Jonathan Thompson is Research Ecologist at the Smithsonian Conservation Biology Institute, Research Associate at the Harvard Forest, and lead author on the paper which appeared in the journal Ecological Applications in late 2011. “The rebounding forests of New England provide a tremendous public benefit by storing carbon that would otherwise contribute to climate change,” said Thompson. To put these findings into context he adds, “In Massachusetts, forests capture approximately 2.3 million metric tons of carbon each year. That’s equal to the amount of carbon dioxide emitted from the energy used by one million American homes annually.” He and his coauthors were able to estimate the extent to which development may chip away at that carbon sink, using an uncommon collection of long-term data and a distinct form of research known as scenario science.

Image right: From this 71-foot eddy-flux tower in a 200-year-old hemlock forest, Harvard Forest scientists have measured carbon dynamics and other ecosystem processes for more than 20 years as part of the Long-Term Ecological Research program. Located in a 35-hectare Smithsonian Global Earth Observatory plot and part of the core measurements for the National Ecological Observatory Network, this tower is a focal point for studies of the eastern hemlock tree and its impending demise from the invasive hemlock wolly adelgid, as well as phenology studies of succeeding hardwoods.
(Photos by David Foster)

For more than 30 years, scientists at the Harvard Forest have scaled towers into the forest canopy and measured the trunks of trees to track how much carbon is stored or lost from the woods each year. This treasure trove of data is part of the national Long-Term Ecological Research (LTER) Network, which is celebrating more than three decades of research this month. This important milestone is marked by six new papers released today in a special issue of the journal BioScience. The forest carbon research is one example of participatory scenario science — a growing trend in ecology featured in a paper by Thompson, David Foster, Director of the Harvard Forest, and their colleagues in the BioScience issue.

Image left: Summer Research Program students monitor soil respiration of decaying wood in a large study comparing carbon, water, and energy fluxes between harvested and unharvested sites.

Harvard Forest is one of four LTER sites in the northeastern U.S. and was awarded a grant by the National Science Foundation to join the Network in 1988. David Foster coauthored the Ecological Applications paper of 2011 and co-edited the new BioScience special issue. He notes, “With three decades of data meticulously collected as part of the LTER Network, we have reached a crucial transition where we are now able to tackle major environmental challenges, such as the fate of forest carbon, across large landscapes.”

Foster adds, “Over the last two centuries, forests have stored more carbon with each passing year in many parts of New England, but the turning point may be in sight for Massachusetts and other urbanizing landscapes if recent development trends continue.” But that’s not the end of the story for Foster: “The good news is that forests are resilient and history is not necessarily destiny. Our research makes a compelling case for expanding support for forestland protection and for the efforts of private landowners to keep their land forested. It reminds us that forests provide important infrastructure that we should invest in, just as we do major civil works projects.”

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The rate of new marine invasions along U.S. coasts has risen sharply in recent decades due to human-aided introductions, often unintentional. Organisms can attach directly to the hulls of ships or be taken up and transported in ballast water (water used by large ships to provide stability and trim during sailing). They can also be introduced with imports of seafood, bait and packing materials. In addition, some species have been deliberately introduced to create new fisheries, though this practice is now very rare. As trade and globalization have increased, so has the opportunity for invasions.

No part of the country is untouched by non-native species. Although most people recognize a few of the common and conspicuous invaders in nearby waters, the full scope of invasions that lurk beneath the water often go unnoticed.

Image left: Chinese mitten crab.

NEMESIS aims to provide comprehensive and synthetic information on hundreds of individual marine species in the continental United States. Created by SERC’s marine invasions lab, the database includes information on how and when invasions occurred, distribution maps and what is known about their impacts. For example, the tunicate Didemnum vexillum (commonly known as D. vex or “rock vomit”) has created serious problems on the West and East Coasts of the United States. This mat-like species grows rapidly and can completely cover aquaculture nets, shellfish beds and sensitive marine environments. The database also includes an interactive map of the U.S., where visitors can search for invaders impacting their own coastlines.

NEMESIS launched March 5 with tunicates, a group that includes the destructive rock vomit. Tunicates, also known as ascidians or sea squirts, are filter feeders that grow on hard surfaces such as docks, rocks or sandy marine sediments. Information for other groups of species will become publicly available over the next year as NEMESIS continues its rollout, starting with crabs, shrimp and crayfish.

