May 14, 2007, 10:29 PM CT

Species Distribution Patterns In Tropical Forests

Looking at a rainforest its easy to see that there are hundreds of different tropical plant species that inhabit the forest. Eventhough the patterns of plant distributions in tropical forests have been widely studied, the reasonings behind these patterns are not as well known. This study, published in Nature, explores these patterns.

A contingent of scientists from around the world, including Panama, Gera number of, USA and Canada, have uncovered that tropical plant species distribution patterns are associated with the plants drought sensitivity.

For this study, the scientists conducted irrigation experiments on 48 native tree and shrub species to determine drought sensitivity between dry and irrigated conditions, which confirmed that species vary widely in drought sensitivity. The scientists also assessed regional plant species distribution across two large plots on opposite sides of the Isthmus of Panama. Through this assessment it was observed that the plants densities at the dry Pacific side in comparison to the wet Atlantic side correlated negatively with drought sensitivity.

"Our results suggest that niche differentiation with respect to soil water availability is a direct determinant of the distributions of tropical plant species," said Dr. Mel Tyree, University of Alberta researcher......... Posted by: Erica      Read more         Source

Sun, 13 May 2007 16:20:48 GMT

Dodecatheon pulchellum

Few-flowered shooting star (or darkthroat shootingstar or prairie shooting star or pretty shooting star) is native throughout western North America. I've so far found it on grass-covered hills with localized moist (but not saturated) soils owing to springtime melts.

Pollination of plants in the genus Dodecatheon is aided by buzz pollination (more), in which a strong pulse of rapid buzzing by a bee vibrates the anthers, causing the pollen to discharge.

The Primulaceae (or primrose family) are predominantly found in the northern hemisphere (map). Viewed together with the closely-related Myrsinaceae and Theophrastaceae, a representative of this trio of plant families can be found almost anywhere in the world, excluding central Africa, parts of Australia and polar regions.

More photographs of this species can be found on the stellar Burke Museum site: Dodecatheon pulchellum. Posted by: Daniel Mosquin      Read more     Source

Sun, 13 May 2007 04:00:44 GMT

Great Smoky Mountains National Park

Ridge upon ridge of endless forest straddles the border between North Carolina and Tennessee in Great Smoky Mountains National Park. World renowned for the diversity of its plant and animal life, the beauty of its ancient mountains, and the quality of its remnants of Southern Appalachian mountain culture, this is America's most visited national park.

 
Things to Do
Great Smoky Mountains National Park is a hiker's paradise with over 800 miles of maintained trails ranging from short leg-stretchers to strenuous treks that may require backcountry camping. But hiking is not the only reason for visiting the Smokies. Car camping, fishing, picnicking, wildlife viewing and auto touring are popular activities.
 
Wildlife
Most visitors come to the Smokies hoping to see a bear. Some 1,600 bears live in the park. From the big animals like bears, deer, and elk, down to microscopic organisms, the Smokies have the most biological diversity of any area in the world's temperate zone. The park is a sanctuary for a magnificent array of animal and plant life, all of which is protected for future generations to enjoy.
 
Spring Wildflowers
The park is a world-renowned preserve of wildflower diversity-over 1,660 kinds of flowering plants are found here, more than in any other North American national park. From the earliest hepaticas and spring-beauties in the late winter to showy rhododendron and azalea shrubs in summer, to the last asters in the late fall, blooming flowers can be found year-round in the park.
 
Ranger-Guided Programs and Special Events
Ranger-guided programs give visitors the opportunity to explore the wonders of the park with a Ranger. Programs are offered in spring, summer, and fall.
 
Write to
Great Smoky Mountains National Park
107 Park Headquarters Road
Gatlinburg, TN 37738
Phone
Visitor Information
(865) 436-1200
Fax
(865) 436-1220

Climate
Great Smoky Mountains National Park has a moderate climate, typified by mild winters and hot, humid summers. When planning a trip to the Smokies, keep in mind that elevations in the park range from 800 feet to 6,643 feet and that the topography can drastically affect local weather. Temperatures can vary 10-20 degrees Fahrenheit from mountain base to top, and clear skies at lower elevations do not guarantee equally pleasant weather on the higher peaks.
 Did You Know?
Money to buy the land that became Great Smoky Mountains National Park was raised by individuals, private groups, and even school children who pledged their pennies. In addition, the Laura Spellman Rockefeller Memorial Fund donated $5 million to create the park. Posted by: Gracy      Read more     Source

May 9, 2007, 11:14 PM CT

Plants tag insect herbivores with an alarm

Rooted in place, plants can't run from herbivoresbut they can fight back. Sensing attack, plants frequently generate toxins, emit volatile chemicals to attract the pest's natural enemies, or launch other defensive tactics.

