Beech trees go all out on seed more and more often, at a cost to their growth
Forest floors are covered in beechnuts, and Ghent University forest ecologist Kris Verheyen says such bumper years are becoming far more common because of climate change.
Anyone walking through a Flemish forest this autumn treads on a carpet of beechnuts. Beech trees are having a so-called mast year, in which they produce far more seed than usual, De Standaard and VRT NWS report. Last year it was the oak's turn. For beech, it is mainly the previous year's summer that determines whether a mast year follows, forest ecologist Kris Verheyen (Ghent University) told VRT NWS.
Mast years used to occur roughly every five to six years; since the start of this century, beech has had one every two to three years. Verheyen sees climate change as the very likely cause, backed by long data series from Britain, Belgium and the Netherlands. In the Netherlands, Nature Today, working with Wageningen University researchers, reports beechnuts on the Veluwe for the fourteenth year in a row, although some nuts are empty after the hot, dry summer.
That is not good news for the tree. Producing so much seed exhausts the beech, especially in a year when drought already made it shed leaves early. The survival strategy also works less well: when abundance becomes the norm, populations of mice, squirrels and wild boar grow along with it and eat more of the seed. In Britain, more frequent mast years have already been linked to slower tree growth, according to VRT NWS.