Recent study provides evidence that fast-growing deciduous plants replaced slower-growing evergreen plants following impact of meteorite that caused dinosaur extinction.
A study published on Tuesday in the journal PLOS Biology reveals that a meteorite that hit Earth millions of years ago – and widely accepted to have led to the mass extinction of the world’s dinosaur population – may have also led to a complete shift in the landscape of plants, particularly in favor of deciduous plants.
According to a recent statement by the researchers, a meteorite 10 kilometers in diameter collided into Earth 66 million years ago, leaving a crater near the town of Chicxulub on the Yukatan peninsula of Mexico. The force of the crater is believed to have been responsible for the disappearance of dinosaurs. However, information about the extinction of terrestrial plants, such as the ecological effects and consequences after the meteorite, is still widely unknown.
“If you think about a mass extinction caused by catastrophic event such as a meteorite impacting Earth, you might imagine all species are equally likely to die,” said lead researcher Benjamin Blonder of the University of Arizona. “Survival of the fittest doesn’t apply — the impact is like a reset button. The alternative hypothesis, however, is that some species had properties that enabled them to survive.”
This hypothesis specifically highlighted comparisons between the evergreen flowering plants and the deciduous flowering plants of the time. In the study, Blonder and colleagues analyzed approximately 1,000 fossilized plant leaves from the last 1.4 million years of the Cretaceous Period and the first 800,000 of the Paleogene Period, a time spanning the impact event of the meteorite collision.
The mass of each leaf was measured in relation to its area, allowing researchers to determine whether or not the leaf was cost-efficient to make for the plant. Additionally, Blonder and colleagues measured the density of the vein networks in each leaf, which help to determine the amount of water a plant can transpire and the rate that a plant can acquire carbon. These observations are important in understanding how much carbon the plant invests in each leaf and the speed at which it is done.
Results showed evidence that after impact, the slow-growing evergreen angiosperms, such as holly or ivy, were replaced by faster-growing deciduous plants. “This tells us that the extinction was not random, and the way in which a plant acquires resources predicts how it can respond to a major disturbance,” said Blonder. “And potentially this also tells us why we find that modern forests are generally deciduous and not evergreen.”
The study provides strong evidence of a large transition from slow- to fast-growing species of plants, but the implications of the results can be seen as much broader. According to the researchers, “Our study reveals a dramatic example of the effect of rapid catastrophic environmental change on biodiversity.”
“Plant Ecological Strategies Shift Across the Cretaceous-Paleogene Boundary,” written by Benjamin Blonder, Dana Royer, Kirk Johnson, Ian Miller, and Brian Enquist, was published in PLOS Biology on Tuesday, Sep. 15, 2014.
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