A Stellar Death

First let's start with a not-so-short-but-kinda overview of star death. Skip to paragraph 3 to go right to the story.

In general, stars go through either one of two types of life cycles. Which cycle the star chooses depends on the mass of the star. If a star is less than ~3 solar masses then it is a 'Main Sequence' star. These stars create energy through hydrogen fusion - two hydrogens get stuck together to form a helium, releasing in energy. After approximately 10 billion years, these stars have converted ~10% of their hydrogen into helium, quite a bit when you consider the enormous amounts of pressure in the cores of these stars and the fact that the outer layers have insufficient pressure to initiate fusion. The helium core contracts and the outer layers expand, cool, and glow red -- a red giant. With the added core pressure, helium fusion begins and lasts ~100,000,000 years, generating heavier elements such as carbon. Then the star collapses and sheds its outer layers into a planetary nebula, the remaining core forming a white dwarf.

If a star is above ~3 solar masses then it spends little time in the Main Sequence and dies a violent death. These massive stars are of the live-large-die-young variety. These big stars have cores that experience greater pressures that increase fusion rates, burning up the fuel faster. After ~10 million years the core is mostly carbon and the star has swollen into a red supergiant, inducing pressures that allow carbon to fuse into iron (a process that takes energy). The star eventually succumbs to the force of gravity and the core collapses in a violent explosion called a supernova. And here's where size comes into play again. If the star is between 1.4 and 9 solar masses then the core collapses into a neutron star. If it is greater than 9 solar masses then the core collapses into a black hole.

Story time!

Recently, scientists have found a new way for stars to die. Articles in Nature this week describe the usual supernova explosion SN2005E. Note that there are different types of supernovae that arise based on how much material a star has and where or how they got it (check out this podcast/transcript for more details). The point of the article is that this supernova, which actually blew up 110 million years ago in the spiral galaxy NGC 1032 in the constellation Cetus, does not match up with any of the accepted models. Telescope images show that there is too little material for the star to have been an exploding giant, and the ejected material (which is usually carbon and oxygen) did not match the other types of supernovae. Light measurements instead show large amounts of calcium and titanium. This suggests that it was an old, low-mass star (because of its location in the outskirts of a galaxy) that was probably siphoning helium off of a neighboring star and that helium eventually ignited the surface of the star, causing the explosion that yielded these elements.

Additionally, this discovery may shed light on the matter of the presence of positrons (positively charged particles) at the center of the Milky Way. It has been a mystery as to where these particles come from. This paper suggests that the titanium in supernova SN2005E is radioactive and decays to produce positrons. Considering the large concentrations of calcium and positrons in our galaxy these unique types of supernovae may actually be very common.

Here are the articles:
Perets, H.B., et al. (2010) A faint type of supernova from a white dwarf with a helium-rich companion. Nature: 465, 322–325. (DOI: 10.1038/nature09056)

Kawabata, K.S. (2010) A massive star origin for an unusual helium-rich supernova in an elliptical galaxy. Nature: 465, 326-328. (DOI: 10.1038/nature09055)

Branch, David. (2010) Supernovae: New explosions of old stars? Nature: 465, 303-304. (DOI: 10.1038/465303a)

(image from seasky.org and zebu.uoregon.edu respectively)

Snails on Speed

This little blurb on ScienceNOW sums up nicely a new article published in The Journal of Experimental Biology:

"Talk about an oxymoron: A snail on speed. No, researchers weren't trying to make the gastropods slide faster—they were trying to improve their memories. When the great pond snail (Lymnaea stagnalis) wades into water low in oxygen, it extends a special breathing tube to the surface. A team of researchers trained snails not to do this by repeatedly poking at their breathing tubes when the snails tried to extend them. Two days later, the team again placed the snails in low-oxygen water. The snails trained in normal water had already forgotten their training, and they extended their breathing tubes twice as often as snails trained in methamphetamine-laced water, the researchers report tomorrow in The Journal of Experimental Biology. The results suggest that meth improves memory, something that has been previously observed in creatures with large, complex brains like rats and humans. But since the snails store their memories in a simple, three-neuron network, the team hopes that studying the meth effect in these gastropods will help pinpoint how the drug's memory magnification powers work."

