Forests are paying a heavy price in the face of climate change. International Forest Day (March 21st) is an opportunity to sound the alarm. In Belgium, repeated droughts and heat waves have weakened ecosystems in local forests, which are particularly affected by insects like bark beetles. The bark beetles attack the trees that are established, explains Pierre Peltzer, a silviculturist. So we cut down the trees attacked by bark beetles and that created clearings. And this winter we had, until the end of last week, quite significant storm winds which knocked down the spruces which were at the edge of the clearing. Climate change is also interfering with the natural cycle. Leaves and flowers appear earlier in the season and always fall later in the autumn. This phenomenon then disrupts the entire ecosystem. Vegetation is at the base of the food chain and we notice that certain species know how to adapt - like caterpillars which hatch earlier since their food, the leaves, arrive earlier, says Corentin Rousseau from WWF Belgium. But some species such as migratory birds arrive too late, the peak of caterpillars is already reached. And they have less food to feed their young. So we have seen their population decline for a few decades unfortunately. One of the answers to save forests is to plant new species from warmer climates. The Arboretum project aims to find species of tree in other climates, warmer and drier, with the idea of ??testing the performances of these trees in terms of resistance to drought, in terms of resistance to pathogens and insects that are with us, and in terms of growth, explains Nicolas Dassonville from the Royal Belgian Forest Society. Globally, forests are home to 80 per cent of terrestrial biodiversity. They also store carbon and filter rainwater.