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Is it possible to have too many trees?
Thinning forests in the Western United States can save billions of gallons of water per year and improve conservation efforts.
- Recent research indicates that dense forests in the Sierra Nevada drain billions of gallons of water from the watershed each year.
- Unusually dense tree stands degrade the vitality of the land, plants, animals, and even the trees.
- Experts recommend managing forest restoration through controlled fires and the thinning of small, fire-prone trees.
Many people view trees as an unassailable good. We learned about their ecological importance every Earth Day. In-between after-school cartoons, public service announcements told us trees were our friends. Celebrities like John Denver sang that trees weren't just essential for our future but America's, too.
The assumption was as clear as it was unspoken: If one tree is good, two trees are better, and 20 trees better still. But that's not proving the case in California's Sierra Nevada forests, where too many trees may threaten the state's ecological stability.
Too many trees, too little water
Restored Sierra Nevada forest stands in the foreground with unthinned forest in the background.
Roughly 60 percent of California's consumable water comes from the Sierra Nevada watersheds, which is why the mountains are nicknamed California's water towers. This mountain range collects snowpack at its higher elevations during the cold winter. Come spring and summer, this snowpack melts and travels into streams, rivers, and underground springs before flowing into the valleys below.
But according to the National Science Foundation (NSF), forested areas in the Sierra Nevada with a surfeit of trees are draining the state's water at an untenable rate.
Trees consume a lot of water to survive. To slake their biological thirst, some species, such as conifers, can extend their roots as far down as 15 meters to access deep-soil water. Once consumed, the water moves up their trunks and into the leaves where it escapes into the atmosphere through tiny pores. This process, called evapotranspiration, removes water from the watershed and renders it inaccessible until it returns as rainfall.
It's inherently a natural process; however, excessive evapotranspiration can stress an area's vital water resources, especially during prolonged droughts.
Researchers at the NSF's South Sierra Critical Zone Observatory looked at water loss from evapotranspiration using data from measurement towers and satellites. They found that forests naturally thinned by wildfires saved billions of gallons of water. From 1990 to 2008, California's Kings River Basin saved 3.7 billion gallons of water annually thanks to its fire-thinned forests. The American River Basin saved 17 billion gallons per year during the same period. Their research was published in Ecohydrology last year.
"Forest wildfires are often considered disasters," Richard Yuretich, director of the NSF's South Sierra Critical Zone Observatory, which funded the research, said in a release. "But fire is part of healthy forest ecosystems. By thinning out trees, fires can reduce water stress in forests and ease water shortages during droughts. And by reducing the water used by plants, more rainfall flows into rivers and accumulates in groundwater."
According to the researchers, "the total effect of wildfires over a 20-year period suggests that forest thinning could increase water flow from Sierra Nevada watersheds by as much as 10 percent."
Through effective forest husbandry, water gains could potentially extend nationwide, but the task is immense. Citing U.S. Forest Service data, the researchers note that 58 million acres of forest require restoration nationally. The costs? An estimated $5 to $10 billion for California alone.
The costs of being (too) green
The Rim Fire of the Stanislaus National Forest, Sierra Nevada, Cali. Suppression efforts cost more than $127 million.
A recent study published in Nature Geoscience suggests people won't be the only benefactors of thinner Sierra Nevada forests. The tress will profit, too.
Researchers from the University of California, Irvine, and UC Merced used field and remote sensing observations to examine tree communities in the mountain range. Focusing on the disastrous 2012–15 dry-spell, they attempted to suss out the causes of the area's widespread tree death. In addition to the below-average rainfall and above-average temperatures, the researchers also noted the "unusually dense vegetation."
Because of the heat-density combination, trees accelerated evapotranspiration and drew more water from the ground than was replenished, resulting in the die-off. Trees at lower elevations were hit the hardest.
"We expect climate change to further amplify evapotranspiration and ground moisture overdraft during drought," Michael Goulden, UCI professor of Earth system science and the study's co-author, said in a release. "This effect could result in a 15 to 20 percent increase in tree death during drought for each additional degree of warming."
As one expects, an unhealthy community of trees ripples out to create an unhealthy environment for all. As Jamie Workman, writer for the Environmental Defense Fund, points out in an op-ed:
"Metastasizing native tree growth also physically alters the temperature, chemistry and biology of the landscape. It crowds out indigenous plant and animal species. Shade tolerant species take over. Deprived of low-intensity, naturally occurring fires, aspen, lupine, sequoia and fireweed can't reproduce. Deer lose edge habitat. Threatened owls and raptors can't navigate through increasingly dense thickets."
