Saturday 30 November 2019


One of the less obvious consequence of global warming is that plants and their pollinators are going to drift away into different time-zones. This will be bad, possibly fatal, for both species. This is a bit hypothetical but bear with me: just sowing a seed of doubt.
  • Plants are sensitive to light
    • almost of all of them capture sun-light to make carbohydrates from CO2 and water
    • there are non-photosynthetic plants like Beechdrops Epifagus virginiana which makes a living sucking carbs from the roots of Beech Fagus sylvatica trees and has lost its ability to use sunlight.
  • Some plants use the sunlight also as a cue for some physiological necessities. Poppies and crocuses practice nyctinasty: as daylight ebbs, the basal petals put on a growth spurt which closes the flowers up against the night. Nobody really knows why they do this and there may not be a single driving cause.
    • Charles Darwin, the consumate observer, thought it was to reduce the chance of freezing
    • or at least it might protect the delicate reproductive parts from storms at night
    • Others have suggested that the habit preserves scent for the day-time pollinators, rather thanwasted on those wastrel moths
    • More convoluted explanation: by closing up a field of poppies, nocturnal predators can more easily see and knock off the insects that munch on plants
  • Even to rather unobservant people like me, it is obvious that each plant species comes into flower in its season. Ivy Hedera helix flowers in the early winter where/when its nectar serves as an important food source; usefully extending the season for honeybees. The berries come later and are a winter essential for non migrating birds. Snowdrops Galanthus nivalis make their play for a reproductive future at the other end of Winter.
  • Insects are more sensitive to temperature
    • Many of them can't even get going in the morning until they have been warmed up by the sun.
    • On a longer time scale, they may well hibernate through the winter (because there is little to eat) and the sun rises later and often behind clouds.
  • If the ambient daytime temperature goes up by 2°C across the year then insects and small mammals are going to wake up earlier and earlier expecting their plant food to be available on time . . . because that's the way it's been for thousands of generations. But the plants, being light-cued, are still on Old Time. The finely balanced mutually beneficial relationship has been sundered. 
  • Life is a tangled web of inter-relations. Evolution is nothing if not pragmatic: whatever works, however it works, will become more common in the population. Most of our scientific explanations of why things are the way we find them are superficial, almost trivial, simplifications of the complex drivers of diversity which make biology so interesting.
Very slow carbon hand-clap, 1st World humanity.

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