A new study suggests that, between 1911 and 2022, land-use change was the primary direct cause of the loss of 75% of natural plant species on the lower slopes of Mount Kilimanjaro. Andreas Hemp of the University of Bayreuth, Germany, and colleagues present these findings in the open-access journal PLOS One on October 29, 2025.
Kilimanjaro is a dormant tropical volcano in Tanzania and Africa's tallest mountain. Millions of people living in the area rely on Kilimanjaro's diverse ecosystems for such benefits as timber, food, and water regulation. But the variety of species found in these ecosystems—their biodiversity—is declining as a result of human-related pressures, such as climate change, pollution, introduction of invasive species, resource extraction, and land-use change.
Understanding which human activities are the main drivers of declining biodiversity on Kilimanjaro and other tropical mountains is necessary to inform mitigation efforts. However, most prior research has focused on climate change, without considering other drivers, and has typically explored the effects instead of the causes of environmental change.
To help clarify the main drivers behind Kilimanjaro's decreasing biodiversity, Hemp and colleagues analyzed historical maps, census data, satellite imagery, and a high-spatial-resolution dataset of nearly 3,000 plant species found in different parts of the region. They focused on plant biodiversity, as it is closely related to the overall biodiversity of an ecosystem.
The analysis revealed that land-use change—for instance, expanding urban areas or converting savanna habitats to agricultural land—was the main cause of plant biodiversity loss between 1911 and 2022. In this time, the lower slopes of Kilimanjaro saw a loss of 75 percent of natural plant species per square kilometer. Land-use change stemmed from rapid population growth and economic development, with population density rising from 30 to 430 people per square kilometer between 1913 and 2022.
Meanwhile, the analysis showed, climate change was not a significant direct cause of biodiversity loss on Kilimanjaro.
These findings could help guide policies to mitigate biodiversity loss, the researchers say. As examples, they highlight specific locations in the Kilimanjaro region that have benefitted from sustainable traditional agricultural practices and establishment of protected areas.
The authors add: "Our research reveals that land-use change driven by rapid population growth—not climate change—was the primary direct driver of biodiversity loss on Mount Kilimanjaro over the past century, with up to 75% of natural species per km² lost on the lower slopes. Encouragingly, traditional agroforestry and protected areas emerged as promising strategies for mitigation."
"Investigating a century of ecological change on Kilimanjaro allowed us to disentangle complex human and environmental impacts. This study was the first, to our knowledge, to link human population densities with plant species densities at a 1 km² scale in a tropical region—made possible by combining remote sensing with extensive ground-based species data. The process required cleaning and verifying ecological field data across diverse vegetation types, highlighting the critical role of biological collections and the taxonomic expertise of herbaria worldwide."
"It was striking to find that, contrary to common narratives, climate change had no measurable effect on local biodiversity trends—emphasizing the urgent need to address socio-economic drivers like land use in conservation policy."
In your coverage, please use this URL to provide access to the freely available article in PLOS One: https://plos.io/3J9oC91
Citation: Hemp A, Miyazawa M, Hurskainen P (2025) Gain and loss: Human and environmental wellbeing – drivers of Kilimanjaro's decreasing biodiversity. PLoS One 20(10): e0334184. https://doi.org/10.1371/journal.pone.0334184
Author countries: Germany, Switzerland, Japan, Finland
Funding: German Research Foundation (DFG), (HE 2719/14-1), Dr. Andreas Hemp.
