Green Forests?

This post contributed by Heather Kirk, a post-doctoral researcher at the Institute of Agricultural Sciences in Zurich, Switzerland When a 9.0 magnitude earthquake caused a series of nuclear accidents in Japan back in March of this year, there was nervousness in North America that nuclear fallout could blow across the Pacific Ocean to reach coastal cities in Canada and the US.  While those fears were largely unfounded according to health officials, West Coast residents have certainly received air-borne “gifts” from Asian countries in the past. Every year, China and a number of other Asian countries are the source of massive dust storms that spread over large portions of the Asian continent, and sometimes even cross the Pacific.  These storms have intensified over the past century as a result of deforestation, overgrazing, and poor water management.  In 2010, East Asia experienced particularly bad droughts that led to food shortages and massive dust storms that lasted for days and traveled thousands of kilometers. In order to address these storms and their causes, China has implemented a tree-planting policy that aims to reduce erosion and evaporation of precious water resources, while providing new sources of economic growth (via timber and tree-fruit production).  The most internationally publicized of these initiatives is the “green wall of China” project, which was initiated in 1978 as part of a larger plan to stop the expansion of the Gobi desert.  The project aims to develop a green belt more than 4000 km in length along the edge of the desert. In the September 22, 2011 issue of Nature, Jianchu Xu, a senior scientist at the World Agroforestry Centre and a professor at the Chinese Academy of Sciences, comments on the detrimental effects of the widespread planting of non-native trees in China, which comprise a large portion of reforestation projects.  Most reforested areas are planted with crop species that include fruit trees, eucalyptus, and rubber, and not with native mixed forests that promote biodiversity and are better suited for providing ecosystem services such as erosion control. Additionally, new forests are being planted in areas that were not historically forested such as grasslands. In his paper, Xu states: “I would like to see China establish parallel forest-management programmes for recovery and restoration of natural forests, and for incorporating working trees into farmlands. Each should include best practices from ecosystem science; a clear definition of tree crop plantations for timber or non-timber products would clarify the separate systems”. Afforestation is an important strategy for carbon sequestration, and can play a valuable role in both ecosystem remediation and economic development.  However all forest are not created equal: some are greener than...

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9/11 dust study, gypsy-moth caterpillar killer, and hummingbird courtship

Studying the 9/11 WTC dust: Coinciding with the tenth anniversary of the September 11, 2001 terrorist attacks, the United States Geological Survey (USGS) recently published a blog highlighting the agency’s study of the environmental and potential health risks of the massive dust cloud that swept across New York City as a result of the collapse of the World Trade Center. The dust was particularly dense, coating outdoor surfaces in a layer of powdered material up to three inches thick. It also penetrated doors, windows and ventilation systems, contaminating apartments and office buildings alike.  The Environmental Protection Agency and the U.S. Public Health Service requested that USGS examine the dust to identify components that might pose a human health threat to the thousands who inhaled it that day and subsequent days USGS found that the dust contained higher amounts of lead, zinc, antimony, copper, and other elements of building materials than found in natural soils. The team also found the less dangerous variety of asbestos–chrysotile asbestos–in most samples at higher levels than what is found in urban particulate matter. The materials found were deemed dangerous enough to indicate a potential health threat and USGS scientists consequently advised that clean-up be conducted with appropriate respiratory protection and dust control measures. USGS scientists also found that dust indoors was highlight caustic and could be chemically reactive with moisture, including eyes, nose, and lungs.  However, rain and other elements helped neutralize the alkalinity of dust outside. Clever caterpillar killer: Scientists have recently discovered how a virus manipulates an invasive species of caterpillar. The gypsy moth caterpillar larvae is renowned for damaging roughly a million acres of forest in the U.S. each year. However, the baculovirus has infiltrated the caterpillars, taking advantage of their insatiable appetites. The virus has become so effective that the U.S. Department of Agriculture sprays it on trees to help control gypsy moth outbreaks. According to the study’s lead author, Kelli Hoover, an entomologist at Pennsylvania State University, the virus works by altering the gypsy moth caterpillar’s behavior. Once infected with the virus, the caterpillars climb to elevated positions and die. Subsequently, the body cavity of the caterpillar is converted into millions of virus particles as well as an enzyme that causes the caterpillar’s exoskeleton to disintegrate. The “liquefied” caterpillar then “rains” onto the leaves below, which other caterpillars eat, further spreading the virus. The researchers claim that knowing precisely how baculovirus overwhelms the gypsy moth could help scientists develop more potent strains of the virus and determine when in the moth’s life cycle it is most vulnerable to infection. Read more at: “How a clear virus kills a hungry...

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