Forests around the world are affected by man-made climate change, suggesting that degradation of woods cannot be ruled out for the future, a new study has revealed.
Taking a risk perspective, a team of scientists of the Potsdam Institute for Climate Impact Research (PIK) caution that global warming puts additional pressure on some of the most valuable ecosystems on Earth.
Lead-author Christopher Reyer said that forests are probably more at risk than previously thought and the observed changes affect forests as important as the Amazon, but also forests on all continents, possibly pushing some of them towards tipping points.
Reyer added that it is scary how little they still know about the resilience of forests, despite all the scientific progress we present in this special issue and from a risk perspective, climate change puts additional pressure on an exceptionally valuable ecosystem whose stability up to now cannot be properly assessed.
Researcher Milena Holmgren of the University of Wageningen said that some tropical forests, such as the Amazon, are also key for regional water cycles, adding that how dense these forests are, affects the amount of rainfall that is recycled and also the amount of water that is retained. When forests become less dense, a smaller amount of water is recycled as rain and also less water is retained in the soil and the growth of grass which burns easily in dry seasons is facilitated.
Holmgren continued that fire can change the rules of the game drastically because grass burns easily and recovers fast whereas trees are very sensitive and need more time. So once a forest has been opened and starts burning, the end result can be a system that resembles a savanna with much grass and fewer trees. This changes the habitat for plants, animals and people.
Holmgren added that the fate of forests is important also because they store huge amounts of the greenhouse gas CO2 and loosing forests and releasing carbon to the atmosphere contributes to climate warming and to the impacts we start to see in many regions of the world.
The study will be published in the Journal of Ecology.