14 DAY TRIAL // Scientists at the Royal Holloway, University of London and the University of Cape Town said in a research published yesterday that the high frequency of fires in the Cretaceous Period, some 120 to 65 million years ago, is responsible for the birth and spread of the first flowering plants.
Apparently, flowers evolved during the earliest part of the Cretaceous, because of the high oxygen levels in the atmosphere (over 25 percent compared to today's 21 percent) and the high incidence of fires.
The evidence supporting this theory was gathered by Professor William Bond of the Department of Botany at the University of Cape Town and Professor Andrew C. Scott of the Department of Earth Sciences at Royal Holloway.
First of all, the very high oxygen level would have provoked wildfires in wetter vegetation than today, the study claims.
Then there is the warmer climate that was more favorable to convectional storms, with their unavoidable lightnings that started fires, and during the dry season, these fires flourished.
All that these fire-causing conditions needed were plants as fuel, and angiosperms (flowering plants) were perfect for the job: they grew rapidly in the open conditions after a fire, they managed to quickly get to maturity before the next fire, thus causing a “flower-fire” cycle.
Professor Bond said that “with fire on their side angiosperms would have been able to penetrate the gymnosperm-dominated forest of the Cretaceous creating their own preferred growing conditions of high light environments.”
Before flowers were invented, angiosperms were herbs, bushes or small trees, for most of the Cretaceous period.
Flowers allowed them to speed up their life cycle and changes within the leaves and the stem made them faster-growing than their gymnosperms competitors.
The fires took the gymnosperm-dominated land and gave it to angiosperms, which is also a possible explanation for today's vast savannas.
As a conclusion, Professor Scott says that “fire has been a neglected process in earth history and now it is time to reassess it’s role in shaping our world”.