Apparently, you need to kiss a lot of frogs before you find a prince.
Turns out you also need to examine a lot of piles of elephant dung before you find a frog. 48.33, to be precise.
Now, if someone could be a bit more quantitative about the frog/prince ratio, we could work out princes per pile of elephant dung.
Showing posts with label conservation. Show all posts
Showing posts with label conservation. Show all posts
Thursday, May 28, 2009
Wednesday, May 27, 2009
No animals, no trees
A couple of recent papers show how seed dispersal is harmed when forest vertebrates disappear - it's not just bees and microbes that provide ecosystem services, we need the big stuff too.
In Biotropica, Stephen Blake of the WCS and colleagues look at seeds in the dung of forest elephants in the Congo. There are a lot:
And in Ecological Applications a US/Thai team look at the impact of bushmeat hunting on the dispersal of the hog plum, Choerospondias axillaris which, as the name suggests needs mammals (although not just pigs) to move it about. The clue is in the paper's title 'Bushmeat poaching reduces the seed dispersal and population growth rate of a mammal-dispersed tree.' "Extinction of C. axillaris is a real possibility, but may take many decades," they add. "Recent and ongoing extirpations of vertebrates in many tropical forests could be creating an extinction debt for zoochorous trees whose vulnerability is belied by their current abundance."
In Guanacaste, Costa Rica, they (especially Dan Janzen) got round this problem by introducing cattle, replacing the large herbivores that had gone extinct in prehistory. The trees thrived as a result. But Guanacaste is a dry forest. To paraphrase the music hall song about the horse and the lighthouse, I imagine it'd be harder to keep a cow in a jungle.
In Biotropica, Stephen Blake of the WCS and colleagues look at seeds in the dung of forest elephants in the Congo. There are a lot:
Analysis of 855 elephant dung piles suggested that forest elephants disperse more intact seeds than any other species or genus of large vertebrate in African forests, while GPS telemetry data showed that forest elephants regularly disperse seeds over unprecedented distances compared to other dispersers. ... Our results suggest that the loss of forest elephants (and other large-bodied dispersers) may lead to a wave of recruitment failure among animal-dispersed tree species, and favor regeneration of the species-poor abiotically dispersed guild of trees.
And in Ecological Applications a US/Thai team look at the impact of bushmeat hunting on the dispersal of the hog plum, Choerospondias axillaris which, as the name suggests needs mammals (although not just pigs) to move it about. The clue is in the paper's title 'Bushmeat poaching reduces the seed dispersal and population growth rate of a mammal-dispersed tree.' "Extinction of C. axillaris is a real possibility, but may take many decades," they add. "Recent and ongoing extirpations of vertebrates in many tropical forests could be creating an extinction debt for zoochorous trees whose vulnerability is belied by their current abundance."
In Guanacaste, Costa Rica, they (especially Dan Janzen) got round this problem by introducing cattle, replacing the large herbivores that had gone extinct in prehistory. The trees thrived as a result. But Guanacaste is a dry forest. To paraphrase the music hall song about the horse and the lighthouse, I imagine it'd be harder to keep a cow in a jungle.
Monday, October 13, 2008
Chainsaw massacre and the need for speed
This feature from yesterday's Observer on Britain's trees is worth a look. It's particularly good on the benefits and threats to urban trees, which was all new to me. When it looks at woodland, and efforts to restore it, I found myself wishing for a lot less Felix Dennis (flying over his woodland in his helicopter, talking nonsense on climate change) and a lot more (any) Oliver Rackham.
There's a sentence about how the Woodland Trust has found itself outbid when trying to buy land in southeast England that made me think of a recent Ecology Letters paper on how to work out when to buy land, weighing uncertainty of it's conservation against the need to buy it before someone else does.
Eve McDonald-Madden of the University of Queensland and her colleagues use a modelling technique called stochastic dynamic programming – often applied to animal foraging behaviour – which predicts what you should do at any given time, given what’s already happened. They come up with an optimal method for decision making, and a simpler rule of thumb which uses current knowledge of the sites conservation value, and the deadline on a decision, to give a deal-or-no-deal answer.
