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Written by: Karen Sullivan, Kim Riley and Terre Logsdon

Published: 25 April 2021

LAKE COUNTY, Calif. – There are some plants (just like people and other animals) that just do better when they grow together and such is the case with buck brush and fawn lilies, two great friends that often grow together because it may be beneficial to both.

It’s not an exclusive relationship, but buck brush (Ceanothus cuneatus) provides the shade that the California Fawn Lilly (Erythronium californiacum) likes, so they are oftentimes found growing and blooming together.

One of the most widespread native plants in California, buck brush, as you might guess by it’s common name, is a food source for deer and is found throughout California and particularly in chaparral landscapes, growing to about 9 feet tall and covered with clusters of small white flowers in April and May here in Lake County.

Dotting the hillsides with the pretty white bush, you can be sure of your ID as no other California native in Lake County presents itself in this way and if you're lucky enough to be hiking a trail while it is blooming, you'll enjoy a beautiful scent welcoming spring!

After flowering, seeds of the buckbrush are, “dispersed when the capsule explodes and propels them some distance. Harvester ants have been known to cache the seeds, which can lie dormant for a long time since fire is required for germination,” according to the California Native Plant Society.

Oftentimes you will find the spectacular fawnlily growing under and nearby buck brush on singular stalks, with one to three flowers each that range from six to 12 inches tall that typically begin blooming just before buck brush, and seeing these two in bloom together is a treat for both your eyes and nose!

Nurseries where you can purchase seeds/starts:
California Fawn Lilly: https://calscape.org/nurseries.php?id=1583&showmap=1 
Buck Brush: https://calscape.org/nurseries.php?id=871&showmap=1 

Terre Logsdon is an environmentalist, certified master composter, and advocate for agroecology solutions to farming. An avid fan and protector of California wildflowers, plants, natural resources, and the environment, she seeks collaborative solutions to mitigate the effects of climate change. Kim Riley is retired, an avid hiker at Highland Springs, and has lived in Lake County since 1985. After 15 years of trail recovery and maintenance on the Highland Springs trails, she is now focused on native plants, including a native plant and pollinator garden on her property as well as promoting and preserving the beauty of the Highland Springs Recreation Area. Karen Sullivan has operated two nurseries to propagate and cultivate native plants and wildflowers, has lived in Kelseyville for the past 30 years, rides horses far and wide to see as many flowers as possible, and offers native plants and wildflowers for sale to the public. You can check her nursery stock here. They are collaborating on a book, Highland Springs Recreation Area: A Field Guide, which will be published in the future. In the meanwhile, please visit https://www.facebook.com/HighlandSpringsNaturalists and https://www.facebook.com/HighlandSpringsRecreationArea.

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Written by: Ryan Wiser, Lawrence Berkeley National Laboratory; Bentham Paulos, Lawrence Berkeley National Laboratory; Dev Millstein, Lawrence Berkeley National Laboratory, and Joseph Rand, Lawrence Berkeley National Laboratory

Published: 25 April 2021

 

Renewable energy’s rapid growth is accelerating a national shift to a carbon-free electric power system.

So far 17 states plus Washington, D.C., and Puerto Rico have adopted laws or executive orders setting goals for reaching 100% clean electricity by 2050 or sooner. And 46 U.S. utilities have pledged to go carbon-free. Now the Biden administration and some members of Congress are proposing to decarbonize the power sector by 2035.

While this much change in 15 years seems ambitious, our new report, “Halfway to Zero,” looks back at the past 15 and finds that power sector emissions are half of what they were projected to be.

We analyzed the “business as usual” projection in the 2005 Annual Energy Outlook published by the Energy Information Administration, the U.S. government’s official agency for data collection and analysis. It projected that annual carbon dioxide emissions from the electric power sector would rise from 2,400 million to 3,000 million metric tons from 2005 to 2020.

Instead, they fell to 1,450 million metric tons – 52% below projected levels. In short, the U.S. electricity sector has managed to march halfway to zero in just 15 years.

Cleaner fuels and more efficient devices

This drop happened thanks to policy, market and technology drivers.

Overall demand for electricity in 2020 was almost exactly the same as in 2005, and 24% lower than projected by federal energy forecasters. This was due partly to economic changes, such as lower economic growth from two recessions and slightly lower population growth.

The U.S. has also become more energy efficient since 2005, thanks to policies and technology improvements. Many devices that power our lives, such as LED lights, get more performance from a kilowatt-hour of electricity now than they did 15 years ago.

