CTFS-SIGEO is a global network of forest research plots committed to the study of tropical and temperate forest function and diversity. The multi-institutional network includes plots across the Americas, Africa, Asia, and Europe, with a strong focus on tropical regions. Ecologists at the Smithsonian Tropical Research Institute established the first forest dynamics plot on Barro Colorado Island in the Panama Canal in 1980.

Image left: Daniel Johnson, a biology graduate student at Indiana University, measures the diameter of a white ash tree in the University’s Lilly-Dickey Woods. The 550-acre woods were recently added to CTFS-SIGEO’s global network of forest research plots. (Photo by F. Collin Hobbs)

Stuart J. Davies, CTFS-SIGEO director and senior staff scientist at the Smithsonian Tropical Research Institute, will make the move along with David Kenfack, CTFS-SIGEO Africa Program coordinator. Davies sees the need for increased presence at the Smithsonian in Washington, D.C. as the network continues to build partnerships within different Smithsonian units.

The scale and intensity of the CTFS-SIGEO research program remains unprecedented in forest science. Scientists monitor the growth and survival of about 4.5 million trees of approximately 8,500 species in 21 different countries. The work aims to increase the scientific understanding of forest ecosystems, guide sustainable forest management and natural-resource policy, monitor the impacts of climate change, and build capacity in forest science. Most recently CTFS-SIGEO added the Lilly-Dickey Woods–a 550-acre forest in Brown County Indiana that is a research and teaching preserve for Indiana University–to its network of forest research plots.

Because of its extensive biological monitoring, unique databases, and the expertise of its partners, CTFS-SIGEO enhances society’s ability to evaluate and respond to the impacts of global climate change. Monitoring so many forest plots at once is providing a comprehensive, yet locally detailed perspective on how the world’s forests are being transformed by global change.  Research on tropical forest dynamics continues, but is joined by new initiatives studying carbon fluxes, temperate forests, ecosystem services, and biodiversity. CTFS-SIGEO and its many institutional partners are leveraging huge intellectual horsepower to transform our understanding of forest-ecosystem structure and function. The network has been so successful that the Smithsonian is now planning to extend its system of earth observatories to the near shore marine realm. –Source: The Plant Press, newsletter of the Department of Botany, National Museum of Natural History.

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Collections will continue to be owned by the National Park Service but will be in the permanent custodial care of the Smithsonian Institution. The agreement formalizing the relationship was signed today by National Park Service Director Jonathan B. Jarvis and the Smithsonian’s Under Secretary for Science Eva J. Pell at the National Museum of Natural History.

Photo right: Jon Jarvis, Director of the National Park Service, and Eva Pell, Under Secretary for Science at the Smithsonian sign an MOU between the two organizations. The partnership gives broader access to National Park Service collections through the Smithsonian’s care and management of them. (Johnny Gibbons photo)

“This agreement benefits science, the American people, and the long-standing and historic relationship between our two organizations,” said Jarvis. “Together we are building a collection that will become an extraordinary tool for the scientific community to study biodiversity, evolution, and the distinctive character of national park ecosystems.”

The Smithsonian echoed the significance of the new agreement. “Two venerable institutions long known for protecting the nation’s heritage, are now working together to enhance care and access to specimens that document the natural environment of our national parks,” said Eva Pell, under secretary for science at the Smithsonian.

Examples of National Park Service collections that the Smithsonian could curate under the new agreement are:

• 138 holotypes – a specimen described in scientific literature to establish a new species – that researchers in Great Smoky Mountains National Park in Tennessee and North Carolina have discovered and described over the past 14 years.

• From George Washington Memorial Parkway in Virginia, 3,000 vascular plant specimens representing 1,326 species, as well as a wide range of specimens from the Potomac River Gorge, including holotypes of shoreflies, caddisflies, and copepods (small crustaceans).

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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 right: These ancient corn cobs date roughly from 6,500-4,000 years ago. A is Proto-Confite Morocho race; B, Confite Chavinense maize race; and C is Proto-Alazan maize race.. (Photo by Tom Dillehay)

Some of the oldest known corncobs, husks, stalks and tassels, dating from 6,700 to 3,000 years ago were found at Paredones and Huaca Prieta, two mound sites on Peru’s arid northern coast. The research group, led by Tom Dillehay from Vanderbilt University and Duccio Bonavia from Peru’s Academia Nacional de la Historia, also found corn microfossils: starch grains and phytoliths. Characteristics of the cobs—the earliest ever discovered in South America—indicate that the sites’ ancient inhabitants ate corn several ways, including popcorn and flour corn. However, corn was still not an important part of their diet.

Image left: Wild forms of Zea mays are called ‘teosinte’. Over time, selective breeding modifies teosinte’s few fruitcases (left) into modern corn’s rows of exposed kernels (right). (Photo courtesy John Doebley.).

