January 12, 2007, 5:05 AM CT

Soil Nutrients And Tropical Forests

Tropical forests are among the most diverse plant communities on earth, and scientists have labored for decades to identify the ecological and evolutionary processes that created and maintain them. A key question is whether all tree species are equivalent in their use of resources - water, light and nutrients - or whether each species has its own niche.

A large-scale study by researchers at the University of Illinois at Urbana-Champaign and eight other institutions sheds some light on the issue. It indicates that nutrients in the soil can strongly influence the distribution of trees in tropical forests. The finding, published this week in the Proceedings of the National Academy of Sciences, challenges the theory that at local scales tree distributions in a forest simply reflect patterns of seed dispersal, said James W. Dalling, a U. of I. professor of plant biology and a principal researcher on the study.

The study evaluated three sites: two lowland forests, in central Panama and eastern Ecuador, and a mountain forest in southern Colombia. The researchers plotted every tree and mapped the distribution of soil nutrients on a total of 100 hectares (247 acres) at the sites. The study included 1,400 tree species and more than 500,000 trees.

The researchers compared distribution maps of 10 essential plant nutrients in the soils to species maps of all trees more than 1 centimeter in diameter. Each of the sites was very different, but at each the researchers found evidence that soil composition significantly influenced where certain tree species grew: The spatial distributions of 36 to 51 percent of the tree species showed strong associations with soil nutrient distributions.........

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January 9, 2007, 9:06 PM CT

Forest Fires Release Mercury

Forest fires release more mercury into the atmosphere than previously recognized, a multidisciplinary research project at the University of Michigan suggests.

The study, which has implications for forest management and global mercury pollution, was published online today (Jan. 9) in the journal Global Biogeochemical Cycles.

Doctoral student Abir Biswas, the paper's lead author, came up with the idea for the project when he was a student at U-M's Camp Davis Rocky Mountain Field Station near Jackson Hole, Wyoming. Wildfires were burning all around the station that summer, and smoke blanketed the camp. Around that time, Biswas happened to read a new scientific paper suggesting the possible role of fires in global mercury emissions.

"There I was, watching forest fires around our field camp, and it seemed like the ideal place to study the problem," he said.

The study Biswas read investigated mercury emissions from the combustion of foliage at locations around the USA and extrapolated to estimate mercury release during forest fires. "I'm interested in earth surface geochemistry so I wanted to approach the question differently," Biswas said.

Over the next two summers, under the direction of U-M professor Joel Blum, Biswas collected core samples of forest soil from burned and unburned areas, using sections of PVC pipe sharpened at one end to obtain the cylindrical samples. He and Blum also collaborated with U-M professor Gerald Keeler and former research scientist Bjorn Klaue to take air samples at Camp Davis-measuring mercury and trace metals over two summers-which provided the scientists with a picture of the atmospheric background on which the fires were superimposed.........

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January 9, 2007, 8:15 PM CT

How Some Invasive Plants Gain a Foothold?

University of California, Riverside genetics Professor Norman Ellstrand led a team of scientists whose findings suggest that harnessing the sexual requirements of some plants can help control the establishment of invasive species.

Using the California wild radish as their model, Ellstrand and graduate student Caroline Ridley at the UCR Department of Botany and Plant Sciences co-authored the research study titled Population size and relatedness affect fitness of self-incompatible invasive plants, reported in the Dec. 29 edition of the Proceedings of the National Academy of Sciences. The current article originated from a doctoral dissertation project by former UCR graduate student Diane Elam. Fellow graduate student Karen Goodell also worked on the project. Elam is now with the U.S. Fish and Wildlife Service's Sacramento office. Karen Goodell now teaches at Ohio State University.

The experiment involved population groups ranging in size from two to 20 plants and was carried out at UCR's Agricultural Experiment Station. The experiment examined whether a biological phenomenon known as the Allee effect could be used to battle the spread of invasive plants. The Allee effect, named after ecologist W.C. Allee, says that the smaller and sparser a given population, the harder and slower it is for that population to establish itself and expand its range.........

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December 28, 2006, 8:31 PM CT

Dust Needed for Brazilian rainfores

More than half of the dust needed for fertilizing the Brazilian rainforest is supplied by a valley in northern Chad, as per an international research team headed by Dr. Ilan Koren of the Institute's Environmental Sciences and Energy Research Department. As per a research findings published recently in Environmental Research Letters, the researchers have explained how the Bodele valley's unique features might be responsible for making it such a major dust provider.

