Gardening in a changing climate
News
CO2 to blame?
Climate change may not be the reason for the gradually-increasing delay in the onset of autumn leaf coloration and leaf fall, as was previously thought: it may actually be caused by rising levels of atmospheric carbon dioxide.
In formulating the new theory, scientists at the University of Southampton subjected poplar trees to different levels of CO2 between planting and maturity.
Weather and leaf-fall data over the last 30 years in Europe show that autumnal senescence has been increasingly delayed, by 1.3 to 1.8 days per decade. There is a strong correlation between increased global temperatures and earlier spring bud break and re-greening, but only a weak link between temperatures and autumn leaf colour change and leaf fall.
The Southampton scientists suggest that trees better able to cope with increased carbon dioxide, rather than higher temperatures, should be selected for growing in the UK.