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Mar
28
2008
Climate change will benefit Scots pines in the far north, new study suggests
Given they’re named after a tiny part of a tiny island, Scots pines Pinus sylvestris enjoy a remarkably wide distribution: they’re the dominant Eurasian tree species. And that allowed University of Minnesota researcher Peter Reich and co-author Jacek Oleksyn to ask a difficult question – how will this widespread species handle climate change? – with a chance of finding an answer. Using long-term data collected from across Europe and North America, they discovered a distinct pattern. A rise in mean annual temperature of 1—4 degrees C enhances survival in northern Europe (at latitudes greater than 62 degrees north, where the mean annual temperature is a bracing two degrees or less). In the somewhat balmier south, the same effective rise will decrease survival. The interpretation on offer – published in Ecology Letters – is that warming reduces cold stress in the north but increases heat stress in the south. So perhaps it’s time to restore the Caledonian forest to its ancient glory. Source: Reich PB & Oleksyn J (2008) Climate warming will reduce growth and survival of Scots pine except in the far north. Ecology Letters DOI: 10.1111/j.1461-0248.2008.01172.x
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Mar
25
2008
New study finds no evidence that climate change causes amphibian decline
The alarming decline in global amphibian populations has been blamed on several factors including disease, climate change and habitat loss – not to mention various combinations of them. The precise causes are difficult to pin down, as often little is known about individual species, living as they do in inaccessible habitats. However, a study published this week in PLoS Biology makes a stab at analyzing what data we do have and rules out climate change as the driving force behind die-offs of harlequin frogs. Species in the Atelopus genus are a pretty endangered lot, but their scarcity owes more to the classical spread of the fungal infection chytridiomycosis than anything else. Southern Illinois University researcher Karen Lips and colleagues performed statistical tests on existing data to show that the most likely cause for amphibian declines in southern Central and northern South America is the repeated introduction of the causative pathogen Batrachochytrium dendrobatidis, most likely aboard a non-native species. The findings are good news in the sense that conservation workers in regions where the disease has yet to emerge can concentrate their efforts on preventing the import of animals that could carry it. Source: Lips KR, Diffendorfer J, Mendelson JR III & Sears MW (2008) Riding the wave: reconciling the roles of disease and climate change in amphibian declines. PLoS Biology DOI: 10.1371/journal.pbio.0060072
Image © Darren Green
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Mar
24
2008
Soot could rival CO2 in melting Himalayan glaciers and Arctic sea ice
Switching from fossil to wood-based fuel could be the wrong sort of green idea. Black carbon – soot to us – is the second most important source of current global warming, according to a paper published this week in Nature Geoscience. In their review, co-authors V. Ramanathan and Greg Carmichael say that the soot created by burning biofuels – wood, dung and crop residues – and “dirtier” coal and diesel, helps form large clouds that absorb and scatter the sun’s radiation, literally topping it all by depositing solar-heating black layers onto otherwise reflective snow and ice. The problem was centered on the West before the 1950s, but deforestation and developing economies make the tropics and East Asia the current hotspots for soot emissions, which combine with other aerosols to produce immense Atmospheric Brown Clouds. Around half the world’s population lives under the local influence of these plumes, but we’re all feeling it somehow. Source: Ramanathan V & Carmichael G (2008) Global and regional climate changes due to black carbon. Nature Geoscience DOI: 10.1038/ngeo156
Image © Tigerx
nb typo corrected 2150 GMT 24.03.08
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Mar
20
2008
Overexploitation destabilizes population sizes, meta-analysis finds
The trouble with rare things – like many of the fish species we’ve driven to near extinction – is that their numbers become prone to extreme swings, rendering them vulnerable to hitting that final zero. That’s the message from a paper published this week in Nature. Dalhousie University biologist Coilín Minto and colleagues analyzed fisheries data from 147 wild populations of fish, comprising a total of 39 species. Historically overexploited species, such as North Sea herring, showed the highest levels of year-on-year variation in numbers. Understanding how variability is affected by population size could help conservationists estimate more accurately the time needed for overfished stocks to recover. Source: Minto C, Myers RA & Blanchard W (2008) Survival variability and population density in fish populations. Nature DOI: 10.1038/nature06605
Image © esemelwe
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Mar
19
2008
Reduced tariffs can benefit trade and wildlife, economic models forecast
The Asian longhorned beetle Anoplophora glabripennis and other invasive species could soon feel the brunt of hard nosed economics, if the authors of a paper published in Ecological Economics have got their sums right. Iowa State University professor of economics John Beghin and colleagues looked at the effect of trade tariff escalations – which protect exports of raw materials but suppress manufactured or processed goods – on the likelihood of invasive species arrival. Because unprocessed goods, such as timber, are far more likely to provide berth for a stowaway alien, biasing trade flows in their favor is likely to have unwelcome consequences. That beautifully finished coffee table, on the other hand, is completely pest free. Beghin’s mathematical models show that reducing the tariff escalation faced by countries exporting both raw and processed products leads to that rarest of things, a win-win situation. Developing countries get to export higher value products, helping their economies, and developed countries enjoy a reduced risk of invasion. Source: Tu AT, Beghin J & Gozlan E (2008) Tariff escalation and invasive species damages. Ecological Economics DOI: 10.1016/j.ecolecon.2008.01.013
