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[EN VIDÉO] Our forests in timelapse thanks to Google Earth See how we’ve changed our planet’s forests since 1984 with a global time-lapse video.
41 million square kilometres: this is the area of earth that the forests still cover. That is about 30% of the emerged surfaces. But in recent decades, forests have been suffering. Of the storms more and more violent, agents pathogens increasingly numerous and virulent, extraordinary forest firesoperations of deforestation. Will they be able to resist, to recover from all these disturbances, to get up again?
This is the question asked by a international team of researchers. Because forests play a key role in regulating the climate. They thus absorb about a third of our emissions of carbon. They also participate in the regulation of water flows, the protection of soils and the conservation of biodiversity. Assess their resilience therefore seems particularly important.
Studies have already shown that rising temperatures and falling humidity, all under the effect of anthropogenic climate change, could make it difficult for some forests to survive. This time, the researchers went a step further. They wondered if these upheavals could degrade the ability of forests to withstand more ad hoc attacks. Of type floodspests, droughts or contamination. Natural as well as anthropogenic attacks.
The researchers worked on an astronomical amount of satellite data. Data collected over twenty years, between 2000 and 2020. It was a machine learning algorithm that helped them sift through this data.
Climate change puts forests to the test
The resilience of a forest, researchers have defined it as its ability to recover after a disruptive event. How do you know if this is the case or not? According to them, when the forest turns into something else — like the savannah — when it changes state, it is a sign that the loss of resilience is complete, that the tipping point has been reached. . Before that, the forest begins to lose productivity.
A few years ago already, Colorado State University researchers (United States) had studied how climate change affects the regeneration of trees after a fire of forest. They had worked on 1,500 sites across five states in the United States. They had observed a significant decrease in tree regeneration between the end of the 20the century and the beginning of the XXIe century. In just over twenty years, forests seemed to be becoming less resilient to fires. More recently, studies revealed that the mortality rate of trees in Europe was skyrocketing or that the Amazon forest was close to a point of no return.
This time, the results of the planet-wide analysis show that more than half of all the world’s forests — whether managed or “intact” — show signs of diminishing resilience. These include tropical, arid and temperate forests. The reason is both increasingly frequent water limitations and climate variability.
However, the global warming seems to have a positive effect on the resilience of some trees. Those of boreal forestsin the latitudes northern regions, apparently benefit from warming and a certain “fertilization” by our carbon dioxide emissions (CO2).
Disturbing work at a time when some are relying on carbon sink what forests do to help us fight global warming. But other studies will have to confirm this. In the meantime, the researchers suggest that mitigating the impact of anthropogenic climate change on forest resilience will require promoting tree species diversity in the future.
Primary rainforest The humidity is high and promotes the growth of epiphytes, those plants that grow on anything, trees, rocks or electric wires. On the ground, the light is rarer, which suits the ferns well. It’s hot. We are in a rainforest © Mrs Brown, Pixabay, DP
Taiga landscape in russia Tall trees, large expanses of water from melting snow and ice, cool temperatures: that’s the taiga. It extends to the north of the planet, as far as the Arctic, from Siberia to Alaska via the Scandinavian countries and Canada. © Baldr80, Pixabay, DP
Eucalyptus forest in Australia An Australian bush landscape with two-tiered flora: scrub and herbaceous plants on the ground and, above, trees with hard or thorny leaves, such as eucalypts. © 12019, Pixabay, DP
Rambouillet forest The Rambouillet forest, located in the south of the Yvelines department, is one of the main forest areas in Île-de-France. It is a wooded area of 200 km², including 14,550 ha of state forest, which extends over the territory of 29 municipalities. The stand consists mainly of oaks, up to 68%, and softwoods (Scots pine and laricio pine) for 25%. This massif has ponds, rocky areas, stretches of sand, valleys and waterfalls. Part of the forest is in the regional natural park of the upper Chevreuse valley. © Pline GNU Free Documentation License version 1.2
Denmark: Grib forest Grib Forest in North Sealand, Denmark. © Malene Thyssen GNU Free Documentation License, Version 1.2 or
Madagascar: Spiny forest Spiny forest in Ifaty, Madagascar, composed of adansonia (baobab), alluaudia procera (Madagascar ocotillo) … © JialiangGao GNU Free Documentation License, Version 1.2
Italy: Forest of Cansiglio Cansiglio forest in autumn Italy © Umberto Salvagnin Creative Commons Attribution 2.0 Generic license.
New Zealand: Paraparaumu Reserve Forest of (Rhopalostylis sapida) Paraparaumu Reserve New Zealand © Pseudopanax Public domain
Panama: La Amistad International Park Panama La Amistad International Park © Dirk Van der Made GNU Free Documentation License, Version 1.
Germany: Forest of Urwald Sababurg © Szent István – Creative Commons Attribution-ShareAlike 3.0 Unported License
Wales: Llyn Crafnant Forest In North Wales, the forest of Llyn Cratnant Erwlas / Flickr – Creative Common License (by-nc-sa 2.0)
Belouve Forest According to Wikipedia: The Bélouve forest is a forest on the island of La Réunion, a French overseas department in the Indian Ocean. It occupies a perched plateau located on the edge of the natural circus occupied by the municipality of Salazie, on the territory of which it is nevertheless located. It can only be reached by a cul-de-sac road that crosses the forest of Bébour coming from La Plaine-des-Palmistes or from the north by a steep hiking trail rising from the islet of Hell-Bourg. It is one of the forests of Reunion which produces the highland tamarind wood used in cabinetmaking. The Grande Mare in the Bélouve forest with the high tamarind woods and the rampart of the Plaine des Lianes forest in the background. Louis Volant / Flickr – Creative Common License (by-nc-sa 2.0)
A rainforest – Mexico City, Mexico A coniferous rainforest in Mexico State, Mexico © Wikipedia
Hoh Forest Hoh Forest in the Olympic Peninsula in Washington State © Goldom GNU Free Documentation License, Version 1.2
Sitka National Historic Park, Alaska Sitka National Historic Park, Alaska © Willow&Monk at Flickr Creative Commons Attribution 2.0 Generic license.
Scots pine forest Pinus sylvestris (Pino Silvestre) © Clément Godbarge GNU Free Documentation License, Version 1.2
Scots pine male inflorescences Scots pine male inflorescences © Beentree Creative Commons Attribution-ShareAlike 3.0 Unported license
Forest Netherlands Delabrata / Flickr – Creative Common License (by-nc-sa 2.0)
Forest in Spain Forest in autumn near Segovia Spain Cuellar / Flickr – Creative Common License (by-nc-sa 2.0)
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