Monday 18 June 2018

Trees detox in a swirl of leaves

In tune with nature: American singer-songwriter Johnny Cash
In tune with nature: American singer-songwriter Johnny Cash

Joe Kennedy

I spoke to Johnny Cash in his dressing room at the old Adelphi in Dublin's Middle Abbey Street once in my Herald days back in the '60s. We talked about his namesake, the Co Wicklow uilleann piper John Cash, whom he had hoped to meet.

One of Johnny's songs, written in 1958, was a lament for a lost love as autumn leaves were falling at his door: he still remembered those blue eyes. Walter Huston, Anjelica's grandfather, and legendary grizzled actor (The Treasure of Sierra Madre) croaked about how the autumn weather "turns the leaves to flame/And I haven't got time for the waiting game" (lyrics Maxwell Anderson; music Kurt Weill).

There has been a symphony of foliage in a scattering of colour as the copper-tinged, yellow-flecked gorgeousness swirls away across the Northern Hemisphere from Kashmir to Kennebunkport; some proud New Englanders see it as being exclusively theirs!

An American poet, Loren Eiseley, asked profoundly: "If man could disintegrate like autumn leaves, fret away, dropping their substance like chlorophyll, would not our attitude towards death be different? Suppose we saw ourselves burning like maples in a golden autumn?"

John Keats found something uplifting about the season at a bad time in his short life - To Autumn written in 1819 when he was suffering from TB. He found the "mellow fruitfulness'' more comforting than the "chilly green of spring". The naturalist Richard Mabey says we all find auguries in the blaze of autumn, prophesies of winter, reminders of our own mortality.

But why do trees change leaf colour, only to shed them? We like to think this is so they can endure. But we really don't know. One opinion was that the autumn tints deterred insect predators, that the degree of colour correlated to the number of aphid species that might attack the trees in spring.

This did not stand up. Herbivorous insects are only sensitive to the ultra-violet and blue end of the spectrum. Yellows responded too, but only because they are a component of green, not an autumnal colour. Mabey says the reason why temperate trees shed their leaves may be partly because the roots don't easily absorb winter water and need to reduce the moisture lost through leaves, and to get rid of toxins. What happens before the great shedding is a transfer of sugars (three-quarters of the dry weight of leaves) back into the tree for storage. After the chlorophyll has gone, what remain are the natural antioxidants, yellow and orange carotenoids and the tomato-red anthocyanin, elements of detox vitality.

All plants have to survive winter. Annuals live on as seeds; perennials keep their buds in or near the ground; trees have buds up high so that leaves can grow in spring. The autumn tints have been led by beeches, sycamores and hazels, ash the first to shed its mantle and the last to replace it in spring. The mighty oak hangs on to drop its acorn bounty for mammals and to be gathered by raucous jays.

So enjoy the colours of the countryside and look to the season ahead, not, we hope, what Johnny Cash foresaw as a "cold, cold wind" to come!

Sunday Independent

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