The original report:
Knight, Kathryn. (2010) Meth(amphetamine) may stop snails from forgetting. The Journal of Experimental Biology: published online. (DOI: 10.1242/jeb.046664)

The ScienceNow story:
http://news.sciencemag.org/sciencenow/2010/05/scienceshot-snails-on-speed.html

Horny Dino

Another new species of dinosaur has been unearthed. This one is a dinosaur from Mexico, specifically the Cerro del Pueblo Formation, the basal formation of the Difunta Group in the Parras Basin within the state of Coahuila. Mexico is not very well known dinosaurily speaking. In fact, only 4 dinosaur species from Mexico have been found and described in the scientific literature. The newly described fossil is 72 million years old and has been named Coahuilaceratops magnacuerna (Koh-WHE-lah-SARA-tops mag-NAH-KWER-na). Analysis of the skull and skeletal bones shows the individual to be an adult, and the remains of a juvenile were also found at the same site. An adult C. magnacuerna was 22 feet long, 6-7 feet tall at the shoulder, had a 6 foot long skull, and weighed 4-5 tons.

Did you catch the "ceratops" part of that name? Yep, it is one of the horned dinosaurs we all know and love. In this case the horns are up to 4 feet long, making it the largest set of horns found on a dinosaur to date. The purpose of the huge horns is unclear, but it is hypothesized that they were related to reproductive success (attracting females, fighting males). The skull also had a very thick nasal bone and a small rounded nose horn unlike horns seen in other ceratopsid dinosaurs.

I suggest going back to the Dino Eco story from April. There you will see a good picture and a description of how North America was in the Late Cretaceous Period. At this time, not much of Central America had formed and Mexico was the southern-most point of the continent. Now this area is dry and deserty, but 72 mya it is thought to have been a humid estuary much like the present-day Gulf Coast, evidenced by fossilized snails and clams. C. magnacuerna was found in an area such as this along with duck-bill dinosaur fossils, two other (less well understood) horned dinosaurs, large tyrannosaurs, and small Velociraptor-like dinosuars. So many fossils in one place suggests a massive death event associated with a large storm, such as a hurricane.

As if the wealth of bones was not enough, researchers also discovered the largest assemblage of dinosaur trackways known from Mexico. The large area that is crisscrossed with the tracks of many dinosaur species shows a diverse picture of species in this area.

Here's the story:
http://www.sciencedaily.com/releases/2010/05/100528124513.htm

Sneaky Males

The boy-meets-girl scenario is not always so simple in nature. Often it is the boy-must-convince-girl and/or boy-must-keep-girl scenario. Many males pick flashy coloration, elaborate dancing, amazing architecture, gift-giving, feats of courage, and cautious mate guarding. This particular story is one of deception, antelope deception that is.

Many antelope mating systems are set up so that a male maintains a territory and females who like a territory will stay there to feed and likely mate with the male of that territory. And so, the higher quality the territory the more likely that a female, or many females, will mate with that particular male. That's the plan anyway.

In the case of the topi antelope, males have found a loophole in the system. Topi antelope females are only in heat for one day per year, and they generally visit multiple territories, mating with resident males during that time. So if you are a male topi antelope you want to keep females in your territory as long as possible to increase the likelihood that you are the father of the most antelope babies. How do you accomplish this? When a female is appearing to leave his territory the male runs in front of her, freezes, stares in the directions she is going, and starts snorting loudly. This is typically a behavior exhibited by animals who detect a predator (a cheetah, lion, leopard, or whatever) -- an alarm snort, if you will. The female then retreats back into the territory. In this case its all a big show, further evidenced by the fact that the male attempts to mate with the female right after the curtain falls. The male is pretending to sense a predator so that the female will stay in his territory. This study, published online in The American Naturalist, is the first case to find males duping females in this way. This is a pretty ingenious and relatively rare behavior, considering it is energetically efficient, safe for the male, and it works because ignoring a predator-alert signal could potentially be fatal.

Bro‐Jørgensen and Pangle, the authors of the paper, tracked 74 female topis in estrus through the years 2005-2009. They observed the females as they visited the territories of various males. They also observed the males in the absence of females. They observed this fake-alarm-sound behavior and found that the females almost always fell for it.