Now, for the first time, researchers reporting in the June 2007 issue of Plant Physiology have identified a specific class of small peptide elicitors, or plant defense signals, that help plants react to insect attack.

In this colorful self-defense strategy, proteins already present in the plant are ingested by insect attackers. Digesting the proteins, the insects unwittingly convert this food into a peptide elicitor, which gets secreted back onto plants during later feedings. Recognizing the secreted elicitor as a kind of "SOS," plants launch defensive chemistry. This defense discovery opens the door for the development and genetic manipulation of plants with improved protection against pests.

Although researchers have long known that some plants distinguish different insect attackers, this defensive behavior has proven difficult to describe at the molecular level. Exceedingly few model systems have been utilized to characterize the potential interactions between what researchers estimate to be at least four million insects and 230,000 flowering plant species. Moreover, highly active plant defense signals can occur at trace levels, too small to easily detect or isolate......... Posted by: Erica      Read more         Source

May 7, 2007, 10:54 PM CT

Tropical plants go with the flow of nitrogen

Tropical plants are able to adapt to environmental change by extracting nitrogen from a variety of sources, as per a new study that appears in the May 7 early online edition of The Proceedings of the National Academy of Sciences.

By demonstrating that not all plants specialize in one specific source of nitrogen, the result turns a usually held theory on its head. It also provides a dose of optimism that tropical forests will be able to withstand environmental shifts in nutritional cycles brought on by global climate change.

Nitrogen is an essential nutrient that plants must absorb from the soil to survive. Most land plants outside the tropics appear to have evolved to rely on just one of three common sources of nitrogen: nitrate (NO3-), ammonium (NH4+), or dissolved organic nitrogen (DON). As a result of this limitation, they commonly inhabit "niches" defined largely by the available nitrogen source. When that source crashes for any reasonoften because of shifts in climatethe plants cannot adapt, with potentially disastrous consequences for natural ecosystems.

However, tropical species appear to be far more adaptable than their temperate kin when it comes to their nitrogen needs. A team of researchers* has observed that, when confronted with shifts in nitrogen availability, these plants simply "flip a switch" and use whatever is handy......... Posted by: Erica      Read more         Source

Tue, 08 May 2007 02:13:42 GMT

Tulipa 'Zurel'

Botany Photo of the Day will have brief written entries on weekends, holidays and my vacations from April through September. – Daniel

Tulipa 'Zurel' is coloured purple and white, photographed here en masse with an errant unknown red tulip. One of the charms of the Roozengaarde tulip fields was the presence of uniformity-breaking individuals in different colours scattered throughout the plots – that little dash of “imperfection” spurred dozens of conversations easily overheard by photographers waiting for the breeze to vanish. Those exclamatory conversations were absent in other fields where a strict uniformity of colour was maintained.

In local news, one of the city papers has covered the upcoming Collectors' Plant Auction: Rare-plant auction boosts UBC garden (link expires on Saturday April 28). Posted by: Daniel Mosquin      Read more     Source

April 30, 2007, 7:02 PM CT

Seeing the trees for the forest

After completing a two-year pilot phase, researchers at the Woods Hole Research Center are expanding the scope of the "National Biomass and Carbon Dataset" for the year 2000 (NBCD2000), the first ever inventory of its kind, by moving into the production phase. Through a combination of NASA satellite datasets, topographic survey data, land use/land cover data, and extensive forest inventory data collected by the U.S. Forest Service Forest Inventory and Analysis Program (FIA), NBCD2000 will be an invaluable baseline data set for the assessment of the carbon stock in U.S. forest vegetation and will improve current methods of determining carbon flux between vegetation and the atmosphere. Work on the remaining 61 mapping zones will be completed at a rate of roughly one zone every seven working days.

As per Josef Kellndorfer, an associate scientist at the Center who is leading the project, "Understanding this flux is critical for the quantification and prediction of atmospheric CO2 concentrations, a major determinant of the greenhouse warming effect in the climate system. Thus, this initiative will directly support the North American Carbon Program, which is a major component of the U.S. Climate Change Research Program".

