- Author: Grace Fruto, UC Davis
- Author: Trina Kleist, UC Davis
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The problem faced by native plants can be compared to a drawn-down bank account: Funds withdrawn are not being replaced.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>
- Author: Molly Stephens
- Author: Roger Bales
The new film "California's Watershed Healing" documents the huge benefits that result from restoring forests to healthier densities. UC Merced's Sierra Nevada Research Institute partnered with the nonprofit Chronicles Group to tell the story of these efforts, the science behind them, and pathways that dedicated individuals and groups are pioneering to scale up these urgent climate solutions.
"California's forests are at a tipping point, owing to both climate stress and past unsustainable management practices that suppressed wildfires and prioritized timber harvesting," explained UC Merced Professor Roger Bales, who was involved in developing the film.
Covering over 30 million acres - nearly a third of the state - these iconic ecosystems provide water, recreation, habitat, carbon storage and serve other needs. But they now contain too many trees, packed too closely together.
"California's diverse ecosystems are facing unprecedented challenges as rising temperatures intensify the threat of wildfires and disrupt the delicate balance of our natural resources," said California Natural Resources Secretary Wade Crowfoot.
The overaccumulation of dead wood, leaves and other organic materials on the forest floor and buildup of small trees - which serve as "ladder fuels" moving fire from the forest floor up into the canopy - has been compounded in recent years by climate warming. Returning more low-severity fire to the landscape is one effective tool for combating heavy fuel loads.
"Restoring fire to these forests, which evolved to experience frequent fire, is critical, despite the risks associated with prescribed, intentional burning," said UC Merced Professor Crystal Kolden. "Partnerships help to give a voice to everyone involved, including historically excluded groups such as the tribes that have burned in these forests for millennia."
"The new production vividly documents the reality of the watersheds' demise and the hard work of new partnerships involving land managers, water agencies, the private sector, counties, universities, community groups and other public agencies to advance the pace and scale of forest restoration," said Jim Thebaut of the Chronicles Group, director and executive producer of the documentary.
"Restoration efforts focus on removing fuels, which lowers the projected severity when a fire does occur," Bales said. "Yet these thinning projects are very expensive. That is where partnerships that can develop creative financing and monetize the benefits of restoration come in."
"We need to use all of the collaborative forest-management, scientific and financial tools at our disposal if we are to address the wildfire challenge at a meaningful scale," said Phil Saksa, chief scientist at Blue Forest, a nonprofit organization focused on creating sustainable investment solutions to environmental challenges. "Leveraging the value provided by all the beneficial outcomes from this work is essential for motivating long-term investments in the natural infrastructure that is our forests and watersheds."
The film explores how scaling up promising investments can ensure a more sustainable future.
"This documentary serves as a poignant reminder that the health of our forests is intrinsically linked to the well-being of our communities," said Crowfoot. "As we confront the impacts of climate change, it is imperative that we scale up our efforts to restore resilient forests, safeguard our water sources and foster thriving communities. By prioritizing sustainable practices, we can forge a path toward a more resilient and sustainable future for all Californians."
"The watershed is a vital component of California's economy, which is interlinked and linked to the United States and the rest of the world," said Thebaut. "It is the foundation for the state's water supply, which is critical to its far-reaching businesses and food security. The current state of the watershed is evidently grave, and unless fast measures are taken, the United States' national security would be jeopardized."
The current film is a sequel to the Chronicles Group's 2019 30-minute "California's Watershed" documentary, which was distributed on PBS and focused on the critical importance of forested headwaters to California's water security. That water supports the state's economy, equivalent to the fifth largest national economy in the world. It also supports the agriculture that is critically important to food security for the United States.
"California's Watershed: Healing" will be shown Sunday, Feb. 18 at the 22nd annual Wild & Scenic Film Festival in Nevada City and Grass Valley, followed by a panel discussion with scientists, decision makers and filmmakers. Event information, including the film trailer, is available online .
This story was originally published on the UC Merced Newsroom website. Read the original posting here: https://news.ucmerced.edu/news/2024/new-film-profiles-immediate-actions-restore-californias-wildfire-vulnerable-forests
- Author: Mario Aguilera
In devastating cases dotting the globe in recent years, climate warming has led to an increase in the number and severity of destructive wildfires. Climate change projections indicate that environmental and economic damage from wildfires will spread and escalate in the years ahead.
While studies have analyzed impacts on land, new research from the University of California San Diego and other institutions indicates that aquatic ecosystems are also undergoing rapid changes as a result of wildfires.
