It is sometimes good to search databases. While going about things as well an international team calls into question an idée reçue on the ancient forests. While they thought that they cease sequestrating some carbon, playing neutrality in exchanges of carbon dioxide with the atmosphere, the ancient forests of temperate zones and boreal continue stocking some carbon in the course of time. Details are given on Thursday in the Natural magazine.

Eight researchers of six countries (Belgium, the United States, Germany, Switzerland, France and Scotland) studied available data on 519 fifteen - eight hundred-year-old forests. They eliminated rainforests, for lack of available information. They note that if an ancient given forest can, unusually, be a source of carbon dioxide, the huge majority remain the pomps with carbon and contribute to contain the increase in the atmospheric content of carbon dioxide. These ancient tempered and boreal forests, which represent 15 % worldwide forested covers, stock every year 10 % carbons pumped by the vegetation of the planet.

More surprising, while the young forests are considered to be true wells of carbon (1), the researchers think that they can often play the inverse role. For them, the creation of new forests often happens after an important disturbance of the soil which stimulates the decomposition of vegetation and liberates more carbon dioxide than trees pump it.

While to conclude these jobs, if they are confirmed? Undoubtedly not that the forest is the ultimate weapon to struggle against climatic warming. On the contrary, as most ancient forest is not protected by international treaties, any intrusion of the man, by papermaking industry for example, would risk transforming them into source of carbon, and therefore aggravating greenhouse effect. Without counting effects on biodiversity.

(1) Some car manufacturers do not hesitate to plant forests to point out then to their clients that their vehicle will be neutral for greenhouse effect.

Picture: © Denis Delbecq