Subscribe
A new study reveals that land-use change caused by rapid population growth, not climate change, was the primary direct cause of the loss of 76 per cent of natural plant species on the lower slopes of Mount Kilimanjaro between 1911 and 2022.
The loss of natural savanna habitats significantly threatens Kilimanjaro’s biodiversity, as savanna ecosystems are crucial for plant species diversity. This decline also affects traditional medicinal plants, primarily found in Kilimanjaro’s lowlands.
The study has been published in the journal PLOS One.
Located in Tanzania, Mount Kilimanjaro is Africa’s tallest mountain, and it is the largest free-standing mountain rise in the world, meaning it is not part of a mountain range.
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.
The objective of the study was to investigate how the main direct and indirect anthropogenic factors affect biodiversity at Kilimanjaro and to assess the role of conservation in relation to biodiversity.
The researchers analysed 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 process involved analysing data from 1911 to 2022, marking one of the most detailed long-term ecological studies in the region.
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 76 per cent of natural plant species per square kilometre. Land-use change stemmed from rapid population growth and economic development, with population density rising from 30 to 430 people per square kilometre between 1913 and 2022.
Demographic and socio-economic factors have driven many land-use changes at Kilimanjaro. By 2000, a corridor of sub-montane forest that once connected Kilimanjaro and Mt Meru had been largely replaced by human settlements and agriculture.
The analysis also showed that climate change was not a significant direct cause of biodiversity loss on Kilimanjaro.
Kilimanjaro’s climate is warming. The glaciers on the top of the mountain are shrinking. But in the lower parts of the mountain, where most species have been lost, rainfall has not really changed and warming is slow. Instead, most of the biodiversity loss is happening where people have cleared land for farming, built towns and used the land more intensively.
The researchers say their findings could help guide policies to mitigate biodiversity loss.
According to researchers, this study is the first to link human population densities with plant species densities at a one square kilometre scale in a tropical region.