The Two (Country) Sides of Forests

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University of Bonn researchers studying how national policies affect forests in border regions

The sudden change in the tree population is obvious. - Whereas the green areas s
The sudden change in the tree population is obvious. - Whereas the green areas show forest coverage in China (beneath the blue line marking the border), the yellow-orange areas on the Russian side indicate deforestation-a sign that national policies impact forest conservation. © Source: earthenginepartners.appspot.com/science-2013-global-forest all images in original size .
How do national policies impact deforestation? Researchers from the University of Bonn have looked into this question at the global scale and have found that, contrary to common assumptions, national strategies have a significant-and visible-influence on efforts to protect forest heritage. Their study has now been published in the journal "Global Environmental Change."

A picture is said to say a thousand words, and researchers led by Professor David Wuepper from the Land Economics Group in the Institute for Food and Resource Economics at the University of Bonn took this as their inspiration to investigate the impact of national policies on forest coverage. They had the idea of using satellite images to analyze forests along the borders between countries. "Ecological zones are often very similar across national borders," explains David Wuepper, who was appointed to a new professorship in the University of Bonn’s PhenoRob Cluster of Excellence as recently as April 2023. "If you have a healthy forest on one side of the border and a completely barren landscape-to exaggerate slightly-on the other, this is often because of the different policies pursued by the two countries."

Professor Wuepper’s group started by gathering large volumes of data together with its research partners. The team from ETH Zurich evaluated 20 years’ worth of satellite data on forests in border regions all over the world to find out how the population and condition of the trees had changed. While they were tackling this, Wuepper’s research group was working its way through the various countries’ policies on forest conservation. Besides relevant legislation, they also considered programs that have an indirect impact on forest coverage, such as those that give landowners financial incentives to protect trees on their property.

Before/after comparison

To undertake their analysis, the researchers first looked to see whether there were any changes in the border regions. Has forest coverage increased or decreased? Has it grown more or less healthy? Along some borders, such as that between China and Russia, differences are easy to spot on the satellite images. Whilst the Chinese side is a lush green, the Russian side is bathed in orange and red-the sign used in the study for deforestation.


"However, changes like this aren’t necessarily down to specific policies," Wuepper points out. "There are other reasons too. For instance, is using the forest important to the country’s economy? Does it have the resources and infrastructure to manage forests in the first place?" Since policies are introduced at clearly defined moments in time, however, a before/after comparison lends itself well to such an investigation. In other words, a sudden or significant shift after a new policy was brought in can be explained by the change in strategy. In the case of China and Russia, this is easy to spot: whilst Russia has been constantly exploiting its forests, China has moved its policy more toward protection. "China had huge problems with soil erosion caused by the loss of its forests," Wuepper explains. "To combat these, it finally launched some massive reforestation schemes to halt this erosion. The policy U-turn is clear to see from the pictures."

Equally clear are the study’s findings: national policies are the main explanation for dramatic changes in the tree population along country borders. According to the researchers, however, there is extreme variation in how well these policies work. "The two most important explanations for effective national policies are how strict they are and whether they really are implemented in the way they were presented on paper." Brazil is a good example. Following years of overexploitation in the Amazon rainforest-due mainly to illegal logging-the government began to take tough countermeasures, introducing satellite surveillance and deploying the military to tackle lawbreakers. The move led to a sharp fall in deforestation. These rules were watered down again under President Jair Bolsonaro, and the progress made was squandered.

The study shows how important national governments are to the protection of our forests. "This is a significant insight," says Wuepper, summing up his team’s findings. "Over the past few years, there has been this general impression that national governments are largely powerless and that relying on national policymaking was seen as almost old-fashioned in a way. Yet national policies are a key cornerstone of forest conservation. Although they can’t replace other initiatives, of course, they can complement them in a game-changing way."

About David Wuepper

David Wuepper has been a professor at the University of Bonn and head of the Land Economics group at the Institute for Food and Resource Economics since April 2023. The group is part of the PhenoRob DFG Cluster of Excellence and is funded by the ERC’s LAND-POLICY Starting Grant. The group has two main areas of research, which complement each other: evaluating policies that promote sustainable land use and appraising the potential of sustainable innovations in agriculture. "The new technologies will be needed if we are to put agriculture-which is one of the biggest drivers of biodiversity loss, climate change and other global environmental problems-on a sustainable footing," David Wuepper says. "I’m looking into how they can be used profitably, where they can most benefit society, and where these two areas overlap."


David Wuepper studied agricultural-economics at Kiel University before completing his doctorate in the same subject at the Technical University of Munich (TUM) in 2016. He then went on to work as a postdoc at TUM and ETH Zurich and as an interim professor at Humboldt-Universität zu Berlin before taking up his current professorial post at the University of Bonn.

The Land Economics group at the University of Bonn was joined by research teams from ETH Zurich in Switzerland, the University of Cambridge in the UK and Wageningen University in the Netherlands to work on the study entitled "Public Policies and Global Forest Conservation: Empirical Evidence from National Borders." Sources of the project’s funding included the ERC Starting Grant "LAND-POLICY" (Grant No. 101075824), which David Wuepper secured when he joined the University of Bonn in the summer of 2023. 390732324) as well as the Bernina Foundation (Professor Thomas Crowther) and the ERC’s ForestPolicy Starting Grant (Professor Rachael Garrett, Grant No. 949932).

David Wuepper, Thomas Crowther, Thomas Lauber, Devin Routh, Solen Le Clec’h, Rachael D. Garrett, Jan Börner: "Public Policies and Global Forest Conservation: Empirical Evidence from National Borders," in: "Global Environmental Change." https://doi.org/10.1016/j.gloenvcha.2023.102770