The Story of the Constant, Changing Forest

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An olive tree from Ithaca, Odysseus’s home

If you’re a writer looking for a good symbol, consider the tree. The author of Genesis did, twice: he placed the tree of life and the tree of knowledge front and center in the Garden of Eden. Homer did, too: When his hero Odysseus returned home after twenty years of war and travel, needing to prove his identity to his skeptical wife, Penelope, he used a tree. “Move our bed into the hallway,” Penelope told her servant, laying a trap. (I’m paraphrasing here.) “It can’t be done,” Odysseus protested. “I carved a post of that bed from a living olive tree.” Only then did Penelope believe the strange man was really her husband, as steady as that post.

Trees have long impressed us with their steadfastness; in fact, some trees from Biblical times are still with us today. But a new story I read recently casts trees in a different role. I first came across a version of this story in a paper published in the journal BioScience in 2007. The authors looked at where trees live using a tool known as a “climate envelope,” which is a line drawn on a map around the entire range where a given species is able to survive. The scientists compared climate envelopes for 130 trees under 2007 conditions to those predicted for the end of the century, using the same computer models that the UN’s Intergovernmental Panel on Climate Change bases its forecasts on. On average, they found that trees’ envelopes moved 700 kilometers north, nearly the distance from Memphis to Chicago.

So does that mean our trees will be moving north as things get warmer? Traveling trees can make great stories: Shakespeare’s Macbeth was vanquished when Birnam Wood moved a few miles to his fortress at Dunsinane Hill. And it would be dramatic indeed if future northern woodsmen and women hunt deer among sprawling live oaks and big-leaf magnolias instead of spruce and pine trees. But the scientists who wrote the BioScience paper noted that actual trees are unlikely to track their climate envelopes’ northward migration in the coming years, at least if unassisted by humans. Trees can “move” up to a few miles in a generation, by setting their seeds aloft in the wind or encasing them in a shell so they can survive a trip in the gut of an animal. But tree generations are long, and most seeds land close to home. Sugar maples, for example, lead a chaste adolescence, and don’t start making seeds until the age of 22 or so. They then send out seeds attached to little helicopters, which spin and float at most the length of a football field before touching down. Scientists estimate trees’ maximum migration rate to be around 50 kilometers per century, with many traveling far slower—a tortoise’s pace in this race.

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An Ecologist Takes on an Invader

An Ecologist’s Battle

Invasive plants are the ones that don’t play well with others. They steal their neighbors’ food and water, and they refuse to share. And you’ll see them all around the Baltimore area: vines smothering stream banks and blanketing entire trees; the brambles tangling and choking the understory; the annuals carpeting the forest floor. They’re the botanical version of an alien invasion.

Or, they can make nice additions to our gardens. Vanessa Beauchamp, an invasive plant ecologist, tells me about a hiker who came upon her research team in a park outside Baltimore. “She asked us what we’re doing, and we explained we’re studying this invasive grass that we think is a really big problem, and we’re trying to understand more about its ecology. And she says, ‘Oh my gosh that stuff is so pretty, I dug up a bunch and planted it in my yard.’”

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A wavyleaf basketgrass carpet

The plant was wavyleaf basketgrass, a native of Europe and Asia. It sounds innocent enough, like a prairie grass that might rustle softly in a summer breeze. And it’s pretty enough, too, with intensely green leaves that unfurl on either side of a central shoot, and a head of spiky seeds that sticks up a foot or so above the ground. The seeds are the problem, though—they hitch rides on pant legs, animals, basically anything that comes by—and disperse to new locations that way. The plant can grow just fine even in the deep shade of a mature forest. In Patapsco Valley State Park, where it was discovered in the mid-1990s, it now carpets acres of forest floor. The Maryland Department of Natural Resources launched a war on it but lost, due to lack of funding. Now the plant has spread to other parks in the area, and experts like Beauchamp fear there may be no containing it.

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A seed head

But if it’s green and pretty, what’s the worry? Beauchamp says it’s all about the community of life in the forest. Exotic plants like basketgrass are newcomers to this community, so nothing has evolved to eat them—a lesson Beauchamp has learned firsthand. “When we worked on wavyleaf basketgrass, we literally spent the summer crawling around on the forest floor. I figured we would just be tick city,” she says. Instead, of the half dozen people on her crew, “We got one tick between all of us. I mean, that’s insane.”

