As light levels reduce and temperatures drop, deciduous trees produce less chlorophyll, which turns green leaves into an array of browns, reds and golds. Trees enter a state of dormancy in order to reduce water loss when climatic conditions restrict water availability, e.g. when the ground is frozen.
Autumn is the season when fungi are most visible in our woodlands. Fungi produce their fruiting bodies in response to rainfall and temperature changes. Species such as the fly agaric (Amanita muscaria), found on birch and pine trees, have symbiotic associations with particular tree species. If you are going to forage for edible fungi in the woods, make sure you are careful to avoid any poisonous species that resemble edible ones.
Many woodland mammals use the autumn's 'natural harvest' to fatten up in order to survive the winter. This is crucial for those that hibernate over the winter. If they don't store enough body fat they will use up all their energy and starve to death. All species of British bat, the dormouse and hedgehog, amongst others, hibernate. If possible, postpone the flailing of hedgerows until the winter, so berries are available as a food source for the remainder of the autumn.
Foresters start to prepare for the winter, the busiest time in the woods. It is the optimum time for both felling and planting operations. When deciduous trees become dormant, no food and water are taken up through the trunk and hence 'the sap stops rising', which makes for more suitable felling conditions. Watch out for any protected species hibernating in the woods. The hibernation roosts of bats are legally protected, so suitable trees need to be assessed before any work goes ahead.
Planting of new tree seedlings can begin after bare-rooted stock have reached dormancy and been 'lifted' from the nursery beds. Dormancy is crucial since it prevents water loss from the seedlings when they are uprooted. The bare-rooted tree planting season runs from late November to late March.