Nature’s eternal cycle in rural Ireland

A SONG by the Clare minstrel, PJ Murrihy, about an old threshing mill brought back memories of days growing up in rural Ireland when the whine of a threshing machine echoed around the countryside. In those times, grain was harvested much later than now.

Last week, we had some lovely days, just like what we expect around now. It was a joy to be out observing the changing season. Autumn heralds striking changes in our plants and trees. Lush green leaves of summer slowly, but ever so perceptibly, turn into various shades of gold, yellow, red, orange and brown, before eventually falling off the trees.

This is a good time for visiting forests and parks, with the oak and yew woods, some hundreds of years of old, in Killarney National Park, being a personal favourite. A lot of deer, both red and sika, are also visible in Killarney these days. In a few weeks, the deer mating (rutting) season will begin, but more about that anon.

While the leaves of trees such as oak, ash and sycamore fade and die before new life springs forth in the coming year, the leaves on evergreen trees, such as pines and firs, survive the winter as their needle shape and waxy coating makes them more resistant to dry conditions and freezing temperatures.

Changes in day length, falling temperatures and lower sunlight trigger a decline in plant growth regulators and leaf tissue starts to die. When a band of dead cells has formed at the base of the leaf stalk, the leaf detaches from the twig and, aided by the wind, is carried off, according to Department of Environment experts.

Chlorophyll, the pigment that dyes leaves green, is abundant in the growing season, masking all other leaf pigments. However, when shorter, colder autumn days start the process of leaf-breakdown, chlorophyll is one of the first compounds to break down and other pigments such as those that cause red and bronze hues begin to show. These autumn-toned pigments accumulate in leaves and build up as the leaf ages.

After flowers are fertilised, the female reproductive organs often develop into fruits or nuts. In autumn, these appear in abundance on many trees and shrubs. Berries, fruits, nuts and cones contain the seeds of a plant and are, therefore, crucial for the cycle of life. They are also an important food for animals and birds over the winter months.

Birds play an important role in seed dispersal: some seeds cannot germinate unless they have been through a digestive tract. The seed is worn down in a bird’s digestive tract and then deposited in faeces. The nutrients in the faeces help the seed to grow. And so nature’s cycle goes on.