As the global climate warms, wildflowers in the Rocky Mountains are blooming longer, which could have bad consequences for high-alpine pollinators.
Over the past four decades, wildflowers in a Colorado Rocky Mountain meadow have continually lengthened their blooming season in response to climate change, according to recent study conducted by a University of Maryland Professor and funded by the National Science Foundation. The study found that half the wildflowers begin to bloom weeks earlier, more than a third reach their peak bloom earlier, and others produce their final blooms later in the year. Decades ago, the bloom season ran from late May to early September. It now lasts from late April to late September.
The findings are consistent with observations made at Rocky Mountain National Park, according to park ecologist Paul McLaughlin.
“Year-to-year it varies, but on average we’re seeing earlier snowmelt, earlier onset of plant growth and earlier flowering as well,” he said.
McLaughlin said an earlier onset of spring creates a longer season for visitors to enjoy wildflowers at the Park, but it’s troubling for mountain ecosystems.
“The trade-off is that there are pollinators that have a symbiotic relationship with the flowers, like hummingbirds and insects,” he said. “With a change of seasons, there’s a possibility of disconnect when pollinators are looking for flowers and when flowers are blooming.”
In other words, those birds and bugs could have a difficult time surviving. McLaughlin also noted that although flowers might bloom earlier in the season, there’s still the danger of late frosts.
“If flowers are blooming sooner, they’re more vulnerable to losing those flowers,” he said. “So when the pollinators arrive, depending on those flowers to feed, those flowers won’t be there.”
University of Maryland Biology Professor David Inouye, who conducted the study, next plans to study hummingbirds and how their fluctuating food source affects the hatching season.
“Hummingbirds that summer in the Rocky Mountains time their nesting so that their eggs hatch at peak bloom, when there is plenty of flower nectar for hungry chicks,” Inouye said in a press release. “But as the bloom season lengthens, the plants are not producing more flowers. The same number of blooms is spread out over more days, so at peak bloom there may be fewer flowers.”
Inouye will next fit hummingbirds with radio transmitters to study how they interact with flowers this summer.
As that information is collected, McLaughlin said he expects a vibrant and colorful season in the Park. Last fall’s flooding and above-average snowfall means there will be plenty of spring and summer moisture for blooming plants.
“We’ll probably have a glorious flowering season,” he said. “I’d certainly encourage people to come up and enjoy them.”
Leia Larsen can be reached at 970-887-3334 ext. 19603.
“Year-to-year it varies, but on average we’re seeing earlier snowmelt, earlier onset of plant growth and earlier flowering.”
Rocky Mountain National Park Ecologist Paul McLaughlin