Nursery at the Reserva Ecologica Guapiacu in the federal state of Rio de Janeiro, Brazil.

Nursery at the Reserva Ecologica Guapiacu in the federal state of Rio de Janeiro, Brazil.
Photo: Robin Chazdon

Where restoring the rain forest really pays off

Humans have already cleared vast tracts of the tropical rain forest, a process which should ideally be reversed for the sake of the climate and the environment. But which rain forests are priorities for restoration? Scientists are trying to answer this question by identifying sites where restoration would be particularly promising.

More than half of the original tropical rain forest has been cleared. A reversal is in prospect, at least in some parts, as restoration is embodied in international agreements on nature conservation (Convention on Biological Diversity) and the Paris Agreement. “We’ve identified hotspots for renaturation, areas where restoration of the tropical rain forest would be particularly helpful. Together, these hotspots cover around 101 million hectares worldwide, roughly the area of Spain and Sweden,” explains Dr Aidin Niamir, researcher at Senckenberg Biodiversity and Climate Research Institute in Frankfurt, Germany.

Niamir worked with international colleagues, studying satellite images to see where tropical lowland rain forests could be regenerated worldwide. The team of researchers calculated the benefits of restoration for these areas, giving positive weight in their balance sheet to the contribution to protecting biodiversity, capturing carbon dioxide, assisting adaptation to climate change and water storage. They made deductions for the costs of restoration and the likelihood that restoration would not lead to a return of the associated biodiversity or that the trees would be logged again in the short term.

Major regional differences in useful regeneration

There were major regional differences in the assessment. For example, it was surprising that in absolute terms the most promising tropical rain forests for restoration are in Rwanda, Uganda, Burundi, Togo, southern Sudan and Madagascar. “Although there was a lot of logging here, it’s also very likely that restoration will have particularly positive effects. In addition, our study shows that it would be cheap and sustainable, as many areas were cleared which in any case are only suitable for agriculture to a limited extent,” Niamir explains.

However, purely in terms of surface area it is worthwhile pressing ahead with restoring tropical rain forest in Brazil, as over half of the areas identified by researchers as being particularly valuable for restoration are in this region. According to the study, there are also a particularly large number of areas in Indonesia and Colombia which could be restoration hotspots. Paradoxically, these are the very countries where existing rain forests are particularly threatened, or which are already being cleared on a large scale.

The study also showed that almost 90 per cent of restoration hotspots are hotspots for protecting biodiversity. “This shows that restoration and existing nature conservation go hand in hand, and suitable measures can reach two goals simultaneously,” Niamir comments.

The international study, which appeared in July in the journal Science Advances, accordingly has entirely practical application. “It’s time to stop debating how much tropical rain forest needs restoring, and talk about where. This means setting priorities, and our analysis supplies ecological and socioeconomic criteria which help reach a concrete decision on the optimal sites for restoration.”



Brancalion, P.H.S., Niamir, A., Broadbent, E., et al. (2019). Global restoration opportunities in tropical rainforest landscapes. Science Advances, doi: 10.1126/sciadv.aav3223