Few of us would be sad to see the ticks disappear. But without the thousands of insects, worms, mites, and spiders that make their living in the forest understory, the woods would be a vastly different—and less lively—place. “Nobody’s looked at how insects are able to use this grass…We see very little insect damage on the grass at all. We see no deer damage,” says Beauchamp. “If there’s no insects eating them, there’s no birds eating those insects, and up and up and up.”

A wavyleaf basketgrass army

Beauchamp moved to Towson University in Baltimore from Arizona five years ago. For an invasive species expert, the move meant more than packing and unpacking boxes—it meant abandoning one biome and learning a new one. Luckily for Beauchamp, Maryland has no shortage of invasive plants, and it didn’t take her long to find one she could claim as her own. “I came across this wavyleaf basketgrass that nobody knew anything about, and I said ‘All right. That’s mine.’”

One of the questions Beauchamp is asking is how aggressive the grass actually is. Many writers on the Web claim it crowds out other plant species, but Beauchamp wonders whether it might just take advantage of openings on the forest floor, especially those created by Maryland’s massive plant-munching deer population. To test how competitive wavyleaf basketgrass is, her research team is growing the grass in a greenhouse alongside other native and invasive grasses, and seeing which puts on the most weight. They hope to have results soon.

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Beauchamp’s dog, with seeds

Beauchamp is also trying to figure out how the seeds disperse. And she thinks she’s found a suspect: pet dogs. When hikers let their dogs run through a basketgrass patch, they “come out looking like a chia pet,” says Beauchamp. Fore more precision, she had her students count the number of seeds sticking to a dog. “We found that a single dog going through this grass for 30 seconds can get over 2000 seeds on it,” she says.

Dogs may not be the only culprit, though; Beauchamp also has her eye on deer. She and her team tested this hypothesis in a rather macabre way: they got severed deer legs from a meat processor, and “walked” the legs through a basketgrass patch. Again, the legs came out covered in seeds.

But Beauchamp admits she can’t answer the most important questions: how much wavyleaf basketgrass is there, and where? “I have absolutely no number to tell you in terms of how many acres this grass covers in Maryland,” she say. “None.” Unfortunately, when she wrote a grant to fund a project that would get at such a number, she got caught in a chicken-and-egg situation: the review panel rejected the proposal, saying Beauchamp and colleagues hadn’t demonstrated how much of a threat the grass poses. “But if I don’t have any money to study it, how can I demonstrate that?” she asks.

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“Walking” the deer legs

So like any good scientist, she’s gotten creative. She mustered a “wavyleaf basketgrass army” of undergraduates and high school teachers to go out and count plants in different locations. She’s also teaming with a Catonsville Community College professor who’s developing a smartphone app that will allow anybody to report a basketgrass sighting, along with GPS coordinates. Beauchamp is hoping the data her team and concerned citizens collect will convince funders and policymakers that the grass is worth studying on a larger scale.

Beauchamp vs. basketgrass

Beauchamp versus basketgrass is the latest chapter in a long saga of human battles against invasive plants. And so far the invaders have scored most of the victories. Here in Maryland, English ivy, Japanese stilt-grass, mile-a-minute weed (an Asian species known as “kudzu of the north”), and other exotics have become far more familiar sights in our parks and forests than most of our native plants. Will wavyleaf basketgrass join this list of dubious characters, or could this be the time we outsmart the weed?

(All photos courtesy of Vanessa Beauchamp)


Counting the Fish in the Sea

The 2010 US census workers had a tough job, but at least they were on land, counting residents with home addresses. 2010 was also the year a group of marine biologists completed a much tougher assignment: a global canvass of ocean residents who don’t fill out forms, live in some of the most remote places on the planet, and often move thousands of miles in a single year. The first study of its scope, the Census of Marine Life has added thousands of new species to the books, and has shown, in the words of project director Jesse Ausubel, that “the ocean’s even richer in diversity than anybody had known.”

The newly discovered Kiwa hirsuta, also known as the Yeti crab. Image courtesy of Chris Allen and the Encyclopedia of Life.

