Artificial light is causing spring to come early

Spring is arriving at least a week early in the UK due to night-time light pollution, according to a new study. 

Beech leaf budding. © ChristineMartin/WTPL
Beech leaf budding. © ChristineMartin/WTPL

New research led by a team of biologists highlights the relationship between the amount of artificial night-time light and the date of budburst in woodland trees for the first time. 

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University of Exeter researchers analysed information collected by citizen scientists. 

The Woodland Trust asked people to note down when they first saw sycamore, oak, ash and beech trees in leaf as part of their Nature’s Calendar initiative. 

Professor Richard ffrench-Constant, one of the authors of the study, said, “We found that artificial lighting can accelerate tree leaves budding, and effectively the onset of spring, by a week. This has got to be bad for nature, particularly because of the knock-on effects.” 

The study found that buds were bursting by up to 7.5 days earlier in brighter areas and that the effect was larger in later budding trees.

Researchers believe that early bud bursting will have an impact on other organisms whose life cycles work in synchronicity with the trees.

For example, the winter moth that feeds on fresh emerging oak leaves is likely to be affected, which may have some effect on birds that rely on it for food.

“At the moment, caterpillars are timed to hatch to make the most of opportunities to feed from freshly budded leaves, and birds hatch in time to feed off the young caterpillars.

“If this cascade effect is thrown out of sync by late budding, wildlife is bound to suffer,” said ffrench-Constant. 

The findings point to the need for further research into the impact of different light quality and provide important information for local councils in charge of lighting levels. 

Read the full paper in the journal Proceedings of the Royal Society B

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