Evolution and the Brown Mouse Lemur

The rainforests of Madagascar highlight, with great clarity, the power the physical environment exerts on evolution. As a study abroad student in the fall of 2006, I was researching the sleep habits of the brown mouse lemur in Ranomafana National Park, a protected tract of land in the high rain-forested mountains of Madagascar’s east coast.

During the day, I bushwhacked through this dense rainforest, attempting to locate two or three of these nocturnal mouse lemurs, who had been fixed with tracking collars, as they slept. In the evening, I waited for the lemurs to wake up so that I could record the size and consistency of their sleeping groups.

creative commons: frank vassen

Microcebus rufus, the brown mouse lemur.

One day, as the sun was setting on the bamboo, ferns, and mossy trees of the forest, I watched as multiple lemurs suddenly emerged and attempted to rouse the female lemur I was tracking from her sleep. These lemurs, all male, were attempting to mate with my study subject.

Female brown mouse lemurs, and indeed many species of female lemurs in Madagascar, are only receptive to mating for a very short period of time each year. To make the most of this short mating season, the male lemurs, deathly focused on a single goal, spend the winter months growing testicles that end up being a quarter of their entire body mass. It is no question, given the males’ months of stored hormonal energy, that there would be a significant interest in my study subject that day. Read the rest of this entry »


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)


Sandy’s Effects on NYC Predicted by Two Recent Studies

E. B. White wrote, “It is a miracle that New York works at all. By rights New York should have destroyed itself long ago, from panic or fire or rioting or failure of some vital supply line in its circulatory system.” On Monday, Hurricane Sandy managed to cut off many of New York’s supply lines in ways they’ve never been tested before. The city lost power, water, and lives. But it was not only White’s fears, but also the predictions of scientists that were realized. Two separate papers, published earlier this year and last, predicted what would happen to New York City if it were struck by a severe storm.

In 2011, a state agency assembled a massive report on climate change in New York. In it, Klaus H. Jacob, a climate scientist at Columbia University’s Lamont-Doherty Earth Observatory, conducted a case study (PDF) on the impact of a 100-year flood on New York City’s transportation system. A 100-year flood is a flood whose severity, on average, is seen only once every hundred years (or has a 1 percent chance of occurring in any given year), which the study equates with a category 1 to 2 hurricane. Jacob looked at three scenarios: a 100-year flood alone, one combined with a 2-foot sea level rise, and another with a 4-foot sea level rise as a result of climate change.

Virtually all the subway lines in lower Manhattan and the tunnels under the East River would be flooded under the worst-case scenario, which indeed closely mimicked reality. (Jacob, 2011)

Jacob identified the areas that would be flooded under each scenario. Using a base flood elevation map of the city as well as known elevations of transportation structures, he found that low-lying streets, subways, and tunnels in the Battery, Jamaica Bay, the Rockaways and other neighborhoods near the city’s shoreline would be particularly vulnerable to flooding. Indeed, those areas were among those that suffered most from Hurricane Sandy. In fact, a record 14 feet, or 4.25 meters, of water swept over the Battery on Monday, matching the case study’s worst-case scenario. Jacob also predicted that the total economic and physical damages for NYC would be $58 billion, $70 billion, and $84 billion in order of worsening scenario. One current estimate stands at $20 billion in losses for the entire Northeast and Mid-Atlantic due to Sandy, so Jacob’s estimates seem to have overshot it. One thing is for sure though. Investing in infrastructure that protect the city from future storms can save money in the long run. As Jacob told New York Magazine, “For every dollar that you spend today, you probably save $4 of not incurred costs later.”

Just months after Jacob’s case study, Ning Lin, a climate scientist at MIT, and colleagues used computer models to predict the impact of a hurricane on New York City. Published in Nature Climate Change in February this year, the study used four climate models to simulate 10,000 synthetic storms, half under the current climate and half under projected warming conditions. The researchers programmed the storm to be within a 200-km radius from the Battery and to gust at wind speeds greater than 20 m/s, or 45 mph (Hurricane Sandy exceeded the models, with 60 mph recorded at Central Park). They found that in the worst-case scenarios, a hurricane would cause a storm surge as high as 4.57 m to 4.75 m at the Battery, which came fairly close to the 4.25 m caused by Sandy.

Two worst-case scenarios estimate surge height at the Battery to range from 4.75 m (left) to 4.57 m (right), coming fairly close to the 4.25 m record surge caused by Hurricane Sandy. (Lin, et al. 2012)

The researchers also found that climate change will only increase the risk of storm surges for the city. Based on historical data on NY-region storms, they predicted that a 1 m rise in sea level in the future will increase the likelihood of a 100-year surge flood occurring as frequently as every 3-20 years and a 500-year flood every 25-240 years by the end of the century. Of course, predicting something as unpredictable as a hurricane is extremely difficult. But the fact that the climate models closely mirrored Hurricane Sandy makes the need to prepare for future severe weather all the more urgent.


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