“Corn was first domesticated in Mexico nearly 9,000 years ago from a wild grass called teosinte,” Piperno says. “Our results show that only a few thousand years later corn arrived in South America where its evolution into different varieties that are now common in the Andean region began. This evidence further indicates that in many areas corn arrived before pots did and that early experimentation with corn as a food was not dependent on the presence of pottery.”

Understanding the subtle transformations in the characteristics of cobs and kernels that led to the hundreds of maize races known today, as well as where and when each of them developed, is a challenge. Corncobs and kernels were not well preserved in the humid tropical forests between Central and South America, including Panama—the primary dispersal routes for the crop after it first left Mexico about 8,000 years ago.

“These new and unique races of corn may have developed quickly in South America, where there was no chance that they would continue to be pollinated by wild teosinte,” Piperno says. “Because there is so little data available from other places for this time period, the wealth of morphological information about the cobs and other corn remains at this early date is very important for understanding how corn became the crop we know today.”

“Preceramic corn from Pardones and Huaca Prieta, Peru,” Grobman, A., Bonavia, D., Dillehay, T.D., Piperno, D.R., Iriarte, J., Holst, I. 2012. . PNAS early online edition, week of Jan. 16, 2012.

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Image right:  American Mistletoe (Phoradendron flavescens) by Mary Vaux Walcott, 1923.  (Image courtesy Smithsonian American Art Museum)

* Mistletoe is found mainly in tropical or temperate areas. Its name refers to species of parasitic plants from families in the order of flowering plants known as Santalales. There are some 1,300 species of mistletoe worldwide.

Image left: The mistletoe Phoradendron serotinum. (Photo by Jorg and Mimi Fleige)

* The word “mistletoe” is thought to derive from the Anglo-Saxon “mist” or “mistel”, meaning dung, and “tan”, meaning twig, or “dung twig”. This derivation stems from the fact that mistletoe is mostly spread by birds, through their droppings.

* Birds also squeeze mistletoe seeds from the fruits before eating them and wipe the seeds on a branch. Mistletoe seeds are covered in a sticky substance so they stay put on a limb until they sprout.

* Mistletoe is semi-parasitic, meaning it invades a living branch of a host tree or bush with a shallow root (called  a “hastorium”) and absorbs food, minerals and water, and also produces food through photosynthesis in its evergreen leaves.

* Viscum album, the European mistletoe, and Phoradendron serotinum, from North America, are the two mistletoe species most commonly harvested and sold during the Christmas holidays.

Image right: The mistletoe Vicsum album (Photo by Malcom Storey)

* Mistletoe is considered a pest in many areas of the world. A host tree or bush heavily infested with mistletoe can be stunted or even die. Still, mistletoe provides an important food source and a nesting place for a variety of bird species.

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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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Images: Photos of Michaux’s sumac by Lytton Musselman

Because Michaux’s sumac grows only in areas with few trees where the vegetation has been disturbed, it has long been assumed that its seeds germinate naturally following exposure to the high-temperatures of a brush or forest fire. Decline of this plant has been attributed to the prevention and suppression of brush and forest fires by humans. In Virginia it grows in only two places: on the grounds of the Virginia Army National Guard Maneuver Training Center in Fort Picket and a mowed railway right-of-way in an undisclosed location.

In a recent series of germination experiments, the scientists exposed different sets of Michaux’s sumac seeds to dry heat temperatures of 140, 176, 212, 248 and 284 degrees Fahrenheit, some sets for 5 minutes and other sets for 10 minutes. (The temperatures were determined based on maximum wildfire surface temperatures and burn times recorded in southeastern U.S. forests.) The researchers found that temperatures above 212 degrees F. killed the seeds. Lower temperatures had virtually no impact on breaking the seed’s dormancy.

The highest germination rates—30 percent—occurred after sulfuric acid was poured on Michaux’s sumac seeds and allowed to scarify (dissolve and weaken) the seed coats. This finding, from an experiment done in 1996, has led the researchers to their next experiment using birds. “We are going to feed the seeds to quail and wild turkey to determine if that breaks the seed dormancy,” says Bolin, a research associate with the Department of Botany at the Smithsonian’s National Museum of Natural History and an assistant professor at Catawba College in Salisbury, N.C. Seed passage through the digestive tracts of frugivorous (fruit eating) birds (and exposure to the acid in the bird’s stomachs) may break the physical dormancy of these seeds and help disperse them as well, the scientists write.

The paper “Germination of the federally endangered Michaux’s sumac (Rhus michauxii), authored by Jay F Bolin, Marcus E Jones (Norfolk Botanical Garden, Norfolk Va.,) and Lytton J Musselman (Old Dominion University, Norfolk, Va.) appeared in the Summer 2011 issue of “Native Plants Journal”

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