Gain and loss: Human and environmental wellbeing – drivers of Kilimanjaro’s decreasing biodiversity

PLOS One | https://doi.org/10.1371/journal.pone.0334184 October 29, 2025 7 / 23 Since we could not delineate built-up areas on the Landsat image from 1976, we used the oldest available topo- graphic maps 1:50.000 from 1982. At that time, only Moshi existed as an urban centre. For the years 2002 and 2022, we used VHR satellite images in Google Earth to delineate the urban centres with built-up areas. The LULC maps were prepared using ArcMap 10.8.2. For more specifications of mapping these LULC classes see Supplementary Information S1 Text. To quantify the change flows, or transitions, between LULC classes and the three time steps (1976, 2002 and 2022), we used the functions in OpenLand R library [39]. We visualized the change flows with a Sankey diagram, which illus- trates relative transitions between the classes for the three time steps, as well as the net and gross changes with a stacked barplot. In order to obtain an overview of the main changes in the landscape since the first census on Kilimanjaro in 1913 [37], we also analysed historical maps from the beginning of the 20th century. The map of Hans Meyer’s Ostafrika-Expedition 1911 [40] at a scale of 1: 300,000 provides very detailed and botanically sound descriptions of the vegetation, especially in the savanna areas of Kilimanjaro. For final delineation of the LULC types (see also S1 Text) we used additional histori- cal information from the map and vegetation description by Meyer (1890) [41] together with information in Volkens (1897) [42], Jaeger (1909) [43] and Klute (1912) [44]. Biodiversity

We used a subset of the 54 land cover types identified by Hemp [23,29,32] for the entire mountain range based on 1,600 releves. We combined the occurring plant communities to fit into our proposed nine classes to create species lists (see Supplementary Information S1 Text for more details). The species numbers resulting from the analysis of the releves are listed in Table 2. The status of endemics (species with a restricted occurrence) follows a list by Gereau, Missouri Botanical Garden (pers. comm./unpublished data). We considered species in the following IUCN categories as Red List species (reviewed at https://www.iucnredlist.org/): Criti- cally Endangered, Endangered, Vulnerable, Near Threatened. The status of neophytes (introduced species) was checked in FTEA (1952–2012) and Kew Plants of the World Online (https://powo.science.kew.org/). Using these figures in order to calculate the number of species per km2 and to compare it with the human population density per km2 required two further steps. We first had to take into account the fact that the number of species increases Table 1. The Land Use and Land Cover classification schema (cp. Fig 2). LULC/ecosystem type Description (1) Agriculture Maize, sunflower and millet fields of smallholder farmers, commercial farms with wheat fields on the western and northern slopes, sugarcane plantations and rice fields south of Moshi (2) Agroforestry Agroforestry including traditional Chagga home gardens and commercial coffee plantations with a sparse tree layer of Albizia schimperiana, Rauvolfia caffra and Cordia africana

(3) Forest Moist forests including riverine and groundwater forests (with Ficus sycomorus, Oxystigma msoo and Khaya anthotheca) and submontane ravine forests with Newtonia buchananii, Entandrophragma excelsum and Mitragyna rubrostipulata in the tree layer (4) Grassland Mosaic of anthropogenic grasslands with Hyparrhenia rufa, Bulbostylis densa and Sporobolus africanus and agricultural fields in the submontane and lower montane zone, especially on steep slopes along the major river valleys and near KINAPA (5) Regeneration Forest regeneration with vegetation recovering after previous disturbances, mainly shrubland with Lantana camara, Carissa edulis and Ochna insculpta (6) Savanna Savanna with grasslands (Cyperus niveus, Themeda triandra and Heteropogon contortus), woodlands and dry forests with Acacia nilotica, Combretum molle and Sclerocarya birrea (7) Forest plantation Forest plantations with exotic tree species (Pinus patula and Cupressus lusitanica) on the northwestern and northern slopes (8) Built-UP Continuous impervious surfaces with infrastructure (buildings, roads, pavements, yards) (9) Water body Lakes https://doi.org/10.1371/journal.pone.0334184.t001