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 9 / 18 70% of their total areas respectively unprotected (Table 1). Fig 3 shows the proportions of these ecosystems that were protected under PPA and OPA categories. PPAs covered 29% (254,632 km²) of the total terrestrial land area within Tanzania whilst OPAs covered an addi- tional 12% (103,897 km²). PPAs covered 80% of the moorland and 54% of grassland ecosystems, respectively. In mangrove ecosystem, PPAs covered only 8% of its total area. In contrast, 32% of miombo woodland ecosystem were under PPAs designations, with an additional 12% under OPAs designations (Table 1). The total number of PPAs was 640, while the number of OPAs was 37. Miombo woodland and montane forest ecosystems were covered by the most PPAs with 232 and 194 respectively, whilst moorland was only covered by one PPA (Table 1). In terms of OPAs, miombo woodland had the highest number [19], with mangrove ecosystem completely lacking any designated OPAs (Table 1). Distribution and abundance estimate of biodiversity features The literature search yielded a total of 3,464 published articles, after removal of duplicates, that were initially considered relevant to the study objective. Of these, 1,576 related to plant species; 1,147 related to vertebrates; and 741 related to invertebrates (Fig 2). Following application of inclusion and exclusion criteria, a total of 228 articles were selected for data extraction, including 102 articles for vertebrates, 82 for plants, and 44 for invertebrates (Fig 2). From these articles, 22,987

biodiversity feature estimates were included from eight terrestrial ecosystems in Tanzania. Of the 22,987 biodiversity features, plants comprised 12,595 counts; vertebrates accounted for 5,963 counts; and invertebrates accounted for 4,429 counts (see S2 Data). These figures are the sum total of biodiversity features reported in each ecosystem category and not unique species. Across ecosystem categories, the montane forest stood out with the highest number of reported biodiversity features at 18 per 100 km², followed by coastal forest and grassland ecosystems, which both had eight features per 100 km². In contrast, acacia savanna, flooded savanna, and miombo woodland ecosystems each had just one biodiversity feature per 100 km² (Table 2). Reported biodiversity features varied considerably between ecosystems and taxonomic groups. Based on the reviewed literature, montane forest ecosystem had the highest biodiversity features totals across all three taxa, with 7,053 plant records (56.0%); 1,600 invertebrate records (36.1%); and 1,874 vertebrate records (31.4%). Coastal forest ecosystem ranked second, with 3,235 plant records (25.7%); 2,176 vertebrate records (36.5%); and 189 invertebrate records (4.3%). In contrast, moorland ecosystem had the lowest number with only 24 vertebrate records (0.4%) and 5 plant records (0.04%) (Table 2; Fig 4). Table 2. Biodiversity features and their estimates per 100 km2 as drawn from the literature. Ecosystem type Vertebrates Invertebrates Plants Total species/100 km² Acacia savanna 218 1472 481 1 Flooded savanna 73 0 230 1

Grassland 365 512 522 8 Coastal forest 2,176 189 3235 8 Montane Forest 1,874 1,600 70,53 18 Mangrove 64 52 61 3 Miombo woodland 1169 604 1008 1 Moorland 24 0 5 2 https://doi.org/10.1371/journal.pone.0336705.t002