Image © andsem | istockphoto
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Mar
13
2008
Survival for endangered parrot depends on its worst predator’s droppings
The endangered hyacinth macaw Anodorhynchus hyacinthinus likes nothing better than to be in a hole. As long as it’s the sort of hole that’s in a tree and makes a good nesting space. However, the scarcity of – and competition for – those sorts of holes has left the world’s biggest parrot in different, altogether less desirable sort of hole, according to a study published in Biological Conservation. Four bird biologists, led by Marco Pizo at the Universidade do Vale do Rio dos Sinos, Brazil, present three stats that tell the story of this particular cruel bind: 95 percent of nest holes are in manduvi Sterculia apetala trees, of which toco toucans Ramphastos toco are the major seed dispersers for its seeds, shifting some 86 percent of the unwieldy fruits. But then – literally – comes the crunch: the toucan ain’t no vegan. That oversized bill is also responsible for 53 percent of egg predation among the nests of the rapidly dwindling macaw population. It’s a cruel world where your very existence depends on your worst enemy. Source: Pizo MA, Donatti CI, Guedes NMR & Galetti M (2008) Conservation puzzle: Endangered hyacinth macaw depends on its nest predator for reproduction. Biological Conservation DOI: 10.1016/j.biocon.2007.12.023
Image © Artmann-witte
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Mar
6
2008
Chemical plays key role in climate regulation… and helps fish find food
Dimethylsulfoniopropionate – let’s just call it DMSP – signals feeding time at the reef, according to a brief paper published this week in Science. Scientists have known for some time that fish are attracted to something in the water that helps them to locate food, but an experiment carried out by Gabrielle Nevitt and colleagues shows that DMSP, a compound produced by phytoplankton and marine algae, is the guiding cue. DMSP has a known link with ocean productivity and its breakdown product – plain ol’ dimethylsulfide – is also thought to exert a major influence on global climate regulation. This dual role, says Nevitt’s team, could help us understand the effects of climate change on the marine ecosystem. Source: DeBose JL, Lema SC & Nevitt GA (2008) Dimethylsulfoniopropionate as a foraging clue for reef fishes. Science DOI: 10.1126/science.1151109
Image © Sean Lema
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Mar
6
2008
Shifting tundra vegetation will increase fire risk, history shows
Climate driven changes in vegetation cover across the most northern land surfaces on the planet will likely result in more carbon-releasing fires, according to a study published this week in PLoS ONE. Philip Higuera, currently at Montana State University, and colleagues examined charcoal and pollen samples from Alaskan lakes, which provide a historical record of plant composition and fire frequency between 14000 and 10000 years ago. Back then, the tundra was dominated by extensive thickets of resin birch Betula glandulosa, and the warming climate is likely to see its widespread return to areas currently occupied by somewhat less flammable herbs. The mass of tangled, resin-laden twigs could turn the area into a tinderbox, with the double whammy that such fires encourage vigorous birch regrowth, making it prone to further blazes. The likely consequence is that another source of carbon dioxide will enter the scene, as vegetation and long-frozen soil go up in smoke. Source: Higuera PE, Brubaker LB, Anderson PM, Brown TA, Kennedy AT & Hu FS (2008) Frequent fires in ancient shrub tundra: implications of paleorecords for Arctic environmental change. PLoS ONE DOI: 10.1371/journal.pone.0001744
Image © Heinz Effner
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Mar
4
2008
Vermont forests march up hills in search of better climes
The line marking the transition between Vermont’s northern hardwood and boreal trees has moved around 100 metres uphill in just 40 years, according to a study published this week in PNAS. In 2004, researchers at Yale and Vermont universities, led by the latter’s Brian Beckage, revisited sites first mapped in 1964 that stretched between 550 and 1160 metres above sea level. As they went they noted changes in the species composition of the trees they found. Disease, acid rain (or snow) and an increase in freeze-thaw events have conspired to make life tougher for some species, easier for others. The observed elevational change was only around half that predicted through climate change models, however, suggesting that the northern hardwood trees will continue their ascent even if warming stops overnight, which of course it won’t. Disturbances, such as those caused by insect outbreaks, likely make this upward progression swifter: the question is whether the Green Mountains of Vermont are high enough for the boreal species to survive! Source: Beckage B, Osborne B, Gavin DG, Pucko C, Siccama T & Perkins T (2008) A rapid upward shift of a forest ecotone during 40 years of warming in the Green Mountains of Vermont. Proceedings of the National Academy of Sciences USA DOI: 10.1073/pnas.0708921105
Image © Jan Tyler
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Mar
3
2008
Ski tourism stresses capercaillies, Black Forest study shows
Want to know if your capercaillies are stressed? Check the steroids in their droppings, say a group of ecologists led by Dominik Thiel at the Swiss Ornithological Institute, Switzerland. Their report, published recently in the Journal of Applied Ecology, shows that ski resorts, and in particular the number of people they attract, are unsettling the birds. Corticosterone metabolites – the breakdown products of stress hormones – were found to be present in significantly greater levels in areas under moderate or high pressure from recreational skiers. With many capercaillie Tetrao urogallus populations in steeper decline than the ski slopes that cut through their habitat, managers need to ensure there are disturbance-free refuges if they’re to avoid the you-know-what from hitting the fan. Source: Thiel D, Jenni-Eiermann S, Braunisch V, Palme R & Jenni L (2008) Ski tourism affects habitat use and evokes a physiological stress response in capercaillie Tetrao urogallus: a new methodological approach. Journal of Applied Ecology DOI: 10.1111/j.1365-2664.2008.01465.x
Image © Richard Bartz
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