By IANS
London : Scientists across Europe have been recording a strange phenomenon — a progressive delay in leaves changing colour and falling in autumn, and an earlier re-greening in spring.
Till now, the phenomenon was ascribed to rising global temperatures or global warming.
But a new study by researchers at Southampton University says the increasing level of carbon dioxide (CO2) in the atmosphere is to be blamed for the phenomena, sciencedaily.com reports.
Over the past 30 years, Europe’s autumnal senescence – the process of leaf discolouration and fall – has been delayed by 1.3-1.8 days every decade.
However, while a strong correlation exists between increased global temperatures and early spring re-greening, the correlation between autumn leaf colour-change and fall and temperature trends in 14 European countries is weak, researchers say .
As part of the study, the researchers exposed two plots of popular trees to ambient and increased CO2 levels.
The trees exposed to increased CO2 retained their leaves far longer and also experienced a smaller decline in the end of season chlorophyll content, resulting in a greener autumn canopy relative to that in ambient CO2.
“The research data provide compelling evidence in terms of both the leaf and canopy that autumnal senescence in such forest ecosystems will be delayed as the atmospheric concentration of CO2 continues to rise, independent of increased temperatures,” said Gail Taylor, who led the study.