Johannesburg — Some of the iconic images people call to mind when speaking about the African continent is wide open expanses like those seen in Kenya's Masaai Mara and the Serengeti National Park in Tanzania. These open spaces are part of what is called rangelands, which can be regarded as land carrying natural or semi-natural vegetation, and provides a suitable habitat for herds of wildlife or livestock.
According to the World Agroforesty Centre, "[r]angelands are more than just grass but rather complex and biodiverse ecosystems. Covering nearly half the world's land area, they are in need of restoration and sustainable management".
A new study in the journal Scientific Reports calls attention to the vulnerability of these landscapes as the climate crisis grows more dire but also offers some hope. These rangelands show potential for recovery.
Titled 'Pathways of degradation in rangelands in Northern Tanzania show their loss of resistance, but potential for recovery' - the report uses 20 years of field data on vegetation with high-resolution satellite images to identify the drivers of degradation within the Northern Tanzanian rangelands and shows that sites that are degraded are more sensitive to environmental shocks like drought.
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The rangelands of Northern Tanzania are home to significant populations of pastoralists and are a stronghold for biodiversity with a variety of animal and plant species of economic, ecological, and socio-cultural importance. Wildlife numbers are falling and degradation is the key contributor to this problem.
"Across Northern Tanzanian rangelands there is considerable variation in the degree of degradation and in anthropogenic and environmental drivers of degradation. For example, in our study area, rainfall varies from 400 to 900 mm, the human population from 5 to 35 people per km2, and livestock densities up to 250 head of cattle per km2. A variety of conservation-related land use restrictions also moderates these landscape conditions. The combination of all of these interacting components makes Northern Tanzania an ideal location to study the processes that shape recovery and resistance in rangeland dynamics," according to the study.
The authors say that semi-arid rangelands are highly vulnerable to changes in weather patterns, human activities, and climate change so they are unable to recover from repeated environmental shocks but say there is still hope as they are able to retain their recovery potential.
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"The results show that the ability of these sites to recover if effectively managed is undiminished, with responsible community management being the key if degradation is to be reduced. That is a really positive message ... the results show that recovery is still there. That actually we can restore and recover these areas if we can give them a break and work out why they are doing worse during those extreme events" said Dr Colin Beale, from the University of York's Department of Biology.
The Maasai people and pastoralists have lived and practised in these areas for centuries, for the rangelands' sustainability, the linking of Indigenous and Local Knowledge is important.
"I have first-hand experience of the impacts of climate change and human pressure on our rangelands. The opportunity from this work for successful restoration and rangeland regeneration is really encouraging for the future of the pastoralist Maasai culture," said Boniface Osujaki, one of the local Maasai co-authors.
The study area consisted of 30,300 km2 of the Tarangire-Manyara ecosystem and the Maasai Steppe of northern Tanzania. Notable droughts in the study region were recorded in 2003-4 and 2016-17 when average rainfall was around 50% below average. The period between October 2019 - January 2020 was the wettest recorded in East Africa in over two decades.
