Quote [EMAIL PROTECTED]: >The results provided a unique dataset, giving a comprehensive insight into >changing flora in rural and urban habitats.
I saw a report on this, and was truly amazed. British agricultural practice has changed out of all measure in the past 20 years. Pasture extent and distribution has changed, weed killer use has changed, crops and cropping patterns have altered. Dissolved nitrogen salts in the rain have doubled - from combustion - and sulphur levels have roughly halved as gas substitutes for coal in power generation, altering soil pH and fertility. The rabbit population, once virtually eradicated by myxomatosis, has since exploded; browsing grass and leaving many dicotyledons to flourish. All of this must have had a major affect upon plant distribution. By contrast, whatever alterations there may have been in the climate are at best disputable, irrespective of what may be expected in the future. Once again, academics jump on a band wagon in order to provide easy copy: I saw that the ESA Venus Express satellite was billed as "studying a model for Earth's climate change", on a planet with a sulphuric-carbonic atmosphere at 400C! British orchids are astonishing opportunists as well. A recently-completed roundabout was covered with early pinks - and a few dandelions - and a friend's lawn is covered with Anacamptis last years, having never had one before, as a result of grazing a pair of donkeys on it. Darwin's calculation - that one Orchis plant's seeds, evenly distributed, would cover the Isle of Wight with plants in the first generation, and the entire planet on the second, has something of the truth in it. It is a wonder that continental isolation has continued for such a long period, with the new and old world orchid flora being so distinct: virtually no monopodials in the New World, only what? Bulbophyllum, Vanilla, Calanthe, Polystachia as shared genera. Given when the flower plants are supposed to have delivered the orchid clade (40My or so BP) - and when the continents came apart (120 My +BP) - I always find this separation inexplicable. ______________________________ Oliver Sparrow +44 (0)20 7736 9716 www.chforum.org _______________________________________________ the OrchidGuide Digest (OGD) [email protected] http://orchidguide.com/mailman/listinfo/orchids_orchidguide.com