I guess this might not be so applicable in the UK, where pretty much everything is already surveyed, so conservation value is well known and budgets and land prices are the main issue. But perhaps it might help in prioritizing. And I thought it was a neat paper in general.
There's a sentence about how the Woodland Trust has found itself outbid when trying to buy land in southeast England that made me think of a recent Ecology Letters paper on how to work out when to buy land, weighing uncertainty of it's conservation against the need to buy it before someone else does.
Eve McDonald-Madden of the University of Queensland and her colleagues use a modelling technique called stochastic dynamic programming – often applied to animal foraging behaviour – which predicts what you should do at any given time, given what’s already happened. They come up with an optimal method for decision making, and a simpler rule of thumb which uses current knowledge of the sites conservation value, and the deadline on a decision, to give a deal-or-no-deal answer.
I guess this might not be so applicable in the UK, where pretty much everything is already surveyed, so conservation value is well known and budgets and land prices are the main issue. But perhaps it might help in prioritizing. And I thought it was a neat paper in general.
Monday, November 12, 2007
The Future of Amazonia
The current New York Review of Books has an excellent piece by John Terborgh looking at the history of development in the Brazilian Amazon, and the forest's future prospects.
Terborgh's story and his arguments are too detailed to do justice here, but this, roughly, is his conclusion:
He then sounds a note of caution: "Unforeseen developments are likely to determine the future of th Amazon... One such unforeseen development is fire, which holds the potential to be the undoing of the Amazon." Pristine tropical forest, he say, doesn't burn. Logging changes that:
Then, he adds, there's climate change, which will reduce rainfall, and dry the Amazon out from west to east (becasue the rain comes off the Atlantic) and threatens the 'savannaization' of the forest. In total, Terborgh's essay is all the more sobering for being balanced and unalarmist.
Terborgh's story and his arguments are too detailed to do justice here, but this, roughly, is his conclusion:
Brazil will continue to pursue its long-cherished goal of integrating the Amazon into the national economy. Much of the forest will go. But I would be surprised to see it vanish entirely because an increasing portion of the Amazon in Brazil, and in neighboring countries, is under formal, legal protection...Short of a complete breakdown of civil authority, the Amazon won't be entirely "lost".
He then sounds a note of caution: "Unforeseen developments are likely to determine the future of th Amazon... One such unforeseen development is fire, which holds the potential to be the undoing of the Amazon." Pristine tropical forest, he say, doesn't burn. Logging changes that:
Logging synergizes fire in two ways. First, cutting down trees opens the forest canopy, admitting sunlight and drying out the leaf litter on the forest floor. Second, the debris of branches, chips, and stumps left behind by logging operations serves as fuel for any subsequent fire.
The first time a tropical forest burns, the damage can hardly be detected from above because the destruction is largely confined to saplings and small trees whose crowns lie below the canopy. But the subsequent presence of large numbers of dead trees greatly increases the fuel available to stoke the next fire. Consequently, second fires burn hotter and more destructively, killing large trees as well as practically all smaller ones. And, of course, second fires generate even more fuel for the third fire. Colleagues of mine who study this subject, notably, Carlos Peres and Jos Barlow of the University of East Anglia (UK) and William Laurance of the Smithsonian Tropical Research Institute in Panama, assert that the third fire spells doom for the forest, since it kills all remaining trees.
Then, he adds, there's climate change, which will reduce rainfall, and dry the Amazon out from west to east (becasue the rain comes off the Atlantic) and threatens the 'savannaization' of the forest. In total, Terborgh's essay is all the more sobering for being balanced and unalarmist.
Friday, October 26, 2007
Sharks, sheep and viruses
Three recent conservation biology-type papers worth a look:
Do shark declines creat fear-released systems?
A model sugesting that if you take pacific sleeper sharks out of the ocean, seals swim deeper, and eat more pollock - which live deep - and fewer herring.
Are cattle, sheep, and goats endangered species?
