Africa's rainforests 'more resilient' to climate change

The tree species found in Africa's tropical forest have survived past extreme events, say researchers

Tropical forests in Africa may be more resilient to future climate change than the Amazon and other regions, a gathering of scientists has said.

An international conference agreed that the region's surviving tree species had endured a number of climatic catastrophes over the past 4,000 years.

As a result, they are better suited to cope with future shifts in the climate.

The event at the University of Oxford looked at the "fate of Africa's tropical forests in the 21st Century".

Conference organiser Yadvinder Malhi, professor of ecosystems at the university, said the main reason was that Africa's climate had been far more variable than, say, the Amazon or South-East Asia, even over the past 10,000 years.

"In some senses, African forests have gone through a number of catastrophes in the past 4,000 to 2,000 years," he told BBC News.

"They are already much lower in diversity, and have lost species that would have been potentially vulnerable. But the species that remain are relatively adaptable, have broad ranges and have adapted to quite rapid changes in rainfall.

"So, overall, the remaining system - although it may be poorer to some extent - may be much more resilient to the pressures from climate change in this century."

Data deficit

The three-day conference - entitled Climate Change, Deforestation and the Future of African Rainforests - focused on the tropical forests of West Africa, which helped highlight a key issue.

"One thing that really came out was how little we know about African climate compared to other regions of the world," Prof Malhi observed.

"There are large gaps [in the data]. If you look at a map of where weather stations are reporting, there is no data coming out of almost the entire Congo Basin."

It was an issue that was also highlighted by one of the speakers, Mark New from the University of Cape Town.

"A colleague of mine put it very nicely when he said that if you took a scale of what is known in various regions, and if you went into West Africa and the Sahel region, which has been extensively studied, and made that 100, if you then went down to the West African coast where the tropical forests are, it would probably be about 50 in terms of relative knowledge," he explained.

"But then if you carried on down to the Congo Basin, then you would probably get five or 10 out of 100."

Prof New added: "One of the critical points that I made is that what we know and understand about what controls the climate and variability, in the Congo especially, is basically zero.

"This makes it very difficult to make any strong predictions of what the future might be."

As well as issues surrounding climate data, the conference also heard about research projects assessing characteristics of the region's tropical forests.

Simon Lewis from the University of Leeds, UK, outlined findings regarding long-term forest plots.

"One of the big findings has been that African forests have more biomass, and have much bigger trees, in comparison with the forests in the Amazon," he told BBC News.

"That is partly because the trees are longer lived so they are becoming bigger over time, and partly because the whole forests are more productive.

"But we are not entirely sure why the African forests are more productive than those in the Amazon."

More than trees

He said that although there was a smaller diversity of tree species in Africa - the second largest area of rainforest on the planet - compared with the Amazon, it did not mean the forests were not important biodiversity hotspots.

"We must not just consider the trees, because in terms of mammal diversity, it is extremely high," Dr Lewis added.

"There are many species of monkeys, and you then have things like pigmy hippos and forest giraffes.

"In terms of its animal diversity, it really is a remarkable place. And the majestic stature of the trees, it is again remarkable."

Prof Malhi explained that the results of the conference would soon be outlined in briefs and drafts for policymakers summarising "some of the key points of what we know and what we need to know".

"We will also make some scientific recommendations about what are the immediate gaps in the research areas, that with a focused effort, we could know in five years time," he added.

"We are also planning to have a smaller follow-up meeting in central Africa, where the region's key policymakers will be invited to attend."