When the inevitable forest fire does occur, Workman adds, it burns hotter, longer and faster. These conflagrations cost more, either as dollars spent to suppress them or lost land, property, and life (sometimes all of the above). According to the U.S. Forest Service, the average cost of fire operations in recent years has been approximately $2 billion annually.
Workman's recommendation is to open Western forests to careful, deliberate thinning. He argues that local private and public entities could manage the forest by removing fire-prone trees and debris, either through logging or controlled fires. Not only would this increase the health of Western forests, it would protect water supplies worth well more than the costs of investment.
"We've known for some time that managed forest fires are the only way to restore the majority of overstocked western forests and reduce the risk of catastrophic fires," James Roche, a National Park Service hydrologist and lead author of the Ecohydrology study, said in the same release. "We can now add the potential benefit of increased water yield from these watersheds."
Acts of ecological juggling
For those of us raised on John Denver and Smokey the Bear, the idea of logging or letting forests burn runs counter-intuitive toward the belief that abundant green equals a healthy ecosystem. It brings to mind worries that big companies may clear cut national forests — placed in public trust for future generations — and that the emissions will exacerbate our already fraught battle with climate change.
These are legitimate concerns.
The U.S. Congress, particularly its Republican representatives, has a history of using devastating wildfires to gin up support for legislation that would limit oversight of the logging industry, open federal lands to private companies, and curb environmental reviews of certain practices, including clear-cutting.
It's been shown that traditional logging practices increase an area's burn capacity. The large trees targeted by loggers are mature and thick-barked, which are more resistant to fire. Meanwhile, the small trees and debris left behind are easily combustible.
However, when performed in good faith and with oversight, targeted clearing efforts can be part of healthy forest management. Controlled fires can sterilize old forests from native fungi that can breed insatiably on old rot. They give new life to tree species such as the Douglas-fir, an evergreen conifer that regenerates following a fire but not well in the shade of an established canopy. And the emissions from controlled, centralized thinning have been overrated in the cultural imagination.
Nor should we confuse the type of burning prescribed by these experts with the inferno-fueled deforestation currently occurring in the Amazon rainforest. The number of active fires in the Amazon is above the historic average with deforestation more than double last year. These burns are not inspired by conservation but industrialization and weakened environmental protections.
We must accept that healthy forest management is a juggling act that requires us to consider, calculate, and react to many different facets. These include reforestation, species selection, fertilization practices, irrigation and drainage practices, and many others. Additionally, forest management is not uniform. Practices that groom a healthy temperate forest, like those found in the Sierra Nevada, don't translate to tropical forests.
But if the question is, is it possible to have too many trees? The answer yes, sometimes, in some places.
- Top 6 ways to suck greenhouse gases out of the atmosphere - Big ... ›
- Does Your Neighborhood Have Enough Trees? - Big Think ›
- AI discovers 1.8 billion trees in NASA images of the Sahara - Big Think ›
- The evolution of rainforests began with the dinosaur-killing asteroid - Big Think ›
Why mega-eruptions like the ones that covered North America in ash are the least of your worries.
- The supervolcano under Yellowstone produced three massive eruptions over the past few million years.
- Each eruption covered much of what is now the western United States in an ash layer several feet deep.
- The last eruption was 640,000 years ago, but that doesn't mean the next eruption is overdue.
The end of the world as we know it
Panoramic view of Yellowstone National Park
Image: Heinrich Berann for the National Park Service – public domain
Of the many freak ways to shuffle off this mortal coil – lightning strikes, shark bites, falling pianos – here's one you can safely scratch off your worry list: an outbreak of the Yellowstone supervolcano.
As the map below shows, previous eruptions at Yellowstone were so massive that the ash fall covered most of what is now the western United States. A similar event today would not only claim countless lives directly, but also create enough subsidiary disruption to kill off global civilisation as we know it. A relatively recent eruption of the Toba supervolcano in Indonesia may have come close to killing off the human species (see further below).
However, just because a scenario is grim does not mean that it is likely (insert topical political joke here). In this case, the doom mongers claiming an eruption is 'overdue' are wrong. Yellowstone is not a library book or an oil change. Just because the previous mega-eruption happened long ago doesn't mean the next one is imminent.
Ash beds of North America
Ash beds deposited by major volcanic eruptions in North America.
Image: USGS – public domain
This map shows the location of the Yellowstone plateau and the ash beds deposited by its three most recent major outbreaks, plus two other eruptions – one similarly massive, the other the most recent one in North America.