Census scientists collected over 6,000 new species, and have already described 1,200 of them in detail. They discovered deep-sea jellyfish, 500-year-old tubeworms, bejeweled copepods and isopods, and a hairy white crab that lives near sulfurous vents on the ocean floor. They found a mat of filamentous bacteria the size of Greece off the coast of Chile, and located a squid previously believed to have gone extinct in the Jurassic. The Census uncovered new life forms even in some of the world’s most studied and heavily trafficked ocean regions, said Ausubel, Census co-founder and program director at the Alfred P. Sloan Foundation, who described the results in a talk in Washington, DC last Thursday.

Each newly discovered species now has its own web page in the online Encyclopedia of Life, which will eventually catalog every known life form on Earth. Pages in the encyclopedia include physical descriptions of the species, scientific information like where the creature is found and how common it is, and, of course, color photos. “It’s like facebook,” Ausubel said. In addition, scientists gathered DNA from every creature found, new or not, for a project called the International Barcode of Life. The iBOL is a reference library made of segments of specific genes that are shared among many forms of life, but whose precise sequence varies in an identifiable way from species to species.

Scientists also learned that many familiar marine animals make long-distance trips across the ocean, “commuting like jetset businessmen” in Ausubel’s words. Census researchers attached acoustic tags to various creatures and released them; the tags then emitted sounds that were picked up by receivers on the ocean floor as the animals passed by. Scientists watched bluefin tuna swim from Mexico to Japan and back in a year, and tracked seals fishing from underwater mountains off the Antarctic coast. They monitored salmon swimming up the west coast of Canada, and learned that many of them don’t make it back to rivers to spawn the next year. And they used the tags to collect data beyond just the animals’ locations; for example, they enlisted leatherback turtles to collect ocean temperature readings during their journeys around the South Pacific. “Animals connect the ocean in incredible ways,” said Ausubel.

Surveying the astounding diversity of marine habitats—coastlines, continental shelves, deep-sea trenches and mountain ranges, the vast open ocean—required a correspondingly varied array of exploratory techniques: “a concerto of technologies,” said Ausubel. To explore the ocean surface and shallow waters, scientists worked from submarines, airplanes, and massive research vessels. For probing the deep ocean, they turned to robotic and remotely controlled vehicles that could operate at depth without risk to human life. In total, the project cost $650 million spread over a decade, and involved almost 3,000 scientists. “Marine biology hasn’t had a tradition of big science” like physics has, said Ausubel, but with the Census of Marine Life, that may be starting to change.

Bathykorus bouilloni, a deep-sea jellyfish. Image courtesy of Kevin Raskoff.

Although Ausubel noted that “extinction is rare in the ocean,” scientists found ample evidence of humans’ effects on life in the sea, few of them good. Overharvesting has depleted the populations of various fish, mammals, and reptiles since the time of the Romans, and in recent times has led to explosions of less desirable creatures, like jellyfish. Modern scourges like the huge floating garbage patches in the Atlantic and Pacific are also harming aquatic life, particularly island-nesting birds that are often found dead with plastic in their stomachs. But the greatest impacts may be yet to come, as humans increase shipping, oil drilling, and underwater communication, and as rising greenhouse gas emissions continue to warm the ocean and make it more acidic. The Census has given scientists a valuable baseline against which to measure future changes to the abundance and distribution of ocean dwellers.

Despite their impressive findings, marine biologists have just begun the hard part of counting every creature in the sea. They believe the ocean could contain a million or more undiscovered species, most of which are likely to be small, rare, and hard to find. And those are just the relatively well-studied multi-cellular ocean dwellers; the number of microbial species in the ocean is far larger, perhaps as many as a billion. Ausubel also noted that few people study most marine life forms, besides the well-known ones like fish and mammals (a hint to any young scientists out there searching for a specialty.)

The seas have long fascinated and mystified us. Over 60 years ago, Rachel Carson’s best-selling book The Sea Around Us told the public about the stunning discoveries in marine biology made possible by World War 2-era innovations in sonar and submarine technology. Since then we have learned much about what lives in the deep sea, and we now know the ocean floor is not barren but in fact teems with strange and wonderful life. But the Census of Marine Life also reaffirms the lure of the unknown that Carson described in her 1951 masterpiece: “We can only sense that in the deep and turbulent recesses of the sea are hidden mysteries far greater than any we have solved.”


