African mountain forests: valuable climate protection resources
The tropical mountain forests of Africa store more carbon per hectare in their above-ground biomass than all other tropical forests on earth. With this great storage capacity, which the Intergovernmental Panel on Climate Change (IPCC) previously estimated to be considerably lower, these forests have made a major contribution to climate protection. This is the conclusion of a study published in Nature by an international network of researchers who are pressing for the preservation of these carbon-rich ecosystems. Dr Andreas Hemp (University of Bayreuth, Germany) and his team investigated carbon stocks in the mountain forests of Kilimanjaro.
The researchers involved in the study examined carbon storage in the above-ground biomass of mountain forests on 226 selected plots spread over 44 regions in twelve African countries. The results showed that Africa's tropical mountain forests store an average of 149.4 tonnes of carbon per hectare. Previously, the IPCC had assumed an average of only 89.3 tonnes of carbon per hectare. The results of earlier research demonstrated that the average storage capacity of the above-ground biomass of tropical forests in Central and South America and the Caribbean is considerably lower than that of the tropical mountain forests in Africa.
“Especially in East Africa, most forests are located in mountainous regions, so they are of crucial importance here for the carbon cycle and climate protection,” says Andreas Hemp. “Our study, which has quantified this storage capacity for the first time, makes clear the ecological damage that the further clearing of mountain forests would cause. And conversely, it also shows the benefits of the reforestation measures supported by many African states.”
Hemp also points to the findings of previous research showing that African mountain forests are biodiversity hotspots and home to a large number of endemic plant and animal species, i.e. species that do not exist anywhere else on earth. This insight alone confirms that efforts to preserve these resources should be intensified.
Large CO2 storage capacity in very large mountain trees
Together with partners in Germany, Kenya, and Tanzania, the Bayreuth biologist has been carrying out research into the flora on Mount Kilimanjaro for more than 30 years. As part of the joint project Kili-SES, funded by the German Research Foundation (DFG), he is investigating the change in vegetation on Mount Kilimanjaro and the underlying climatic, economic, and social causes.
For the study, which was published in Nature in August, he and his research team carried out systematic measurements in mountain forests on Mount Kilimanjaro. “If you know the height, circumference, and wood density of the tree trunks, you can determine the amount of carbon stored in the trees with some accuracy,” explains Hemp.
As destructive cyclones are relatively rare in Africa, the comparatively high carbon stocks of African tropical forests are to a significant degree based on the high storage capacity of very large trees, which can grow undisturbed in both mountain and lowland regions. The tallest trees in Africa are found on Mount Kilimanjaro, as a research group led by Dr Andreas Hemp discovered in 2016.
Aida Cuni-Sanchez et al.: High aboveground carbon stock of African tropical montane forests, Nature (2021).