Wind and solar power dramatically outperformed expectations, delivering 13 times more generation in 2020 than projected. Emission-free nuclear generation largely held steady.

Finally, natural gas generation grew rapidly, driven by the shale gas revolution and low fuel prices. This pushed much of the generation of coal – the most carbon-intensive electricity source – out of the market.

These shifts have delivered many benefits. Total electric bills for consumers were 18% lower in 2020 than the Energy Information Administration had previously projected, saving households US$86 billion per year.

Reduced sulfur and nitrogen emissions, especially from less coal generation, led to a steep drop in such health impacts as respiratory disease. Premature deaths due to power-sector air pollution fell from 38,000 to 3,100 per year. And declining employment in the coal industry was more than offset by job growth in other areas, notably solar power.

The other 50%

Many assessments of energy transitions assert that it takes decades for societies to shift fully from one energy source to another. But our study shows that dramatic changes in emissions can happen much more quickly.

This doesn’t guarantee that getting to zero will be easy, though.

Wind, solar and battery technologies will be central to further decarbonization. Accelerating their deployment will require a laser focus on maintaining reliability, with new transmission lines and changes to power-system planning and operations. It will also call for careful attention to ecological impacts and heightened sensitivity to effects on workers and communities.

Fortunately, much of the generation and storage needed to hit a zero-carbon target is already in development. Developers have requested access to the transmission grid for 660 gigawatts of new wind and solar generating capacity and 200 gigawatts of storage. That represents more than half of what could be required. Not all proposed projects will be built, but the scale indicates tremendous commercial interest.

Using this much wind and solar raises the question of how to meet the last portion of demand on cloudy or windless days. Many technologies could fill this gap, such as longer-duration storage, hydrogen or synthetic fuels, fossil or biomass generation with carbon capture, advanced nuclear power, and geothermal energy. All require more research.

Our study offers two central lessons as the nation moves forward. First, policy and technology are both key to cutting emissions. Second, our ability to predict the future is limited. It will be crucial to adapt as government agencies and power companies gain policy experience, and technologies advance in unexpected ways.

[Deep knowledge, daily. Sign up for The Conversation’s newsletter.]

Ryan Wiser, Senior Scientist, Lawrence Berkeley National Laboratory; Bentham Paulos, Affiliate, Electricity Markets & Policy Group, Lawrence Berkeley National Laboratory; Dev Millstein, Reesearch Scientist, Lawrence Berkeley National Laboratory, and Joseph Rand, Senior Scientific Engineering Associate, Lawrence Berkeley National Laboratory

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Written by: Robert Sanders

Published: 25 April 2021

How many Tyrannosaurus rexes roamed North America during the Cretaceous period?

That's a question Charles Marshall pestered his paleontologist colleagues with for years until he finally teamed up with his students to find an answer.

What the team found, published this month in the journal Science, is that about 20,000 adult T. rexes probably lived at any one time, give or take a factor of 10, which is in the ballpark of what most of his colleagues guessed.

What few paleontologists had fully grasped, he said, including himself, is that this means that some 2.5 billion lived and died over the approximately 2 1/2 million years the dinosaur walked the earth.

Until now, no one has been able to compute population numbers for long-extinct animals, and George Gaylord Simpson, one of the most influential paleontologists of the last century, felt that it couldn't be done.

Marshall, director of the University of California Museum of Paleontology, the Philip Sandford Boone Chair in Paleontology and a UC Berkeley professor of integrative biology and of earth and planetary science, was also surprised that such a calculation was possible.

"The project just started off as a lark, in a way," he said. "When I hold a fossil in my hand, I can’t help wondering at the improbability that this very beast was alive millions of years ago, and here I am holding part of its skeleton — it seems so improbable. The question just kept popping into my head, 'Just how improbable is it? Is it one in a thousand, one in a million, one in a billion?' And then I began to realize that maybe we can actually estimate how many were alive, and thus, that I could answer that question."

Marshall is quick to point out that the uncertainties in the estimates are large. While the population of T. rexes was most likely 20,000 adults at any given time, the 95% confidence range — the population range within which there's a 95% chance that the real number lies — is from 1,300 to 328,000 individuals. Thus, the total number of individuals that existed over the lifetime of the species could have been anywhere from 140 million to 42 billion.

"As Simpson observed, it is very hard to make quantitative estimates with the fossil record," he said. "In our study, we focused in developing robust constraints on the variables we needed to make our calculations, rather than on focusing on making best estimates, per se."

He and his team then used Monte Carlo computer simulation to determine how the uncertainties in the data translated into uncertainties in the results.