Yom Kippur and the Science of Fasting

Last week, I along with millions of people took off work and went 25 hours without food or water. No, we weren’t orchestrating a spontaneous hunger strike; we were observing Yom Kippur, the holiest day of the Jewish calendar. The instruction to fast comes from the Bible, but the Bible also tells us to do all kinds of other things—sacrifice animals, stone adulterers—that even the most pious ignore today. So why do we continue to find this one relevant? I believe the answer can be sought not just in religious texts, of which I confess to being almost entirely ignorant, but also in science.

Maurycy Gottlieb’s “Jews Praying in the Synagogue on Yom Kippur”

Physiologically, fasting sets off a chain of chemical and electrical signals in the body. After the stomach empties the last bits of a meal into the small intestine, it releases a hormone called ghrelin, which activates a region deep in the brain known as the hypothalamus. The hypothalamus then sends out a nerve signal that manifests as hunger, and we feel an unpleasant sensation in our stomach. That meal we ate also provided a surge in glucose, a simple sugar that fuels the brain, and when the surge ends we feel weak, tired, and sluggish until our next meal.

I’m familiar with the bodily effects of hunger, but I also notice changes in my mental state when I fast. The hyperactive part of my brain that normally wants to execute plans and think a million things—what Buddhists sometimes call the “monkey mind”—seems to shut down, or at least quiet down. I feel grumpy and pessimistic; I become contemplative; I write; if I go to services, I feel more like praying than I normally would. I also notice a heightened sense of connection to others. In an intangible but distinct and sometimes powerful way, I feel linked to people in other places who are also fasting now, as well as to people who have fasted in other times.

I began wondering this year if there was a connection between fasting and what was happening in my brain. If I were a neuroscientist, I could put some fasting people in MRI machines, like what Richard Davidson at the University of Wisconsin does with meditating monks. But I’m a writer, not a scientist, so I did the unscientific thing and called a few friends.

For Rhea Kennedy, who has fasted on Yom Kippur for many years, going without food doesn’t necessarily lead to turning inward (“I’m usually pretty introverted anyway,” she observes), but she does find herself feeling profound empathy with “other people who can’t eat for some reason.” Rhea also feels herself linked with people who lived in the past. “It affects the way I relate to my Jewish ancestors and survivors of the Holocaust,” she says. “A lot of [their experiences] had to do with food deprivation.”

Laura Bellows, another friend with a long history of fasting, echoes Rhea’s experience of empathy with those for whom going without food may not be a choice. “It makes me feel like this is a little taste of what it’s like to be hungry,” she says. Laura also finds that fasting enhances the intensity of her prayers, and creates a sense of bonding with her community. “I feel very connected to those with whom I’ve fasted,” she says. “It’s as if we’ve been through this communal hardship together.”

Muslims also report feeling empathy during fasting for Ramadan. Here are a couple of examples:

“At one point he [a Washington, DC taxi driver] said that Ramadan and fasting have a broader social impact because they are ‘a reminder of people who cannot eat,’ and how lucky we are.” (from the blog No Kid Hungry)

“When [Emad Meerza, a Muslim community leader in Bakersfield, CA] fasts, he thinks about others around the world who are also fasting — not by choice, but because of famine, war or political strife. Through our own suffering, he says, empathy is born.

‘The only way to feel that is to feel a little bit of that pain,’ he says.”

(from the Bakersfield Californian)

These are anecdotes, not even close to the kind of data that would be needed to approach this question scientifically. Unfortunately, from what I can tell, scientists haven’t sought the answer either. I conducted article database searches on various combinations of terms like “Yom Kippur,” “fasting,” “psychology,” “science,” “empathy,” “mental states,” “hunger,” and “food deprivation,” but turned up little that seemed to address a link between religious fasting and the brain. Maybe I’m missing it—if you know of such a study, please drop me a line; I’d love to know about it.