It has been known for more than a decade that the existence of the Amazon rainforest depends on a supply of minerals washed off by rain from the soil in the Sahara and blown across the Atlantic by dust. By combining various types of satellite data, Dr. Koren and his colleagues from Israel, the United Kingdom, the United States, and Brazil have now for the first time managed to obtain quantitative information about the weight of this dust. Analyses of dust quantities were performed near the Bodele valley itself, on the shore of the Atlantic and at an additional spot above the ocean.

The data revealed that some 56 percent of the dust reaching the Amazon forest originates in the Bodele valley. They also showed that a total of some 50 million tons of dust make their way from Africa to the Amazon region every year, a much higher figure than the prior estimates of 13 million tons. The new estimate matches the calculations on the quantity of dust needed to supply the vital minerals for the continued existence of the Amazon rainforest.........

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December 18, 2006, 9:09 PM CT

Discoveries Of New Species In Borneo's Rainforests

Researchers have discovered at least 52 new species of animals and plants this past year on the island of Borneo. The discoveries, described in a new WWF report, include 30 unique fish species, two tree frog species, 16 ginger species, three tree species and one large-leafed plant species.

"The more we look the more we find," said Stuart Chapman, WWF International Coordinator of the Heart of Borneo Program. "These discoveries reaffirm Borneo's position as one of the most important centers of biodiversity in the world and why conservation there is so important."

Some of the creatures new to science include: a miniature fish, the world's second smallest vertebrate measuring less than a third of an inch in length and found in the highly acidic blackwater peat swamps of the island; six Siamese fighting fish, including one species with a beautiful iridescent blue-green marking; a catfish with protruding teeth and an adhesive belly which allows it to literally stick to rocks; and a tree frog with striking bright green eyes. The new ginger plants more than double the number of the Etlingera species found to date.

Several of these new species were found in the "Heart of Borneo," an 84,000 square mile mountainous region about the size of Kansas that is covered with equatorial rainforest in the center of the island. Large areas of the forest are at risk from destructive logging and expanding rubber, oil palm and pulp plantations. Since 1996, deforestation across Indonesia has increased to an average of 7,700 square miles each year, an area slightly smaller than Vermont. Today only half of Borneo's original forest cover remains.........

Posted by: Kelly      Permalink         Source

December 18, 2006, 4:54 AM CT

Frankincense Trees Overexploited For Christmas Scent

Current rates of tapping frankincense - which as per the Bible was given to the baby Jesus by the three wise men at Christmas and which will feature in thousands of Nativity plays in coming days - are endangering the fragrant resin's sustained production, ecologists have warned. Writing in the recent issue of Journal of Applied Ecology, ecologists from the Netherlands and Eritrea say that over tapping the trees results in them producing fewer, less viable seeds.

Frankincense is an aromatic hardened wood resin obtained by tapping Boswellia trees. For thousands of years, frankincense has been hugely important both socially and economically as an ingredient in incense and perfumes. But, say the ecologists, its production in the Horn of Africa is declining because Boswellia woodlands are failing to regenerate.

The ecologists hypothesised that poor regeneration was due to the fact that intensive tapping meant that the trees were diverting too much carbohydrate into resin, at the expense of reproductive organs, such as flowers, fruit and seeds. Working in south-western Eritrea, they tested the hypothesis by looking at how a number of seeds intensively tapped trees produced, and their germination rates, compared with untapped trees.

As per one of the authors of the study, Professor Frans Bongers of Wageningen University: "This study strongly suggests that there is competition between investment of carbohydrates in sexual reproductive structures and synthesis of frankincense in Boswellia papyrifera. At all study sites, trees subject to experimental tapping produced fewer flowers, fruits and seeds than trees that were exempt from tapping. Furthermore, tapped trees produced smaller fruits with seeds of lower weight and reduced vitality than non-tapped trees".........

Posted by: Erica      Permalink         Source

December 17, 2006, 8:03 PM CT

Logging, Mineral Exploitation Could Erase Two-thirds of Congo Basin

Do you know, the Congo Basin loses some 3.7 million acres a year to agriculture, logging, road development, oil exploitation and mining? Yes, this is what the WWF's Central African regional office (CARPO) said in a recent report.

And, if logging and mineral exploitation continues at the current rates in the world's second largest tropical forest - after the Amazon forests - two-thirds of it could disappear within just 50 years! - the environmental group WWF fears.

With the forests' disappearance, about 400 mammal species are under threat as their habitat is getting destroyed too! The animals include the world's largest populations of lowland gorillas, chimpanzees, bonobos and forest elephants.