The "rise of the breed" 200 years ago, followed by more recent selection for increased productivity has led to a dangerous drop in the genetic diversity of domestic animals. "Many industrial breeds now suffer from inbreeding, with effective population sizes falling below 50... It is therefore important to take measures that promote a sustainable management of these genetic resources; first, by in situ preservation of endangered breeds; second, by using selection programmes to restore the genetic diversity of industrial breeds; and finally, by protecting the wild relatives that might provide useful genetic resources."
(Andrew Marr says that whenever you see a newspaper headline ending in a question mark (Is this the most evil man in Britain?; Are working mothers poisoning their children? and so on) you should answer 'no'. I'm not sure if the same applies for the scientific literature.)
Barley yellow dwarf viruses (BYDVs) preserved in herbarium specimens illuminate historical disease ecology of invasive and native grasses
Invasive species are often thought to thrive because they escape all the diseases and predators that keep them in check back home. But this study suggests that the diseases that invaders bring with them are just as important as the ones they leave behind.
In California, over the past two centuries European grasses have almost completely displaced the native prairie. Carolyn Malmstrom and her colleagues think that one factor in their success was the viruses they brought with them. For example, they have previously shown that native grasses growing alongside exotics have higher levels of cereal yellow dwarf viruses.
But this doesn't put the viruses at the scene of the crime. Now they've taken a step towards that (although how you ever prove such an idea, I don't know). Using herbarium specimens from 1917, they have recovered some of the oldest plant viral sequences so far and, by comparing them with European relatives, show that the disease probably showed up along with the plants — and also hopped from California to Australia in the late nineteenth century — and may have been a useful ally in the invaders battle against the natives.
Do shark declines creat fear-released systems?
A model sugesting that if you take pacific sleeper sharks out of the ocean, seals swim deeper, and eat more pollock - which live deep - and fewer herring.
Are cattle, sheep, and goats endangered species?
The "rise of the breed" 200 years ago, followed by more recent selection for increased productivity has led to a dangerous drop in the genetic diversity of domestic animals. "Many industrial breeds now suffer from inbreeding, with effective population sizes falling below 50... It is therefore important to take measures that promote a sustainable management of these genetic resources; first, by in situ preservation of endangered breeds; second, by using selection programmes to restore the genetic diversity of industrial breeds; and finally, by protecting the wild relatives that might provide useful genetic resources."
(Andrew Marr says that whenever you see a newspaper headline ending in a question mark (Is this the most evil man in Britain?; Are working mothers poisoning their children? and so on) you should answer 'no'. I'm not sure if the same applies for the scientific literature.)
Barley yellow dwarf viruses (BYDVs) preserved in herbarium specimens illuminate historical disease ecology of invasive and native grasses
Invasive species are often thought to thrive because they escape all the diseases and predators that keep them in check back home. But this study suggests that the diseases that invaders bring with them are just as important as the ones they leave behind.
In California, over the past two centuries European grasses have almost completely displaced the native prairie. Carolyn Malmstrom and her colleagues think that one factor in their success was the viruses they brought with them. For example, they have previously shown that native grasses growing alongside exotics have higher levels of cereal yellow dwarf viruses.
But this doesn't put the viruses at the scene of the crime. Now they've taken a step towards that (although how you ever prove such an idea, I don't know). Using herbarium specimens from 1917, they have recovered some of the oldest plant viral sequences so far and, by comparing them with European relatives, show that the disease probably showed up along with the plants — and also hopped from California to Australia in the late nineteenth century — and may have been a useful ally in the invaders battle against the natives.
Tuesday, April 03, 2007
The coming era of jellyfish ascendancy
I admit it, my devotion to the work of George Monbiot (or The Monb, as he's apparently known in some environmental circles) borders on the unhealthy.
But this piece on marine conservation, and the overfishing of top predators such as sharks, is really excellent.
The Spanish fishing industry, he writes, is "traditionally dominated by Galician fascists". There's no fascist like a Galician fascist.
But this piece on marine conservation, and the overfishing of top predators such as sharks, is really excellent.
The Spanish fishing industry, he writes, is "traditionally dominated by Galician fascists". There's no fascist like a Galician fascist.
