UCD scientists are seeking clues to indicate how modern plants might react to radical climate change, writes Claire O'Connell
Unlocking secrets from the prehistoric past could help us protect today's plants against the ravages of global warming. By combining clues from the fossil record with live data on how hardy plants weather environmental change in the lab, researchers at University College Dublin (UCD) want to understand how ecosystems respond when faced with climate change.
The focus of the fossil research is a natural global warming event and mass extinction that happened 200 million years ago. "There was an extinction event between the Triassic and Jurassic periods and I'm interested in the role environmental change has played in that," says Dr Jennifer McElwain, a lecturer in paeleobotany and plant paeleo-ecology at UCD's school of biology and environmental science.
"We want to understand what's going on in the past but also to use the past as a guide to make projections for what may happen in the future."
Until recently McElwain was an assistant curator at the Field Museum in Chicago and led two expeditions to Greenland to collect plant fossils. Her team took fossil samples from exposed cliff rocks that were laid down just before, during and after the extinction. "You crack with a hammer and if there's a fossil leaf there's a line of weakness and you can open it," explains McElwain, who has now shipped two tonnes of the fossils back to Dublin.
Earlier this year she won a €1.75 million Marie Curie Excellence grant from the European Commission to fund a UCD team that will look at how fossil biodiversity changed 200 million years ago when greenhouse gases and global temperatures rose on a scale that compares to the present.
"We see major ecological changes happening at about four degrees Centigrade warmer, which is where we are predicted to go at a worst-case scenario by the end of this century," says McElwain.
The scientists hope to pick up valuable ecological data from the fossil record about the types of plants that survived the prehistoric global warming event and the ones that didn't. One hypothesis centres on leaf size: "One thing we see across this interval is that the plants where the leaves became smaller were the survivors and the species which had very large leaves went extinct. The bigger the leaf surface the less able to cool, so we think the large-leaf taxa reached lethal temperature limits."
While fossils provide a record of changing leaf size and shape, they are less forthcoming about biochemistry, and this is where experiments with well-chosen living plants can dovetail with the fossil work, explains McElwain.
In conjunction with UCD, she will set up specialised rooms to grow ancient lineages of die-hard "living fossil" plants like cycads, ferns, monkey puzzles and Gingko biloba under tightly controlled conditions of temperature and atmospheric gases.
"Atmospheric oxygen was probably about 14 per cent at the Triassic-Jurassic boundaries so it's exceptionally low," she says. "We want to grow plants in long-term sub-ambient oxygen, as far as we know no-one in the world has done this."
Working with ecophysiologist Prof Bruce Osborne, she hopes to find out what's going on inside these living fossils in the lab as they respond to changes in the environment. The team will also look for internal physiological responses and whether they relate to outer changes like leaf shape, something that can be studied in the fossil record.
Ultimately the goal is to help make plant conservation more effective as we face up to our current global warming episode. "We want to use the information to predict 'extinction prone-ness' - what type of ecology is going to be more prone to extinction in the next hundred years. We can't conserve everything, we have to target conservation efforts," she says.