Might Jews, Muslims, Mormons, Hindus, and others have developed and maintained fasting practices in part because they understood a mind-body connection that scientists have yet to make? Empathy is a near universal human experience, and has also been observed in rats and monkeys. But it has been a puzzle for neuroscience to figure out how one brain can share an experience occurring in another, entirely distinct brain.

Recently, some scientists have looked to systems of nerve cells known as mirror neurons, which are thought to fire in ways that mimic what we believe to be happening in the brains of others. V. S. Ramachandran, a neuroscientist at the University of California, San Diego and a prominent mirror neuron proponent, has even called them “empathy neurons.” Other scientists question this link, and some doubt whether humans truly have neurons dedicated to mimicking others’ brain activity. But whether due to mirror neurons or not, I do find it suggestive that our processing centers for emotions like empathy seem to be located not in the thought-processing and decision-executing regions of the brain—the frontal lobes—but in deeper regions of the brains. Our understanding of the neurological basis of empathy is described in a paper by psychologists Stephanie Preston of the University of California at Berkeley) and Frans de Waal of Emory University.

Which lobe contains empathy?

Does that mean thinking and deciding require more fuel than emoting? Many times I have become extremely hungry after doing sustained, mentally demanding work, suggesting to me that concentrating hard and long might demand more energy than, say, sitting by a stream. But while some studies have shown that people do better on certain difficult mental tasks when supplied with a sugary drink, it seems that in general the brain consumes a nearly constant amount of fuel no matter what it’s doing. Ferris Jabr wrote a good review of some of this research for Scientific American recently.

Regardless, hunger does seem to make it hard to concentrate on the kinds of tasks we normally think of as “work.” I’ve had that experience, Rhea and Laura both reported it, and so did Jonah Lehrer. It happens to millions of office workers every day; it’s why schools provide free breakfast to students. Perhaps it’s mainly because we get distracted by hunger, but for some reason we can’t seem to concentrate and think well without food in our stomachs. On the other hand, we can contemplate, pray, and feel connected.

My naïve hypothesis, then, is that fasting may quiet the noisy thought-processing and decision-making brain regions, and give us a chance to listen to a softer, less pushy voice—one that has less to say about the day-to-day that consumes us most of the time, but a lot to say about the longer and deeper currents that run under our lives. And one of those currents seems to be a sense of connection to other living beings on our planet. Fasting is not sufficient to hear this voice—we also need to choose to listen, perhaps by going to a prayer service, or by spending time in a quiet place. (Lehrer in his blog post described a fast not leading to a religious state of mind.) But maybe fasting makes the listening easier.

Many in the popular press continue to write about the supposed rift between science and religion. (See a Time article, a Discover blog post, and a 2010 book for some examples.) Ritual fasting seems to me like a perfect meeting place, where science can help elucidate the value of religious traditions, and religion can stimulate scientific investigation. I’d love to see scientists take on this kind of research.


Rachel Carson and the Power of Science Writing

Is the pen mightier than the sword? Fifty years ago this month, one of those rare books was published that seems to have proven the famous saying true. Powerful industries opposed the book, but only succeeded in increasing its renown. President Kennedy appointed a commission to investigate; the commission reported that the author’s findings were correct. The book galvanized an environmental movement, led to laws and regulations that protected the country’s air and water, and brought treasured species like the bald eagle back from the edge of extinction.

The book, as you might have guessed, was Silent Spring, and the author Rachel Carson. Today we might wonder how such an influential writer could ever have emerged, but in the 1950s and ’60s Carson was a celebrity. And it wasn’t for writing scary books about pesticides; her main beat was the ocean. Carson became most famous for The Sea Around Us, which told the public about the stunning advances in scientists’ understanding of marine life. “With that book Carson not only became an international superstar, she became the most trusted voice in public science,” says Linda Lear, who wrote a biography of Carson. “She never wrote any article for the academic community. She wrote for the public, because she wanted the public to understand the world they lived in, the natural world.”

