Autumn Seasons of Mists and Turquoise Sky
The first autumn shades of reds, oranges and browns, fall in the gentle changing month of September. Perhaps some sunny days, but now longer, cooler nights, then increasing wind and rain cause plant and animal communities to undergo profound changes in their lifestyles.
In early autumn, the sun though now in retreat, is still intense during the day, drawing moist air upwards from the land surface. However, the lengthening nights accompany a sharp drop in temperature, bathing the countryside in mist, heavy dew, and even frost on clear nights.
Autumn Woodland Watercolour Artwork by Alison Langridge
Towards October, deepening depressions far to the north of the British Isles can put a swift end to the gorgeous autumn days of an Indian summer. The winds they generate are typically vigorous northwesters which bring chilly blasts and windy rain. This turn for the worst has been associated with the autumn equinox when the sun's latitude decrees a few days and nights of equal length. It is often a foretaste of future storms in Scotland, where October sees the first flurries of snow on the hills.
Autumn Deer Watercolour Artwork by Alison Langridge
Throughout summer, the life support system of deciduous trees has been the green pigment chlorophyll which interacts with sunlight to provide the power source to manufacture all the tree's nutrients. With shorter days and the weakening sun, common trees can no longer sustain chlorophyll production, and the system begins to shut down. Yellow and red pigments replace the green pigments of chlorophyll. A sudden bout of chill weather after an Indian summer triggers hurried adjustments in this tree pigmentation when sap pressure is still high. Leaves start to appear gilded with gorgeous vivid colours.
The colours of autumn leaves are, however, mere staging posts in a more magical withdrawal. As ground temperatures drop, the root systems of trees find it harder to extract water. So the tree sheds its leaves to preserve the tree's dwindling resources. Each leaf stem is excluded from the tree by a particular cell layer that cuts it off from the life-giving sap. The autumn winds then hasten the removal of dead leaves.
The woodland floor is now awash with colours of discarded leaves. Autumn fungi seem to emerge overnight, drawing sustenance from the decaying litter around them. The type of litter or soil may explain an otherwise unpredictable and erratic distribution of fungi.
For example, the scarlet fly agaric flecked with creamy scales flourishes in conifer woods and many exotic fungus forms. The strange earthstars spring up in beechwoods, while the giant puffball appears in field hedgerows or sometimes in gardens. In general, a hot summer followed by a moist autumn seems to produce the best fungi forms.
A blanket of leaf litter helps protect the roots of trees and a host of cold-blooded animals that, like deciduous trees, can no longer maintain the metabolic turnover needed for full activity. In October, many invertebrates such as snails and insects creep into crevices. Under stones or bark, beneath fence posts become a refuge where these creatures can hibernate safely in a state of inertia. The hollow withered stems of hogweed make a perfect overwintering chamber for earwigs, for example, and a cosy cushion of moss is an inviting haven for ladybirds.
Amphibians and reptiles may also hibernate together, especially in northern areas. Sometimes they are united in their shared attraction to a traditional good overwintering site, but possibly they also benefit from a little collective body warmth with other creatures. It makes sense that community living among snakes during winter means finding a mate more quickly when they emerge in spring.
Toads may overwinter with lizards and both in turn with snakes. Snakes also hibernate at the end of September but may remain active for up to a month afterwards if it is warm enough for them to do so. They need to save their body fat to sustain them through five months of winter.
If the weather is mild, many plants, such as daisies, herb robert and even poppies, continue to flower late into November. The coastline supports some particularly stunning late flowers in sea rocket and the sea holly whose colours seem to echo to perfection the soft blue-green mist of the autumn seascape.
Herb Robert
Some plants which flowered profusely in spring, such as the sweet violet and the wood sorrel, are now quietly engaged in the second wave of self-propagation. Only close inspection of the plant's foliage will reveal these curious autumn flowers, which, having no petals, no nectar and almost no pollen, exude no scent to attract insects. These flowers are self-fertilising. They can still provide seed if they later bloom in a cold, wet spring when no insects have emerged.
Other autumn flowers such as dead nettles, vetches and peas produce seeds just as well as their spring counterparts and provide an ingenious addition to the plant strategy for survival.
Bees are now deprived of summer's rich nectar and pollen; ivy flowers offer a late bonanza. In October and November, ivy's modest flowers produce a heavy nectar flow while its pollen is highly accessible to insects with short tongues, such as the numerous flies and wasps.
On a sunny day, ivy attracts many flying insects, including the red admiral, comma, and painted lady butterfly. They have an invaluable opportunity to stock up on their energy reserves before laying a batch of overwintering eggs or before hibernation.
The fruit of brambles, although rotting, likewise serves as a last-ditch fuelling station where they are tapped for their sugary secretions.
Many insects, however, do not escape from the autumn cold. The house spider tegenaria feast and grow large on the corpses of dying insects. Outside amongst the glorious colours of autumn, there is a riot of spiderwebs. There are the hammock webs of the money spider Linyphia. Their webs course over brambles, gorse and grassy fields, enabling them to trap many insects. Sometimes these webs on mass float atop rising air alighting on bushes many miles away. The spiders frequently pilot their webs on these journeys.
As the insect population declines, birds and small mammals switch to eating the profusion of fruits, berries and seeds. Acorns, hazelnuts, sweet chestnuts and other nutritious seeds are littered everywhere on the woodland floor to be hoarded by mice voles and squirrels for winter consumption. Even badgers will eat nuts, berries, apples, plums and even edible fungus. A fox will eat all that it can find.
Birds and mammals are valuable agents for seed dispersal. Many shrubs such as spindle, holly and yew proclaim their ripe seeds by lurid red colours and offer a sweet, palatable fleshy coat as a reward. Mistletoe berries glisten on eye-catching white against their evergreen foliage and are especially valued by thrush birds.
Jays birds fly high over oakwoods with their crops gorged with acorns. They will cache this bounty in the ground against leaner times in winter. Inevitably these buried acorns are forgotten or are scattered by plundering animals to the great benefit of the parent oak. Jays play an especially intriguing role in the spread of oak woods uphill since the trees have no other means of sending their bulky seeds upwards.
Bramblings migrate to escape the grip of their native Scandinavian winter when there is a good beach mast. Many other birds adopt the same strategy resulting in a vast influx of autumn migrants. Typical of foggy October nights is the thin plaintiff seep of red wings, which along with fieldfares, navigate across the North Sea to join our thrushes in exploiting the berry harvest.
Tens of thousands of pink-footed geese journey from Iceland, flying noisily into Scottish stubble and pasture. At least we can distinguish these as foreign visitors, but it becomes impossible to establish nationality for others. Estuaries throng with redshank, and other waders from polar regions mingle freely with British representatives of the same species.
Many British blackbirds and song thrushes leave in autumn for the relative luxury of southern Europe while others of their kind arrive from abroad. By mid-November, our plant and animal communities have therefore made other far-reaching adjustments for their well-being and survival and now brace themselves for winter.