Oxford researchers find African forests even more productive than Amazonia.

Whilst most studies on the ecosystem functioning of tropical forests have focussed extensively on Latin America or Asia, researchers at the University of Oxford say comparing findings with studies in Ghana has produced interesting and differing results showing that more studies need to be made in Africa.

Tropical forests cover large areas of equatorial Africa and play a significant role in the global carbon cycle. Scientists from the Leverhulme Centre for Nature Recovery, in close partnership with collaborators at the Forestry Research Institute of Ghana (FORIG), have been looking at the carbon budget in both the Amazon and West Africa by undertaking detailed field assessments of the carbon budget of multiple forest sites.

The researchers monitored 14 one-hectare plots along an aridity gradient in Ghana. When compared with an equivalent aridity gradient in Amazonia that they had previously studied using the same measurement protocol, the studied West African forests generally had higher productivity and more rapid carbon cycling.

Their findings have been published in Nature Communications: Contrasting carbon cycle along tropical forest aridity gradients in West Africa and Amazonia.

Lead author Huanyuan Zhang-Zheng, a postdoctoral researcher at the Centre, said:

“Tropical forests are so diverse that we are constantly surprised when opening new study sites. I became  fascinated with West African forests because of this study, but I am sure there are more fascinating tropical forests yet to discover.”

“When we’re talking about carbon budgets, you can’t just study a stand of forests and imagine that applies to even nearby forests. Carbon budgets vary greatly from wet to dry regions in the tropics.

“Having studied the carbon budget in the Amazon it was interesting to see that West African forests are more productive, have more photosynthesis and absorb more energy. And we don’t quite understand why this is the case. This is an important region and shouldn’t be ignored. Our new findings were able to tell us a different story than our previous studies in the Amazonia, and has stimulated new questions and new research.”

The work carried out is part of the Global Ecosystem Monitoring network (GEM), an international effort to measure and understand forest ecosystem functions and traits, and how these will respond to climate change. GEM was created 2005 under the leadership of Prof Yadvinder Malhi. The GEM network describes the productivity, metabolism and carbon cycle of mainly tropical forests and savannas.

Professor Malhi said:

“Ecology is a global science, and equal long-term partnerships are essential to produce both better science and fairer science. This work is the product of decades of long-term partnership between Oxford and institutions in both Africa and South America, work that seen many local students trained and graduating and contributed to building local capacity in environmental science.”

The study is also a fruit of successful collaboration with the Forestry Research Institute of Ghana – CSIR, many scientists from which made fundamental contributions to the study and are coauthors of the publication.

One of the lead Ghanaian collaborators, Said Akwasi Duah-Gyamfi, Senior Research Scientist, CSIR-Forestry Research Institute of Ghana, said:

“It was a wonderful experience to be part of the research team, and most importantly to explore and generate knowledge on topical issues about forests in Africa.”

Read the paper in full: Contrasting carbon cycle along tropical forest aridity gradients in West Africa and Amazonia

Read more about GEM: The Global Ecosystems Monitoring network: Monitoring ecosystem productivity and carbon cycling across the tropics