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COUNTRYSIDE NEWS November 2014
We’re all faced by important life-changing decisions from time to time. Should I stay or should I go now? Will it be red sauce, brown sauce or no sauce at all? Should I take out the extended warranty? (No to the last one, obviously). At this time of year we’re also seeing the signs of an important decision made by our trees – whether or not to keep their leaves over the winter. Of course, it’s a bit daft to talk of trees “deciding” to keep their leaves or not. What’s actually going on is that each species has evolved to follow whichever ecological strategy works best for them. Those species that lose their leaves in autumn are known as deciduous trees, and they derive a number of benefits from this lifestyle. Shedding leaves reduces water loss and may also lessen damage from predators. Bare branches have less wind resistance and trap smaller amounts of snow and so can minimise storm damage over the winter months. On the down side, deciduous trees cannot photosynthesise without their leaves and so they have to effectively become dormant for several months of the year. The alternative to being deciduous is, of course, adopting an evergreen lifestyle. Evergreen plants do lose, and replace their leaves, they just do it gradually throughout the year rather than all in one go. This allows them to photosynthesise all year round and also means that they don’t have to expend lots of energy growing all their leaves at once. They do, however, have to maintain and replace their leaves constantly and may well suffer from relatively high levels of insect damage. So, it’s all swings and roundabouts really – there are benefits and drawbacks to both strategies. We generally think of broad-leaved trees being deciduous and conifers as evergreen, but there are exceptions to this. In many of our woodlands at the moment you might spot a conifer with yellow-brown leaves (or even no leaves at all) - this will almost certainly be a larch. This is the only deciduous European conifer, although it’s not strictly native to the UK – none of our native conifers shed their leaves in autumn. Larches can also be identified by their twigs. As the leaves fall, their woody shoots remain behind, giving the twigs a Autumnal larch characteristic knobbly appearance. Larch can be valuable to wildlife, the seeds providing food for squirrels, siskins and other birds. The young buds and cones are eaten by grouse and several species of moth caterpillars feed on the leaves. There are several species of broad-leaved evergreen trees, including oaks, acacias and maples; however there are few that are native to the UK. Holly is an obvious example and nicely topical as we plunge headlong towards Christmas. With its dark green, glossy leaves Holly holly is a familiar tree of woodlands and hedgerows. The leaves have a deserved reputation for spikiness, which acts as an effective deterrent against animals which might fancy eating them. However, take a good look at a mature holly tree and you may well find that the leaves towards the top of the tree are not at all spiked. This is probably due to the lack of tall herbivores in this part of the world, giraffes not being a common sight in East Lothian. Female holly trees will be bearing berries just now, which are an important source of food for many birds and are often closely guarded, especially by mistle thrushes. Birds also appreciate the dense, protective cover provided by hollies and small mammals may hibernate in the dense leaf litter below the trees. Incidentally, holly was one of the woods traditionally involved in the manufacture of bagpipes, although it is less commonly used nowadays.