- Author: Dr. Cameron Barrows
- Editor: Eliot Freutel
A blog re-post from our Lead Scientist Dr. Cameron Barrows on the importance of preserving those organisms that are at the core of each ecosystem, using Joshua Trees (Yucca brevifolia) as an example.
“We should preserve every scrap of biodiversity as priceless while we learn to use it and come to understand what it means to humanity.” – E.O. Wilson
“Important” is a word we use to indicate something has value. The problem with “important” as an adjective within a context of science or natural history is that the value being ascribed to that something is subjective, that value is in the eyes of the beholder, and has no context with regard to a comparison with other “somethings”. I was recently asked to describe the ecological importance of Joshua trees and realized that if I stuck to that criteria how subjective that description would be, and as such, not terribly valuable. Were Joshua trees more or less ecologically important than creosote bushes or ironwood trees? I decided to redefine my assignment and ask the question of what would change if Joshua trees were suddenly gone? This is where a solid framework in natural history is essential. Imagining the changes wrought if a species was suddenly absent, plucked from the landscape within which it occurs, requires understanding what interrelationships that species has with other species, and how strong or essential those interrelationships are.
To understand what would change if a species suddenly disappeared, I first imagine that species as the hub of a wheel, with connections to other species as spokes of that wheel. Think about the “experiment” European colonists have been engaged ever since their arrival in North America: the elimination of wolves and coyotes from the North American landscape. If wolves and coyotes are at the hub my wheel, the spokes are the many prey species the wolves and coyotes eat. Remove wolves and coyotes and all those prey items become more abundant. If all those prey species become more abundant, the plants they eat become less abundant. Some of those plants are important to songbirds, so songbirds become less abundant. Some of those plants might be important to humans, the crops we eat or what our livestock eat, and so our food supply might become at risk. The superabundance of those prey species may only be temporary since their populations will grow until they reach a limit in their food supply, then starvation and disease will limit their growth. However, before then, the lack of plants could lead to higher rates of soil erosion and limit vegetation recovery. All these outcomes have already happened. Perhaps our experiment was not such a good idea.
Putting Joshua trees at the hub of a species wheel, the spokes are the multitude of species that use or depend on these Mojave Desert icons. One is the Joshua tree's primary pollinator a diminutive moth, Tegeticula antithetica, and another is a beetle, Sycophorus yuccae. Lose the Joshua tree and one or both of these insect species may go extinct. The beetle's larvae burrow into the stems and trunks of Joshua trees, which may not be ideal for the Joshua trees, but those larvae are important food for ladder-backed woodpeckers. Lose the Joshua tree and the woodpeckers may abandon the Mojave Desert. There is a long list of other birds, that while all may not depend solely on Joshua trees, their abundance in the Mojave Desert is closely tied to healthy stands of this tree yucca. Scott's orioles, ash-throated flycatchers, cactus wrens (yes, they often nest in cactus, but where cactus are scarce, they use Joshua trees), western screech owls (reusing ladder-backed woodpecker excavated holes), house finches, phainopeplas, loggerheaded shrikes, great-horned owls, ravens, and red-tailed hawks are all obligate or prefer to be tree nesters, and Joshua trees are often the only trees for hundreds of square miles across the Mojave Desert. Lose the Joshua trees and the dawn chorus of birds becomes much quieter. Western fence lizards and desert spiny lizards can be common on rock outcrops and cliff faces, but when boulders are not available both lizards readily occupy Joshua trees and thrive there. Desert night lizards are abundant (at times) living in extended family groups beneath the fallen branches of living Joshua trees, the Joshua trees and their branches providing a cooler-moister microclimate than would otherwise be available and creating a small food web between termites eating decaying cellulose, the night lizards eating the termites, and desert night snakes eating the tiny lizards. I count at least 17 spokes in the wheel surrounding Joshua trees, without even beginning to address the below-ground systems of mycorrhizal fungi and other soil organisms. Another way to characterize this hub and spoke model is as a keystone. Remove the keystone from a stone arch then the arch falls. Remove Joshua trees and the abundance of many Mojave Desert species is reduced or lost altogether.
Joshua trees are sensitive to temperature and aridity, and so climate change represents a real threat to their occurrence within much of their existing distribution. Large swaths of Joshua trees already are showing no signs of successful reproduction, no young seedlings are to be found. For non-naturalists, the still standing forests of only adult trees provide a false perception that all is well, but those standing trees germinated under a very different climate than the one their potential offspring currently face. There are higher elevation populations that are more resistant to climate change, and where seedlings are common, at least so far. Still, those higher elevation populations (as well as those at lower elevations) are also at risk from wildfire which, in deserts where fire was previously exceedingly rare, natural selection has not provided the tools to survive such events.
