- Author: Trina Kleist
- Posted by: Gale Perez
Auto emissions 'fertilize' fuel
Joshua trees burning in the Mojave Desert are the victims of changing patterns of wildfire, fueled by the spread of grasses that are not native to the region, restoration ecologist Justin Valliere told media in recent interviews.
Valliere, who specializes in the impacts of invasive grasses, drew the links connecting non-native invaders, air pollution and the existential threat fire now poses to the beloved trees.
“Invasive grasses in the Mojave Desert are completely altering the fire regime there… and leading to more frequent fires,” Valliere told the Washington Post.
Non-native grasses already have spread across large swaths of southern California. One factor sparking their growth, including in parts of the Mojave, is air pollution from populated areas. Emissions from cars and trucks contain nitrogen, which is like fertilizer that floats into the air, then dumps all over the landscape, Valliere told radio station KPCC-FM, part of Southern California Public Radio.
Nitrogen pollution “might seem like a good thing, but a lot of research, including my own, has shown that it really favors these invasive species over native species,” Valliere told the radio host.
The non-native grasses are tough and don't break down as quickly as native flowers. “They dry out really quickly in spring and summer… (creating) this continuous fuel bed across landscapes,” Valliere continued. “They catch fire really easily, then they carry fire very well” from tree to tree.
While air pollution "fertilizer" probably is not a major factor in the York Fire, due to its location, nitrogen does contribute to fire danger in other parts of the Mojave and elsewhere in the state. "Invasive grasses do very well in areas without nitrogen deposition, too, but where nitrogen does blow in, it makes their impacts even greater," Valliere explained.
Invasive grasses are “just so widespread at this point that there's no way we're ever going to eradicate them,” Valliere said. “We need to focus our efforts on really sensitive areas or areas where we're trying to restore native vegetation after a disturbance like a fire.”
Related links
Valliere has spent years researching native landscapes and how to restore them in southern California. He now is an assistant professor of UC Cooperative Extension, specializing in landscape restoration.
The York Fire was contained on Aug. 20, after burning more than 93,000 acres in southern California and Nevada. Three years ago, the nearby Dome Fire scorched more than 43,000 acres and killed an estimated 1.3 million Joshua trees, the U.S. National Park Service reported.
Read Valliere's comments in the Washington Post article, “Wild, weird and iconic, California's Joshua trees face a new threat: fire."
Listen to Valliere's comments in the podcast, "Wildfires are threatening beloved Joshua trees in the Mojave Desert," by KPCC-FM radio, a member of Southern California Public Radio.
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From the UC Davis • Dept. of Plant Sciences website • News: Sept. 1, 2023
Trina Kleist is the Communications Specialist for the Dept. of Plant Sciences at UC Davis. Her contact information is tkleist@ucdavis.edu, (530) 754-6148 or (530) 601-6846.
- Author: Trina Kleist
- Posted by: Gale Perez
It all started with pumpkin seeds
Justin Valliere has been hired to expand the Department of Plant Sciences' reach in the fields of invasion and restoration ecology. Valliere started as an assistant professor of UC Cooperative Extension in July.
Valliere seeks ways to restore California's native plant communities amid the onslaught of invasive plants and a range of environmental changes. He thinks it's important to bring youngsters into the research world, training them to care about nature and inspiring them to form the next generation of restoration professionals. Cooperative Extension offers a great way to combine these threads into a network that can be cast across the state and used as a model elsewhere, Valliere said.
He hopes to enhance restoration efforts statewide, enthused by the progress of his most recent projects in southern California's Mojave Desert and Santa Monica Mountains. His work includes the impacts of automotive emissions (they add nitrogen to the biological system, while making it less tolerant of drought), and the results of mowing non-native, invasive grasses (it reduced non-native grass cover and led to a slight increase in native bunchgrass).
“California has huge amount of ecosystem diversity,” Valliere explained. “CE already is such an effective system for supporting agriculture, but it's also an important model for natural resource management and restoration… There is a real need for help advising folks through-out the state about managing and restoring natural lands, and I'm excited to help bolster that.”
That's because natural lands and native ecosystems help both agriculture and urban areas. “Native plants serve all kinds of critical functions for people's well-being as well as for agriculture,” Valliere said. “Native plants sustain pollinators, they help provide clean water, they improve soil quality.”
Get the kids involved
Valliere grew up in a small town in rural Massachusetts, where the whole family worked in the vegetable garden. He conducted his first experiment at the age of seven or eight, he recalled: The family dug a new well, and he was fascinated by the soil brought up from the deep. How would pumpkin seeds grow in that mysterious muck compared to the surface soil of the garden? “They barely grew at all,” Valliere continued with a laugh. “That was my very first time I realized, ‘Wow, soil is really important for plant growth!'”
As a teen, he participated in the local 4-H program. His passion was pressing plants. Though a lot of them were weeds come over from Europe, he didn't yet know the difference, and if the judges at the county fair did, they didn't mind. His collections won blue ribbons.
By high school, Valliere got involved with removing invasive plants. “Even in my lifetime, I've seen them taking over the forests of New England,” he said ruefully. “Invasive species was one of the things that really hooked me.”
