Tuesday 15 January 2013, 18:15
Can I introduce Kay Haw, Conservation Adviser at the Woodland Trust with an insight into our woodlands in winter.
A dormant silence cloaks the trees in winter, by shutting themselves down they endure the harshest elements. Short days and cold weather stop them growing their beautiful foliage. For frost would freeze the water within their leaves, causing sharp ice crystals to pierce and damage the delicate cell walls inside.
Though the trees themselves may slumber they continue to support life, offering shelter and food for many woodland creatures. Noctule bats love to hibernate in tree hollows and woodpecker holes make very desirable roosts. Their favourite foods are large moths that sometimes still fly in winter. On warmer days the bats may rouse and set out to hunt.
Great spotted woodpeckers drum on trees to define territories, and the distinctive sound carries further in winter without tree canopies as buffers. Deadwood is especially attractive for them as they peck out wood-boring insect larvae and glean spiders from cracks in bark.
To call any wood ‘dead’ is rather misleading because, standing or fallen, so-called deadwood is teeming with life. Wood decay fungi send out their mycelial networks, breaking down tough cellulose that few others can exploit. Deep inside rotting wood the grub-like larvae of magnificent stag beetles spend of the most years of their lives. The transformation to beetle comes only when they need to mate, and they die soon after.
Detritus fills tree rot holes and crevices, providing homes for centipedes and woodlice. These then offer a delicious meal for nuthatches and tree creepers that dart up and down the trunks. Some butterflies and moths lay their tiny intricate eggs on trees to overwinter until spring; purple hairstreak eggs can be found at the base of oak buds. Others survive the winter as larvae and some as hibernating adults.
On the forest floor fungi and bacteria work hard to decompose leaves shed in autumn, recycling nutrients back into the soil. The warm leaf litter provides an excellent refuge from the winter cold for spiders, millipedes, woodlice and larvae. Ladybirds find it a perfect place to hibernate.
Tiny springtails (1-2mm) are some of the myriad species that feed on decaying leaves. If disturbed, they spring uncontrollably into the air to escape. Amazingly, a single bound can cover a distance around 100 times their own body length.
This gathering of insects entices hungry birds to forage for prey. Blackbirds can often be seen flicking dead leaves about and rustling around the undergrowth searching for tasty morsels. Whereas high up in the branches rooks are found tending to their nests, gathering together in rookeries. This is a prime time for some DIY before the nesting season.
Hungry tawny owls are on the wing at night searching for unfortunate small mammals and birds. Favouring mature trees, the male hoots and the female screeches echo eerily through the woods. The common shrew is a favourite owl food, as they themselves are nocturnal hunters. With such tiny bodies and high metabolisms these little rodents cannot hibernate during winter like some mammals.
The roots of trees and their fallen leaves offer prime hedgehog and dormouse hibernation spots. This sleep state drastically lowers their metabolism, temperature, heart rate and breathing. Living off their fat stores, they conserve energy and survive cold winter months that offer little food. As the weather warms they awaken ravenous, searching for any bounties on offer.
Piles of leaves also attract hibernating frogs and toads that nestle deep within them. But even as early as January they can be seen heading toward their breeding ponds. Brumation is the reptile form of hibernation, but rather than truly sleeping they slow down right and eat rarely. Hidden in piles of logs or rocks, or under leaves or roots, snakes and lizards can go all winter without food.
Ferns, mosses and lichens still decorate trees and woodland, bringing welcoming flashes of green. The hart’s tongue fern with its long slender leaves is a pleasing sight. Lichens adorn bark and rocks with their many forms; some crusty, some leafy and others like unruly beards.
The UK does have a few native evergreens, and the berries of holly are an important source of winter food for many birds and small mammals. Yew trees keep their needles to give wildlife shelter from the freezing winds and pounding rain. In Scotland, the Scot’s pines of the ancient Caledonian forest retain their greenery too.
Although many think of ivy as a tree killer, it can be a fantastic wildlife resource. In winter it keeps its leaves, offering hiding places from the elements. It flowers in autumn providing a late pollen source, while its berries supply early sustenance in spring. Ivy uses trees to support its growth but is not a parasite. In woodland settings it is seldom a problem for healthy trees.
Few plants grow in winter, but in January elegant snowdrops push through the cold soil and dead leaves to herald a new year of life in the woods. These and other early flowers offer insects important pollen and nectar supplies. Fertilised queen bumblebees spend winter under the soil. Emerging as temperatures rise they busy themselves making a nest for this year’s brood.
At all stages of development trees are filled with life. The older they become the more creatures’ call them home. It is vital we cherish and protect them all because one ancient tree can be a habitat to more species than a hundred young ones. Regardless of age or season, trees and woods provide the world with so much wonder to be thankful for.
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Tuesday 15 January 2013, 15:40
Wednesday 16 January 2013, 10:26