Carpets of bluebells in woodlands are a much-loved sign of spring, but the flowers could struggle as the climate changes, a study suggests.
Researchers analysed hundreds of thousands of “citizen science” records of the changing seasons to help predict the impacts of warming temperatures on 22 species of plants and trees found in the UK countryside.
Spring plants have an optimum time for coming into leaf and flower which gives them the best chance to grow and reproduce, but with rising temperatures caused by global warming that time is likely to shift.
Some plants such as bluebells may not be flexible enough to keep up with the shift in spring, and may suffer as a result, the research suggests.
The study drew on more than 200,000 records from between 1998 and 2014 from the Woodland Trust’s Nature’s Calendar, in which members of the public submit sightings of the natural world’s seasonal changes such as first flowers and leaves.
Researchers used the data to look at species across their geographical range, where they would experience different environmental conditions such as temperatures, to help predict how they were likely to respond to warmer springs with climate change.
First leafing or flowering dates for all 22 species were sensitive to warmer spring temperatures, the study showed, and they would come into leaf or flower between three and eight days earlier for each 1C increase in temperatures.
Some seven of the 22 species - silver birch, alder, beech, ash, wood anemone, cuckooflower and cocks-foot - are likely to be able to keep track with future changes in climate, the study published in the journal Global Change Biology found.
But four species may struggle to keep up: bluebells, garlic mustard, sycamore and larch.
There were also indications lesser celandine may have difficulty keeping up with the changes.
The remaining species, including hawthorn, rowan, dog rose and oaks, did not show a consistent pattern.
Christine Tansey, research and evidence coordinator at the Woodland Trust, who led the study at the University of Edinburgh’s School of Biological Sciences, said: “Plants have an optimum time for developing leaves and flowers - if they get it right, this will maximise their chances for growth and reproduction.
“As long-term temperatures change, it may alter the optimum timing for plants to develop.”
Dr Kate Lewthwaite, Woodland Trust citizen science manager, said the study showed how important the Nature’s Calendar records were in predicting the effects of the changing climate over time, and urged people to take part in the scheme.
“The English bluebell is an iconic woodland species so this prediction is a wake-up call for the possible effects of climate change on much loved parts of our natural world,” she said.