Those experiences also shaped his appreciation for environmental education programs that involve kids. Combining such programs with research, management and restoration could be a creative solution to educational challenges in California, plus strengthen the pipeline for future professionals in restoration and management, Valliere said.
He brings his expertise after teaching most recently at California State University Dominguez Hills. Valliere earned a bachelor's degree in biology from Green Mountain College in Vermont and a doctoral degree in plant biology from the University of California, Riverside. He worked as a postdoctoral fellow at the La Kretz Center for California Conservation Science at UC Los Angeles; and as a research fellow at the University of Western Australia.
Related links
Check out the Valliere Applied Plant Ecology Lab website, focused on how to restore treasured landscapes in a changing world.
Valliere's publications are listed here.
Valliere on being a scientist and gay: UC's queer climate scientists on making science as diverse as the natural world
Original source: UC Davis Department of Plant Sciences News, August 25, 2023
California Invasive Species Week is June 3-11. This is the perfect time to raise awareness about the impact of invasive plants on our natural ecosystems and the importance of making informed plant choices. Invasive species can have detrimental effects on local flora and fauna, often outcompeting other plants for resources and disrupting local ecosystems.
By selecting plants that are well-suited to your environment and not invasive, you can make a positive contribution to preserving California's diverse landscapes. Many invasive plants can be aesthetically pleasing and low-maintenance, making them a popular choice for gardeners. However, invasive plants can spread rapidly, taking over natural habitats and causing significant environmental damage. Invasive species often have few natural predators, enabling them to grow uncontrollably and outcompete other plants for resources like water, sunlight, and nutrients. This can lead to the loss of biodiversity, reduced habitat quality for wildlife, and increased risk of erosion and wildfires.
Examples of Invasive Plants in California:
1. Periwinkle (Vinca major)-This evergreen groundcover is a popular species because of its beautiful purple blooms. Periwinkleforms dense mats that can smother native plants and alter soil chemistry. Instead of periwinkle, try planting native groundcovers like California lilac (Ceanothus spp.) or hummingbird sage (Salvia spathacea).
2. Fountain grass (Pennisetum setaceum)-This ornamental grass is highly adaptable and has invaded many natural habitats, including grasslands and coastal sage scrub. Instead, opt for native grasses like purple needlegrass (Stipa pulchra) or deergrass (Muhlenbergia rigens) or the smaller version (Muhlenbergia dubia).
3. Pampas grass (Cortaderia selloana)-A tall, clumping grass with feathery blooms that can quickly dominate landscapes and outcompete native species. Consider planting native ornamental grasses such as blue grama grass (Bouteloua gracilis) or switchgrass (Panicum virgatum) as alternatives to pampas grass.
4. Tree of heaven (Ailanthus altissima)-This fast-growing tree can release chemicals that inhibit the growth of other plants and can sprout vigorously from root fragments. Plant California native trees like sycamore (Platanus racemosa) or western redbud (Cercis occidentalis) instead of the invasive tree of heaven.
Celebrate Invasive Species Week!
Additional Resources:
organization dedicated to protecting California's wildlands from invasive plants through
research, restoration, and education.
•California Native Plant Society (CNPS)-https://www.cnps.org/-CNPS is a non-profit
organization that promotes the understanding and appreciation of California's native plants and
preserves them in their natural habitat.
•PlantRight-https://plantright.org/-PlantRight works with California's nursey industry to keep
invasive plants out of our landscapes and promotes the sale of non-invasive alternatives.
- Author: Randall Oliver
Reposted from UC ANR news
Early detection increases the chances of eradicating pests
Trees provide shade to keep us cool, produce oxygen for us to breathe and calm our nerves. Numerous studies have demonstrated that even brief contact with trees and green spaces can provide significant human health benefits such as reductions in blood pressure and stress-related hormones. Trees also reduce noise and visual pollution, help manage storm water runoff, reduce erosion and provide habitat for birds and wildlife. Trees naturally capture carbon, helping to offset the forces of climate change. They also increase the value of our properties and communities. In short, trees are essential to our well-being.
Unfortunately, invasive pests pose an ongoing threat to California's forests in both urban and wildland settings. Invasive insects such as goldspotted oak borer and invasive shothole borers have killed hundreds of thousands of trees in Southern California and are continuing to spread. Meanwhile, other pests and diseases such as Mediterranean oak borer and sudden oak death are killing trees in Northern California.
While the situation may sound dire, it is not hopeless. Of course, the best way to stop invasive pests is to prevent them from entering the state, as the California Department of Food and Agriculture has done on many occasions. For example, several months ago, CDFA border inspectors seized a load of firewood containing spotted lanternfly eggs (a pest that is causing extensive damage on the East Coast). When pests do sneak in, the next defense is to catch them early before they become established. Finally, even if pests do become established, they can be managed if not completely eradicated.
A few examples may help to illustrate why invasive tree pests deserve action, but not panic.
