Embracing Autumn: Nature’s Season of Transformation
By Science and Environment Editor Leah Moynihan
Vibrant shades of orange, yellow and red blanket the landscape as if an artist hand painted each tree overnight. A gust of wind blows the fragile skeletons of leaves to the ground. Nature is in preparation for the changes ahead. Autumn is a time of transformation, where the natural world is hectic with activity, and the landscape immerses us in a fairy-tale.
The autumnal equinox occurs when the days become shorter, and the dark nights sneak up on us earlier. In the northern hemisphere, autumn comes to life on 23 September and passes the baton onto winter on 21 December. However, autumn was not always seen as a season by itself; in most cultures there were only two seasons. The term “harvest” first appeared in the 14th century, yet the period between summer and winter has always been recognised as a time of change. Celebrations would echo through most farming communities as the crops were gathered at the end of the harvest season. These festivities were full of thanks through prayers to their god or gods to ensure a fruitful crop. Autumn is also celebrated as a time of rebirth through death. All Hallows Eve allows us to remember the connection with those lost to us as well as those left behind on this earth.
The tilt of the earth on its axis causes the life-sustaining cycle of the seasons. Winter is experienced by the hemisphere that is tilted away from the sun. The cold blows in and plants and animals sense the temperature drop. They begin their preparation for winter in an almost military fashion. Photosynthesis slows down as the trees get sleepier. Chlorophyll production in the leaves is turned off when certain weather conditions are experienced. This is a pigmented chemical that allows plants to retrieve sunlight to make energy. It is sensitive to the cold and other pigments such as carotenoids take over. This triggers the distinctive orange of autumn, and it is the same pigment found in carrots. After a few weeks, the leaves drift to the ground and create a warm blanket. They have been removed by the tree at a point called the abscission layer due to sensitivity to various hormones. It is not worth the energetic cost for the tree of keeping the leaves throughout the tough winter.
The trees say farewell to their once radiant leaves and prepare themselves for a long sleep. Animals do the same by stashing treasures that will get them through the winter. They put on significant amounts of weight as food consumption is increased. They enter a state of deep sleep called hibernation, where the animal’s metabolism slows down. This allows them to survive when food is scarce during the winter months. Their fur also undergoes a transformation. It changes colour and grows thicker, altering them to look like an almost entirely different species. They can then blend into their new winter environment and hide from hungry predators.
Some animals avoid the cold and migrate. They journey hundreds of miles on epic expeditions in search of warmer climates. For other species, autumn is a time to show off their strength. Male deer compete in ferocious fights for mating rights from September to November. The females’ young will open their eyes for the first time in spring when food is more secure. Salmon and sea trout also spawn in autumn after enduring the swim upstream during the summer to their birthplace. Curiously, grey seal pups enter the world in autumn after their parents spend the summer feasting on abundant fish stocks. Therefore, autumn is a time of renewal and creation.
Fungi also flourish in autumn as you may observe when you stroll through a woodland. Bizarre structures hang from the bark like miniature balconies, dazzling in colours that only nature could procure. Mushrooms fruit in autumn with warmer temperatures favouring a later fruiting date. Fungi blossom in warm and wet conditions, and they can add vibrant life to a dark woodland, when all the shrubs and trees have gone into dormancy.
Autumn is a hectic time for nature, but it tends to be a time of warmth and wonder for us. As the natural world around us changes, we can appreciate the shifting colours. We observe squirrels scurrying around and strong deer showing off their antlers proudly. Instead of dreading the winter, autumn allows us to enjoy the transition and look forward to what else nature has to offer.