They also recorded the sounds made by males and found that they could be classified into three categories: a real alarm sound, a false alarm sound, and a regular grunt or snort. When they played these recorded sounds to 60 different females they observed that the females ignored the regular grunts but froze in place at the real and fake snorts. This suggests that the sound itself (excluding the visual, body language signals) is close enough that real and fake are indistinguishable to the females.

Smooth, very smooth.

Jakob Bro‐Jørgensen and Wiline M. Pangle. (2010) Male Topi Antelopes Alarm Snort Deceptively to Retain Females for Mating. The American Naturalist: 176, published online. (DOI: 10.1086/653078)

Here are a couple of write-ups about the article:
http://www.nytimes.com/2010/05/25/science/25obantelope.html?ref=science#
and
http://www.time.com/time/health/article/0,8599,1991425,00.html

(image from http://newsimg.bbc.co.uk)

Hammering Away

Hammerhead sharks (Family Sphyrnidae) get their name, and are easily recognizable, due to their uniquely shaped heads which are laterally expanded and dorsal-ventrally compressed (the cephalofoil) with an eye at each end. The group itself is approximately 20 million years old, and after its initial evolution it underwent divergent evolution producing species of various head and body sizes and head shapes (much of this evolution occuring within the last 6 million years). Body sizes range from as small as 3 feet (just under 1 meter) to the largest, the great hammerhead (Syphyrna mokarran), at 18 feet (about 5.5 meters). The bonnethead shark (Sphyrna tiburo, from Caribbean and tropical eastern Pacific Ocean) has the least laterally expanded head (18% of the body length) while the winghead shark (Eusphyra blochii, from Australia) has the most laterally expanded head (50% of the body length). These two species also have the most divergent cephalofoil shape as well as some of the smallest body sizes at maturity.

There are various hypotheses as to the function of the cephalofoil. One popular hypothesis is that the wing-shaped head provides lift and greater maneuverability in the water. Sharks are also known for their electroreception abilities, and it is speculated that the lateral head extensions enhance this capacity, making prey detection and capture more efficient.

A new paper published in Molecular Phylogenetics and Evolution analyzes mitrochondrial and nuclear DNA to infer the phylogeny for all species in the group. They took DNA from each of the eight hammerhead species to construct a new phylogenetic structure ("family tree" or "gene tree") for the group. The researchers used four mitochondrial genes and three nuclear genes (amounting to 6292 total base pairs in the study). Mitochondrial DNA is maternally inherited and nuclear DNA is from both parents, and these DNA types undergo differing mutation rates. By tracking the mutations in the genes, researchers can look at evolution of a species/group over time. Using this technique, they found that large (>200cm) and small (<150cm)>

Why the evolution of small body sizes? One reason may be in their development, specifically progenesis or neoteny (adults retaining juvenile characteristics). A smaller body size means that the cephalofoils may not provide as much lift in the water, but, that's ok if you develop gain other functions such as enhanced binocular vision, prey capture, and/or maneuverability. Also, all small-bodied sharks are restricted to continental shelf habitats while large-bodied sharks tend to be pelagic and circum-globally distributed. This could reflect their evolutionary origins, as increased size allows for trans-oceanic movement and colonization - either as small sharks evolving big, moving, then evolving some lineages small again or a large widely distributed shark evolved into smaller species.

So what does all this boil down to?

"The new phylogenetic hypothesis does not challenge the existing classification and taxonomy of the family Sphyrnidae. Nonetheless, we note that proposed subgenera remain paraphyletic. Continued recognition of two distinct genera (Eusphyra and Sphyrna) makes sense given the monophyly of the genus Sphyrna and the degree of divergence between Eusphyra and Sphyrna. If there is a need for subgeneric taxonomic categorization, we advocate using the inferred phylogeny as a guide for defining monophyletic subgenera."