Thursday, March 15, 2007
Oekologie #3
Here beginneth the third edition of the Oekologie blog carnival. Thank you everyone who took the time to send in posts. It was great to receive such a diverse bunch — we've got just about every group of organism and every part of the world represented, at scales ranging from the global to the backyard, and addressing just about every issue you can think of. So here we go…
Crime! Julie from The Human Flower Project has sent in a cool story on the banning of the Hungarian hovirag harvest. The hovirag is a snowdrop, sold in Hungary as a mark of coming spring, but now grievously over-picked (and with a street value somewhat greater than crack, apparently). The flower is also the source of the protein that, put into to GM potatoes, led to the controversy around the experiments by (Hungarian-born) Arpad Puzstai.
Deceit! GrrlScientist at Living the Scientific Life posts on a neat piece of mimicry — the moth that pretends to be a jumping spider.
Pestilence! Jennifer Forman Orth at the Invasive Species Weblog reports on beech bark disease, which involves an invasive insect infesting the tree, which leads to a fungal infection, which leads to trouble.
Meanwhile, showing that not you don't need to cross an international borders to be an invasive species, Paul Decelles at The Force that Through… points the finger at red cedar, a native of the eastern US now making trouble further west. And then defends his position.
Goats! Aydin at Snail's Tales discusses the impact of goats on the past and future vegetation of the Mediterranean. "If we want to return at least some of the land to its original, pre-grazing, pre-human state, the goats must go," he says.
The Mediterranean is interesting because it has diverse plant life, even though it has seen millennia of heavy human impact, suggesting that the plants have coevolved with people and their animals. (This has also equipped Mediterranean plants to do well in places like California and Australia.) But, of course, whether this flora was in place before people showed up — and if not, what was — is another matter.
That's enough exclamation marks.
Fish: Stephen Leahy at, um, Stephen Leahy points us to his story discussing the concept of peak fish — global catches have levelled off (not sure what's happened to global fishing effort, but it seems unlikely to have fallen), and may soon start falling.
Another option for providing seafood is fish farming. The US government has proposed to extend fish farming into federal waters, 3 to 200 miles offshore. But Lish at Science Ripsaw is worried it that this would deplete nutrients and increase pollution.
Oil: Tom Elko at Sky Blue Waters reports on the concerns around the environmental impact and property rights issues of the MinnCan pipeline. If built (which is looking likely) it would carry crude oil from Canadian oil sands (which are environmental and carbon-emissions bad news in themselves) to refineries in Minnesota.
Milk(weed): Miconia at A Neotropical Savanna meditates on Asclepia.
I know it's not a very scientific reaction, but…
Eeuuw: GrrlScientist reports on a blind, cave-dwelling Madagascan snake (that looks like a worm), rediscovered more than 100 years after the last known specimens were collected. They avoid the light, and sniff out their prey — the eggs and larvae of ants and termites.
Eeuuw II: The pygmy-hog-sucking louse (as a part-time copyeditor and punctuation geek, I place those hyphens with some confidence). Sticking up for the bloodsuckers at Endangered Ugly Things, Garfman makes the excellent point that every large, cuddly and charismatic species in danger of extinction also has (probably several) parasites that depend on it for their own survival. Coendangered is the technical term, apparently.
Mangroves: On the Ecological Society of America's blog, Edward Barbier has posted an authoritative guide to the issues surrounding the loss and restoration of mangrove forests, particularly regarding their ability to buffer against storm and tsunami damage.
Barbier — who has done lots of research into the interactions between development, mangroves and ecosystem services (the mangroves usually come off worse) — argues that the debate around the benefits and costs of replanting, that have followed from the 2004 Indian Ocean tsunami, is oversimplified.
Cheetahs: Over at Laelaps, Brian Switek highlights something that was new to me — Iranian cheetahs. Brian writes about the Wildlife Conservation Society's work to conserve this population.
(This also made me intrigued about another thing I know nothing about — what issues a US conservation organizations faces when it works in Iran — in terms of dealing with both the Iranian and US governments.)
Bats: Jennifer Pinkley at The Infinite Sphere discusses how the eastern pipistrelle's more catholic taste in habitat and roosts has made it "more adaptable to changing environmental pressures" than its close relative the gray myotis.
