Another Life: That everything in nature is connected to everything else is a useful if tantalising truism, not all that helpful in trying to tease out the current flux of wildlife's adaptation to climate change.
What is real change in what we see, and what simply a response to "normal" extremes of weather? What things are we seeing just because we are looking - and perhaps, now, looking harder and more often? Time of flowering, for example, is controlled by a chemical messenger from a plant's leaves, which usually measure the length of the night, quite independent of climate. A very cold spell may hold up the flowers, but not indefinitely, and, as every gardener knows, a very warm spell early in the year will bring plants into leaf and flower earlier. But, wrote Anthony Huxley in 1974, "variations from the average are usually to be measured only in days". His fine book Plant and Planet (Allen Lane) has been educating me for 30 years, and it will fall to his botanical successor to describe how far the rules have changed in the intervening decades. Another great naturalist-writer - Richard Fitter, now 90 - has kept records of flowering in the countryside around his Oxfordshire home for half a century.
Analysed now by his ecologist son, Alastair, they show the suddenness of response to global warming. Flowering dates for 385 plants through the 1990s were an average of 4.5 days earlier than for the previous four decades, and 60 of the species had flowered a full fortnight earlier.
It's against such background that we must judge extraordinary flowering dates in Ireland. John MacNamara, the Burren naturalist, found clusters of harebells in bloom in the Caher Valley nature reserve on the winter solstice, December 21st, and heath milkwort and a blue gentian in full bloom at Ballyreen, opposite Cloch Scoilte, on February 17th. In 15 years of records, he tells me, his earliest date for a gentian, the Burren's most stunning spring bloom, was March 31st.
The general flowering season of the gentian is from the middle of April to the middle of June, and for most of the rest of the year the plant's little rosettes are virtually invisible. But the Burren's limestone soaks up warmth like a storage heater, and perhaps the golden weeks in February were enough to trigger response in a single precocious plant. Botanists will watch gentian events closely over the next few weeks.
Does it matter much, in any case, when things flower? It matters to flowers needing pollination to reproduce, and to bumble bees needing early nectar; perhaps even to early butterflies. It's the wider links in nature that count - especially if they fail to connect. "Mis-matches" of adaptation to climate change could cost some species dearly, as research is beginning to show.
Take, for example, the blue tits and great tits, now flitting high through the oakwoods of Killarney. Both are drawn to breed among oaks by the abundance of spring caterpillars that feed on the first leaves, and they time their first broods accordingly. The hatch of caterpillars from the overwintered eggs of moths is, in turn, timed for their food: they must be ready to eat the oak leaves just as they break from their buds and before the trees pump too much tannin and other phenols into them as a defence against the chewing of herbivores. Caterpillars that eat the leaves early grow faster and survive better. Young blue tits, too, grow better on a tannin-free diet.
Everything in this food-chain depends on synchrony - so what happens if it gets out of phase? In a study at the Netherlands Institute of Ecology, spring temperatures have warmed by two degrees and oak bud-burst now occurs about 10 days earlier than it did 20 years ago. Caterpillars are hatching 15 days earlier, which seems a dramatically rapid change to result from natural selection. The tits are still laying their eggs at much the same time and have yet to show any decline, but, say Dutch scientists quoted in Scientific American, "it's only a matter of time".
Are Irish oaks, too, beginning to jump the gun? Some 10 years ago, I began checking the progress to bud-burst of half-a-dozen tree species in my garden, including an oak, as a volunteer in the Irish Budburst Survey run by Thomas Cummins (at 7, Mill Lane, Palmerstown, Dublin 20). It's far too soon for the jumble of dates in April to make any pattern: I do it, as Cummins suggests, mainly for the pleasure of visiting the trees day by day.
In an era of increasing ecological disorder, such attentive, Zen-like witness can seem the only appropriate response. Nature will adapt in its own way and at its own pace and survive greatly changed, quite possibly, without many of the ecosystems in which homo sapiens has grown comfortable
