Researchers from Boston and Harvard universities and the University of Wisconsin-Madison say the findings give clues to ecological changes in response to a warming world and may help predict effects on important agricultural crops, which depend on flowering to produce fruit.
The researchers compared modern flowering times to historical records compiled by iconic American naturalists Henry David Thoreau and Aldo Leopold.
Native plants such as serviceberry and nodding trillium are blooming 11 days earlier, on average, in the area around Concord, Mass., where Thoreau worked, the researchers said.
In Wisconsin, where Leopold gathered records of blooming plants like wild geranium and marsh marigold, the change is even more striking, with plants blooming on average nearly a month earlier than they did 67 years ago when Leopold made his observations.
"These historical records provide a snapshot in time and a baseline of sorts against which we can compare more recent records from the period in which climate change has accelerated," Wisconsin-Madison wildlife ecology Professor Stan Temple said.
The findings have important implications for predicting plant responses to changing climate, the researchers said, essential for plants such as fruit trees that are highly susceptible to the vagaries of climate and weather.
"Earlier blooming exposes plants to a greater risk of experiencing cold snaps that can damage blossoms and prevent fruiting," Temple said in a UW-Madison release.
The study has been published online in the journal PLoS One.
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