Microbes: Coturnix at A Blog Around the Clock alerts us to PLoS Biology's glut of papers on ocean microbial diversity (i.e. metagenomics). This is way-cool stuff right now (see also previous post on this blog).
Semantics: Matt at the Behavioral Ecology blog has sent in a post entitled 'Is rape adaptive?', which also discusses whether 'rape' is a good word to apply to forced copulations in (non-human) animals. The consensus appears to be not and, although I usually favour strong words and try to avoid jargon, I agree.
Celebrity: Mike at 10,000 birds muses on the ethics of twitching, and the motivations of twitchers. Naturalists, paparazzi, rubberneckers, or all of the above?
Memories: for me at least, with Jeremy Bruno, and the Voltage Gate's guide to tropical dry forest.
Jeremy mentions Guanacaste in Costa Rica, conservation success story (thanks to the idea of introducing large domestic herbivores to do the seed-dispersal job once done my extinct species), macroecological hotspot, and a place I visited while researching ITBOAH (I had to get a mention in somewhere). One of the remarkable things about Costa Rica is that this forest is about half-an-hour's drive from cloud forest containing a totally different set of species.
Global: John Feeny at Growth is Madness! muses on whether spreading the news that we're in the middle of the earth's sixth mass extinction since the Cambrian will help turn people on to conservation.
And Vbecer00 at Reconciliation Ecology also touches on the issue of how you get people to care in his/her post on, well, just about every issue in conservation — why do it, how to do it, and how to make it work.
Local: Join Dave Bonta at Via Negativa for a walk in the snow in Plummer's Hollow, and benefit from his sharp eyes. The man knows his neighbourhood, and his shrews.
Or, you could visit Wayne at Niches, and read his reports on the effects of heavy rains on the creeks on his property in Athens, Georgia.
And finally….
Personals: Johan Stenberg is in Sweden, feeling lonely. Cheer Johan up and join his journal club on insect-plant ecology, at (where else but the) Insect-Plant Ecology blog.
So there you have it. Oekologie — opening your minds, grossing you out, winding you up, bringing you together. Thanks again, and be sure to check out the next edition in a month's time on the Behavioral Ecology Blog.
Crime! Julie from The Human Flower Project has sent in a cool story on the banning of the Hungarian hovirag harvest. The hovirag is a snowdrop, sold in Hungary as a mark of coming spring, but now grievously over-picked (and with a street value somewhat greater than crack, apparently). The flower is also the source of the protein that, put into to GM potatoes, led to the controversy around the experiments by (Hungarian-born) Arpad Puzstai.
Deceit! GrrlScientist at Living the Scientific Life posts on a neat piece of mimicry — the moth that pretends to be a jumping spider.
Pestilence! Jennifer Forman Orth at the Invasive Species Weblog reports on beech bark disease, which involves an invasive insect infesting the tree, which leads to a fungal infection, which leads to trouble.
Meanwhile, showing that not you don't need to cross an international borders to be an invasive species, Paul Decelles at The Force that Through… points the finger at red cedar, a native of the eastern US now making trouble further west. And then defends his position.
Goats! Aydin at Snail's Tales discusses the impact of goats on the past and future vegetation of the Mediterranean. "If we want to return at least some of the land to its original, pre-grazing, pre-human state, the goats must go," he says.
The Mediterranean is interesting because it has diverse plant life, even though it has seen millennia of heavy human impact, suggesting that the plants have coevolved with people and their animals. (This has also equipped Mediterranean plants to do well in places like California and Australia.) But, of course, whether this flora was in place before people showed up — and if not, what was — is another matter.
That's enough exclamation marks.
Fish: Stephen Leahy at, um, Stephen Leahy points us to his story discussing the concept of peak fish — global catches have levelled off (not sure what's happened to global fishing effort, but it seems unlikely to have fallen), and may soon start falling.
Another option for providing seafood is fish farming. The US government has proposed to extend fish farming into federal waters, 3 to 200 miles offshore. But Lish at Science Ripsaw is worried it that this would deplete nutrients and increase pollution.
