Desertification threatens the Amazonian carbon well is the conclusion of the study published in the March edition of Science. Look back on a survey in which the Nancy INRA played an active role. Can the Amazon forest suffer from desertification? That was the question that the study coordinated by Olivier Phillips of the University of Leeds asked. He published his results in the March 2009 issue of Science magazine. The British researcher relied on the international surveillance network of the Amazonian forests (Rainfor) in which the INRA participates. The researchers collected data from the forest's aerial biomass before and after 2005, the year of the great desertification, in order to measure the forest's behavior. Head of research on the rainforest's adaptation to climate changes at the Mixed Research Unit Forestry Ecology and Eco-physiology Department (UMR EEF), Damien Bonnal played an active role. The ecophysiologist was in French Guiana where he spent 13 years prior to returning to the Lorraine region last October. The relationships between Champenoux and Kourou date back to the 1990s and have always been very tight. Both centers are interested in tree regeneration, their tolerance to desertification and their mortality rate. Logically, they participated in the study headed by Olivier Phillips. "One of the interests of the study, underlines Damien Bonal, is to have undertaken a synthesis of all the data collected from all the parcels studied from Brazil to Ecuador including French Guiana." That is a hundred-odd forest sites spread over 600 million hectares of the Amazon. The growth data, some of which have been noted over 50 years, concern more than 100,000 trees. The study of young shoots and mortality also enable the calculation of aerial biomass that was done by adding growth and regeneration and subtracting the mortality. "We remarked two things: before 2005, this biomass is positive, the forest stores carbon. After 2005, for the majority of sites, the biomass diminishes. This result is explained by a higher mortality." Suddenly, the Amazon forest sequesters less CO2. If the Amazon were to undergo several desertifications, notably provoked by profound climate change, the carbon well would be threatened. Given the area of this forest, the slightest modification would impact the entire planet. Research undertaken by the Nancy INRA today aims at identifying the trees most sensitive to desertification and discovering how different species behave among each other : "In the event of a desertification, is a tree with the longest roots beneficial to those with short roots or, on the contrary, do they compete ?" The forests of the Lorraine region are also present to answer the question. © photo JM-G - Fotolia.com

EEF: Forest Ecology and Ecophysiology The "Forest Ecology and Ecophysiology" Mixed Research Unit has the mission of studying the physical and biological bases of interactions between the factors of the environment and the functioning of trees and forest ecosystems.

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