The greatest uncertainty in these numbers, Marshall said, centers around questions about the exact nature of the dinosaur's ecology, including how warm-blooded T. rex was.

The study relies on data published by John Damuth of UC Santa Barbara that relates body mass to population density for living animals, a relationship known as Damuth’s Law.

While the relationship is strong, he said, ecological differences result in large variations in population densities for animals with the same physiology and ecological niche.

For example, jaguars and hyenas are about the same size, but hyenas are found in their habitat at a density 50 times greater than the density of jaguars in their habitat.

"Our calculations depend on this relationship for living animals between their body mass and their population density, but the uncertainty in the relationship spans about two orders of magnitude," Marshall said. "Surprisingly, then, the uncertainty in our estimates is dominated by this ecological variability and not from the uncertainty in the paleontological data we used."

As part of the calculations, Marshall chose to treat T. rex as a predator with energy requirements halfway between those of a lion and a Komodo dragon, the largest lizard on Earth.

The issue of T. rex's place in the ecosystem led Marshall and his team to ignore juvenile T. rexes, which are underrepresented in the fossil record and may, in fact, have lived apart from adults and pursued different prey.

As T. rex crossed into maturity, its jaws became stronger by an order of magnitude, enabling it to crush bone. This suggests that juveniles and adults ate different prey and were almost like different predator species.

This possibility is supported by a recent study, led by evolutionary biologist Felicia Smith of the University of New Mexico, which hypothesized that the absence of medium-size predators alongside the massive predatory T. rex during the late Cretaceous was because juvenile T. rex filled that ecological niche.

What the fossils tell us

The UC Berkeley scientists mined the scientific literature and the expertise of colleagues for data they used to estimate that the likely age at sexual maturity of a T. rex was 15.5 years; its maximum lifespan was probably into its late 20s; and its average body mass as an adult — its so-called ecological body mass, — was about 5,200 kilograms, or 5.2 tons.

They also used data on how quickly T. rexes grew over their life span: They had a growth spurt around sexual maturity and could grow to weigh about 7,000 kilograms, or 7 tons.

From these estimates, they also calculated that each generation lasted about 19 years, and that the average population density was about one dinosaur for every 100 square kilometers.

Then, estimating that the total geographic range of T. rex was about 2.3 million square kilometers, and that the species survived for roughly 2 1/2 million years, they calculated a standing population size of 20,000. Over a total of about 127,000 generations that the species lived, that translates to about 2.5 billion individuals overall.

With such a large number of post-juvenile dinosaurs over the history of the species, not to mention the juveniles that were presumably more numerous, where did all those bones go? What proportion of these individuals have been discovered by paleontologists? To date, fewer than 100 T. rex individuals have been found, many represented by a single fossilized bone.

"There are about 32 relatively well-preserved, post-juvenile T. rexes in public museums today," he said. "Of all the post-juvenile adults that ever lived, this means we have about one in 80 million of them."

“If we restrict our analysis of the fossil recovery rate to where T. rex fossils are most common, a portion of the famous Hell Creek Formation in Montana, we estimate we have recovered about one in 16,000 of the T. rexes that lived in that region over that time interval that the rocks were deposited," he added. "We were surprised by this number; this fossil record has a much higher representation of the living than I first guessed. It could be as good as one in a 1,000, if hardly any lived there, or it could be as low as one in a quarter million, given the uncertainties in the estimated population densities of the beast.”

Marshall expects his colleagues will quibble with many, if not most, of the numbers, but he believes that his calculational framework for estimating extinct populations will stand and be useful for estimating populations of other fossilized creatures.

"In some ways, this has been a paleontological exercise in how much we can know, and how we go about knowing it," he said. "It's surprising how much we actually know about these dinosaurs and, from that, how much more we can compute. Our knowledge of T. rex has expanded so greatly in the past few decades thanks to more fossils, more ways of analyzing them and better ways of integrating information over the multiple fossils known."

The framework, which the researchers have made available as computer code, also lays the foundation for estimating how many species paleontologists might have missed when excavating for fossils, he said.

"With these numbers, we can start to estimate how many short-lived, geographically specialized species we might be missing in the fossil record," he said. "This may be a way of beginning to quantify what we don’t know."

Marshall's co-authors are UC Berkeley undergraduate Connor Wilson and graduate students Daniel Latorre, Tanner Frank, Katherine Magoulick, Joshua Zimmt and Ashley Poust, who is now a postdoctoral fellow at the San Diego Natural History Museum.

Robert Sanders writes for the UC Berkeley News Center.