That's just how I would have said it :o)


Here's the paper:
Kim, Douglas D., Philip Motta, Kyle Mara, Andrew P. Martin. (2010) Phylogeny of hammerhead sharks (Family Sphyrnidae) inferred from mitochondrial and nuclear genes. Molecular Phylogenetics and Evolution: 55(2), 572, (DOI: 10.1016/j.ympev.2010.01.037)

Here's a write up (but reading the above paper is actually easier and more informative):
http://www.sciencedaily.com/releases/2010/05/100518113132.htm


(images from livescience.com and arkive.com via seapics.com respecitvely)

To the Letter

In the May 7th issue of the journal Science a letter signed by 255 prominent scientists was published. This letter, "Climate Change and the Integrity of Science," speaks to "the recent escalation of political assaults on scientists in general and on climate scientists in particular." The letter states that many of these attacks are "driven by special interests or dogma, not by an honest effort to provide an alternative theory that credibly satisfies the evidence." And although all of the signers were not climate scientists (they were all members of the National Academy of Sciences and some Nobel laureates), they all agreed that the mis-framing of climate science and the questioning of scientists' motives is disturbing. This mis-framing and questioning coming from as high up as the U.S. Congress.

"Statements by Sen. James Inhofe (R-Okla.), accusing climate scientists of fraud and calling 17 of them ... potential 'criminals', helped provoke the response..."

"Inhofe has claimed that the Intergovernmental Panel on Climate Change, which shared the 2007 Nobel Peace Prize with former Vice President Al Gore, is a deliberate fraud. He has called for investigations of possible violations of federal law by some climate researchers."

The letter calls for an end to threats of criminal prosecution and an end to the lies being spread about scientists, likening it to McCarthy-like witch hunts. It lays out what is science and what is not. It also lists the accepted, fundamental conclusions about climate change:

"(i) The planet is warming due to increased concentrations of heat-trapping gases in our atmosphere. A snowy winter in Washington does not alter this fact.

(ii) Most of the increase in the concentration of these gases over the last century is due to human activities, especially the burning of fossil fuels and deforestation.

(iii) Natural causes always play a role in changing Earth's climate, but are now being overwhelmed by human-induced changes.

(iv) Warming the planet will cause many other climatic patterns to change at speeds unprecedented in modern times, including increasing rates of sea-level rise and alterations in the hydrologic cycle. Rising concentrations of carbon dioxide are making the oceans more acidic.

(v) The combination of these complex climate changes threatens coastal communities and cities, our food and water supplies, marine and freshwater ecosystems, forests, high mountain environments, and far more."

(which I just had to quote because it was put so well)

Throughout the letter, and again at its closing, society's role in the treatment of their scientists and responsibility to themselves is emphasized.

"Society has two choices: We can ignore the science and hide our heads in the sand and hope we are lucky, or we can act in the public interest to reduce the threat of global climate change quickly and substantively."

This is an intreguing publication. One, I might add, that was rejected by most major newspapers (likely because they have taken a chopping knife to their science sections). I suggest reading the actual letter, and I've also included an editorial and a policy/society article.

Here's the story:
http://news.stanford.edu/news/2010/may/climate-051210.html

and here's the letter:
Climate Change and the Integrity of Science (2010). Science: 328(5979), 689-690. (DOI: 10.1126/science.328.5979.689)

Hanson, Brooks (2010). Stepping Back; Moving Forward. Editorial. Science: 328(5979), 667. (DOI: 10.1126/science.1190790)

Jasanoff, Sheila (2010) Testing Time for Climate Science. Science: 328(5979), 695-696. (DOI: 10.1126/science.1189420) (Summary)

Birds of a Feather

After a brief hiatus, in which I was sunburned beyond all recognition (UV rays bad), its back to the sciencey goodness. I figured I would lead off with a story about feather evolution, and if you've been reading this blog then you know that I just love a good feather evolution story. This one was reported on the ScienceNOW website.

It is generally agreed that birds evolved from small dinosaurs about 150 million years ago. As you may already know, the first birds weren't exactly the best fliers. There has been a debate on about how the feathers of these early birds/later dinos were actually used - for gliding or for more sustained flight.

Robert Nudds of the University of Manchester and Gareth Dyke of University College Dublin took a close look at a 100 million year old bird by the name of Confuciusornis. They were looking to see whether or not the feathers of this bird were strong enough to provide both lift and withstand breaking due to rapid flapping of the arms/wings.

