By Mikaela Weisse and Marcelo Matsumoto
Brazil is the poster child of using forest monitoring effectively to reduce deforestation. Deforestation in the Brazilian Amazon has declined by nearly 70 percent since 2005, thanks in part to the Brazilian government’s satellite monitoring program known as PRODES (Program to Calculate Deforestation in the Amazon). PRODES data are the official national statistics on deforestation, used by the Brazilian government to establish public policy and track progress towards deforestation reduction goals. Now this annually updated data is available on Global Forest Watch.
Although PRODES data was first made publicly available in 2003, anyone who wanted to view and understand the data would have needed technical skills and resources. By putting it on the easy-to-use, interactive GFW map, PRODES can now be a go-to resource on the Brazilian Amazon for a much wider group of stakeholders, from academics and journalists to policymakers, with just the click of a mouse or a tap on the phone.
PRODES: a brief introduction
INPE (Brazil’s National Institute for Space Research) has been monitoring forests in the Brazilian Amazon since its first deforestation inventory for 1977-1979 using printed versions of Landsat satellite imagery. The agency began its annual tracking efforts under the PRODES program in 1988, which has continued to the present day. PRODES differs from other forest change data on GFW—like UMD Annual Tree Cover Loss—in several important and complimentary ways.
First, PRODES is created using a combination of computer and human analysis. It’s come a long way since its early days when images were all hand-marked by analysts year-to-year, which was expensive and slow. Now computers do the heavy lifting, but the method still involves human interpretation. The expert knowledge of the analysts allows PRODES to identify actual deforestation rather than tree cover loss.
Second, PRODES does not identify patches of loss smaller than 6.25 hectares—the size of roughly 8 soccer fields—even though the resolution is higher at 30-meters like UMD annual tree cover loss data. This criteria results in less error, but also limits the detection of smaller patches.
Third, PRODES is updated annually, but its monitoring year runs from August 1 to July 31. The 2015 PRODES data, for example, shows deforestation that occurred between August 1, 2014 and July 31, 2015. This time period allows for better image collection, since July-August is the middle of the dry season, when the forest is less likely to be covered by clouds, and is more aligned with typical clearing cycles in the region.
Finally, PRODES coverage focuses only on the Brazilian Amazon. The data is often misinterpreted as Brazil’s national deforestation rate by the press and other organizations, but it leaves out other major forested biomes in the country, including the Cerrado and Atlantic forest.
|PRODES||UMD Annual Tree Cover Loss|
|Resolution||30 meters, but minimum patch size of 6.25 ha||30 meters (minimum patch then is 0.09 ha)|
|Method||Image segmentation, then analyst interpretation||Automated decision tree|
|Observation Period||August 1 – July 31||January 1 – December 31|
The importance of official data
PRODES is the first official national forest change data set on Global Forest Watch. This kind of data is extremely important for advocacy and monitoring using the government’s own data. There have been cases where the Brazilian government renounced conclusions of analyses because they used other non-official data sets. With PRODES, because the data has been produced, validated and approved by the government, findings cannot be easily dismissed in discussions of policy.
PRODES enables the Brazilian government to monitor deforestation on private land and within protected areas, and has become the standard for other monitoring projects in the Brazilian Amazon. For example, the voluntary Soy Moratorium, which has been very effective at removing deforestation from the soy supply chain, is monitored and enforced using a derivative of the PRODES data. On Global Forest Watch, users can now approximate official monitoring results using this standard data. The numbers may not exactly match the official estimates due to the complicated accounting methods used for areas covered by clouds, but this is a good start.
Brazil remains at forefront of effective monitoring
PRODES is not the only forest monitoring data set for the Brazilian Amazon—DETER a daily deforestation alert analysis for the Brazilian authority oversight which is compiled and publish monthly basis, SAD is a monthly alert product from Imazon, and UMD tree cover loss is an annual global data set from the University of Maryland and Google. All of these data products have different methodologies, and thus different utilities for monitoring the state of the Brazilian Amazon. There is not one correct data set for identifying deforestation in the Brazilian Amazon; rather, comparing where they overlap or don’t overlap can lead to additional insight about the state of Brazil’s forests.
That said, the Brazilian government endorses PRODES as the basis of official deforestation statistics, so any insights or analysis targeting the Brazilian government will likely be better received if they are based on PRODES data.
In many ways, PRODES provided the inspiration for Global Forest Watch, as it showed the world that improved monitoring of deforestation can lead to improved management of forests. By making this data even more accessible, we hope that the tradition of sharing official and independent data will spread around the globe!