Oil: Tom Elko at Sky Blue Waters reports on the concerns around the environmental impact and property rights issues of the MinnCan pipeline. If built (which is looking likely) it would carry crude oil from Canadian oil sands (which are environmental and carbon-emissions bad news in themselves) to refineries in Minnesota.
Milk(weed): Miconia at A Neotropical Savanna meditates on Asclepia.
I know it's not a very scientific reaction, but…
Eeuuw: GrrlScientist reports on a blind, cave-dwelling Madagascan snake (that looks like a worm), rediscovered more than 100 years after the last known specimens were collected. They avoid the light, and sniff out their prey — the eggs and larvae of ants and termites.
Eeuuw II: The pygmy-hog-sucking louse (as a part-time copyeditor and punctuation geek, I place those hyphens with some confidence). Sticking up for the bloodsuckers at Endangered Ugly Things, Garfman makes the excellent point that every large, cuddly and charismatic species in danger of extinction also has (probably several) parasites that depend on it for their own survival. Coendangered is the technical term, apparently.
Mangroves: On the Ecological Society of America's blog, Edward Barbier has posted an authoritative guide to the issues surrounding the loss and restoration of mangrove forests, particularly regarding their ability to buffer against storm and tsunami damage.
Barbier — who has done lots of research into the interactions between development, mangroves and ecosystem services (the mangroves usually come off worse) — argues that the debate around the benefits and costs of replanting, that have followed from the 2004 Indian Ocean tsunami, is oversimplified.
Cheetahs: Over at Laelaps, Brian Switek highlights something that was new to me — Iranian cheetahs. Brian writes about the Wildlife Conservation Society's work to conserve this population.
(This also made me intrigued about another thing I know nothing about — what issues a US conservation organizations faces when it works in Iran — in terms of dealing with both the Iranian and US governments.)
Bats: Jennifer Pinkley at The Infinite Sphere discusses how the eastern pipistrelle's more catholic taste in habitat and roosts has made it "more adaptable to changing environmental pressures" than its close relative the gray myotis.
Microbes: Coturnix at A Blog Around the Clock alerts us to PLoS Biology's glut of papers on ocean microbial diversity (i.e. metagenomics). This is way-cool stuff right now (see also previous post on this blog).
Semantics: Matt at the Behavioral Ecology blog has sent in a post entitled 'Is rape adaptive?', which also discusses whether 'rape' is a good word to apply to forced copulations in (non-human) animals. The consensus appears to be not and, although I usually favour strong words and try to avoid jargon, I agree.
Celebrity: Mike at 10,000 birds muses on the ethics of twitching, and the motivations of twitchers. Naturalists, paparazzi, rubberneckers, or all of the above?
Memories: for me at least, with Jeremy Bruno, and the Voltage Gate's guide to tropical dry forest.
Jeremy mentions Guanacaste in Costa Rica, conservation success story (thanks to the idea of introducing large domestic herbivores to do the seed-dispersal job once done my extinct species), macroecological hotspot, and a place I visited while researching ITBOAH (I had to get a mention in somewhere). One of the remarkable things about Costa Rica is that this forest is about half-an-hour's drive from cloud forest containing a totally different set of species.
Global: John Feeny at Growth is Madness! muses on whether spreading the news that we're in the middle of the earth's sixth mass extinction since the Cambrian will help turn people on to conservation.
And Vbecer00 at Reconciliation Ecology also touches on the issue of how you get people to care in his/her post on, well, just about every issue in conservation — why do it, how to do it, and how to make it work.
Local: Join Dave Bonta at Via Negativa for a walk in the snow in Plummer's Hollow, and benefit from his sharp eyes. The man knows his neighbourhood, and his shrews.
Or, you could visit Wayne at Niches, and read his reports on the effects of heavy rains on the creeks on his property in Athens, Georgia.
And finally….
Personals: Johan Stenberg is in Sweden, feeling lonely. Cheer Johan up and join his journal club on insect-plant ecology, at (where else but the) Insect-Plant Ecology blog.