What would happen if we imagined creosote bushes suddenly disappeared? There are as many as 60 insects associated with creosote bush, including 22 species of bees that feed only on its flowers. Long-tailed brush lizards are most commonly found hiding in the branches of creosotes bushes, and desert iguanas are particularly fond of eating their flowers. Desert tortoises often dig their burrows below these shrubs and rest in the shade offered by creosote bushes. Black-throated sparrows and black-tailed gnatcatchers will nest in the branches of these desert-ubiquitous shrubs. Creosote bushes appear more resilient to the effects of climate change than are Joshua trees. That said, most (not all) of the recruitment I am seeing is happening at higher elevations. At least 65 above ground spokes extend from the creosote bush hub. However, comparing Joshua trees to creosote bushes is no more valid than comparing apples to oranges as they do not share any “spokes”, each encompasses a distinct array of species. One is no “more important” than the other. Rather, these numbers emphasize and underline the often-unappreciated richness and diversity of California's deserts. The numbers also emphasize what may be lost or diminished if these “hubs” are lost. Our deserts are not barren wastelands. That is the important take-home message.
Nullius in verba
Go outside, tip your hat to a chuckwalla (and a cactus), think like a mountain, and be safe.
- Author: Eliot Freutel
Dear California Naturalists and Climate Stewards:
We are pleased to introduce you to the new Volunteer Portal! Over the last year, we've developed a new platform for our naturalists, stewards, and instructors to record, review, and generate reports on their volunteer service. This replaces the UCANR VMS (volunteer management system) and provides new capabilities and will streamline some common processes.
This week, we are transitioning to this new Volunteer Portal and this post provides the information you need to get started in the new system. Here is the link to the new Volunteer Portal. Please use the email address which is associated with your existing VMS profile to ensure that you are matched up with the information we transferred over to the new system.
You should be receiving an invitation via email to create an account for the new portal. If you didn't receive it in your inbox, please be sure to check your spam or junk folders. If you didn't receive the email, here is the link to the new Volunteer Portal (same link as above). This is a multi-phase roll out so we ask for your patience as we add in the hours and information from the previous VMS.
As with any application transition, we may encounter some bugs or errors in the transfer of data. Please know, that we have a team of people working behind the scenes to resolve any issues that arise as quickly as possible. For general questions, please join us for open office hours. We have scheduled office hours (Tuesdays 3:30-4:30 PM; Wednesdays 5:30-6:30 PM; and Fridays 9-10 AM) to answer your questions over the next several weeks (from 2/16 through 3/8). These optional office hours are intended to address general questions and provide general help and information regarding the new Volunteer Portal. Please feel free to drop-in at any time during these hours as your schedule permits.
The link for all these office hours is the same (Join Zoom Meeting: https://ucanr.zoom.us/j/94384448938?pwd=YU9UVHNQVUtrTjZISENLNmwyNGtQZz09; Meeting ID: 943 8444 8938; Passcode: calnat)
We will be producing some simple video tutorials and FAQs on the most basic tasks such as recording hours (or for instructors only, creating a new course and uploading your course participants).
For any pressing issues please reach out to Eliot Freutel (firstname.lastname@example.org), please start the subject line with “Volunteer Portal Help” in the subject line. Please hold all general questions for the open office hours.
The CalNat Program Team
- Author: Eliot Freutel
After 9 years of expanding and improving the California Naturalist program and helping to usher in the UC Climate Stewards course, our Coastal Northern California Community Education Specialist, Brook Gamble, is moving on to a new organization.
Brook has been at the forefront of CalNat's evolution and has molded many of the systems we use to make our program the success it is today. As one of our lead communicators, her success was in large part because she had her finger on the pulse of our community and kept us focused on your needs, interests, and challenges. As the longest standing staff member, she has served as a faithful well of wisdom for our team. While it saddens us to lose such a creative, intelligent, and generous force, we wish for nothing but incredible moments awaiting her on this next adventure.
Please take a moment to share your favorite Brook memories in the comments and join us in a fond farewell as we send her off to incredible things. Thank you for everything, Brook!
- Author: Sabrina L. Drill
The US Global Change Research Program (USGCRP) is hosting a series of public engagement workshops in January and February as part of its Fifth National Climate Assessment “to solicit feedback on climate change-related issues that are important to the public.”
Developing the USGCRP was a key component of the Global Change Research Act of 1990. With representation from 13 federal departments and agencies, the USGCRP's mission is to coordinate “a comprehensive and integrated United States research program which will assist the Nation and the world to understand, assess, predict, and respond to human-induced and natural processes of global change.” Every for years, the Program delivers a National Climate Assessment to congress and the people of the US. From their website, the "NCA is required to a) integrate, evaluate, and interpret the findings of the Program and discuss the scientific uncertainties associated with such findings; b) analyze the effects of global change on the natural environment, agriculture, energy production and use, land and water resources, transportation, human health and welfare, human social systems, and biological diversity; and c) analyze current trends in global change, both human-induced and natural, and project major trends for the subsequent 25 to 100 years."
Work is underway to produce the 5th National Climate Assessment (NCA5).
Thirty public engagement workshops will be held in January and February, beginning January 11th. Workshops are free to attend but registration is required. Each workshop will focus on a different topic or region. Topical sessions are listed below. Go here to see the complete list of Topical and Regional sessions by clicking on NCA5 Engagement Workshops.
