Archive for April, 2008

Apr

30

2008
 
 

Watching the detectives



Protected areas don’t always protect as well as they should, study reveals

rainforest dawnConservation projects often hinge on areas of land being given protection, but little is known about how well many protected areas actually do their job. Studying four of the world’s major moist tropical forests, a group of Duke University researchers led by Stuart Pimm found that inaccessibility can be a tree’s best friend. Protected areas within the Amazon and Congo forests, for example, nestle within largely well-forested surrounding areas, which keeps them relatively safe. The Atlantic Coast and West African protected areas, by contrast, are more fragmented: unfortunate, given their status as biodiversity hotspots. The study, published this week in PNAS, nonetheless throws welcome light on the way that large scale conservation initiatives work, or don’t. Source: Joppa LN, Loarie SR & Pimm SL (2008) On the protection of “protected areas”. Proceedings of the National Academy of Sciences USA DOI: 10.1073/pnas.0802471105

Image © Joe Gough

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Apr

23

2008
 
 

Black days ahead



Climate change helps native beetle devastate forest carbon sink

small but deadlyA tiny beetle the size of a grain of rice could affect carbon emissions to the tune of 270 megatonnes by 2020, according to a study of British Columbia’s forests. The findings of Natural Resources Canada forestry experts Werner Kurz and colleagues, published this week in Nature, chronicle the latest Dendroctonus ponderosae outbreak, which is an order of magnitude greater than anything previously observed. The figures are staggering: 130000 square km were attacked by the end of 2006, resulting in the loss of some 435 million cubic m of timber. This raises the status of the beetle as an important factor in carbon sequestration plans, as the current outbreak has shifted the forest from being a carbon sink to a major carbon source. The worst of it is that climate change, brought about largely by there being too much carbon in the atmosphere already, has allowed the beetle to expand its range into areas that were previously off limits. Future models of forest carbon flow need to take into account not only the very large (fire, drought, wind) but also the very small (bugs) things that influence them. Source: Kurz WA, Dymond CC, Stinson G, Rampley GJ, Neilson ET, Carroll AL, Ebata T & Safranyik L (2008) Mountain pine beetle and forest carbon feedback to climate change. Nature DOI: 10.1038/nature06777

Image © Doug Linton

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Apr

21

2008
 
 

Heavy metal rock(cress)



Pollution-gobbling weed gives up its genetic secret to success

heavy metal fanMost plants don’t like heavy metals such as zinc or cadmium, but Arabidopsis halleri will happily put down roots in the most contaminated soils. Reporting in Nature this week, a team of scientists led by Max Planck Institute biologist Ute Krämer – now at the University of Heidelberg – has unraveled the genetic basis underlying the little weed’s hardiness. Extra copies of the HMA4 (HEAVY METAL ATPASE 4) gene – are responsible: splicing it into the much more famous A. thaliana confers the same pollution-tolerating ability. Toxins are stored in the plant’s leaf cells, raising the possibility of developing plants that, when harvested, could drain contaminated soil of its poisonous elements. Even weeds have their strengths. Source: Hanikenne M, Talke IN, Haydon MJ, Lanz C, Nolte A, Motte P, Kroymann J, Weigel D & Krämer U (2008) Evolution of metal hyperaccumulation required cis-regulatory changes and triplication of HMA4. Nature DOI: 10.1038/nature06877

Image © Vasiliy Koval

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Apr

15

2008
 
 

Major headache



Scientists still grapple with big question: are trees carbon source or sink?

Major oak -- there's a lot of carbon in Sherwood!Forests account for a huge chunk — around one fifth — of the world’s carbon dioxide emissions. So it stands to reason that by avoiding cutting trees down, say, in the Amazon, we can reduce those emissions by leaving carbon in situ. Take the logic one step further and planting new forests suddenly seems like the dream answer to our atmospheric woes. Rik Leemans and colleagues blow a hole in that one: writing in Carbon Balance and Management, the Wageningen University and Netherlands Environmental Assessment Agency collaborators highlight the infinite complexities of the issue. Demands for agricultural land tussle with those for carbon plantations, questions hang over whether those plantations should be temporary or permanent, and the value of “social potential” — the additional benefits that include nature conservation — are every bit as hard to pin down as the amount of carbon a forest actually stores. But there is some good news. Although plantations take around twenty years to compensate for the carbon emissions during their establishment, thereafter they can — if planted in the right place and managed in the right way — help in the battle to lower those dreaded parts per million in the sky. The question is… by how much? Source: van Minnen JG, Strengers BJ, Eickhout B, Swart RJ & Leemans R (2008) Quantifying the effectiveness of climate change mitigation through forest plantations and carbon sequestration with an integrated land-use model. Carbon Balance and Management DOI: tba, but download here

