Wednesday, March 21: it's the International Day of Forests

What if we took a little height on the occasion of the International Day of Forests, which takes place every year on March 21st? Planet, a company specializing in satellite imagery, compiled a video sequence of the 7134 images of forests it took in a single day. Thanks to a fleet of no less than 200 mini-satellites, the company has been photographing oceans, forests and various infrastructures from the atmosphere. These tools are very practical, for example, for evaluating forest area and attesting to deforestation phenomena

Compilation of 7134 images of forests covering 4 continents, captured in a single day. © Planet Labs 2018

For example, minisatellites captured these images near the Bolivian Andes. The disappearance of nearly 2,000 hectares of forest in just six months, in favor of sugar cane fields. The authors indicate that according to Mongabay, a website specializing in environmental science, it was an operation to prepare the extension of the San Buenaventura sugar refinery.

The images are striking, even for a phenomenon that has existed for decades. In its report entitled " Global Assessment of Forest Resources ", the United Nations measured between 2000 and 2010 an average annual deforestation of 13 million hectares. This represents the area of ​​Nicaragua! This frantic pace had already softened: in the 1990s, deforestation averaged 16 million hectares razed per year. The United Nations Food and Agriculture Organization (FAO) assessed global forest resources in 2015 at 3,999 million hectares. That is 30.6% of the planet's territory

FAO has conducted forest resource assessments since 1948. One might be tempted to compare the figures for each. This is not possible. First of all because the methodology has changed in 70 years, and thankfully. Institutional, financial and technical resources have evolved to better quantify the areas and types of forest. Then the very term "forest" has changed in seven decades. What is a forest, according to the FAO?

The forest, definitions

1948. " Earth with vegetative associations dominated by trees of any size, able to produce wood or other products, to influence the climate or the water regime."

1958 Same definition to a detail added: "lands providing shelter for livestock and wildlife."

1980. "All types of vegetation where trees cover more than 10% of the soil."

1990. Developed countries: "Ecological systems with a minimum crown cover of 10%, generally associated with wild flora, fauna and natural soil conditions, and not subject to agronomic practices. 100 hectares are considered. "
Developing countries: "Crown-planted land of more than about 20% of the area; […] with trees more than 7 meters high and capable of producing wood […]." [19659005] 2005 "Land covering more than 0.5 hectares with trees greater than 5 meters and a cover of more than 10% of the canopy […]and does not include land that is predominantly agricultural or urban."

In 70 years, our relationship with the forest has changed, semantics with. From a purely productivist definition, the forest becomes an ecosystem. It is gradually understood that it contains a fragile biodiversity to defend. The next FAO assessment will take place in 2020. While it is good to take a step back to evaluate a phenomenon, it will need to be looked after very closely.