Led by School of Biological Sciences Professor Jonathan Shurin's laboratory, the researchers compared how aquatic systems change with the input of burnt plant matter, including effects on food webs. Their results are featured in two research studies published in the journal Global Change Biology.
Among the findings emerging from the research, scientists show that fire chemically transforms plant debris and changes the role of aquatic ecosystems as key players in the carbon cycle. The shifts point to a fundamental change in the way these aquatic systems store, process and emit carbon.
The findings also are important since aquatic ecosystems serve as sinks that capture water flows and store carbon in their sediments.
“The effects of wildfires are not limited to terrestrial systems,” said Postdoctoral Scholar Chris Wall, a member of Shurin's group and first author of one of the studies. “When we think about wildfires increasing, especially in the West, it's important to remember that burned materials flow directly into waterways that are vital for people and wildlife. We're now recognizing that wildfires can greatly influence ecosystem health, with implications for water resources, like aquifers and recreational fishing.”
The findings emerged from a series of experiments conducted at UC San Diego, and carry implications for aquatic ecosystems in areas such as the Sierra Nevada mountains—where Shurin's group conducts research—and other regions.
“We've seen the impact that these huge fires have had on watersheds, so we're working in these natural systems to understand how different components of climate change are altering the ecosystems,” said Shurin, a faculty member in the Department of Ecology, Behavior and Evolution.
Many normally functioning lake and pond ecosystems tend to emit more carbon dioxide than they absorb since they receive carbon into their system from neighboring sources. The new study showed that this relationship could change with the increased input of burned wildfire materials. The study found that ponds receiving burned materials had overall less carbon dioxide emissions relative to unburned material, indicating a shift toward greater carbon storage.
“Burned plant matter fuels the biological carbon pump of lakes, allowing them to soak up more CO2 from the atmosphere,” said Shurin. “However, this capacity for increased carbon storage was lost as the amount of burned material increased, with treatments receiving the greatest amounts of burned plant material exhibiting highest CO2 export to the atmosphere.”
“More frequent and intense wildfire may alter the capacity of aquatic systems to store, transform and exchange carbon with the atmosphere,” the researchers conclude in the paper. They note that in the future, forecasts of climate change should include integrative models that account for feedbacks between aquatic and terrestrial ecosystems in order to fully understand changes to the global carbon cycle.
The study was conducted on experimental pond systems across a 90-day testing period. The researchers tested various amounts of burned and unburned plant matter at 10, 31, 59 and 89 days. As part of their studies, the researchers fertilized sage plants with nitrogen so they could track the chemical's movement from plant leaves into the food web and into hosts such as plankton. This labeling allowed them to track the path dead plants follow through plankton and other aquatic species and determine how this transfer of nitrogen differed in response to burning.
“By using the nitrogen tracer in plant materials, we found less burned plant-derived nitrogen was being incorporated by zooplankton, indicating that burning reduced the transfer of nitrogen to higher organisms,” said Wall. “This agreed with other findings, which showed burned treatments had lower carbon dioxide concentrations, greater oxygenation and higher rates of photosynthesis relative to unburned treatments.”
“Burning changes the chemistry of leaves and that affects their cycling through freshwater ecosystems,” said Shurin.
As the influence of burnt matter rose, the experimental ponds shifted in the makeup of their inhabitants. Unburned test ponds displayed species characteristic of aquatic systems such as zooplankton. Ponds with heavy loads of burned material, on the other hand, transformed into havens for insects such as mosquitoes.
“These impacts were shifted by fire treatment,” the researchers noted in their report. “Burning increased the elemental and organic composition of detritus, with cascading effects on ecosystem function.”
Authors of the study include: Christopher Wall (UC San Diego postdoctoral scholar), Cody Spiegel (UC San Diego master's student), Evelyn Diaz (UC San Diego undergraduate student), Cindy Tran (UC San Diego undergraduate student), Alexia Fabiani (UC San Diego PhD student), Taryn Broe (UC San Diego PhD student), Elisabet Perez-Coronel (former UC San Diego postdoctoral scholar), Sara Jackrel (UC San Diego assistant professor), Natalie Mladenov (San Diego State University professor), Celia Symons (UC Irvine professor) and Jonathan Shurin (UC San Diego professor).
The study was supported by the National Science Foundation (award number 2018058).
This story was originally published on the UC San Diego newsroom site. See the original article here: https://today.ucsd.edu/story/wildfires-also-impact-aquatic-ecosystems
- Author: Mary Burich, CLEAR Center
Are cattle a secret weapon for taking on California wildfires?