The Book of the Month Club edition of Silent Spring, with Supreme Court Justice William O. Douglas’s endorsement. Source: wikipedia

Carson was able to write authoritatively about science in part because she came from the academic science community; she earned a master’s degree in zoology from Johns Hopkins University in 1932. Today she might have moved naturally over to that university’s science writing program (where my co-bloggers and I now reside) and launched her career that way, but in her day she was forced to blaze her own trail. She attempted freelancing, which was apparently no easier then than it is today, but also got herself noticed by the Bureau of Fisheries (now the US Fish and Wildlife Service), where she was hired to translate marine science into accessible prose. Though she excelled at this job and moved up through the government bureaucracy, she was also setting herself up for an independent writing career. “What she really wanted to do is publish her way out of government,” says Lear.

So Carson was a science writer who started out, like many, as a celebrator of science. But because of her scientific training, she recognized the dangers that certain scientific advances—especially those in atomic physics and chemistry—posed to the ecosystems she loved. However, Silent Spring is not anti-science; rather it uses science to questions humans’ use of scientific knowledge in the post-World War 2 period. In answering these questions, Carson makes full use of her prodigious writing skills, eloquently synthesizing the best government and academic science of her time.

It would be nice if we could say Carson’s pen had vanquished the overuse and misuse of toxic pesticides, but with a few notable exceptions like DDT, most of them are still around. And as anyone who reads the news knows, the world is awash in all kinds environmental threats—endocrine disruptors, farm runoff, greenhouse gases. So where are the next generation (or two) of Rachel Carsons—writers who bring a scientific issue to the public’s attention and inspire citizens and politicians to act? Nancy Langston, environmental historian and the University of Wisconsin-Madison, says part of the problem is the sheer amount being written. “Every time another book comes out such as…Our Stolen Future—that was the first really popular account of endocrine disruptors—people say, ‘Oh, it’s the next Silent Spring,’ but there are dozens of these each year. And I think a lot of people get overwhelmed.”

I’m particularly curious what Carson would have done with climate change, the most pervasive environmental threat today. After all, many talented science writers have taken up their pens (or more likely their computer keyboards) in the hope of overcoming the ignorance and inertia surrounding this issue. One who stands out for me is Elizabeth Kolbert, whose brilliant book Field Notes from a Catastrophe (which, like Silent Spring, was first serialized in the New Yorker) places climate change in its terrifying, civilization-destroying historical context. But did Field Notes lead to a presidential commission? Has legislation been passed? Have most Americans even heard of this book? Unfortunately, the answer to all three of these questions seems to be no.

It isn’t the fault of Kolbert or any other writer. The industries and groups opposing action on climate change are far more organized and sophisticated than those Carson was up against. “With climate change this isn’t just a debate, there’s a well-oiled machinery that actively propagates doubt, and is invested in that, and is tied up in the fossil fuel industries, and in making sure that legislative inaction is perpetuated,” says Rob Nixon, an environmental writer and Rachel Carson Professor of English at the University of Wisconsin-Madison.

Nixon does point to Bill McKibben’s recent Rolling Stone article “Global Warming’s Terrifying New Math,” where he writes that enough fossil fuel reserves are already on the books of major oil companies to warm the planet far beyond 2 degrees Celsius, the limit of what scientists believe might not be catastrophic. McKibben “has committed himself very squarely to this topic, very single-mindedly, so I think he’s the closest we come” to Carson today, says Nixon. Without question, McKibben’s article earned a lot of attention; for a week or two I found myself in conversations about it almost daily. But only for a week or two. The article also has the danger of doing exactly the opposite of what he probably intended: making the problem look so massive, and the industries driving climate change so mighty, that there is nothing we who have only our pens can do.

So can we still earnestly go around saying, “The pen is mightier than the sword.”? This famous line, from a now-obscure 19th-century play, encapsulates a sentiment that has probably given succor to many an idealistic writer, perhaps even Carson. And it would seem to follow that with the rise of the Internet and self-publishing, the daily avalanche of words would be enough to overpower any opposing force. But the opposite is true: with more words published than at any time before, each one seems to matter less. It’s hard to break through, and even harder to last: trending today, gone tomorrow. Will anyone recapture Carson’s gift for cutting through the fog? I don’t know, but for the sake of all members of the community of life, I certainly hope so.

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Postscript: for my own amusement, I decided to try updating the famous line for the bureaucratic age. Let’s see if this proverb catches on: “Writing is a more effective means of advancing change than military action.”