So there you have it. Oekologie — opening your minds, grossing you out, winding you up, bringing you together. Thanks again, and be sure to check out the next edition in a month's time on the Behavioral Ecology Blog.
Friday, February 09, 2007
Just Science day 5: Kill and cure?
The best way to protect an endangered species might be to ... cull it.
That's the conclusion reached by Michael Bode and Hugh Possingham in a theoretical analysis published recently in Ecological Modelling. The problem that they address is the tendency of some species to show boom-and-bust population dynamics. This seems a particular feature of tightly linked predator-prey systems: if predator is rare, prey booms, predator has lots of food, predator booms, prey crashes, predator starves, predator crashes, and so on. The Canadian lynx-hare system is the most famous example.
At the bottom of the cycles, population sizes might be so small that either predator or prey is highly vulnerable to extinction - by some other event, such as disease or disaster.
Bode and Possingham model various options for damping these cycles by removing some predators, prey, or both, from the system. "Remarkably," they say, "if the interventions are enacted at the appropriate time, infrequent culling of a small number of individuals significantly reduces the probability of extinction of the predator."
My first thought when I saw this, was that we probably rarely know enough about a species' population dynamics to know when the best time to cull is, and that such a move would be politically untenable. But, as Bode points out, the most likely candidates for such a move are large game-park species, such as elephants, about which we know quite a lot. It's also heartening that their (as they say, simplistic) simulation suggests that culling prey (which would be plants for elephants, I suppose) is more likely to be effective than predators, and that culling would be needed only rarely.
They conclude:
I swapped e-mails with Bode, and besides mentioning that, in parks with very high elephant densities, such as Kruger, culling elephants seems 'almost unavoidable' (the issue seems to have flared up most recently in late 2005, judging by this BBC story), he also mentioned that similar issues were arising in Australia regarding koalas and kangaroos. As he says, why is it always the cure animals?
All I can say is I'm glad I don't have to make these decisions. Culling animals is clearly a terrible business - particularly for long-lived, highly social species such as elephants. But we now effectively control the destiny of all large, slow-breeding vertebrates. If the only places they can survive is in the parks we set up, and if we take a truly utilitarian and, dread word, holistic view of conservation, then we also have to take the responsibility of 'managing' their populations. Science isn't he only thing to guide us on such decisions, but it's best ot take as informed and clever a decision as possible, towards which Bode and Possingham's ideas can only help.
That's the conclusion reached by Michael Bode and Hugh Possingham in a theoretical analysis published recently in Ecological Modelling. The problem that they address is the tendency of some species to show boom-and-bust population dynamics. This seems a particular feature of tightly linked predator-prey systems: if predator is rare, prey booms, predator has lots of food, predator booms, prey crashes, predator starves, predator crashes, and so on. The Canadian lynx-hare system is the most famous example.
At the bottom of the cycles, population sizes might be so small that either predator or prey is highly vulnerable to extinction - by some other event, such as disease or disaster.
Bode and Possingham model various options for damping these cycles by removing some predators, prey, or both, from the system. "Remarkably," they say, "if the interventions are enacted at the appropriate time, infrequent culling of a small number of individuals significantly reduces the probability of extinction of the predator."
My first thought when I saw this, was that we probably rarely know enough about a species' population dynamics to know when the best time to cull is, and that such a move would be politically untenable. But, as Bode points out, the most likely candidates for such a move are large game-park species, such as elephants, about which we know quite a lot. It's also heartening that their (as they say, simplistic) simulation suggests that culling prey (which would be plants for elephants, I suppose) is more likely to be effective than predators, and that culling would be needed only rarely.
They conclude:
Most current methods of ecosystem control attempt to keep a single species population below a certain threshold, or between fixed bounds, leading to highly inefficient management. Furthermore, unnecessarily high levels of culling can generate considerable public opposition. Given the clumsy nature of such static controls, this view may be reasonable. Our dynamic control solution has the substantial benefit of minimising the preventable culling of organisms, and being extremely cost-effective.
I swapped e-mails with Bode, and besides mentioning that, in parks with very high elephant densities, such as Kruger, culling elephants seems 'almost unavoidable' (the issue seems to have flared up most recently in late 2005, judging by this BBC story), he also mentioned that similar issues were arising in Australia regarding koalas and kangaroos. As he says, why is it always the cure animals?
