Posts Tagged: plants
Car fumes, weeds pose double-whammy for fire-loving native plants
Wildflower displays threatened
Northwest of Los Angeles, springtime brings native wildflowers to bloom in the Santa Monica Mountains. These beauties provide food for insects, maintain healthy soil and filter water seeping into the ground – in addition to offering breathtaking displays of color.
They're also good at surviving after wildfire, having adapted to it through millennia. But new research shows wildflowers that usually would burst back after a blaze and a good rain are losing out to the long-standing, double threat of city smog and nonnative weeds.
A recent study led by Justin Valliere, assistant professor in the UC Davis Department of Plant Sciences, found that native wildflowers and other plants that typically flourish following a fire were, instead, replaced by invasive plants on land that received the kind of nitrogen contained in vehicle emissions.
“Many native plants in fire-prone areas rely on fire, and some are entirely dependent on it. Some are even most abundant after a fire,” said Valliere, a UC Cooperative Extension specialist in invasive weed and restoration ecology. “But we found that these fire-following species may be especially vulnerable to the combination of nitrogen pollution and invasive plants.”
That's part of the reason why native plants in these mountains have been declining.
Seeds – banked in the soil and waiting to sprout
The problem faced by native plants can be compared to a drawn-down bank account: Funds withdrawn are not being replaced.
It starts with fire, an important ecological process, Valliere said. Flames burn through plants on the surface and return their nutrients to the soil. Seeds sleeping in the ground wait for the next rain to sprout, then use those nutrients to grow.
“Plant diversity is often highest in growing seasons immediately after a site burns,” he said.
But invading plants have many advantages over native ones. They often sprout earlier, grow faster and create more seeds, all while tolerating drought.
“They're like cheaters,” Valliere said. “They don't follow the same rules.”
Nitrogen, too, is an important piece of every plant's nutrition. They all get a fertilizing boost from nitrogen that floats up in vehicle emissions and falls to the ground. But the invaders use nitrogen and other nutrients to grow faster, winning the race for water and sunlight. As a result, fewer native plants reach maturity, producing fewer seeds that keep their populations thriving.
When the bank balance reaches zero
The 2013 Springs Fire gave Valliere a unique opportunity to study the combined impacts of wildfire and extra nitrogen. He and colleagues from UC Riverside and the National Park Service created test plots in the Santa Monica Mountains where the fire had burned. Then, they added nitrogen to the soil to mimic the amount and type that LA's smog would deposit. Over the study's three years, native plants that typically would have flourished after wildfire instead declined even faster in the plots with added nitrogen.
Native seeds sprouted, but didn't flower. Over time, the soil's bank of seeds drew down.
“Each seed has one chance to flower and reproduce,” Valliere said. “If a seed grows and gets outcompeted, that seed has lost its chance to replenish the seed bank.”
Without the chance to replenish their bank account, native plants will die out, and the whole ecosystem will be thrown out of balance.
“There is inherent value in biodiversity,” Valliere said. “These invasive weeds could prevent the re-establishment of native shrubs after fire, sometimes forever altering the plant community.”
The loss of native plants can have cascading effects on the larger environment, he added. Problems can include the loss of native bees that feed on the flowers, and mudslides when rain makes hillsides unstable.
This problem is likely to repeat in similar areas where biodiversity is highest after wildfires – including parts of the Mediterranean basin, southern Africa and Australia. The addition of city smog “could have serious consequences for the biodiversity of fire-prone ecosystems worldwide,” Valliere warned.
Read the paper, “Nitrogen deposition suppresses ephemeral post-fire plant diversity,” by Justin Valliere, Irina Irvine and Edith Allen.
This article was first published on the UC Davis Department of Plant Sciences website.
/h3>/h3>/h3>Gearing Up for 13th Annual UC Davis Biodiversity Museum Day
Meet the scientists! Ask questions! Plans are underway for the 13th annual UC Davis Biodiversity Museum Day, a free "Super Science Day" for the public to see science in action and learn about 10 UC Davis museums and collections. The event is set for Saturday, Feb. 10, the weekend...
Entomologist Jeff Smith, who curates the Lepidoptera collection at the Bohart Museum of Entomology, shows butterfly specimens to guests. (Photo by Kathy Keatley Garvey)
Billy Thein of the California Raptor Center introduces a golden eagle to the crowd at a recent UC Davis Biodiversity Museum Day. (Photo by Kathy Keatley Garvey)
The Center for Plant Diversity creates a "petting zoo" at which folks can pet a pine cone. (Photo by Kathy Keatley Garvey)
Gearing Up for UC Davis Biodiversity Museum Day: Crowdfunding Is First
This is a winter event you won't want to miss. The event: The 13th annual UC Davis Biodiversity Museum Day, a Super Science Day. It's an opportunity to see scientists in action. It's day when you can visit such biological museums or collections as the Phaff Yeast Culture Collection, Bohart...
Crowdfunding is underway for the UC Davis Biodiversity Museum Day.
At the 12th annual Biodiversity Museum Day, children delighted in the science at the Bohart Museum of Entomology. (Photo by Kathy Keatley Garvey)
Professor, entomologist and UC Davis doctoral alumna Fran Keller, seen here in the Bohart Museum of Entomology, discusses black widow spiders during the 12th annual UC Davis Biodiversity Museum Day. (Photo by Kathy Keatley Garvey)
Managing toxic plants
Some plants thrive even in dry years, while others need wet years to really blossom. It's no surprise, then, that this year the University of California Cooperative Extension (UCCE) Fresno office has received several inquiries about potentially toxic plants and how to deal with them. Even if these...
Of Bugs and Plants and Eagles...and More...
Of bugs and plants and eagles...and more... The 12th annual UC Davis Biodiversity Museum Day, set Saturday, Feb. 18 on the university campus, will feature 11 museums or collections in what is billed as a "Super Science Day." Frankly, it's a super way to learn about science, it's super free, and...
The Bohart Museum of Entomology's live petting zoo draws scores of visitors. Here a youngster gets acquainted with a stick insect, aka walking stick. (Photo by Kathy Keatley Garvey)
The Center for Plant Diversity, aka Herbarium, located in the Esau Science Hall, includes a petting zoo. Visitors can "pet" pine cones. (Photo by Kathy Keatley Garvey)
Raptor Center volunteer Billy Thein introduces the crowd to a golden eagle during a UC Davis Biodiversity Museum Day. (Photo by Kathy Keatley Garvey)
Know your plants! This group of young visitors at the UC Davis Arboretum and Public Garden display gets acquainted with plants. (Photo by Kathy Keatley Garvey)