Can attempts to adapt to global warming do worse rather than better? A scientific study, carried out by several French laboratories involving the National Center for Scientific Research (CNRS) and published in the journal Oikoswarns about assisted migration strategies of tree species from warmer and drier regions, implemented in European forests.
Five researchers believe that this planting of native species in higher latitudes (that is to say further north) “risks, in the long term, favoring a runaway climate”, we learned from the Ecology laboratory. and dynamics of anthropized systems, at the University of Picardie Jules-Verne, in Amiens.
A helping hand to nature
For several years, forest managers have been concerned about global warming and the adaptation of tree and shrub species. “Especially since the dispersal capacity of trees does not allow them to migrate as quickly as they should to follow a much more rapid warming of temperatures,” explains Jonathan Lenoir, one of the researchers at the National Center for Scientific Research ( CNRS), which participated in the study.
The temptation is therefore great to import and plant, now, species more adapted to the new climate to come. But this boost to nature could have poorly controlled consequences. “We are not saying that assisted migration should be prohibited, but we suggest respecting the original resources of the forests,” says Jonathan Lenoir. The idea is to develop genetic diversity within the same species. »
A change in the forest canopy
Because the problem is the physiological characteristics of the southern species selected for this migration of different species. “If they are more resistant to drought, these species from warmer regions have smaller and sometimes persistent leaves which drastically change the composition of the forest canopy,” explains the University of Picardy, in a press release.
And cause a butterfly effect. “This change in canopy, composed of smaller leaves that transpire a lower quantity of water, could degrade the microclimate of the undergrowth and increase the risk of fire if the transplanted species have a high degree of flammability, as c This is the case of maritime pine,” the press release continues. “The leaves are a crossing point in the water cycle and the change of species modifies the circulation of water,” adds Jonathan Lenoir who studied, with his colleagues, the physiological traits of 106 European and northern species. American.