NEMESIS was designed in partnership with the U.S. Geological Survey. NEMESIS focuses on invasions in marine and estuarine waters, while the USGS Nonindigenous Aquatic Species database focuses on invasions in freshwater habitats of the U.S. The complementary databases were designed to be compatible, allowing for joint syntheses across marine and freshwater habitats in the U.S.

The NEMESIS database is a long-term and dynamic program that will continue to grow over time. Records are updated regularly as new species are discovered and new research becomes available. For more information on NEMESIS or recent updates, visit the NEMESIS home page and the NEMESIS Interactive Invasions Map.

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Roughly 10 percent of all plant species are orchids, making them the largest plant family on Earth. But habitat loss has rendered many threatened or endangered. This is partly due to their intimate relationship with the soil. Orchids depend entirely on microscopic fungi in the early stages of their lives. Without the nutrients orchids obtain by digesting these host fungi, their seeds often will not germinate and baby orchids will not grow. While researchers have known about the orchid-fungus relationship for years, very little is known about what the fungi need to survive.

Image right and below: Flowers (right) and leaves (below) of the orchid Goodyera pubescens, commonly known as the downy rattlesnake orchid, endangered in Florida. (Photos by Melissa McCormick/SERC)

Biologists based at the Smithsonian Environmental Research Center in Edgewater, Md., launched the first study to find out what helps the fungi flourish and what that means for orchids. Led by Melissa McCormick, the researchers looked at three orchid species, all endangered in one or more U.S. states. After planting orchid seeds in dozens of experimental plots, they also added particular host fungi needed by each orchid to half of the plots. Then they followed the fate of the orchids and fungi in six study sites: three in younger forests (50 to 70 years old) and three in older forests (120 to 150 years old).

Image right and below: Leaf (right)  and flowers (below) of Tipularia discolor, the cranefly orchid, endangered in New York and Massachusetts, and threatened in Michigan and Florida.

After four years they discovered orchid seeds germinated only where the fungi they needed were abundant—not merely present. In the case of one species, Liparis liliifolia (lily-leaved twayblade), seeds germinated only in plots where the team had added fungi. This suggests that this particular orchid could survive in many places, but the fungi they need do not exist in most areas of the forest.

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Image left: A desert tortoise, Gopherus agassizii. (Image by Mike Jones, courtesy Encyclopedia of Life)

“Roads are barriers to dispersal for lots of species and usually it takes many generations to show up in the genetic structure of an animal,” says one of the paper’s co-authors Emily Latch, a postdoctoral researcher at the Smithsonian Conservation Biology Institute’s Center for Conservation and Evolutionary Genetics, and now an assistant professor at the University of Wisconsin-Milwaukee. “Because tortoises have such a long life span, we didn’t think the roads would influence their genetic structure so quickly, but they did.”

The study shows for the first time that recent landscape features such as roads “can have rapid effects on the genetic structure of a localized population and are detectible almost immediately,” in as little as one generation, the scientists report. As a result, the scientists conclude, “Roads may become increasingly important in shaping the evolutionary trajectory of desert tortoise populations.”

For the study, DNA samples were taken from 859 tortoises living in an area of 23,969 acres. “A huge number of samples,” for such a small area, Latch says. Data also was taken on each animal’s sex, location, and location elevation and slope.

Image right: A tortoise in the Mojave Desert. (Image courtesy Wikipedia)

The tortoises were sampled as part of a tortoise relocation effort at Fort Irwin Army Training Center and the animals were located by having people walk map transects in the desert. They picked-up, labeled and took data and DNA samples for every tortoise encountered.

“The adult individuals were initially genotyped to develop a baseline genetic database of translocated and resident tortoises so that family groups hatched after the translocations could be identified to particular parents, and the reproductive success of translocated and resident tortoises compared,” says Smithsonian geneticist Rob Fleischer, head of the Center for Conservation and Evolutionary Genetics and senior author on the paper. “This is important to determine if translocation is really an effective mitigation step. It was serendipity that led to our finding a surprising level of genetic structure.”

Roads may inhibit gene flow in desert tortoises by the reptiles being hit by cars, picked up by travelers, and predation and disease associated with pets released by the roadside. Eroded banks and increased vegetation along desert roads also may provide places for the tortoises to burrow and forage for food, causing them to move along a road rather than to cross it.

The article “Fine-Scale Analysis Reveals Cryptic Landscape Genetic Structure in Desert Tortoises,” by Emily K. Latch, William I. Boarman, Andrew Walde, and Robert C. Fleischer appeared recently in the journal PLoS ONE.

