Dear EarthTalk: I’ve noticed that wildflower blooms in the mountains have been coming earlier and earlier in recent years. Is this a sign of global warming? And what does this mean for the long term survival of these hardy yet rare plants?
As always, it’s hard to pin specific year-to-year weather-variations and related phenomena – including altered blooming schedules for wildflowers – on global warming. But longer term analysis of seasonal flowering patterns and other natural events do indicate that global warming may be playing a role in how early wildflowers begin popping up in the high country.
University of Maryland ecologist David Inouye has been studying wildflowers in the Rocky Mountains near Crested Butte, Colorado for four decades, and has noticed that blooms have indeed begun earlier over the last decade. Aspen sunflowers, among other charismatic high country wildflowers, used to first bloom in mid-May, but are now are doing so in mid-April, a full month earlier. Inouye thinks that smaller snow packs in the mountains are melting earlier due to global warming, in turn triggering early blooms.
Smaller snow packs not only mean fewer flowers (since they have less water to use in photosynthesis); they can also stress wildflower populations not accustomed to exposure to late-spring frost. According to Inouye’s research, between 1992 and 1998 such frosts killed about a third of the Aspen sunflower buds in some 30 different study plots; but more recently, from 1999 through 2006, the typical mortality rate doubled, with three-quarters of all buds killed by frost in an average year thanks to earlier blooming.
Inouye’s worrisome conclusions are backed up by experiments conducted by fellow researcher John Harte, who over a 15 year period used overhead heaters in nearby wildflower study plots to accelerate snow melt. The results were the same: Wildflowers bloomed early and not as vigorously.
Several studies in Europe have shown that some species of wildflowers there may be able to migrate north and to higher elevations as the climate warms, but Inouye fears his beloved Aspen sunflowers and many other American wildflowers may be lost forever as they are not able to migrate as quickly as needed in order to survive widespread surface temperature increases and escape extinction.
Harte is also gloomy about the prospects for Colorado’s mountain wildflowers. He predicts that the wildflower fields he and Inouye have been studying will give way to sagebrush desert within the next 50 years, whether or not the governments of the world can get a grip on greenhouse gas emissions.
As a hedge against such dire predictions, the nonprofit Center for Plant Conservation is spearheading seed collection efforts on thousands of rare wildflower species across the U.S. for inclusion in the Colorado-based National Center for Genetic Resources Preservation, a repository for both common and rare prized American plant seeds. The banked seeds, useful if not solely for preserving the genetic makeup of species that may go extinct in the wild, can also be used for future restoration projects on otherwise compromised landscapes.
CONTACTS: David W. Inouye ; Center for Plant Conservation, www.centerforplantconservation.org; National Center for Genetic Resources Preservation, www.ars.usda.gov/main/site_main.htm?modecode=54-02-05-00.
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