They applied Euler-Bernoulli beam theory (or Engineer's beam theory) to this feathery conundrum. This theory is used by engineers to calculate the load bearing strength of structural beams. The thoery was tested out on the bird's primary feathers (outer edge of wing - the big ones) because they bear the most load. After taking lots of measurements of the feathers (diameters, lengths, etc) and combining it with the estimated body weight of the bird, they plugged the values into the Euler-Bernoulli equations. The conclusion: The wings would have buckled under the stress. The same analysis was performed on the older (140 mya) Archaeopteryx. It also failed.

Other scientists are not completely sold on these conclusions. They cite examples of fossils found in lake and marine sediments, saying that some flight (rather than simple gliding) took the birds to those distances. Also, fossilized feathers can be difficult to measure accurately which could affect the results of the calculations.

The story link:
http://news.sciencemag.org/sciencenow/2010/05/did-first-feathers-prevent-early.html

(image from http://www.toyen.uio.no/palmus/galleri/montre/english/161_632.htm)

Thanks to You

I know that we've already past Mother's Day but it was recent enough that this video is still relevant. Besides, its too good not to post.

The Butt of the Problem

The journal Industrial & Engineering Chemistry Research published a paper this week about cigarette butts. China, where the authors are from, has 300 million smokers and consumes 1/3 of the world's cigarettes. According to the article, approximately 4.5 trillion (yeah, that wasn't a typo) are tossed into the environment annually. These butts can last up to 15 years in the sea and are known to contain ingredients that are toxic to fish. The authors were able to identify nine different chemicals when they immersed cigarette butts in water. They applied these extracts to N80, a steel used in oil pipes, and found that the chemicals protected the pipes from rusting, even under harsh conditions. This discovery could potentially save the oil industry millions of dollars ('cause they need more money) in pipe repair and replacement, and it is a novel use for a big litter problem (a better reason in my opinion).

Here's some links:
http://news.bbc.co.uk/2/hi/science_and_environment/10116050.stm
http://www.reuters.com/article/idUSTRE64C10W20100513

Surround-o-Vision

Surround sound technology in the movie theater has become standard, and it is also a very popular technology used in homes around the world to enhance the movie experience. Surround sound essentially gives you a 3D sound experience, you can hear what is happening on and just-off camera.

Now, researchers at MIT's Media Lab have developed what they are calling Surround Vision. Envision the qualities of surround sound applied to what you are seeing visually - that seeing what's just off-camera effect.

“If you’re watching TV and you hear a helicopter in your surround sound,” says Santiago Alfaro, a graduate student in the lab who’s leading the project “wouldn’t it be cool to just turn around and be able to see that helicopter as it goes into the screen?”

They are achieving this through the use of standard, Internet-connected handheld devices. Say you are watching a sports event - football, nascar, whatever - and you want to see what is happening off the right side of the screen. All you have to do is point your cell phone (or iPad, or whatever) in that direction and the image shows up. Have more than one device? Cool, you can get more than one angle.

"How they did it: Once he’d rigged up a handheld with the requisite motion sensors, Alfaro shot video footage of the street in front of the Media Lab from three angles simultaneously. A television set replays the footage from the center camera. If a viewer points a motion-sensitive handheld device directly at the TV, the same footage appears on the device’s screen. But if the viewer swings the device either right or left, it switches to one of the other perspectives. The viewer can, for instance, watch a bus approach on the small screen before it appears on the large screen."

The next step is user studies. The researchers are partnering with various companies that have saved feature footage or are interested in developing the technology. Further applications could include interactive TV in genres such as children's programing and criminal-forensics procedural dramas.

Here's the link that includes video: http://web.mit.edu/press/2010/augmented-tv.html

(image from avtinc.net)

Boob Lift

Yet another entry into the "Groundbreaking science - men like boobs" category.

This is a story about hitchhiking boobs, or rather boobs that are good for hitchhikers.

Picture this: Its a sunny day at the beginning of summer and you're in France driving down the road in Presqu'lle de Rhuys in Brittany. You see a young woman dressed in a pair of neat jeans, light sneakers, and a white figure-hugging shirt and she has her thumb out to catch a ride. Do you stop? Why?

