Kathriona Devereux: The science behind glorious autumn hues

Kathriona Devereux is actively looking for ways to divert negative feelings and is finding consolation in Nature.
Kathriona Devereux: The science behind glorious autumn hues

CHANGING LANDSCAPE: An autumn scene in Fitzgerald Park in The Mardyke, Cork

THE words ‘senescence’ and ‘pronk’ are two new additions to my vocabulary.

You’d think in my advanced state of adulthood, and with my supposed knowledge of science-related matters, that I’d know the word for the autumnal turning of the leaves, but nope, not until recently. Senescence was a new one on me.

But everywhere I walk at the moment the word is coming to my lips. Autumn is in full swing and I am finding great pleasure (and distraction) in the small rituals of conker collecting and leaf gathering.

My children are stomping through crispy leaf piles belting out renditions of “Autumn leaves are falling down” to the tune of “London Bridge is burning down”. Nature tables in classrooms around the country are heaving with crackling red and golden leaves, pine cones and horse chestnuts.

Autumn is usually my favourite season. It’s the start of a new academic year and all the possibility and promise that brings, but this year autumn just feels like an appetiser to a long, nerve-wrecking winter. I’m actively looking for ways to divert this negative feeling and I’m finding consolation in Nature.

There is a London plane tree at the Lough which is slowly shedding its leaves into a glorious golden deposit. Each morning a greater pool of yellow leaves has gathered at its base. I’m finding its beautiful unravelling quite therapeutic!

After the school run, a lap of the Lough and an appreciation of this golden wonder is helping me drop my shoulders, unfurrow my forehead and inhale deeply before a day of talking to people in my computer. It’s a dose of optimism. Possibly also assisted by a coffee from the nearby The Lough Café.

(As an aside, kudos to Cork City Council for the installation of the ‘Birds of the Lough’ ‘Fish of the Lough’ and ‘Trees of the Lough’ display boards in recent months. I’d been misidentifying London plane trees as maple trees for years before these information boards cured my ignorance!)

There is a complex chemical process happening when the leaves of deciduous trees turn and fall. Some of this is primary school science so forgive me if I’m stating the obvious, but some of us might like a refresher!

Leaves get their green colour from a chemical called chlorophyll, which helps the tree take in sunlight and through the process of photosynthesis convert carbon dioxide and water into energy/glucose and oxygen.

Once the availability of sunlight begins to diminish as the days get shorter, the tree starts a process of separating the leaves from the tree and cutting off the supply of chlorophyll.

When the chlorophyll starts to fade, the other pigments in the leaves get their opportunity to shine. Carotenoids are responsible for orange and yellow pigments and are present in leaves throughout the year but are hidden by the greenness of chlorophyll.

Anthocyanins create shades of red and purple and are formed by the interaction of the remaining chlorophyll and glucose in the leaves.

Environmental conditions influence these chemicals, which is why each autumn season is different, and why Ireland generally doesn’t experience the vivid red palette of autumn colours associated with other parts of the world.

Sunny days and cool nights after a dry summer are the perfect recipe for making lots of anthocyanins. Those are not typical Irish weather conditions and are more likely to be found in places like New England in the U.S where “leaf-peepers” travel great distances to bear witness to Mother Nature’s beautiful Fall displays.

On a recent shoot for the upcoming series of RTÉ’s 10 Things To Know About, I interviewed UCC’s Prof Astrid Wingler, who not only introduced me to the word ‘senescence’ but also to how modern technology is being used to monitor the timing of seasonal events.

By using gadgets that measure the chlorophyll levels of leaves, cameras that monitor leaf growth and satellites that look at changes to the tree canopy throughout the year (as well as a huge amount of computational analysis), researchers are trying to create a comprehensive picture of how climate change is affecting the growing season in Ireland or the amount of C02 trees can take out of the environment.

They are particularly interested in measuring senescence as it hasn’t been studied in detail in Ireland or globally. Understanding the changing patterns of the growing season will also help assess or predict the impacts of climate on the insects and birds who rely on the trees.

For most of us, the changing of the leaves represents a beautiful nature scene but for some scientists it represents an exciting opportunity for scientific discovery.

‘Pronk’, in case you were wondering, is the jump of a springbok. A children’s library book schooled me on that word I didn’t know I needed to know.

If you’ve exhausted the small pleasure of admiring autumnal leaves, I recommend putting “springbok pronking” into Youtube and indulging in three minutes of David Attenborough’s voice, cute bouncy animals, classical music and glorious landscapes. Smile on your face afterwards guaranteed.

Daylight saving hours

I’ve written before about the need to abandon Daylight Savings Hours and I’ve seen suggestions on social media that this might be a good year to shelve it forever!

EU MEPS voted to scrap Daylight Saving hours in 2021, but I wonder could we start a campaign to scrap it before the October bank holiday weekend. An hour less in bed on a non-jazzy bank holiday is not what we need right now!

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