California's cattle ranchers contribute a significant amount to the region's culture, economy and food supply, but do they also inadvertently help to temper the wildfires that have been plaguing the state? And if so, is it a better alternative – environmentally speaking – to letting grasslands burn?
A new study published in the journal Sustainability delves into the topic, weighing the advantages – and disadvantages – grazing cattle bring to the table. Researchers, including scientists from University of California, Davis and UC Agriculture and Natural Resources, set out to calculate the greenhouse gas emissions of cows consuming vegetation that would otherwise burn in wildfires. Then they estimated the GHG emissions that would result should that forage be untouched and therefore, consumed by fire, eventually comparing the two.
Feeling the burn
Given the severity of California's recent wildfires and the belief they will continue and even escalate in the near future, it's a discussion worth having, said Frank Mitloehner, an expert in animal agriculture and air quality from UC Davis, director of the CLEAR Center and one of the researchers who contributed to the peer-reviewed article.
“Each year from 2010 to 2020, California lost on average 89,000 acres of grassland to wildfires,” said Mitloehner, who is also a Cooperative Extension specialist. “In addition to the obvious disruption and devastation they caused, the fires spewed greenhouse gases and harmful particulate matter such as black carbon into the air and into our atmosphere. Those alone threaten climate health and human well-being.”
A fast and furious gas
Cattle are adept at eliminating herbaceous fuel as they graze. However, at the same time, their specialized digestive system produces methane that is expelled most often in the form of enteric emissions … more commonly known as belches. By way of background, methane is a potent greenhouse gas that warms the atmosphere at 25 times the rate of carbon dioxide over 100 years. But it's only in the atmosphere for 10 to 12 years after it's emitted. Following that, it's broken down into carbon dioxide and water vapor.
For that reason, Mitloehner refers to methane as a “fast and furious” gas. Furious because it warms with a vengeance and fast because it does so for only a short time, especially when compared to carbon dioxide. Furthermore, because of the biogenic carbon cycle, whereby plants extract carbon dioxide from the atmosphere for photosynthesis, the warming of methane and its byproducts can end entirely when it's hydrolyzed and used by plants.
How researchers calculated emissions
In order to determine if grazing, methane-emitting cattle are better for the atmosphere than burning grasslands, Mitloehner and the other researchers employed a method known as “Monte Carlo simulation,” a mathematical technique used by scientists to predict outcomes of an uncertain event.
Looking exclusively at methane emissions, they found it's better to have cows eat vegetation than to have wildfires burn it. Granted, it's only marginally better, but when one considers other advantages of animal agriculture and conversely, other disadvantages of widespread, uncontrolled fire, the conversation suddenly shifts.
“Even if cattle provided no other benefit to us, which certainly is not true, we can now make the case that they are helpful to us in yet another way,” Mitloehner said.
Friends or foes?
It goes without saying that one would be hard pressed to find much good to say about wildfires, but that doesn't hold true for animal agriculture. The industry provides jobs and supports the economy in other ways as well. Plus, it is a major source of protein-rich food that is in increasing demand as the world's population continues on a trajectory toward 10 billion people by the year 2050.
Where global warming is concerned, the industry is in the unique position of being able to reach net-zero warming, also known as climate neutrality, if it continues to aggressively chip away at its methane emissions, which Mitloehner asserts is of critical importance to the planet. “Few other sectors can reduce its warming to net zero and still be of service to society, but agriculture can because of the way methane behaves in the atmosphere,” he said.
To be clear, grazing cows are no match for wildfires. Yet, in addition to everything else the sector does for us, slowing the burn and keeping relatively more methane from entering the atmosphere are not nothing.
In addition to Mitloehner, authors of the study are Cooperative Extension advisors Sheila Barry, Devii Rao and Theresa Becchetti; Rowan Peterson, Ermias Kebreab and Minju Jung of UC Davis; and Felix Ratcliff and Kaveh Motamed of LD Ford.
This article was first published on the website of the CLEAR (Clarity and Leadership for Environmental Awareness and Research) Center at UC Davis./h3>/h3>/h3>/h3>/h3>
- Author: Daniel K Macon
There's still time to register for our first-ever Sierra Foothills Rancher's Fire Academy! We'll be covering topics like using prescribed fire to control rangeland weeds, planning your own prescribed fire, fire tool basics, ranching hardening, and managing livestock during wildfire. You'll learn from local and regional fire experts, UC researchers, and from your fellow ranchers! Each session is just $10 per ranch (with up to four people from each ranch eligible to participate)!