More Autumn

The End of Autumn - 14 December 2016
The colours are autumnal, the bare trees wintry.

There are at least three common definitions of autumn. The first, and the one I grew up with, is the astronomical definition of autumn as lasting from the autumn equinox (September 21) to the winter solstice (December 21). The second, meteorological definition, defines autumn as lasting from September 1 to November 30. The third simply asserts that autumn is the period between summer and winter.

I like this third definition, because it is fuzzy, and natural systems have fuzzy boundaries. I think of autumn as the time when trees lose their leaves; plants die back; and fruit and seeds ripen and are harvested. It is the period between the lush greens of summer decorated with colourful flowers and the drab browns of bare earth and branches of winter. A period of transition without any limiting dates.

Late Fall - 22 December 2016
A single green leaf recently fallen from a hazel bush
contrasts the the dark browns and blacks of the rotting leaves around.

December, when most of the photographs in this post were taken, is clearly at the end of autumn, if not actually in winter, by any of these definitions. It also contains one of the turning points of the year: the winter solstice, after which, the days will grow longer, and eventually start to warm up. 

In the countryside, while there is still much evidence of autumn, the scenery is increasingly taking on the drab and bare appearance of winter; not withstanding the occasional glimpse of spring.

A Touch of Spring - 11 December 2016
Bright hazel catkins, with alder catkins behind, bring a feeling of spring to the park.

Certainly, in December 2016, there still much of the feel of autumn in Milton Country Park, but at the same time winter is beginning to appear. The reeds around the pits in are an autumnal golden brown, and there are still a few leaves left on the trees, whose mainly bare branches speak of winter. The thick carpet of dead leaves on the ground have turned from yellow to a deep rich brown darkening into black as decomposition gathers pace. In contrast, emerging hazel catkins bring a real spring-like feel to the park, especially when they sparkle in the early morning sun.

Goose Summer

Goose Summer - 1 December 2016
Fallen leaves floating on still blue water on a clear bright 'Goose Summer' day 

'Goose summer ' is an old term for spells of fine weather during autumn; the name referencing the custom of eating geese during the autumn after they had been fattened in the previous months. It was during one such spell, that I came across this mass of leaves floating on calm water. A scene that, for me, sums up such weather and that 'Goose Summer' seems the perfect title. 

'Goose summer' later was contracted to 'gossamer', and eventually lost its connection to the weather, and, instead, used to refer to dew covered spider's webs which are visible on clear, cold, autumn days.  But, the loss of goose summer, like its opposite 'sprat weather' (dark, damp, miserable, late autumn days when it barely gets light), leaves the English language the poorer.

Drowned Leaves - 22 December 2016
Fallen leaves decorate the roots and concrete rubble at the bottom of the lake

As the season progresses, the floating leaves become saturated and fall to the bottom of the water where they can still be seen decorating the rubble and roots.

Brambles

Colourful Brambles - 18 November 2016
Not necessarily noted for their contribution to autumn colours
this bank of brambles presents a colourful sight

One plant that does not immediately spring to mind when autumn colours are mentioned is the humble bramble. Yet, although, not all bushes change colour, those that do can be quite spectacular, with individual leaves turning a brilliant red that is as bright as anything that more renowned trees, such as maple, can offer.

Bramble Leaves - 11 December 2016
Some bramble leaves turn a vibrant and intense red in autumn

Happy Christmas

This is my last post of 2016, so thank you for taking the time to read this blog, and hope you will continue to do so in 2017.  Merry Christmas and a happy New Year. 

Next: Last Fruit, First Shoots  

Autumn Leaves 2016

Poplar Leaves - 2 November 2016
When on the tree, the yellow and red leaves would have been admired;
on the ground, the range of colours is actually increased.

We all admire the brilliantly coloured leaves of autumn while they are still on the tree. But when they fall off the tree, onto the ground, our attitude changes; their beauty is forgotten and we see them only as a nuisance. They make our streets and gardens untidy; they block the drains; and, they form a slippery layer on the railway lines, stopping the trains running to time. All that is left is to collect them up, and either burn them or put them in the rubbish; except for gardeners, who use the dead leaves for compost.

Contrasting Leaves - 8 November 2016
The maple leaf contrasts strongly with the surrounding oak leaves
in colour, shape and texture.

But there is still plenty of visual interest in the leaves as they rot away on the ground.  While the vibrant colours remain for a few days at least after the leaves have fallen, the range of colours is increased, not only by browns, dark purples, and blacks of the decomposing leaves, but also by different coloured leaves from adjacent trees.  Similarly, there are strong contrasts in shape and texture when a leaf from one tree falls on the leaves from a different type of tree.

Why Leaves Turn Red and Yellow

Fallen Leaves - 8 November 2016
Most of the colour of dead leaves derives from the breakdown of chlorophyll
unmasking yellow and orange pigments already present.

The process by which a living green leaf, producing sugar and oxygen from sunlight and air, turns bright red or yellow, and eventually falls to earth and rots away, starts when the length of the night exceeds a certain value. The tree then builds a barrier between the leaf and the rest of the tree, cutting the leaf off from nutrients absorbed through the roots, and tree from the sugar created in the leaf. As a result the green chlorophyll pigment decays, and exposes the yellow and orange colours of the xanthophylls and carotenoids normally present in the leaf. 
 

Maple Leaves - 8 November 2016
Red pigmentation develops after the leaf is already dying.
What is the advantage to the tree?

Interestingly, the red colours come from a third group of pigments, the anthocyanins, which are only synthesised when the leaf is dying. It is not entirely clear what the advantage to the tree is to have red leaves in autumn. Theories include: to warn off aphids which might want to use the tree as an overwinter host; to undermine the camouflage of herbivores; or, to attract birds to the tree to eat berries which may otherwise be overlooked. The anthocyanins in maple leaves have been shown to stunt the growth of any nearby saplings.

The Weather For It

The best display of autumn colour is produced when a moist growing season is followed by a dry autumn with sunny days and cool, but not frosty nights. Heavy rain, gales and frost are all likely to bring a premature end to the display.

Folklore, Legend and Medicine

Oak Leaves - 8 November 2016
With a mass of leaves like this, it is easy to see why the Lakota believed
they had been dropped as a protective blanket.

Fallen leaves, though such a prominent feature of the countryside in their season, do not feature greatly in folklore. They have been associated with fairies, with a swirl of leaves believed to be evidence of fairies dancing. Catching a falling leaf, particularly at the beginning of autumn, is said to protect the catcher from illness, or, more specifically, colds, throughout the winter.

But, perhaps, the most charming legend is that of the Lakota American Indians. The god who looks after living creatures saw the suffering of the plants and flowers as they shivered in the increasing cold of Autumn. Feeling sorry for them, the deity ordained that the trees should shed their leaves over the earth as a blanket to keep the plants warm. In return, the trees were allowed one great last blaze of glory.

I could find no reference to any medicinal use of fallen leaves.  However,  a Finnish company is developing the technology to extract natural pigments from the leaves for use in the clothing and cosmetic industries. The residual biomass is high in nutrients with possible uses as a fertiliser.

Next: More Autumn