Now is the time Colorado’s famed wildflowers are in full bloom. Enjoy it while you can. This annual riot of color is not immune to climate change.
In recent decades, winter snow has been melting earlier. That shift has not been lost on Drummond’s rockcress (Boechera stricta), a mustard plant native to the Rockies (above). The results of a 38-year field study reveal that Drummond’s rockcress flowered 13 days earlier in 2011 than in 1973.
The ecologists who published these results in a recent issue of Proceedings of the Royal Society of London—Biological Series found that this change is not a simple matter of individual plants flowering earlier in the year. It turns out that the population of wildflowers has undergone gradual genetic changes that have also helped it adapt.
The rockcress, typical of alpine plants, is programmed to set its buds as soon as the snow abates. This hurry-up-and-flower habit evolved during a time when snows stuck around until as late as June and fell again in October. But the plant also responds to other cues signaling the time to bloom, such as length of day. What happens as the warm, snow-free days coincide with much shorter days?
“Global climate change imposes severe new stresses on organisms,” Duke University ecologist Jill Anderson, the study’s lead author, said in a press release. “Species that cannot evolve fast enough risk extinction.”
Indeed, Anderson and her colleagues warn that if climate change continues at the same rate, by 2100 Drummond’s rockcress will need to bloom a month sooner than it does now. And in springtime Colorado, the difference of a month can mean the difference of a full hour of daylight.
Some plants can migrate to higher elevations to escape the heat and strike a balance among contradictory blooming cues, but that is not an option for Drummond’s rockcress. At the end of each summer, the seeds fall just beneath the mother plant. That means it needs to find a way to thrive right where it lives.
One option: become an even earlier early-bloomer.
Photo: Flowers and buds on rockcress in the Colorado Rocky Mountains: earlier each year. (David Inouye)