10% of the geographic range of endemic/near-endemic vertebrate species, and only 26% of endemic species have at least half of their range protected [75]. Such limited spatial coverage undermines the effectiveness of PAs in conserving biodiversity and exacerbates risks from habitat loss and fragmentation, particularly for wide-ranging and long-distance dispersal species [76] under acceler- ating climate change [77]. Williams, Rondinini [78] have further demonstrated that many mammal species remain without effective population-level protection, especially in tropical biodiversity hotspots where PA coverage is minimal. The concentration of conservation efforts only within PAs also compromises habitat connectivity. In Tanzania, about half of PAs remain connected, while many forest reserves exist as isolated fragments [63,79,80]. Wildlife corridors that are essential for maintaining ecological connectivity between PAs have declined in both number and functional integrity due to increasing land-use change and human encroachment [81]. For instance, in the Tarangire-Manyara ecosystems [65], and in the Kilombero valley [79], key corridors have experienced severe degradation. Kitendeni wildlife corridor in northern

Tanzania, once 10 km wide [82], has narrowed to 6 km [83]. Such losses mirror a global trend where migratory routes are increasingly overlooked in conservation planning, leading to widespread disruption of animal movements [84,85]. Collec- tively, these patterns underscore the urgent need for conservation approaches that extend beyond PA boundaries and reinstate ecosystem-scale connectivity to enhance biodiversity resilience and the long-term sustainability of conservation efforts. The need for an Ecosystem-Based Conservation framework While the international commitment to protect 30% of the world’s surface by 2030 is necessary, achieving meaningful biodiversity conservation requires inclusive and elevated conservation approaches that extend beyond PAs. Despite wide agreement that PPAs (IUCN category I-III) are the best approach for conserving biodiversity, they are limited in extent and exclude many species of key conservation importance [86]. In Africa, extending conservation practices beyond PAs remains underutilised, despite its potential to safeguard diverse taxa [87]. Our results indicate that a large proportion of Tanzania’s ecosystems remain unprotected, reinforcing the need for ecosystem-scale approaches that can complement formal PAs. Rapid human population growth in Africa is projected to increase fivefold by the year 2100 [88,89], exacerbating pres- sures on ecosystems. OPAs (IUCN category IV-VI), which comprise over 60% of the global protected-area network, are