Shrubs Bred for Sparse Seeds Still Spread

This post contributed by Celia Smith, ESA Education Programs Coordinator In response to growing concern about the ecological and economic impact of invasive species, there has been increasing interest in developing cultivars of ornamental shrubs that produce few or sterile seeds. However, in a study published in the October issue of BioScience, researchers at Washington University in St. Louis and the Chicago Botanic Garden found that many cultivars currently marketed as “safe” are still potentially invasive. Invasive plant species present an ecological paradox. Many popular woody plants used in horticulture and landscaping grow readily in varied moisture and soil conditions; display numerous, long-lived blooms; and produce succulent fruits that attract birds and other backyard visitors. Yet the same characteristics that allow these species to easily adapt and thrive can also lead to invasive growth beyond the confines of a carefully managed garden. In an effort to evade laws controlling the spread of invasive plants, the selection of  common woody shrubs such as Japanese barberry and burning bush to produce fewer seeds has become popular, resulting in cultivars that are advertised as ‘safe’ or ‘non-invasive.’ Yet there is very little research to define what makes a cultivar ‘safe,’ let alone confirm whether or not it could be used to effectively control population growth of a species. Given this lack of evidence, the authors reasoned that population modeling of 19 common species of shrubs, trees, herbs and grasses could yield much needed data on the effects of seed reduction. Their results were illuminating: simply limiting seed production in cultivars was insufficient to reduce invasive potential, because seed abundance is just one of many traits that influence how fast or densely a species can grow (case in point: click here for another timely blog post about a study documenting the effects of plant height on seed dispersal).  For example, according to the BioScience article, reducing the seed production of long-lived species—like the shrubs and trees at your local nursery— by even 95% would still fail to control population increases. Furthermore, the offspring of cultivars do not necessarily produce fewer seeds themselves; in fact, they could prove significantly more fecund than their parents if they were to cross-breed. Based on these results, the most effective way to manage the dispersal of invasive plant species may be to invest the time and funds necessary to research, develop and market more varieties that are completely sterile. An alternative solution may be to encourage gardening using native plant species. Of course, this study is predicated on the assumption that invasive species are inherently harmful; indeed, the authors lead off by stating: : “Invasive woody plants pose...

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Fall migrations

This post contributed by Nadine Lymn, ESA Director of Public Affairs Now that mid-October has arrived, many of us notice the shortening days, dark mornings, and new chill in the air.  Thoughts turn to cozy indoor activities, hot beverages, and away from such outdoor hobbies such as gardening.  But while we have the luxury of moving many of our activities indoors during the upcoming winter chill, other species in North America—primarily birds and butterflies—are either preparing for long travel or are already en route to southerly destinations. As noted in a wild bird blog for nature enthusiasts, some 350 species of birds in North America migrate, the majority of them to wintering destinations that include Mexico, Central and South America, and the West Indies: “In North America there are four major migration routes, known as the Atlantic, Mississippi, Central and Pacific Flyways. A flyway can generally be described as a broad geographical area of travel consisting of hundreds of widely diverse, individual migration routes. No two species of birds will travel exactly the same route from beginning to end.” The U.S. Geological Survey provides an in-depth description of the  migration routes birds take as they leave the U.S. on their way to various wintering grounds.  Some species, such as many shorebirds, begin their fall migration as early as July, while others, like goshawks, redpolls and waxwings may not get started until winter. As many birders know, most birds migrate during the night.  According to the USGS website, the most likely hypothesis for this is that this maximizes birds’ ability to refuel and rest.  Birds traveling all night can come to rest at daybreak and begin to find food; if they flew all day and came to rest at night, they would be unlikely to garner food, which they urgently need after long exertion.   There are, however, some daytime migrants, among them loons, cranes, and pelicans as well as soaring birds which depend upon thermals for their flight. This website lets you find out what birds may be passing through your area now and in the coming months. Birds are not the only ones taking flight in the fall.  Butterflies are also on the move, with the Monarch butterfly probably the most well-known of these.  And even though many of us lose interest in gardening when summer ends, the National Wildlife Federation (NWF) points out the value of gardens that offer late blooming plants such as asters and goldenrods for fall migrants, including hummingbirds and various species of butterflies, such as the monarch, painted lady, and cloudless sulfur. Cape May, New Jersey, is a key resting spot for migrating monarchs,...