CARPO director Laurent Some said in the report,.

Tropical forest is vanishing at a rate of 5 percent a decade, wrecking habitats and releasing 3 billion tonnes of carbon dioxide a year, which is a fifth of global greenhouse emissions.........

Posted by: Erica      Permalink         Source

December 17, 2006, 8:00 PM CT

Bell Pepper, with Loads of Taste and Medicinal Values

Bell pepper is of three basic types - red, green, yellow and a number of more. Each has its own taste and medicinal value, plus the delicacy of being delicious too. Bell pepper is most usually known as the capsicum as it is derived from the capsicum plant. Bell pepper contains a recessive gene which eliminates the capsaicin in the fruit.

Capsaicin:

The chemical compound capsaicin (8- methyl- N-vanillyl-6-nonenamide) which is the active component of the chili peppers. It is an irritant to mammals and produces a burning sensation to the human tissues when brought in contact. Capsaicin and several related compounds are called capsaicinoids and are produced as a secondary metabolite, by chili peppers, probably as deterrents against herbivores. Pure capsaicin is a hydrophobic, colorless, odorless, and crystalline to waxy compound.

Medical:

Capsaicin is currently used in topical ointments to relieve the pain of peripheral neuropathy such as post-herpetic neuralgia caused by shingles. It may be used in concentrations of between 0.025% and 0.075%.

Herpes Zoster, colloquially known as shingles, is the reactivation of the virus varicella zoster, leading to a crop of painful blisters over the area of dermatome.

It may also be used as a cream for the temporary relief of minor aches and pains of muscles and joints linked to arthritis, simple backache, strains and sprains. The therapy typically involves the application of a topical anesthetic until the area is numb. Then the capsaicin is applied by a therapist wearing rubber gloves and a face mask. The capsaicin remains on the skin until the patient starts to feel the "heat", at which point it is promptly removed. Capsaicin is also available in large adhesive bandages that can be applied to the back.........

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December 13, 2006, 6:27 PM CT

Soil Nutrition And Carbon Sequestration

USDA Forest Service (FS) researchers from the FS Southern Research Station (SRS) unit in Research Triangle Park, NC, along with colleagues from Duke University, published two papers in The Proceedings of the National Academy of Science (PNAS) that provide a more precise understanding of how forests respond to increasing atmospheric concentrations of carbon dioxide (CO2), the major greenhouse gas driving climate change.

Building on preliminary studies reported in Nature, the scientists observed that trees can only increase wood growth from elevated CO2 if there is enough leaf area to support that growth. Leaf area, in turn, is limited by soil nutrition; without adequate soil nutrition, trees respond to elevated CO2 by transferring carbon below ground, then recycling it back to the atmospheric through respiration.

"With sufficient soil nutrition, forests increase their ability to tie up, or sequester carbon in woody biomass under increasing atmospheric CO2 concentrations," says Kurt Johnsen, SRS researcher involved in the project. "With lower soil nutrition, forests still sequester carbon, but cannot take full advantage increasing CO2 levels. Due to land use history, a number of forests are deficient in soil nutrition, but forest management -- including fertilizing with nitrogen -- can greatly increase growth rate and wood growth responses to elevated atmospheric CO2".........

Posted by: Erica      Permalink         Source

December 13, 2006, 4:36 AM CT

Lightning Fires Help Preserve Oak Forests

Oak forests may be approaching extinction but lightning fires may play a vital role in their regeneration, as per Case Western Reserve University biologists.

Paul Drewa, assistant professor in Case's biology department, and graduate student Sheryl Petersen, suspect that these kinds of fires may provide a natural mechanism to deter encroachment of shade tolerant hardwoods, particularly red maples that are crowding out oaks and other plants on the ground floors of numerous forests throughout the eastern United States.

In an article for the April-recent issue of the Journal of the Torrey Botanical Society, the scientists examined regional weather patterns to see if environmental conditions exist for the occurrence of lightning fires in Appalachian forests of Adams and Pike Counties in southern Ohio.

The likelihood of lightning fires increases through the summer when the frequency of lightning strikes reaches its greatest peak in late August, coinciding with dry environmental conditions," said Drewa.

Drewa and Petersen also observed that from 1993 to 2005, 29 lightning fires were reported in Ohio's fire protection areas, with 70 percent of those occurring during the summer.

"Human alterations to the natural fire regime, particularly decades of fire suppression, have changed oak-dominated ecosystems in southern Ohio and throughout the eastern US," reported.........

Posted by: Erica      Permalink         Source