The Huckleberry Ridge eruption occurred 2.1 million years ago. It ejected 2,450 km3 (588 cubic miles) of material, making it the largest known eruption in Yellowstone's history and in fact the largest eruption in North America in the past few million years.
This is the oldest of the three most recent caldera-forming eruptions of the Yellowstone hotspot. It created the Island Park Caldera, which lies partially in Yellowstone National Park, Wyoming and westward into Idaho. Ash from this eruption covered an area from southern California to North Dakota, and southern Idaho to northern Texas.
About 1.3 million years ago, the Mesa Falls eruption ejected 280 km3 (67 cubic miles) of material and created the Henry's Fork Caldera, located in Idaho, west of Yellowstone.
It was the smallest of the three major Yellowstone eruptions, both in terms of material ejected and area covered: 'only' most of present-day Wyoming, Colorado, Kansas and Nebraska, and about half of South Dakota.
The Lava Creek eruption was the most recent major eruption of Yellowstone: about 640,000 years ago. It was the second-largest eruption in North America in the past few million years, creating the Yellowstone Caldera.
It ejected only about 1,000 km3 (240 cubic miles) of material, i.e. less than half of the Huckleberry Ridge eruption. However, its debris is spread out over a significantly wider area: basically, Huckleberry Ridge plus larger slices of both Canada and Mexico, plus most of Texas, Louisiana, Arkansas, and Missouri.
This eruption occurred about 760,000 years ago. It was centered on southern California, where it created the Long Valley Caldera, and spewed out 580 km3 (139 cubic miles) of material. This makes it North America's third-largest eruption of the past few million years.
The material ejected by this eruption is known as the Bishop ash bed, and covers the central and western parts of the Lava Creek ash bed.
Mount St Helens
The eruption of Mount St Helens in 1980 was the deadliest and most destructive volcanic event in U.S. history: it created a mile-wide crater, killed 57 people and created economic damage in the neighborhood of $1 billion.
Yet by Yellowstone standards, it was tiny: Mount St Helens only ejected 0.25 km3 (0.06 cubic miles) of material, most of the ash settling in a relatively narrow band across Washington State and Idaho. By comparison, the Lava Creek eruption left a large swathe of North America in up to two metres of debris.
The difference between quakes and faults
The volume of dense rock equivalent (DRE) ejected by the Huckleberry Ridge event dwarfs all other North American eruptions. It is itself overshadowed by the DRE ejected at the most recent eruption at Toba (present-day Indonesia). This was one of the largest known eruptions ever and a relatively recent one: only 75,000 years ago. It is thought to have caused a global volcanic winter which lasted up to a decade and may be responsible for the bottleneck in human evolution: around that time, the total human population suddenly and drastically plummeted to between 1,000 and 10,000 breeding pairs.
Image: USGS – public domain
So, what are the chances of something that massive happening anytime soon? The aforementioned mongers of doom often claim that major eruptions occur at intervals of 600,000 years and point out that the last one was 640,000 years ago. Except that (a) the first interval was about 200,000 years longer, (b) two intervals is not a lot to base a prediction on, and (c) those intervals don't really mean anything anyway. Not in the case of volcanic eruptions, at least.
Earthquakes can be 'overdue' because the stress on fault lines is built up consistently over long periods, which means quakes can be predicted with a relative degree of accuracy. But this is not how volcanoes behave. They do not accumulate magma at constant rates. And the subterranean pressure that causes the magma to erupt does not follow a schedule.
What's more, previous super-eruptions do not necessarily imply future ones. Scientists are not convinced that there ever will be another big eruption at Yellowstone. Smaller eruptions, however, are much likelier. Since the Lava Creek eruption, there have been about 30 smaller outbreaks at Yellowstone, the last lava flow being about 70,000 years ago.
As for the immediate future (give or take a century): the magma chamber beneath Yellowstone is only 5 percent to 15 percent molten. Most scientists agree that is as un-alarming as it sounds. And that its statistically more relevant to worry about death by lightning, shark, or piano.
Strange Maps #1041
Got a strange map? Let me know at email@example.com.
The pandemic has many people questioning whether they ever want to go back to the office.
If one thing is clear about remote work, it's this: Many people prefer it and don't want their bosses to take it away.
When the pandemic forced office employees into lockdown and cut them off from spending in-person time with their colleagues, they almost immediately realized that they favor remote work over their traditional office routines and norms.
As remote workers of all ages contemplate their futures – and as some offices and schools start to reopen – many Americans are asking hard questions about whether they wish to return to their old lives, and what they're willing to sacrifice or endure in the years to come.