-John Barrat

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Ichthyologists Gene Helfman, professor emeritus at the University of Georgia, and Bruce Collette, of the Division of Fishes at the Smithsonian’s National Museum of Natural History, provide accurate, entertaining, and sometimes surprising answers to more than 100 common and not-so-common questions, such as “Can fishes breathe air?” “How smart are fishes?” and “Do fishes feel pain?”

They explain how bony fishes evolved, the relationship between fishes and sharks, and why there is so much color variation among species. Along the way we also learn about the devils hole pupfish, which has the smallest range of any vertebrate in the world; “Lota lota,” the only freshwater fish to spawn under ice; the Candiru, a pencil-thin Amazonian catfish that lodges itself in a very personal place on male bathers and must be removed surgically; and many other curiosities.

With more than 100 photographs—including two full-color photo galleries—and the most up-to-date facts on the world’s fishes from two premier experts, this fun, accessible, and informative book is the perfect bait for any curious naturalist, angler, or aquarist.

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Image left: SERC scientist João Canning Clode observes a green porcelain crab in his laboratory at the Smithsonian Environmental Research Center.

But what happens to these fair-weather travelers during a severe cold snap, such as the one that occurred in January 2010 across much of the southeastern and eastern United States? To investigate, Smithsonian Environmental Research Center scientist João Canning Clode and colleagues at the Environmental Research Center in Edgewater, Md., tested the cold-water tolerances of invasive green porcelain crabs (Petrolisthes armatus) in their laboratory. Crabs were collected in Georgia and brought to the lab where they were subjected to one of three temperature treatments. The first was a control treatment of constant moderate winter temperature. The second was treatment in which the temperature was dropped to mimic the cold snap of January 2010, and the third treatment consisted of the extreme cold temperatures of a severe winter.

Canning-Clode and his colleagues found that most of the crabs in the control treatment survived (83%), but many of the crabs in the second cold treatment (61%) and all of the crabs in the third extreme cold treatment (100%) died. Crabs that survived cold treatment number two were sluggish, possibly making them more susceptible to predation and impacting their ability to feed, the scientists determined.

The scientists determined that prolonged exposure to cold temperatures also may compromise the green porcelain crab’s ability to overcome cumulative cold events, such as the two other record cold snaps that occurred in February and March of 2010.

Image right: A green porcelain crab (Photo by Juan Antonio Baeza)

The loss of more than 60% of their population during each cold period might explain the recent dramatic decline of the green porcelain crab in Georgia in 2010, suggesting that extreme cold spells may limit or prevent the northward spread of this invasive species.

Several climate models used to predict how species will react to climate change in the next 100 years have projected a continued decline of global biodiversity and increased spread of introduced species. Many of these models focus on temperature increases, but few have evaluated the impact of severe weather like cold snaps, Canning-Clode and his colleagues write in a paper on their study recently published at PLoS ONE.

For Canning Clode “the core message of this paper is that yes, climate change is happening, but cold is also part of this change. We believe these periodic cold events will limit the range expansion of Petrolisthes armatus as well as other Caribbean creep species” –Monaca Noble, SERC

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Image right: The Smithsonian’s Barro Colorado Island was the site of the first large-scale, long-term forest dyanmics plots. Now there are 42 forest dynamics plots worldwide that use the same methodology, the Smithsonian Institution Global Earth Observatory system managed by the Center for Tropical Forest Science. (Photo by Marcos Guerra)

“Air pollution is fertilizing tropical forests with one of the most important nutrients for growth,” said S. Joseph Wright, staff scientist at the Smithsonian Tropical Research Institute in Panama. “We compared nitrogen in leaves from dried specimens collected in 1968 with nitrogen in samples of new leaves collected in 2007. Leaf nitrogen concentration and the proportion of heavy to light nitrogen isotopes increased in the last 40 years, just as they did in another experiment when we applied fertilizer to the forest floor.”

Nitrogen is an element created in stars under high temperatures and pressures. Under normal conditions, it is a colorless, odorless gas that does not readily react with other substances. Air consists of more than 75% nitrogen. But nitrogen also plays a big role in life as an essential component of proteins. When nitrogen gas is zapped by lightning, or absorbed by soil bacteria called “nitrogen fixers,” it is converted into other “active” forms that can be used by animals and plants. Humans fix nitrogen by the Haber process, which converts nitrogen gas into ammonia—now a principal ingredient in fertilizers. Today, nitrogen fixation by humans has approximately doubled the amount of reactive nitrogen emitted.

