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 15 / 23 could be found for the lowlands of Kilimanjaro [36]. Consequently, we conclude that climate change did not significantly influence observed biodiversity trends or land use in the lowlands. If it had been a primary driver of land use change, we would expect to see negative impacts on subsistence agriculture and agroforestry, yet these categories showed significant gains. However, this differs from the situation above the cultivation belt within the national park. There, signs such as glacier retreat [59] indicate a gradual decline in regional humidity and precipitation, and an interplay between increasing human activities and decreasing humidity leads to an increasing frequency and intensity of forest fires, affecting biodiversity espe- cially in the upper montane forest zone and the subalpine ericaceous belt [20]. Forest fires are also frequent in the humid lower montane forest zone near cultivated areas in the vicinity of larger anthropogenic clearings due to a changing micro- climate with increasing air temperature and decreasing humidity [60]. In the last 120 years, Kilimanjaro has lost about 50% of its forest area [23]. This not only affects biodiversity, but also has far-reaching consequences for the regional climate. Deforestation leads to a significant increase in maximum air temperature and cloud base height [61], which on Kilimanjaro primarily affects the upper regions within the national park and even the glaciers [62] and impairs the area’s ability to pro-

vide vital NCPs, especially water. This interaction demonstrates that climate change is not always a challenge originating from outside but also a “homemade” problem caused by regional land-use change and boosting together biodiversity loss. However, such changes (e.g., the increase in wild fires) have not been observed in the lowlands of Kilimanjaro. Land use change: Main driver of biodiversity loss Land use change and intensification are the main drivers of the decline of biodiversity and ecosystem services globally [3,5,63,64], exceeding the impact of climate change, particularly in tropical areas [11,14,65–67]. For Kilimanjaro, Fig 9 illustrates the effects of population-induced natural habitat loss on species diversity. Species den- sity of natural species (including endemics and Red List species) correlates closely with Fig 7, indicating that land-use change, notably ecosystem loss, is the primary cause of reduced species density (Fig 9A). Fig 8. House building activities on Kilimanjao between 1990 and 2016. Left: Buildings (black dots) 1990; Right: New buildings (red dots) 2016. Blue lines: town centres; green line: KINAPA (National Park Boundary). Buildings digitized by Ethan Oleson based on time-series Google Earth images and the 1:50,000 Ordnance Survey topographic sheets. Reprinted from World Imagery Basemap (Esri, Maxar, Earthstar Geographics, and the GIS User Community) under a CC BY license, with permission from Esri Deutschland GmbH, original copyright 2024. https://doi.org/10.1371/journal.pone.0334184.g008