Red striped palm weevil eradicated in Laguna Beach
When red striped palm weevil, a highly destructive palm pest native to Indonesia, was discovered in Laguna Beach in October 2010, a working group was quickly formed to develop a management plan. The small but diverse group included international palm weevil experts, research scientists from University of California Riverside, CDFA and U.S. Department of Agriculture, UC Cooperative Extension personnel from San Diego, Orange and Los Angeles counties and county entomologists from the agricultural commissioner's offices in Orange and San Diego counties.
The resulting response included a pheromone-based trapping program, public advisory and targeted insecticide treatments. Within two years, additional trapping and inspections could not find any signs of continued infestations. Early detection was key to the success: the infestation in Laguna Beach was identified early, so the weevil population was still relatively small. In addition, Laguna Beach is geographically isolated, the local climate is much cooler than the weevil's place of origin, and the eradication effort was well funded by state and federal agencies. Eliminating invasive pests where such conditions are not present may prove more difficult.
Invasive shothole borers attack Disneyland
The Disneyland Resort in Anaheim contains 16,000 trees and over 680 different tree species. When park officials identified an infestation by invasive shothole borers in 2016, their initial attempts at vanquishing the insects with pesticides produced mixed results. Then, they consulted with experts from UC Riverside and UC Cooperative Extension and together designed and followed an integrated pest management program that included monthly ground surveys, a trapping program that helped to detect infestation hot spots and find and remove the source of beetles, and occasional pesticide treatments on selected trees. The park went from a large number of beetles in 2017 to very low levels today. There are still some beetles, but resulting damage is extremely low, and although monitoring programs continue, the park's landscape team has been able to turn its focus elsewhere.
Goldspotted oak borer spotted in Weir Canyon
When goldspotted oak borer was confirmed in Orange County's Weir Canyon in 2014, a team from Irvine Ranch Conservancy, the organization that manages the area on behalf of Orange County Parks, sprang into action. UC Cooperative Extension and the US Forest Service assisted IRC in developing a management program, and over the ensuing years, IRC has actively collaborated with OC Parks, The Nature Conservancy, OC Fire Authority, and CAL FIRE to control the existing infestation and stop its spread. IRC has surveyed the oaks in the area yearly to monitor the infestation and guide each year's management actions.
To reduce the spread of the infestation, IRC removed more than 100 severely infested oaks in the first few years of management (no severely infested oaks have been found in the last few years of surveys). Additionally, more than 3,000 tree trunks have been sprayed annually in the late spring to kill emerging adult beetles and newly hatched offspring.
In the most recent survey of the oaks in Weir Canyon, the IRC team found only 12 trees with new exit holes, and most of those had just one to two exit holes per tree, which is an extremely low number. With the situation well under control, IRC is now considering modifying its annual spraying program and adapting other less aggressive treatment options. Finally, IRC has been actively planting acorns to mitigate losses due to the removals as well as the Canyon 2 Fire of 2016.
As these brief examples demonstrate, insect pest infestations can be managed or even eradicated if caught early enough. Early detection not only increases the chances of success, but also minimizes the cost of pest management efforts.
What you can do to prevent infestation
While management actions will vary depending on the insect or disease, species of tree and location, there are a few steps that will lead to greater success in fighting tree pests and diseases.
- Keep your trees healthy. Proper irrigation and maintenance go a long way toward keeping trees strong and resistant to pests and diseases.
- Check your trees early and often for signs and symptoms of tree pests and diseases. These may include entry/exit holes, staining, gumming, sugary build-ups, sawdust-like excretions, and branch or canopy dieback. Use available tools like the UC IPM website to determine probable causes of the problems.
- Talk with experts (arborists, pest control advisers, researchers and advisors from the University of California and other institutions), and report pest findings to your county Agricultural Commissioner.
- Evaluate the extent of tree damage and determine a management plan. Remove severely infested branches and trees that may be a source of insect pests that can attack other trees.
- Properly manage infested wood and green waste. Chip wood and other plant materials as small as possible. Solarization or composting can further increase the effectiveness of chipping. It is generally best to keep those materials close to where they originated, but if you absolutely need to move them, first make sure the facility where they will be sent is equipped to process them. Always tightly cover materials while in transit. If working with a tree care professional, insist that proper disposal is part of the job requirements.
- Many invasive tree pests can survive in down wood for long periods. When buying or collecting firewood, always obtain it as close as possible to where you are going to burn it and leave leftover firewood in place.
- Author: Anne E Schellman
Why Not Move Firewood?
By bringing wood from home, you can unknowingly spread invasive pests and diseases that can harm trees. This includes dry, aged, and seasoned wood. Once you arrive at your destination, pests can emerge from the firewood and spread to the trees and forests where you camp. Invasive and hard-to-control pests kill several million native trees every year, causing environmental and economic problems.
Did you Know?
New infestations of tree-killing insects and diseases are often found in campgrounds and parks as a result of campers moving firewood!
This trip, tell your friends and family why you aren't bringing firewood. For more information about firewood pests and resources for finding good firewood, visit the Don't Move Firewood web site. To learn about many of the invasive wood-boring pests and associated diseases and problems, visit the UC IPM web site.
First posted on August 30, 2021
Anne Schellman has been the Coordinator for the Stanislaus County Master Gardeners since 2018.