Image left: The Smithsonian’s Barro Colorado Island was the site of the first large-scale, long-term forest dyanmics plots. Now there are 42 forest dynamics plots worldwide that use the same methodology, the Smithsonian Institution Global Earth Observatory system managed by the Center for Tropical Forest Science. (Photo by Marcos Guerra)

Nitrogen comes in two forms or isotopes: atoms that have the same number of protons but different numbers of neutrons. In the case of nitrogen, the isotopes are ¹⁴N and ¹⁵N, although only about one in 300 nitrogen atoms is the heavier form. Imagine nitrogen in the ecosystem like a bowl of popcorn. Normally the ratio of popped (light) to unpopped (heavy) kernels stays the same, but when someone starts to eat the popcorn, the lighter, popped kernels get used up first, increasing the ratio of heavy to light kernels (or ¹⁵N/¹⁴N in the case of the ecosystem). Light nitrogen is lost through nitrate leaching and as gases such as N2, and various forms of nitrous oxides or “noxides,” some of which can be important greenhouse gases. In the fertilization study in Panama, mentioned earlier, N₂O emissions were tripled.

“Tree rings provide a handy timeline for measuring changes in wood nitrogen content,” said Peter Hietz from the Institute of Botany at the University of Natural Resources and Life Sciences in Vienna, who faced down a tiger when sampling trees in a monsoon forest on the Thailand-Myanmar border. “We find that over the last century, there’s an increase in the heavier form of nitrogen over the lighter form, which tells us that there is more nitrogen going into this system and higher losses. We also got the same result in an earlier study of tree rings in Brazilian rainforests, so it looks like nitrogen fixed by humans now affects some of the most remote areas in the world.”

“The results have a number of important implications,” said Ben Turner, staff scientist at STRI. “The most obvious is for trees in the bean family (Fabaceae), a major group in tropical forests that fix their own nitrogen in association with soil bacteria. Increased nitrogen from outside could take away their competitive advantage and make them less common, changing the composition of tree communities.”

“There are also implications for global change models, which are beginning to include nitrogen availability as a factor affecting the response of plants to increasing atmospheric carbon dioxide concentrations,” said Turner. “Most models assume that higher nitrogen equals more plant growth, which would remove carbon from the atmosphere and offset future warming. However a challenge for the models is that there is no evidence that trees are growing faster in Panama, despite the long-term increases in nitrogen deposition and atmospheric carbon dioxide.”

Decades of atmospheric nitrogen deposition have caused major changes in the plants and soils of temperate forests in the U.S. and Europe. Whether tropical forests will face similar consequences is an important question for future research.

The Smithsonian Tropical Research Institute, headquartered in Panama City, Panama, is a unit of the Smithsonian Institution. The Institute furthers the understanding of tropical nature and its importance to human welfare, trains students to conduct research in the tropics and promotes conservation by increasing public awareness of the beauty and importance of tropical ecosystems. Website: www.stri.org.

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Image right: Horn snails (Photo by Kevin Lafferty)

“Just as people use airplanes to fly overseas, marine snails may use birds to fly over land,” said Mark Torchin, staff scientist at the Smithsonian. “It just happens much less frequently. There’s also a big difference between one or two individuals ending up in a new place and a really successful invasion, in which several animals survive, reproduce and establish new populations.”

The discovery of the hitchhiking snails, published in Proceedings of the Royal Society: B, has broad implications. “Not only snails but many intertidal organisms may be able to ‘fly’ with birds,” said first author of the study, Osamu Miura, assistant professor at Japan’s Kochi University and former postdoctoral fellow at the Smithsonian Tropical Research Institute in Panama.

Chance events that occur only once in a great while may be extremely important in the history of life. In 1940, George Gaylord Simpson, who studied natural history as recorded in fossils, coined the term “sweepstakes dispersal” to describe the unlikely events in which animals cross over a barrier resulting in major consequences for the diversity of life on Earth. Simpson was thinking about land-based animals that might “get lucky” and cross between continents or islands by floating on rafts of debris. Sometimes such events result in devastating biological invasions—introducing new diseases, wiping out resident species or causing economic damage to food crops.

Image right: Osamu Miura collecting snails.  (Photo by Mark Torchin)

The idea of land snails hitching rides on birds goes back to Charles Darwin, who speculated that migratory birds could transport snails to distant places. In fact, birds are thought to have carried land snails 5,500 miles from Eur

ope to Tristan de Cunha Island in the South Atlantic Ocean and back. But this is the first report of a marine snail “flying” from one ocean to another.

