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These California wildflowers use seed banks to beat drought

In environments with highly variable climates, it can be a struggle for many plants to adapt and survive. Places that can be extremely wet one year and extremely dry the next require species to adapt to this variability. To that end, many species of wildflowers in these environments use seed banks as a survival tool, allowing them to keep a portion of their seeds dormant in the soil rather than spending them all at once. Ultimately, this helps ensure long-term survival.

California is one of those places where the climate can be extremely variable. A recent study, published in the journal Ecology, shows how resilient native wildflowers were during the state’s most recent drought. Researchers from the University of California, Davis analyzed over 22,000 seedlings from soil cores collected in Northern California during the fall of 2012 and 2014. Their findings showed that seeds from native wildflowers increased more than 200 percent underground, and aboveground growth increased 14 percent. They also found that seeds from exotic grasses decreased 52 percent and 39 percent belowground and aboveground, respectively.

“Seed banking is a form of bet-hedging,” explains Marina LaForgia, a graduate student in the UC Davis Department of Plant Sciences and lead author of the study. “Wildflowers take on low risk but also low reward, whereas grasses are high-risk, high-reward plants. They’re not savers. They increase dramatically during wet years and decrease in dry years. Wildflowers are less dramatic. They are there, but they’re switching where they place the highest proportions of their population.”

The increases to wildflowers’ seed banks were even more significant amongst the drought-tolerant wildflowers. Belowground, these wildflowers increased seed banks by 263 percent, while wildflowers that are intolerant to drought increased their seed bank by 119 percent.

“Even wildflowers that are considered intolerant to drought appeared resilient to a single extreme drought event,” says LaForgia. “However, more frequent, severe or prolonged future droughts could eventually exceed these native species’ capacity to put more and more seeds into the seed bank for their long-term survival.”

The findings from this study indicate that native wildflowers should be used as an integral part of future restoration strategies. Along with their resilience to drought, they’re not too hard on the eyes either.

By Connor Ertz, Staff Writer

Image Credit: Marina LaForgia/UC Davis

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