Image © Nick Atkinson

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Apr

9

2008
 
 

Something else in the water



Ghosts of residents past and present show up in pond water, DNA analysis reveals

pee-souperPond water is a veritable soup of DNA, the ingredients of which are the shattered fragments of mucus, urine, faeces and remains of its past and present inhabitants. To Université Joseph Fourier researcher Gentile Ficetola and colleagues, that soup tells tales. The group carried out lab and field tests on samples of water that were known to have contained – or not – American bullfrogs Rana catesbeiana, an invasive species that causes declines in many native amphibian populations. Using molecular techniques designed to extract tiny stretches of DNA, the Grenoble-based team showed that it is possible to detect the presence or absence of a given species – great news for those wishing to track the progress of an invasion front. Writing in Biology Letters, they also suggest the ability to detect secretive, low-density populations should help other conservation projects too. Source: Ficetola GF, Miaud C, Pampanon F & Taberlet P (2008) Species detection using environmental DNA from water samples. Biology Letters DOI: 10.1098/rsbl.2008.0118

Image © Michael Mill

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Apr

7

2008
 
 

Larger than life



Big mammals go extinct faster than more highly-strung little ones

wish I was a red squirrelWith hearts beating ten to the dozen and precious little by way of stored bodyfat reserves, you’d expect small mammals to be most susceptible to that grimmest of reapers, extinction. Yet the ability to sleep in times of stress could be the thing that saves them whilst their larger cousins are dropping like flies, according to a Scandinavian group of scientists led by University of Oslo researcher Nils Chr. Stenseth. Writing in PNAS this week, they present their findings from a large group of fossils from the Neogene Old World: large mammals have shorter “duration times” – they evolve more often, but also die out faster – than small mammals. Although our mega-mammalian taxonomic bias could perhaps explain this observation, there’s a more concrete possibility. The longest-lived groups of these fossils are littered with moles, mice, hamsters and flying squirrels, animals that typically exhibit “sleep-or-hide” – hibernating or burrowing – habits to weather out the worst of times. Us big guys just keel over. Source: Liow LH, Fortelius M, Bingham E, Lintulaakso K, Mannila H, Flynn L & Stenseth NC (2008) Higher origination and extinction rates in larger mammals. Proceedings of the National Academy of Sciences USA DOI: 10.1073/pnas.0709763105

Image © Rick Wylie

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Apr

1

2008
 
 

Floating ideas



Ballast-free ship could prove a cheaper way to prevent invasive species

A better way to transport cargoWouldn’t it be great to stop transporting alien species around the planet in ships’ ballast water? Current regulations force operators to install expensive filtration systems, which combine with UV and/or chemical treatment to weed out the array of unwelcome stowaways. An alternative, the ballast-free ship, replaces traditional ballast tanks with “trunks” that can be opened or closed to the outside as required. The forward movement of the ship creates a constant flow of water through the trunks, ensuring that the ship is only ever using local seawater. And there’s an unexpected benefit, according to a model study – using a physical model, rather than a mathematical one – carried out by Miltiadis Kotinis and Mike Parsons at the University of Michigan Marine Hydrodynamics Laboratory. Writing in the Transactions of the Society of Naval Architects and Marine Engineers, the U-M researchers suggest their design can also deliver fuel savings because of its greater efficiency. At anything up to 7.3 percent, that could mean a 650-foot bulk carrier hauling 32000 metric tons of cargo from the Great Lakes to Europe and back would pocket an extra $150000. And that’s no April Fool’s joke, unlike this one… Source: Kotinis M & Parsons MG (2008) Hydrodynamic investigation of the ballast-free ship concept. Transactions of the Society of Naval Architects and Marine Engineers DOI: tba

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