Even before the pandemic, there were people asking whether office life jibed with their aspirations.
We spent years studying “digital nomads" – workers who had left behind their homes, cities and most of their possessions to embark on what they call “location independent" lives. Our research taught us several important lessons about the conditions that push workers away from offices and major metropolitan areas, pulling them toward new lifestyles.
Legions of people now have the chance to reinvent their relationship to their work in much the same way.
Big-city bait and switch
Most digital nomads started out excited to work in career-track jobs for prestigious employers. Moving to cities like New York and London, they wanted to spend their free time meeting new people, going to museums and trying out new restaurants.
But then came the burnout.
Although these cities certainly host institutions that can inspire creativity and cultivate new relationships, digital nomads rarely had time to take advantage of them. Instead, high cost of living, time constraints and work demands contributed to an oppressive culture of materialism and workaholism.
Pauline, 28, who worked in advertising helping large corporate clients to develop brand identities through music, likened city life for professionals in her peer group to a “hamster wheel." (The names used in this article are pseudonyms, as required by research protocol.)
“The thing about New York is it's kind of like the battle of the busiest," she said. “It's like, 'Oh, you're so busy? No, I'm so busy.'"
Most of the digital nomads we studied had been lured into what urbanist Richard Florida termed “creative class" jobs – positions in design, tech, marketing and entertainment. They assumed this work would prove fulfilling enough to offset what they sacrificed in terms of time spent on social and creative pursuits.
Yet these digital nomads told us that their jobs were far less interesting and creative than they had been led to expect. Worse, their employers continued to demand that they be “all in" for work – and accept the controlling aspects of office life without providing the development, mentorship or meaningful work they felt they had been promised. As they looked to the future, they saw only more of the same.
Ellie, 33, a former business journalist who is now a freelance writer and entrepreneur, told us: “A lot of people don't have positive role models at work, so then it's sort of like 'Why am I climbing the ladder to try and get this job? This doesn't seem like a good way to spend the next twenty years.'"
By their late 20s to early 30s, digital nomads were actively researching ways to leave their career-track jobs in top-tier global cities.
Looking for a fresh start
Although they left some of the world's most glamorous cities, the digital nomads we studied were not homesteaders working from the wilderness; they needed access to the conveniences of contemporary life in order to be productive. Looking abroad, they quickly learned that places like Bali in Indonesia, and Chiang Mai in Thailand had the necessary infrastructure to support them at a fraction of the cost of their former lives.
With more and more companies now offering employees the choice to work remotely, there's no reason to think digital nomads have to travel to southeast Asia – or even leave the United States – to transform their work lives.
During the pandemic, some people have already migrated away from the nation's most expensive real estate markets to smaller cities and towns to be closer to nature or family. Many of these places still possess vibrant local cultures. As commutes to work disappear from daily life, such moves could leave remote workers with more available income and more free time.
The digital nomads we studied often used savings in time and money to try new things, like exploring side hustles. One recent study even found, somewhat paradoxically, that the sense of empowerment that came from embarking on a side hustle actually improved performance in workers' primary jobs.
The future of work, while not entirely remote, will undoubtedly offer more remote options to many more workers. Although some business leaders are still reluctant to accept their employees' desire to leave the office behind, local governments are embracing the trend, with several U.S. cities and states – along with countries around the world – developing plans to attract remote workers.
This migration, whether domestic or international, has the potential to enrich communities and cultivate more satisfying work lives.
The potential of CRISPR technology is incredible, but the threats are too serious to ignore.
- CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) is a revolutionary technology that gives scientists the ability to alter DNA. On the one hand, this tool could mean the elimination of certain diseases. On the other, there are concerns (both ethical and practical) about its misuse and the yet-unknown consequences of such experimentation.
- "The technique could be misused in horrible ways," says counter-terrorism expert Richard A. Clarke. Clarke lists biological weapons as one of the potential threats, "Threats for which we don't have any known antidote." CRISPR co-inventor, biochemist Jennifer Doudna, echos the concern, recounting a nightmare involving the technology, eugenics, and a meeting with Adolf Hitler.
- Should this kind of tool even exist? Do the positives outweigh the potential dangers? How could something like this ever be regulated, and should it be? These questions and more are considered by Doudna, Clarke, evolutionary biologist Richard Dawkins, psychologist Steven Pinker, and physician Siddhartha Mukherjee.
Measuring a person's movements and poses, smart clothes could be used for athletic training, rehabilitation, or health-monitoring.