Visualising 2018 tree cover loss with Global Forest Watch.

Camellia Williams
Vizzuality Blog
Published in
5 min readMay 8, 2019


Global Forest Loss.

Our planet lost 12 million hectares of tropical tree cover in 2018. Of that, 3.6 million hectares were primary forest — an area equivalent to the size of Belgium. But does a fact like that help you understand how much forest loss occurred? Or where? Or why? Making sense of big numbers is easier with data visualisation. With Global Forest Watch you can see where forest loss is most pervasive, threatening indigenous lands, or reducing biodiversity, so we can act quickly when deforestation happens where it shouldn’t.

Global tree cover loss in 2018. Each pink pixel represents an area where tree cover has been lost. Global Forest Watch.

National forest loss in Brazil.

Of all the countries in the world, Brazil lost the greatest area of tropical primary rainforest in 2018 — 1.3 million hectares in total. Although this figure is less than the 2016–2017 fire-related spike, it’s still above historical levels. Worryingly, tree cover loss is occuring in places that should be protected from deforestation.

Threats to indigenous lands.

Brazil’s 2018 Presidential elections ushered in a new leader who cares little for the environment, and its impact is already visible across Brazil. Anticipating that environmental protections would be relaxed, loggers and ranchers began a land grab of areas near and within indigenous territories the moment Jair Bolsonaro took office.

Hotspots of primary forest loss near and within indigenous territories in Brazil. Graphic by World Resources Institute.

Areas set aside for the exclusive use of uncontacted indigenous peoples living in isolation are particularly vulnerable because they are not officially demarcated indigenous territory. The exclusion of non-indigenous people from these areas is created by an official order that has to be renewed every three years, but that hasn’t stopped non-indigenous people from moving in and clearing trees.

One such area where this is happening is the Ituna Itatá Reserve, a place where uncontacted indigenous peoples live, sleep, forage, hunt, and raise their children. The people here have no communication with the outside world, nor any awareness of the changing political landscape, and yet they have a ring-side seat of the deforestation happening around them.

GLAD alerts within the boundaries (outlined in blue) of the Ituna Itatá Reserve clearly show when the illegal deforestation began and how quickly it spread.
Clockwise from top left, composite satellite images of just a small portion of the Ituna Itatá Reserve from Quarter 1 2018, Quarter 2 2018, Quarter 3 2018, Quarter 4 2018. Satellite imagery reveals extensive clearing within the boundaries of the Ituna Itatá Reserve over the course of 2018. What we cannot assert from these images is what caused the change. However, given that the only people who should be occupying this area are an uncontacted group of indigenous peoples without access to machinery, we must ask ourselves who caused it.

Instituto Socioambiental (ISA) has been using satellite imagery to raise a red flag and speak on behalf of the indigenous people living within the Ituna Itatá Reserve. Their reports of illegal deforestation have been published by Thomson Reuters Foundation News and Mongabay, and I recommend reading them if you are interested in learning more about the struggles indigenous peoples and forest advocates are currently facing in Brazil.

When we look at the wider region around Ituna Itatá using GFW’s inbuilt analysis tools, we’re able to see that GLAD alerts in the region peaked in August 2018, and that this peak was well above normal levels. Putting data into context like this helps us understand if the loss we are seeing is something we need to worry about. If it is, we can easily share our findings with those who can do something about it.

Ituna Itatá Reserve lies within the Senador José Porfírio region, which experienced a higher than normal number of GLAD alerts in June 2018 and August 2018. Explore the dashboard on Global Forest Watch.

Ituna Itatá Reserve lies within the Senador José Porfírio region, which experienced a higher than normal number of GLAD alerts in June 2018 and August 2018. Explore the dashboard on Global Forest Watch.

Zooming back into Ituna Itatá Reserve, we can check the health of vegetation using satellites images that make use of the Normalized Difference Vegetation Index (NDVI), which incorporates information on both red and near-infrared reflectance. Healthy plants absorb most of the visible light that hits them, but when there are no plants that light gets reflected back into space. These bare areas show up as bright green patches in the images, and angular shaped patches or long wiggly lines are likely to be markers of man-made clearings. There’s a tutorial if you’d like to learn how to use the recent satellite imagery feature.

The bright green patches show where light is being reflected back in space, indicating an absence of vegetation, or in this case, trees. The straight blue line marks the edge of the Ituna Itatá Reserve boundary, everything to the right is currently protected by a government order which means non-indigenous are not excluded from the area.

Global Forest Watch allows anyone, including you, to take a closer look at what’s happening in places reserved for indigenous peoples. A fast, smooth zoom enables and encourages deeper exploration of what’s occurring. No one can hide from satellites in the sky and with weekly GLAD alerts, any change in forest cover can be detected and reported in almost real-time. This is the power of data visualisation: it provides compelling, irrefutable evidence that allows us to speak up for the people and places that are not being heard.

Good news for Indonesia.

But it’s not all bad news. Indonesia saw a 63% reduction in primary forest loss from its peak in 2016 when new legal protections of peatlands were introduced. More recent government policies—which include a moratorium on issuing new licenses to use land designated as primary forest and peatland—have also helped slow deforestation.

The clearing of rainforest to make way for oil palm plantations has attracted much media attention, and with a recently added ‘Global Plantations’ data layer, you can now use Global Forest Watch to explore where they are located. (Note: only data for 2015 is currently available). Although the moratorium is likely to stop any further conversion of pristine primary forest, GLAD alerts will help researchers, land managers, and interested citizens alike keep watch over Indonesia’s forests.

The Global Plantations data layer maps out plantations across Indonesia and classifies them by type. (Only data for 2015 is currently available). Map: Global Forest Watch.

With so many different data layers at your fingertips, Global Forest Watch is the perfect way to visualise data in ways that makes it easier to digest, understand and use the 2018 tree cover loss data. Informed by data and inspired by compelling visualisations, every one of us can become a champion of our planet’s forests and the people who call them home.

Visit the places that are most important to you on Global Forest Watch today and start sharing your stories with the help of data visualisation.



Camellia Williams
Vizzuality Blog

Communications Manager at Restor and former Lead Writer at Vizzuality