Plant diversity increases due to global warming, York scientists say

Diverse plant life near Hull
Diverse plant life near Hull
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The local variety of plants is on the increase in many areas where the climate is changing rapidly, researchers have said.

While climate change is threatening wildlife on the global scale, at a local level the diversity of plants is rising in places where the climatic conditions, particularly rainfall, have changed the most, a study suggests.

The scientists, from the University of York, said they thought "disruption" of local plant communities by rapid climate change - particularly rainfall - could be allowing new species in faster than existing plants vanish.

They point to the example of bee orchids, which love warm conditions and have started arriving at a much wider variety of sites across northern England, taking advantage of the changing climate.

The study used data from plots averaging 25 square metres at locations around the world where the number of different plants - the area's species richness - had been re-measured after an interval of at least 10 years.

The study, published in the journal Current Biology, found that local plant species richness increased most in the coldest parts of the world, and where the climate had changed the most.

Lead author Dr Andrew Suggitt, from the University of York's Department of Biology, said: "We used a large dataset of over 200 studies in which botanists had counted the number of plant species present in survey plots situated all around the world.

"We tested for the influence of climate change alongside other well-known drivers of diversity change, finding that the local differences in climate, and exposure to climate change, were responsible for a substantial part of the change in plant species numbers found in these surveys.

"Our models suggest that typical rates of climate change in cooler regions of the world are driving an increase in local species richness of 5% per decade."

He said the figure was large if it continued over decades, with humans already changing the climate for more than half a century and set to continue to do so, and that it had "substantial implications" for future natural systems.

The study suggests species richness had increased 9.1% per decade at locations where temperature had changed the most, and 10.8% where rainfall has changed the most.

But it warned that it was important not to confuse climate change's local positive effects on the number of species with the fact that it was increasing the global extinction risk for a substantial proportion of the species on Earth.

And the researchers said it was unlikely that the spread of the variety of species was in "equilibrium" given the speed of ongoing climate shifts.

Co-author Professor Chris Thomas said the findings do not mean the botanical world "gets a clean bill of health".

He said the world is in "the Anthropocene" epoch, in which human activity has been responsible for substantial declines in wildlife at the global level, with some plants becoming extinct and many more endangered.

"However, there is a disconnect between what is happening at that global level and the average change to plant diversity that can be observed in, say, a one metre square plot of ground," he said.

"The effect of climate change may not be as dramatic as a meadow being turned into a car park, or a forest being cut down, but it's a pervasive effect that is already evident over vast areas of the Earth's land surface."

He added: "The data we have analysed tells us that colonists are tending to arrive faster than incumbents disappear, giving rise to slight increases in plant diversity in places where the climate is changing the most."