Quick Summary
- Native wildflowers saved a lot of seeds during California鈥檚 drought 鈥 201 percent more than usual
- Exotic grasses decreased their seed bank by 52 percent during the drought
- Drought-tolerant wildflowers enjoyed the greatest increases
- Effects of a prolonged drought remain unknown, though the flowers appear resilient during short-term drought
Native wildflowers were surprisingly resilient during California鈥檚 most recent drought, even more so than exotic grasses. But signs of their resilience were not evident with showy blooms aboveground. Rather, they were found mostly underground, hidden in the seed bank, according to a study from the University of California, Davis.
For t, researchers analyzed more than 22,000 seedlings from soil cores collected at 新澳门六合彩内幕信息鈥檚 in Northern California during the fall of 2012 and 2014. They found that seeds from native wildflowers increased 201 percent underground, while aboveground growth increased 14 percent.
Meanwhile, seeds from exotic grasses decreased 52 percent belowground, while aboveground growth decreased 39 percent.
鈥淓ven wildflowers that are considered intolerant to drought appeared resilient to a single extreme drought event,鈥 said lead author Marina LaForgia, a graduate student in the lab of professors Susan Harrison and Andrew Latimer in the 新澳门六合彩内幕信息 Davis Department of Plant Sciences. 鈥淗owever, more frequent, severe or prolonged future droughts could eventually exceed these native species鈥 capacity to put more and more seeds into the seed bank for their long-term survival.鈥
Seed banking for survival
Seed banks are a clever survival tool native wildflowers use to weather highly variable like California, where one year can be extremely dry and the next extremely wet. To take advantage of both of those climates, they keep a portion of their seeds dormant in the soil rather than spending them all at once. This helps ensure their long-term survival.
During the drought, the wildflowers operated like someone who has kept their job during an economic crisis but is wary of losing it. The person continues to produce and make money, but they save a greater proportion of it in the bank rather than spend it as they may have before the crisis. Similarly, native wildflowers were still germinating and producing seeds, but they saved a greater proportion of that seed underground, waiting for more favorable conditions to emerge.
鈥淪eed banking is a form of bet-hedging,鈥 LaForgia said. 鈥淲ildflowers take on low risk but also low reward, whereas grasses are high-risk, high-reward plants. They鈥檙e not savers. They increase dramatically during wet years and decrease in dry years. Wildflowers are less dramatic. They are there, but they鈥檙e switching where they place the highest proportions of their population.鈥
Tolerance levels
While nearly all wildflowers added to their seed banks during the study period, the increases were especially striking among drought-tolerant wildflowers:
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Aboveground, drought-tolerant wildflowers increased by about 13 percent, while drought-intolerant wildflowers decreased slightly.
- Belowground, drought-tolerant wildflowers increased seed banks by 263 percent, while wildflowers considered intolerant to drought increased their seed bank by 119 percent.
The spike in native wildflowers and drop in grasses was fairly consistent across species and not due to any particular 鈥渂readwinner.鈥 Eleven of 15 grasses declined, while 65 of 81 wildflower species increased the amount of seeds they stored.
Look out below
The study indicates that native annual wildflowers should be an integral part of future restoration strategies, even though their emergence might not be immediate.
鈥淲hen looking at how plant communities respond to disturbance, we mostly just think about what goes on aboveground,鈥 LaForgia said. 鈥淏ut if you really want to think about how a plant community is responding, it鈥檚 important to keep the entire life cycle of that population or individual in mind. You get a very different answer by just looking at the aboveground community.鈥
新澳门六合彩内幕信息 Davis professors Harrison and Latimer are the study鈥檚 senior authors. Additional co-authors include Marko Spasojevic of 新澳门六合彩内幕信息 Riverside and Erica Case of 新澳门六合彩内幕信息 Davis.
Research for the study was supported by a National Science Foundation Graduate Research Fellowship grant, a 新澳门六合彩内幕信息 Davis Jastro Shields Research Grant, and the Hatch Project.
Media Resources
Kat Kerlin, 新澳门六合彩内幕信息 Davis News and Media Relations, 530-750-9195, kekerlin@ucdavis.edu