Sub-Saharan Africa is set to experience a population growth explosion, warns the United Nations in its latest data projections for 2100.
Dr João Vidal, a research fellow at the department of plant sciences and the Afromontane Research Unit (ARU) at the University of the Free State, predicts that the most rapid population growth zones in Africa are in or around mountains.
Therefore, he says, the importance of managing these mountain ecosystems sustainably in order to maintain the benefits to such a growing population is critical.
The link between human population growth and the demand for water will impact these mountain grasslands.
All of Africa’s important rivers originate in mountainous areas. The sustainable management of mountain landscapes is therfore vital for the sustained provision of quality water in suitable quantities.
“Water is already limited in some places. This year we are facing another drought in South Africa, and if it was not for the mountains, it could have been much worse. The long-term resilience of Southern Africa’s mountains and their ecosystem services should be an absolute priority for both research and conservation,” says Vidal.
Implications of population growth
As a mountain ecologist, his recent research is centred on developing indicators for monitoring biodiversity change in Southern Africa’s mountains. This is a collaborative research project with the South African Environmental Observation Network (SAEON), Ezemvelo KZN Wildlife, and the University of Pretoria.
Human population growth, as predicted for Southern Africa, has several implications for natural-resource management and biodiversity conservation.
“Southern Africa has one of the highest proportions of grassland-dominated mountains in the world, comparable only to Central Asia,” says Vidal.
In December, United Nations secretary-general António Guterres spoke at the launch of the 2021 Global Humanitarian Overview.
He said, “Conflict, climate change and Covid-19 have created the greatest humanitarian challenge since the Second World War.
“The number of people at risk of starvation has doubled. Hundreds of millions of children are out of school. Levels of extreme poverty have risen for the first time in 22 years.”
According to Vidal this new scenario of the impact of population growth significantly increases the pressure on mountain environments and their biota, since people will have to find alternative ways of feeding their families, their animals, while the economy struggles to recover globally.
Through his research, Vidal – together with a growing community of practices for Southern Africa’s mountains – aims to understand the socio-ecological functioning of these montane grasslands in order to encourage a science-policy-action interface for their sustainable management in a changing world.
Measuring environmental change caused by population growth
Since much global mountain research is focused on forest-dominated mountains, Vidal and his collaborators are developing specific tools to track climate change in grassy mountains.
He explains, “When you look at the available tools for tracking climate change in mountains, you have a tree line for many mountains in the world. However, with the Southern African grassy mountains, it is impossible to use such a tool. We are working on alternative ways for measuring environmental change in our mountains.
“As it gets warmer, certain communities of grasses may retract towards higher elevations because they need a certain minimum temperature to survive. The problem seems to be that current climate change is occurring at a much faster rate than most species might be able to retract. This means that higher temperatures may lead to habitat losses for temperature-vulnerable groups.
“Climate change is also making mountains increasingly vulnerable to ecological invasion by non-native species. The severe temperatures in mountains are a good barrier for many problematic lowland species.
“But with warmer temperatures in the mountains, these barriers are being weakened, increasing the number of potentially invasive plants in our mountains. With higher temperatures, there is potential for a large guild of invasive trees to overrun grassland mountains affecting water-flow into dams and rivers. Examples are pines, willows, gums, and wattles, to name a few.
“The presence of invasive trees, especially along rivers, has long-term negative impacts on the functioning of mountain catchments. These trees destabilise riverbanks, extract large amounts of water, and cause local extinction of endemic montane biodiversity. In drier environments such as grasslands, this exacerbates the fragile water productivity,” he adds.
Value of grassy mountains
It is important to draw attention to the value of natural grassy mountain systems around the world and to how threatened they are. The world’s grassy mountains need to be better studied and better placed on the global stage.
This will encourage policy makers to recognise these systems and implement appropriate measures to facilitate their sustainable management.
For the first time in 20 years, the IPCC report included a chapter focusing solely on mountains.
“Policymakers are finally realising how disproportionately important mountain environments are and how dramatically they are affected by climate change,” says Vidal.
However, African mountains are underrepresented in research literature; it is the only continent for which there is no data included in the IPCC report.
There is an urgent need to represent African mountains – especially Southern Africa’s mountains – on the global stage when it comes to climate change,” states Vidal.
Vidal is conducting this study on the impact of population growth on, inter alia, montane grassland in partnership with Dr Ralph Clark, Director of the ARU on the UFS Qwaqwa campus.