February 4 | 10 AM–2:30 PM PT
January 11 | 12 PM–4 PM ET
Ecosystems, Ecosystem Services, and Biodiversity (PDF)
January 12 | 12 PM–4 PM ET
Energy Supply, Delivery, and Demand (PDF)
January 18 | 10 AM–2 PM ET
Sector Interactions, Multiple Stressors, and Complex Systems (PDF)
January 18 | 11 AM–3 PM ET
Land Cover and Land-Use Change (PDF)
January 18 | 11 AM–3 PM ET
Air Quality (PDF)
Jan 18 | 12 PM–4 PM ET
Tribal and Indigenous Peoples (PDF)
January 26 | 12 PM–4 PM ET
Coastal Effects (PDF)
January 28 | 1 PM–5 PM ET
Agriculture, Food Systems, and Rural Communities (PDF)
January 31 | 12 PM–4 PM ET
February 1 | 2 PM –6 PM ET
February 7 | 11 AM–3:30 PM ET
February 7 | 1 PM–5 PM ET
February 9 | 10 AM–2 PM ET
Climate Effects on U.S. International Interests (PDF)
February 9 | 12 PM–4 PM ET
February 11 | 11:30 AM–3 PM ET
Human Health (PDF)
- Author: Cameron Barrows
A "Natural History Note" From UC California Naturalist's lead scientist, Dr. Cameron Barrows.
“It is that range of biodiversity that we must care for - the whole thing - rather than just one or two stars.” – Sir David Attenborough
That range of biodiversity includes the panoply of life occupying a region. Everything from charismatic species (those one or two stars), bighorn sheep, collared lizards, wolves, and mountain lions, to microscopic soil organisms. Everything from diaphanous-winged butterflies and damselflies to the parasitic wasps that keep insect populations from becoming so numerous that they would otherwise consume all plant life on earth. Everything from towering sequoias to pond scum. Those microscopic soil organisms are essential for helping plants convert inorganic minerals to the building blocks of life and for capture moisture in an ever more arid desert. That pond scum is an organic factory converting sunlight and carbon dioxide to oxygen.
In 1798 Thomas Malthus, an English economist, published an essay on the principle of population growth. Malthus' math was elegant, and its conclusion undeniable. In the absence of factors that limit population growth, populations will grow geometrically until some critical food resource was exhausted and then the population would crash into oblivion. Malthus was thinking humans, but his conclusions are applicable to all species. Arguably no other document was as inspirational to both Charles Darwin and Alfred Russel Wallace for their independent development of the Theory of Natural Selection. Malthus' math was clear; based on any species' reproductive capacity, we should be neck-deep in lizards, spiders, voles, wrens, bighorn sheep and coyotes. Obviously, that is not the case, but from those two conclusions, what the math predicted and what we can see with our own eyes, Darwin and Wallace deduced that species underwent a struggle for existence. That struggle included within and between species competition, avoiding predation, parasitism, disease, and natural disasters. That struggle was real and intense enough that only those individuals that could survive those challenges would ultimately survive and pass their genes on to the next generation. So, species are being subjected to an on-going gauntlet of threats, as are the parasites and viruses and predators, ensuring that species do not reach such numbers that their populations would then crash into oblivion.
Aldo Leopold, in his essay “Thinking like a Mountain”, acknowledged that early on he too fell into the trap of valuing species as “good” or “bad”. “Good” species were those charismatic vegetarians like deer and sheep and squirrels. “Bad” species were non-human carnivores, wolves and coyotes and mountain lions. Leopold, in his early years, sought to rid the rangelands of predators to ensure that deer and other “good” species could proliferate. Proliferate they did, so much so that they ate all the available palatable plants, the forests and rangelands were degraded, and the deer began to die of starvation. It was a mistake people have repeated and continue to repeat to this day. Mountain lions and wolves are now gone from eastern North America, and the deer populations have exploded causing widespread starvation and disease. Not long ago I heard a local bighorn sheep biologist celebrate the death of a mountain lion because it meant more sheep would survive, but he did not include the reality that “his” sheep now face hillsides incrementally devoid of palatable food and flowing springs because of climate change.
A few years back I attended a lecture by a young biologist telling of his efforts to explain to cattle ranchers why their animals were faced with food shortages. The ranchers were convinced that the bison, who shared the grasslands with their cattle, had become too abundant and needed to be “culled”. The biologist patiently explained that, based on his analyses, that the bison and cattle were selecting different plants to eat. The ranchers argued back that the bison must be to blame. The biologist again patiently explained that it was not the bison, it was jackrabbits that were competing with their cattle for food. The ranchers stared is silence, trying to identify where the biologist's analysis and logic had been in error. One of the ranchers finally spoke, not to the biologist but to the other ranchers, and said that perhaps they (the ranchers) had been overzealous in killing coyotes. A healthy coyote population would have kept the jackrabbit population from a Malthusian population trajectory, and so would have left sufficient forage for bison, jackrabbits, and the ranchers' cattle. Attenborough's call for to care for and protect biodiversity, all species (including humans), is the only sane path forward.