With local researchers in the hill country of Rwanda, researchers Göran Wallin and Johan Uddling study how Africa’s largest remaining tropical montane rainforest is reacting to climate changes.
“It’s extremely exciting to carry on and develop collaboration with another university in a relatively unexplored area,” says Wallin, at the Department of Biological and Environmental Sciences.
Close to 260 different types of trees and many other rare species grow in Rwanda’s tropical montane rainforests, where the Nyungwe National Park covers an area of more than 1,000 square kilometres. The forest is of vital importance to residents as a source of income from ecotourism, but it is also important as a carbon sink and for water control. Africa’s two major rivers, the Congo and the Nile, originate in these mountains, and the rivers are replenished by precipitation.
“In addition, this is a biodiversity ‘hot spot’ in the world, and it’s a serious matter if the forest suffers damage and species disappear,” Uddling says.
More than 12 million people live in Rwanda, an area the size of Småland that is called “Land of a Thousand Hills”. In 1994 the brutal Rwanda genocide claimed the lives of more than 800,000 Tutsi. Consequently, when the president of the National University of Rwanda contacted SIDA at the beginning of 2002 for help in building up the university, the country still was reeling from the civil war.
“We collaborate on environmental research in particular and began both student and researcher exchanges with the University of Rwanda,” says Wallin. He coordinates the University of Gothenburg’s environmental research collaboration with Rwanda, which also involves several other institutions at the university there.
Working with local researchers, Wallin and Uddling conduct research on how climate changes are affecting the Nyungwe tropical montane rainforest.
“Our fundamental question is how tropical tree species, which are adapted to a stable and already hot climate, pull through if it gets warmer. The long-standing hypothesis has been that they are close to their temperature optimum,” says Uddling.
There is no change of seasons in tropical areas close to the equator. In Nyungwe’s montane rainforest, the temperature during the warmest month is only one degree higher than during the coldest month, so the species there probably have poor genetic potential for being able to handle large fluctuations in climate. Nor can the trees in Nyungwe, many having a diameter of more than a metre, move to a higher elevation to cope with heat stress.
“Since many tree species grow atop the mountain ridge, not many possibilities exist. Perhaps other species adapted to higher temperatures could later take their place, but biodiversity certainly will undergo change in this area,” says Wallin.
Climax species will likely suffer, in contrast to the pioneer species.
“As a rule, pioneer species more readily adapt to changes, while climax species are extremely dependent on long continuity and presumably have greater difficulty in adapting to a higher temperature,” Wallin says. “In previous studies, we have seen that climax species from high elevations experience great heat stress when they are planted in lower elevations, which suggests that they are especially sensitive to increases in temperature.”
But the Nyungwe tropical montane forest is not just important from a biodiversity standpoint.
“Apart from its great variety of species and ecotourism as an income source, the area is also a significant carbon sink, since the trees absorb carbon dioxide. It is also a source of water for Rwanda’s agriculture because many of the major rivers come from this particular mountainous area,” Uddling says.
Even though both SIDA’s and Rwanda’s bureaucratic systems sometimes have resulted in delays for research, Wallin thinks it has been easy to collaborate with the Rwandan researchers.
“On the whole, I have had very positive contacts. When I began the collaboration, it was scarcely 10 years after the 1994 genocide, and many of the researchers and students we work with have experienced terrible things. But everything has worked amazingly well. Rwanda is a country that is developing well today and that has many good development trends.”
Through good funding provided by SIDA and recently also by the Swedish Research Council and the Research Council for Environment, Agricultural Sciences and Spatial Planning, it has been possible to develop several sizeable research projects.
“We are in the initial phase of establishing new research stations and experiments. And then both our group here at the University of Gothenburg and in Rwanda can grow, thanks to receiving this funding,” Uddling says.
The goal of the research is to find out how the forests are affected by climate change.
“But the social goal is to have fun in the meantime, and the societal and humanistic goal is to continue having good collaboration and building expertise in a poor country,” Uddling says.