All I can say is I'm glad I don't have to make these decisions. Culling animals is clearly a terrible business - particularly for long-lived, highly social species such as elephants. But we now effectively control the destiny of all large, slow-breeding vertebrates. If the only places they can survive is in the parks we set up, and if we take a truly utilitarian and, dread word, holistic view of conservation, then we also have to take the responsibility of 'managing' their populations. Science isn't he only thing to guide us on such decisions, but it's best ot take as informed and clever a decision as possible, towards which Bode and Possingham's ideas can only help.
Monday, February 05, 2007
Just Science day 1: cave bugs and shoot-em-ups
Not much time today (or tomorrow), so just a quick one drawing attention the juiciest morsels that popped into my inbox this morning.
First, and most closely related to this blog’s core themes, we have an interesting paper in Micobial Ecology by Raina Maier and her colleagues looking at the impact of tourists on the bacteria living in Kartchner Caverns, AZ.
These caves were opened to tourists in 1999. With admirable foresight (it’s depressing how rare this kind of thing is), researchers surveyed the caves’ microbial biota before opening, and now they reveal what’s changed as a consequence of having 200,000 people pass through the caves each year.
Raina's team found that the most heavily used areas had higher diversity, and different community composition — more Proteobacteria, fewer Firmicutes. This is probably a mixture of people bringing in bugs, and an increase in organic matter in the caves, say the researchers.
What we don’t know is what these changes mean for, say, nutrient cycling, food webs and so on in the caves, and whether they are something that should be of conservation concern. Microbial conservation is something I’d like to know more about, so if anyone has any pointers, please point them.
Three other things caught my eye:
1. Technological Forecasting and Social Change has a special issue of interesting-looking articles on terrorism and technology.
2. The Journal of Experimental Psychology reports that ‘action gaming enhances visuospatial attention throughout the visual field’ – i.e. playing Halo and its ilk makes you sharper-eyed. Whether this does you any good, and whether you get worse at anything else (insert your own joke about leaving the house, talking to girls etc.), is another matter.
3. And Psychopharmacology (always a favourite) finds that people who drink more coffee get more of a kick out of it. Which, given habituation and everything, seems to be the wrong way around. But I can’t tell from this abstract whether this is a consequence or cause of drinking lots and lots of lovely coffee.
There. That wasn't too bad. Back tomorrow.
First, and most closely related to this blog’s core themes, we have an interesting paper in Micobial Ecology by Raina Maier and her colleagues looking at the impact of tourists on the bacteria living in Kartchner Caverns, AZ.
These caves were opened to tourists in 1999. With admirable foresight (it’s depressing how rare this kind of thing is), researchers surveyed the caves’ microbial biota before opening, and now they reveal what’s changed as a consequence of having 200,000 people pass through the caves each year.
Raina's team found that the most heavily used areas had higher diversity, and different community composition — more Proteobacteria, fewer Firmicutes. This is probably a mixture of people bringing in bugs, and an increase in organic matter in the caves, say the researchers.
What we don’t know is what these changes mean for, say, nutrient cycling, food webs and so on in the caves, and whether they are something that should be of conservation concern. Microbial conservation is something I’d like to know more about, so if anyone has any pointers, please point them.
Three other things caught my eye:
1. Technological Forecasting and Social Change has a special issue of interesting-looking articles on terrorism and technology.
2. The Journal of Experimental Psychology reports that ‘action gaming enhances visuospatial attention throughout the visual field’ – i.e. playing Halo and its ilk makes you sharper-eyed. Whether this does you any good, and whether you get worse at anything else (insert your own joke about leaving the house, talking to girls etc.), is another matter.
3. And Psychopharmacology (always a favourite) finds that people who drink more coffee get more of a kick out of it. Which, given habituation and everything, seems to be the wrong way around. But I can’t tell from this abstract whether this is a consequence or cause of drinking lots and lots of lovely coffee.
There. That wasn't too bad. Back tomorrow.
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