How do forests recover after logging? New network seeks to find out

Scientists find a big gap in our knowledge of logged-over forests in the tropics - with potentially significant benefits.
The idea of the undisturbed, pristine tropical rainforest captures people’s imagination — and the priorities of researchers and donors.

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BOGOR, Indonesia — They are the forgotten forests.

Logged or “disturbed” forests are fast expanding throughout the tropics, though they have not received anywhere near as much attention as so-called primary (“old-growth”) forests — until now.

A new global network of institutions — the Tropical Managed Forests Observatory (TMFO) — is for the first time studying managed forests at the regional and global scale, comparing the way forests in the Amazon, the Congo Basin and Southeast Asia recover after selective logging.

The idea of the undisturbed, pristine tropical rainforest captures people’s imagination — and the priorities of researchers and donors, says Plinio Sist, a scientist with the Center for International Agricultural Research for Development (CIRAD) who coordinates the network, which includes the Center for International Forestry Research (CIFOR).

But it’s just as important to understand the dynamics of the vast areas of forest — 400 million hectares worldwide — that are managed for timber production, Sist and colleagues write in a new paper that sets out the aims of the TMFO.

“There’s a big gap in our knowledge in terms of logged-over forests in the tropics, and we think there is a lot of data that is not being used yet, and that it’s time to make that data valuable,” he said.

“Time is our enemy. Tropical forests are disappearing very quickly, so our challenge is to say that those forests can be used, but used in a more sustainable way than is currently happening.”

As another new study by CIFOR researchers explains, logged or “production” forests have values that are often overlooked, leaving them vulnerable to further degradation such as further clearing or fires. Logged tropical forests, the authors write, are diverse and provide a multitude of important ecosystem services — increasing the urgency to focus conservation strategies on them.


The project began two years ago and makes use of data collected over decades by 20 research institutions from nearly 500 permanent plots in nine countries.

The researchers are using this huge data set to understand how quickly forests in different regions recover biomass, timber volume and biodiversity after they are logged.

The aim is to provide useful information for forest managers and policy makers about what compromises they can make as they balance logging with conservation and other values.

“What we want to answer is, according to the composition of the forest in the Amazon, or in Borneo, if you harvest say 10 trees per hectare, then the recovery of the biomass will take X amount of time, the timber recovery will take Y and the biodiversity will be Z in 30, 40 or 50 years,” Sist said.

“So at least the politicians will not be able to say, We didn’t know.”


It is a strategy that reflects the reality facing forests in tropical countries. Half of them have already been cleared or logged, and half of the standing primary tropical forests have been designated for timber production.

We are only two years old and the results have been quite impressive: We have already published two papers, with a third one in preparation

Plinio Sist

And while some would like to protect all the tropical forests that remain, Sist says that is highly unlikely to happen.

“Realistically the area covered by protected areas worldwide will not reach more than 10 [percent], maximum 20 percent of the land cover,” Sist said.

“So we have to consider that tropical forests, like most temperate forests, will have to be managed properly in order to have an impact on conservation of biodiversity.”

What good sustainable forest management can do, he says, is keep natural forests standing, while producing some economic goods — such as timber — and environmental services like water and carbon storage.

“Just because they are very rich in species and very complex to understand, that doesn’t mean there is no way to manage them properly,” he said.

“It means of course you will not go back to the pristine condition but at least you will conserve a lot of species — and they won’t be flattened to make way for palm oil,” he said.

So far, policy makers have not always recognized the importance of these forests, Sist says.

For example, in Indonesia, the recently extended moratorium on new logging concessions in the country included only primary forests — yet many forests there are being over-exploited, Sist says. Once a forest is exhausted it will no longer be profitable, and is likely to be converted for oil palm.

“I think it’s a very dangerous path, and I hope that logged-over forests will be given more attention for their role providing not only timber but also environmental services.”

“If scientists also consider logged-over forests, then we will show decision-makers that they are important ecosystems.”


This is what the TMFO aims to do: bring together and generate global knowledge about these ecosystems.

“This network has been very dynamic in such a short time,” Sist said. “We are only two years old and the results have been quite impressive: We have already published two papers, with a third one in preparation.”

A key part of its success so far, Sist said, is the participatory nature of the project. Each institution retains control over its own raw data, and provides a synthesis of this data to the TMFO, which uses it to create a meta-analysis.

“This has been a very helpful strategy, because the researchers are much more confident to collaborate as there’s no sharing of raw data.”

This is important for institutions in tropical countries, many of which are under-resourced and might resent providing their data to a developed-country organization that has a greater capacity for publication.

“We consider that those who are implementing those plots are the ones that know their data best. And it means we also help with capacity building at each institution,” Sist said.

The next step, Sist says, is to strengthen and homogenize the data, which will require traveling to the field to conduct supplementary measurements.

And the scientists are keen to broaden the group to include more institutions, he says.

“People are getting more and more excited about the potential of this network.”

For more information about this story please contact Plinio Sist at or Robert Nasi at

The Tropical Managed Forest Observatory is coordinated by CIRAD and supported by the Sentinel Landscapes program of the CGIAR Research Program on Forests, Trees and Agroforestry (FTA)

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