I鈥檓 puzzled by beech trees. They are deciduous and their leaves turn bronze in the autumn, but they don鈥檛 fall off the tree. Instead, they hang on until spring when other plants are putting out their new leaves. How do these trees benefit from this different approach to deciduousness?
鈥� This approach does benefit a beech鈥檚 ecosystem. Leaf litter is a resource to the forest and any leaves shed by beech trees in spring will extend the litter period until autumn when the other species, usually maples, drop their leaves. One noticeable beneficiary is beechdrops, a flowering plant devoid of chlorophyll that is a symbiont of beech. It blooms in late summer.
In winter, the retained beech leaves are noticeable and act as flags to alert deer and turkeys to the presence of beechnuts. After ingesting the nuts, these animals distribute surviving seeds in their faeces. Also, predators, such as foxes, coyotes and weasels recognise beech groves as harbours for their rodent prey.
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Interactions between multiple species create and maintain vibrant ecosystems. Member species must benefit their ecosystems, or they may not have a place in which to survive.
Donald Windsor, Norwich, New York, US
One reader disputes the claim 鈥� Ed
鈥� Brought up in a beech wood, I dispute the assertion that the trees retain their leaves over winter. Mature trees do not 鈥� this is a characteristic of young beech saplings, most noticeable in hedges. Flexing saplings, unlike stiff trees, are not likely to be uprooted by gales, nor shattered by heavy sticky snowfall, so retaining leaves is less dangerous.
I have seen similar, if less noticeable, retention in seedlings of other trees, such as cherry-plum 鈥� although in this instance, photosynthesis may continue into winter. I fancy oak seedlings may also retain brown leaves, if to a lesser degree than beech.
鈥淧redators, such as foxes, coyotes and weasels recognise beech groves as harbours for rodent prey鈥�
Peter Urben, Kenilworth, Warwickshire, UK
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