The Carrizo Plain, a stretch of mid elevation desert tucked on the eastern edge of San Luis Obispo County, California, is carpeted with wildflowers right now, a spectacle often seen after dry years are followed by a season of heavy rains. The massive atmospheric rivers of the past winter, desperately needed and causing much excitement, as well as damage across the state, have given way to superblooms of native wildflowers in the deserts of California and Arizona.
Following this winter’s heavy rains, California is currently erupting in wildflower superblooms. As warming temperatures make droughts longer and more intense in the arid West, superblooms will likely become less frequent. Photo of current Antelope Valley superbloom by Ashok Boghani.
Rainfall has been well above average this year in California, though not shockingly so. While the rains have been a welcome reprieve to the dry days of the state’s three-year drought, giving a brush of hope and coloring the hills and plains of wildflowers, there’s a chance that we will see fewer such blooms across the landscape in the future. That is because these native plants are already under stress due to habitat loss and climate change.
For one thing, climate change is delaying when the annual rains start. A UC Davis experiment released in March of this year and still under peer-review, found that a later start to the rainy season, coupled with colder temperatures at the outset of the rainy season, will reduce germination rates of many California native wildflowers. Comparing their experimental findings to historical data regarding wildflower growth, the researchers found that climate change is likely already harming the germination of many species in California.
“Rainfall variation among years can have profound effects on wildflower populations,” said Johanna Schmitt, one of the researchers on the experiment. “And in California, the rainy season is becoming more variable.”
Other research also indicates that warming temperatures will impact wildflowers. Warmer, drier winters, for example, have been linked to a decrease in native wildflower diversity in California. And a study from the University of Washington found that warmer and drier summers affect how plants go from flower to seed, resulting in a shorter flower-to-seed transition. In other words, climate change will not only impact when and how quickly flowers blooms, but also when flowers produce seeds.
As climate change delays when the rainy season starts in California, many native wildflowers will experience reduced germination rates. Photo by Rob Bertholf.
The Carrizo Plain, a stretch of mid elevation desert tucked on the eastern edge of San Luis Obispo County, California, is carpeted with wildflowers right now. Photo of an earlier superbloom there by croft.de / Bureau of Land Management.
Climate change could also impact superblooms specifically. As warming temperatures make droughts longer and more intense in the arid West, superblooms will likely become less frequent — though they could become more spectacular due to a larger buildup of seeds in between large blooms.
Richard Minnich, an ecology professor at UC Riverside, acknowledges that climate change will impact native flowers, but cautions against over-stating the impact, including when it comes to changing rainfall patterns.
“Rather than being prospective, I’d rather be retrospective, and I can tell you that there’s always been gigantic variability in rain and flower production in California,” he said. This variation can be seen not just year to year, but decade to decade.
More than that, however, Minnich points to the toll that non-native plants have already taken on the state’s native flora. Indeed, the species at the center of the recent UC Davis experiment, all from the Streptanthus, or jewelflower, genus, have been greatly impacted by many non-native species overtaking their habitat for over a century.
“The biggest impact we have on the wildflowers are all of these aggressive European and Middle Eastern annuals. They’re also annuals, but they’re mostly grasses and mustard, so they crowd them out,” said Minnich, whose book, California’s Fading Wildflowers, digs into this issue.
As Minnich pointed out, spectacular wildflower blooms once occurred across a range of ecosystems and were marvels nearly every year. Just over a century ago, for example, fields of poppies grew across Los Angeles County, and were popular destinations in the spring for those in the city to view.
As non-native plants took over grassland landscapes, the native wildflowers were crowded out. Today, they reside primarily in heavily protected areas like Carrizo Plain National Monument, Anza-Borrego State Park, or truly inhospitable places for non-native Mediterranean species, like Death Valley in the Mojave Desert. They also find refuge in vernal pools — water-filled depressions in soils made by lava flows that are less hospitable to non-native species — and in the semi-toxic soils of serpentine, a plentiful rock in California that provides a haven for threatened endemic species in the state.
What does this all mean for wildflowers? Wildflowers in California have been fighting for their survival for hundreds of years, ever since the introduction of non-native species. And now climate change will add another layer to the flowers’ plight.
As climate change and the continuing presence of non-native species threatens these plants, the spectacle of the superbloom will become increasingly rare. So, as we venture out to marvel at the painted hills of California, it is ever more important that we be mindful as we take in the colors: don’t step on the plants or pick them — they need any leg up they can get.
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