In the NBCD2000 initiative, begun in 2005, data is being analyzed in 66 ecologically diverse regions, termed "mapping zones", which span the conterminous United States. Within each mapping zone data from the 2000 Shuttle Radar Topography Mission are combined with topographic survey data from the National Elevation Dataset (NED) to produce a radar-based height map of vegetation. Subsequently, this map is converted to estimates of actual vegetation height, biomass, and carbon stock using survey data from the U.S. Forest Service FIA program and ancillary data sets from the National Land Cover Database 2001 (NLCD2001) project. The NLCD2001 data layers are crucial inputs to the NBCD2000 project as they provide land cover and canopy density information used in the stratification/calibration process......... Posted by: Erica      Read more         Source

April 30, 2007, 6:56 PM CT

Plants with male and bisexual flowers on the same plant

What would be the opening chapter of the Kamasutra of plant sex? A good pick would be a description of the numerous ways in which plants arrange their sexual organs: from both sexes in the same flower to sexes separated in different flowers or individuals. One widespread sexual strategy that remains an evolutionary enigma is the production of both male and bisexual flowers in the same plant, which occurs in approximately 4000 species. What is the advantage of producing these redundant male flowers? Mario Vallejo-Marin and Mark Rausher, evolutionary biologists from Duke University, report that producing male flowers can make a plant a better mother, in the recent issue of the American Naturalist. The authors showed this counter-intuitive benefit of a "male" strategy through a series of field experiments with horsenettle, a common weed in North Carolina. The experimental demonstration that male flowers can sometimes increase seed number supports a new interpretation that male flowers increase not only male but also female reproductive success.

So what is the mechanism through which male flowers increase female reproductive success? Such a benefit may arise if resources saved by producing smaller male flowers are reallocated to increased seed production, if male flowers are more attractive to pollinators, or if male flowers remove less pollen from pollinators than bisexual flowers, thus increasing the amount of non-self pollen available for fruit-producing flowers. Which one of these mechanisms is responsible for the "good mothers" in Vallejo-Marin and Rausher's study? "We don't know yet," says Mario, "but these alternatives could easily be tested through more experiments." Data from an unrelated study indicate that the female advantage of producing male flowers is not unique to horsenettle. To what extent strategies traditionally interpreted as "male" also benefit female fitness in other species remains an open and interesting question......... Posted by: Erica      Read more         Source

Sun, 29 Apr 2007 15:52:19 GMT

Rhododendron periclymenoides

BPotD is in brief entry mode on weekends and holidays from April through September. – Daniel

Thank you to Earl B. of the eastern USA for sharing today's photograph with us. This photograph was taken on April 6, 2007.

Pink azalea or Pinxterbloom azalea is a native of the eastern United States. Flower colour and form can be highly variable (see previous link and the Kemper Center for Home Gardening to view examples). This species will be present in UBC Botanical Garden's new Carolinian Forest. Posted by: Daniel Mosquin      Read more     Source

April 23, 2007, 10:44 PM CT

Prehistoric mystery organism verified as giant fungus

Scientists at the University of Chicago and the National Museum of Natural History in Washington, D.C., have produced new evidence to finally resolve the mysterious identity of what they regard as one of the weirdest organisms that ever lived.

Their chemical analysis indicates that the organism was a fungus, the scientists report in the recent issue of the journal of Geology, published by the Geological Society of America. Called Prototaxites (pronounced pro-toe-tax-eye-tees), the organism went extinct approximately 350 million years ago.

Prototaxites has generated controversy for more than a century. Originally classified as a conifer, scientists later argued that it was instead a lichen, various types of algae or a fungus. Whatever it was, it stood in tree-like trunks more than 20 feet tall, making it the largest-known organism on land in its day.

"No matter what argument you put forth, people say, well, thats crazy. That doesnt make any sense," said C. Kevin Boyce, an Assistant Professor in Geophysical Sciences at Chicago. "A 20-foot-tall fungus doesnt make any sense. Neither does a 20-foot-tall algae make any sense, but heres the fossil".

The Geology paper adds a new line of evidence indicating that the organism is a fungus. The fungus classification first emerged in 1919, with Francis Hueber of the National Museum of Natural History in Washington, D.C., reviving the idea in 2001. His detailed studies of internal structure have provided the strongest anatomical evidence that Prototaxites is not a plant, but a fungus......... Posted by: Erica      Read more         Source