Mount Kilimanjaro is losing its native plants - but why?

Over the past century, the lower slopes of Mount Kilimanjaro have lost most of their natural plant species. A new study shows that the main culprit wasn’t shifting temperatures or changing rainfall – It was people.

Expanding farms, towns, and roads steadily replaced natural habitats, wiping out an estimated 75 percent of native plant species per square kilometer between 1911 and 2022.

The research was conducted by Andreas Hemp of the University of Bayreuth, Germany, and colleagues.

Plants in the Kilimanjaro region

The study pulls together over 100 years of maps, satellite images, population data, and painstaking botanical surveys from nearly 3,000 plant species across the Kilimanjaro region.

By looking backward through time, the researchers were able to separate what was driven by human land use from what might have been driven by climate.

Their conclusion is blunt. Land-use change – fueled by rapid population growth and economic development – was the primary direct driver of biodiversity loss on Africa’s tallest mountain.

People press Kilimanjaro’s plants

Kilimanjaro is more than a postcard peak. Its foothills and mid-elevation zones provide water storage, soil protection, timber, fruit, and farmland for millions of people in northern Tanzania.

But that same human dependence has come at a cost. As villages expanded and cash crops spread, savannas, woodlands, and other natural vegetation on the lower slopes were converted to fields and settlements.

Between 1913 and 2022, population density in these zones ballooned from about 30 people per square kilometer to about 430. At that pace, even small clearings accumulated into a landscape-level loss.

Human impact outweighs warming

Most studies on tropical mountains in recent decades have looked first to climate change for explanations of biodiversity decline. Warming is real on Kilimanjaro, especially higher up, and it affects glaciers, cloud formation, and fire regimes.

But this study found that, at the spatial scale of one square kilometer and across more than a century, climate change was not a significant direct cause of biodiversity loss on Kilimanjaro.

What mattered most was what people did on the ground – what they cleared, what they planted, what they built.

“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 percent of natural species per square kilometer lost on the lower slopes,” wrote the researchers.

“Encouragingly, traditional agroforestry and protected areas emerged as promising strategies for mitigation.”

Piecing together lost forests

To get to that conclusion, the team had to combine old and new data. Historical maps showed what vegetation looked like under colonial rule in the early 1900s. Census records documented how fast people arrived and where.

Modern remote sensing traced the spread of towns, roads, and farms. The most laborious piece was the plant data: thousands of species records collected across forests, savannas, farmed landscapes, and protected zones.

“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.”

Their approach was unusually fine-grained for a tropical region. “Investigating a century of ecological change on Kilimanjaro allowed us to disentangle complex human and environmental impacts,” the scientists explained.

Where Kilimanjaro’s plants held on

Even though the overall trend was severe loss, the analysis also picked up bright spots. Some areas under traditional agroforestry retained surprisingly high plant diversity. In these systems, people grow coffee or bananas in shade or mix trees with crops.

Small protected areas also held onto more native species than surrounding, heavily used land. That finding matters because it shows that biodiversity decline is not inevitable in a densely populated landscape – it depends on the land-use model.

The authors note that the lower slopes face the greatest exposure because they’re easiest to reach, best for farming, and the first to urbanize.

Once natural vegetation is replaced wholesale, little room remains for narrow-range species, understory plants, or slow-growing trees.

The loss of plants, in turn, erodes overall ecosystem diversity because plant structure and composition set the stage for insects, birds, and mammals.

People hold Kilimanjaro’s fate

Because climate change did not show up as a direct driver in this century-scale analysis, the policy implication is clear.

Kilimanjaro’s biodiversity future will depend much more on what happens with land rights, agricultural expansion, urban planning, and protected areas than on temperature alone.

That doesn’t mean climate can be ignored; it acts on water supply, fires, and upslope shifts. But if habitat is gone, species have nowhere to move.

Many view Kilimanjaro as a symbol of climate change, but this study reveals another story unfolding alongside it. Clearing, farming, and building have been far more destructive to local plant diversity than warming itself. That’s sobering – but also empowering.

A path forward for conservation

Unlike global CO2 levels, land use can be governed locally. Where traditional, tree-rich agriculture and well-managed reserves were in place, nature fared better.

Tanzania and local communities now have a practical path to stop the loss. They can protect what’s left, support agroforestry, and plan expansion to keep the mountain’s green belt from shrinking further.

The study is published in the journal PLOS One.

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