Scientists working at the Smithsonian in Panama have long been interested in how the rise of the Central American land bridge more than 3 million years ago drove speciation and increased biodiversity. It formed a barrier between marine species, some of which evolved in their new surroundings, becoming new “sister” species that could no longer mate with their former relatives.

By studying the genetics of two sister species of horn snails, Cerithideopsis californica and C. pliculosa, collected at 29 different locations in mudflats and mangrove habitats from California to Panama on the Pacific and from Texas to Panama on the Atlantic, the researchers discovered that, about 750,000 years ago, these snails invaded the Atlantic from the Pacific, and then, about 72,000 years ago, Atlantic populations returned to invade Pacific shores.

“Shorebirds mostly move back and forth across Central America via a couple of flyways,” said Torchin. “We think that the snails were able to cross the Isthmus of Tehuantepec in Mexico because it’s a major bird flyway and is a relatively flat and narrow stretch of land with ideal tidal flat habitat on either side.”

“There is a chance that the hitchhiking snails benefited native populations by bringing in new genes that helped them resist common parasites that castrate the snails and keep them from reproducing,” said Ryan Hechinger, associate research biologist at the University of California, Santa Barbara. “Now we are looking at the parasite genes to see if they jumped Central America too.”

“Understanding that such hitchhiking occurs can help reveal where new species might have become established or where they might establish in the future,” said Eldredge Bermingham, STRI director and staff scientist. “I am here in Panama watching as snails fly over my head. Tongue in cheek, I fail to understand why others did not notice this before! I suspect our interpretation of this phylogeographic pattern would make George Gaylord Simpson smile.”

Reference: Osamu Miura, Mark E. Torchin, Eldredge Bermingham, David K. Jacobs, Ryan F. Hechinger. Proceedings of the Royal Society: B. (Sept. 14, 2011)

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Image left and below right: Male Micronesian kingfisher chick, born Aug. 20. (Photos by Mehgan Murphy)

This species is extremely difficult to breed due to incompatibility between males and females and the inability of some parents to successfully raise their own chicks. The chick that hatched at the Bird House was incubated and raised by its parents. Keepers weighed it each day to make sure it did not need supplemental feeding. A final pathology report will provide more information about the cause of its death.

“We are encouraged that this pair showed an interest in one another and delighted that they produced fertile eggs,” said Warren Lynch, bird unit manager at SCBI. “We are hand-rearing the chicks, which involves feeding them at two-hour intervals, seven to eight times per day. Should the adults produce fertile eggs again, we will likely let them try to raise the chicks themselves while closely monitoring their parenting skills.”

Micronesian kingfishers flourished in Guam’s limestone forests and coconut plantations until the arrival of the brown tree snake (Boiga irregularis), an invasive species that stowed away in military equipment shipped from New Guinea after World War II. Because these reptiles had no natural predators on Guam, their numbers grew and they spread across the island quickly. Within three decades, they hunted Micronesian kingfishers and eight other bird species to the brink of extinction.

In 1984, Guam’s Department of Aquatic and Wildlife Resources captured the country’s remaining 29 Micronesian kingfishers and sent them to zoological institutions around the globe—including the National Zoo—as a hedge against extinction. The Association of Zoos and Aquariums created a Species Survival Plan for the birds. The SSP pairs males and females in order to maintain a genetically diverse and self-sustaining population.

Image right: Female chick born July 25.

To date, 16 chicks have hatched at SCBI, and each provides scientists with the opportunity to learn about the growth, reproduction, health and behavior of the species. Five of SCBI’s kingfishers have gone to other zoos to breed.

“We’re proud that SCBI has been a part of the Micronesian kingfisher recovery from the start, and we hope this pair continues to produce healthy offspring and contribute to its species’ survival,” said Chris Crowe, bird keeper at SCBI. “Both chicks are thriving. The female flies short distances and is increasingly confident and vocal, and the male is beginning to grow feathers and has a healthy appetite for crickets, mice and small lizards.”

As the captive population increases, the U.S. Fish and Wildlife Service and Guam’s Department of Aquatic and Wildlife Resources continue to look for suitable release sites in Guam. The availability of release sites continues to shrink, however, due to deforestation and human expansion. Controlling the brown snake population remains a significant challenge as well, though researchers have made progress in developing a variety of barriers, traps and toxicants. Scientists are hopeful that initiatives for snake control and forest protection signify that the reintroduction of the Micronesian kingfisher may soon become feasible. Additionally, field studies of a different subspecies of wild kingfishers are underway on Pohnpei, another Micronesian island, to secure essential biological information on wild populations and to test various reintroduction techniques for use on Guam.

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