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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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Recycled oil rigs could aid life in the deep seas

This post contributed by Nadine Lymn, ESA Director of Public Affairs Typically the size of a football field and reaching a height of several hundred meters, the production life of an offshore oil or gas rig is over once it’s drained its location’s energy supply.  Then a company must retire and remove the rig. Conceived by the former U.S. Minerals Management Service (now reorganized as the Bureau of Ocean Energy Management) the Rigs-to-Reefs (RTR) program recycles retired rigs as artificial reefs with the aim of aiding marine communities and fisheries and saving the gas and oil industry significant money.  Often a rig is dragged to a new location and then sunk to create an artificial reef.  So far restricted to shallow waters, the first RTR conversion took place in 1979, off Florida’s coast and since then other programs have been put into place elsewhere around the globe, such as in Southeast Asia. In a review article published in the October issue of Frontiers in Ecology and the Environment researchers Peter Macreadie, Ashley Fowler, and David Booth note the growing pressure to expand the RTR program to the deep seas, areas 500 meters or more in depth. Though relatively rare in the deep sea, natural reefs are increasingly threatened.  And with more than 6,500 rigs due for retirement by 2025, the time seems ripe to consider creating deep-sea artificial reef complexes, say the authors. “Thousands of massive oil rigs reaching the end of their production life all at once is unique to the present time,” explains Macreadie.  “The newer rigs are very different to these ‘old school’ fixed-jacket style rigs; they don’t have anywhere near as much structure.” Macreadie and colleagues highlight existing research on the consequences of rigs in shallow water to outline the potential benefits and detriments that retired rigs might offer deep-sea communities.  For example, rigs might be especially helpful in protecting marine life against illegal trawling.  The rigs’ large internal spaces could offer shelter to fish and other organisms, which could be especially beneficial to species that are long-lived, slow-growing, and slow to reproduce and therefore most vulnerable to overfishing.  However, the authors note that while the crossbeams and large internal space of recycled rigs may be useful habitat for larger organisms, small fish and invertebrates would likely not find suitable habitat in rigs until coral and other encrusting species create a more hospitable environment. Artificial reefs created by retired rigs could also offer “stepping stones” for animals to move between vast expanses of soft bottom sediment.  Removing long-distance barriers could be good or bad, depending on the species, say the authors. Other potential risks associated...

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New grants promote greater understanding of infectious disease

This post contributed by Lindsay Deel, a Ph.D. student in geography at West Virginia University and Intern with ESA’s journal Frontiers in Ecology and the Environment Infectious diseases won’t know what hit them. A massive new collaborative effort between funding sources in the United States (US) and United Kingdom (UK) takes aim at infectious diseases from ecological and social perspectives, reported the National Science Foundation (NSF) in a recent press release. The overall goal of the suite of eight projects is to improve understanding of the factors affecting disease transmission, said NSF, but a major focus will also be on building models to help predict and control outbreaks. Each of these projects examines different themes within the global context of infectious disease. For example, Tony Goldberg (Professor of Epidemiology, University of Wisconsin–Madison) and colleagues will investigate the spread of HIV from its origin in monkeys to humans by examining similar viruses that are currently impacting wild monkeys in Uganda. This project will also study human social factors – such as awareness, beliefs, and behaviors – surrounding the transmission of such diseases. Another project helmed by David Rizzo (Professor of Plant Pathology, University of California–Davis) will explore how interacting forest disturbances – such as fire and drought – may control the emergence, persistence, and spread of invasive pathogens using the case of sudden oak death – a disease caused by a non-native pathogen, Phytophthora ramorum. “Over the past 10 years, potentially millions of trees in California and Oregon coastal forests have died as a result of this emerging disease,” explains Rizzo. “The goal of this new grant is [to] link this new disturbance agent (sudden oak death) with pre-existing disturbance agents (fire, drought) in coastal forests.” Samantha Forde (Professor of Ecology and Evolutionary Biology, University of California – Santa Cruz) will lead a project using a simplified laboratory system of E. coli bacteria and its viruses as a model to study why some viruses have evolved the ability to infect multiple host species, while others can only infect one.  “This will further a general understanding of the dynamics of disease in natural systems and help to improve public health initiatives,” she says. From the modeling perspective, Armand Kuris (Professor of Biological Sciences, University of California at Santa Barbara) and colleagues will delve into the complexity of ecological systems and how the level of complexity might influence disease dynamics.  Kuris and colleagues hope to bring the role of infectious diseases into the core of ecological thinking, comparable to the roles of predation, competition, disturbance and resource quality. Joseph Tien (Professor of Mathematics, Ohio State University) will examine the recent cholera epidemic in Haiti. ...

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