August Nature Notes
The woodlands of the British Isles have had a strange and interesting history. The Younger Dryas ice age lasted for about 1300 years during the late Pleistocene from about 12,800 to 11,500 years ago. During this ice age, a vast ice sheet covered Britain down as far as about the Thames Valley. South of that, it was still too cold to support the lush forests we see now. The habitat was probably tundra as experienced now on places like Svalbard where just a few dwarf willows grow in the summer when the ice melts. By about 10,000 years ago, Britain was experiencing temperatures slightly warmer than now.
As ice retreated, the forests of Europe spread into the land we now call Britain. This process took hundreds of years and was probably begun by various willows, Hairy and Pendulous Birches, Juniper and Scots Pines. Our two native oaks were probably introduced by the Eurasian Jay. Often also called the Oak Jay, this bird obsessively collects acorns in the autumn and carries them to open areas and buries them in the ground. Many of these acorns are forgotten about by the birds and they germinate to form new oak trees. It is thought that by doing this, oak trees spread through northern Europe at a rate of about one kilometre per year. Once everything had moved in, the English Channel formed.
Woodlands develop by a process called succession. From bare ground the first plants to grow may be mosses and grasses, then broad leaved herbs such as daisies, dandelions and thistles. Then small shrubs arrive, like hawthorn, Hazel and field maple followed by birches, willows if it is damp and then high forest trees such as Scots Pines, Pedunculate and Sessile
Oaks, Sycamores, Ash, Hornbeam and Elm. This process can take 50 years or more, and the woodland will not be properly mature until it is at least 100 years old. Indeed, we cannot refer to woodland as truly ancient until it is about 400 years old. By that time it has built up a huge biodiversity of dozens of species of ground flora like Bluebells, Wood Anemones, Wood Sage, Wood Sorrel, Bramble and ferns such as Bracken and Broad Buckler Fern. Also, the wood becomes full of hundreds of species of fungi, bacteria and animals such as Spring-tails, Woodlice, Wasps, Moths, and other insects. Then spiders, frogs, snakes, bats, birds, Wood Mice, Dormice, Weasels, Hedgehogs, Foxes and Badgers arrive. Finally, maybe, in come Deer and Wild Boar.