Bees, plants waking up earlier each spring

Hurricanes, heat waves, floods and droughts may grab the headlines when it comes to the effects of global climate change, but I sometimes worry that it's the subtle stuff that could ultimately wreak the most havoc.


This could be the case with the timing of when bees "emerge" each spring, and the flowers and plants they pollinate.

Scientists report that over the past 130 years – as the start of spring gets earlier as the Earth's climate warms – several species of North American bees are emerging about 10 days earlier each year, with most of this shift taking place since 1970. This is according to a new study published today in the Proceedings of the National Academy of Sciences.

So, why should we care about bees, when all they do is sting us when we step on them in the backyard? Well, chew on this: Since bees are the world's most important pollinators of flowers and plants, any change in this crucial relationship could prove devastating:

"85% of the world's plant species are pollinated by animals, and bees are widely thought to be the main animal pollinators," says Rachael Winfree, an entomologist at Rutgers University and a co-author of the study. "Therefore, if we lost bees, we would eventually lose most of the world's plant species. In addition, 75% of the world's crop plant species are pollinated by animals, again mostly by bees."

The branch of science in this research is known as "phenology," an ancient study that measures the timing of life-cycle events of all animals and plants. I covered this a few years ago when I wrote an article about Project Budburst, which uses citizen-scientists to track the annual flowering of plant species across the USA.

"A shift in 10 days over 130 years as shown by the bees is a lot from the point of view of an insect, whose lifetime is measured in weeks," says Winfree.

The study was led by Ignasi Bartomeus, also of Rutgers.

Although the flowers the bees pollinate have also emerged earlier at and equal pace, Bartomeus and his team say "mismatches" between the flowers and bees could occur in the future if climate warming continues at the current rate:

"If bees and plants responded differently to climate change then, for example, bees could emerge in the spring before plants were flowering, in which case the bees would die because they wouldn't have anything to eat," Bartomeus reports. "Or plants could flower before the bees emerged, in which case the plants would not be pollinated and would fail to reproduce.

"If mismatches did occur and caused the local extinction of pollinators or plants, this could affect people, because of the widespread importance of pollinators and animal-pollinated plants."

Bartomeus and his co-authors used contemporary and museum data dating back to the 1880s to examine climate-associated shifts in the spring emergence of 10 wild bee species from northeastern North America. The authors also used information from four published studies to track shifts in the annual spring flowering of 106 native plant species that the bees pollinate.

While other studies have found that various plants and animals are emerging earlier in the spring as the climate warms, this was the first one to look at multiple species of bees, which are important to ecosystems and humans because they are pollinators.

http://content.usatoday.com/communities/sciencefair/index