This experiment tested the effect of a woman's bust size on the rate of help offered when hitchhiking. A woman, exactly as I described above, was fitted with various sized bras/lifts (A-cup, B-cup, and C-cup) and asked to hitchhike. Twelve hundred drivers (774 men and 426 women) were tested for their responses to the woman and her boobs.

Male drivers were shown to have significantly different responses to cup size. C-cup being significantly different than A-cup but not to B-cup, and A-cup and B-cup were not significantly different from each other. Female drivers showed no significant difference between cup sizes. To sum up, the bigger your boobs the more likely male drivers are to stop and give you a lift.

So, once again, men like boobs. Any boobs are good, but bigger boobs are better. Again, you're shocked, I can tell.

Here's the paper:
Guéguen N. (2007) Bust size and hitchhiking: a field study. Percept Mot Skills: 105(3 Pt 2), 1294-1298. (PMID: 18380130)

Something's Fishy

This week I'm apparently all about PNAS articles. This story also comes from that journal and is about changing the brains of fish.

Georgia Tech scientists have been applying chemicals to developing Cichlid fish embryos in order to manipulate genes. In these experiements they found differences in general brain patterns, differences evident in early development neurogenesis.

Let's step back for a second. There is a popular theory known as "late equals large" that explains the way brains evolve across species. The brain starts off as a blank slate, and as the embryo starts to develop, the anterior (front) and posterior (back) parts of the brain are specified. The next step is neurogenesis where precursor cells start to replicate and then mature into neurons. The later the this switch from precursor cell to neuron (the shutting off of replication and then maturation of cells) occurs the larger the brain. This is where the "late equals large" theory comes into play. It says that the brains of different species are similar in those early stages but differentiate in the later stages of development and neurogenesis.

So back to fish brains. The study looked at the brains of six species of Cichlid fish from Lake Malawi, three of those species from a rock-dwelling lineage and three from a sand-dwelling lineage (remember that Cichlids are known for their adaptive radiation). The authors of this paper found differences in the general brain patterning as early as 48 hours after fertilization. This is before neurogenesis begins.

When they repeated the experiments 2-4 days after fertilization they found that the sand-dwelling species had a larger expression of the gene wnt1, an important factor in posterior brain development, specifically the thalamus which is used in processing vision. Since the sand-dwellers are visual hunters this makes sense. The rock-dwelling species have larger cerebra (or telecephala) which is thought to help navigate 3D environments. However, the genomes of these species are very similar, but the variation you see in their brains is dramatic.

Ok, so now they knew the brains were similar, but different. At what point and how do these differences take place? According to the "late equals large" theory, most of the changes would occur in later stages of brain development.

To test this, developing fish brains were exposed to lithium chloride for 3-5 hours during an early stage of anterior-posterior patterning in order to alter gene expression. After that, samples were taken at various developmental stages. In each sample it was found that Wnt signaling was up-regulated, a change that reallocates brain precursors to the posterior thalamus. Ah-ha! The brains did not develop normally suggesting that a signal early in development, rather than late, causes differentiation in these species.

Overall, they have challenged the "late equals large" theory by showing that there are differences in the developmental process earlier than previously thought.

Here's the article:
Sylvester, Jonathan B., et al. (2010) Brain diversity evolves via differences in patterning. Proceedings of the National Academy of Sciences: published online. (DOI: 10.1073/pnas.1000395107)
and http://www.sciencedaily.com/releases/2010/05/100503161342.htm

(image from www.malawicichlidhomepage.com)

Diminutive Dino

In 1895, Franz Baron Nopcsa examined a set of small sauropod dinosaur bones and concluded that they belonged to a species subjected to island dwarfism, and named it Magyarosaurus dacus. Island dwarfism (phyletic nanism) is the reduction in size of large animals that occurs when a species' gene pool is limited to a very small environment, such as an island, and the particular conditions in that environment (competition, food sources, territory, etc.). M. dacus was a titanosaurian sauropod from the Upper Cretaceous (Maastrichtian) and was about the size of a horse, which is very small when compared to other sauropod species. Since then, with the discovery of other large sauropods at the same site, it has come into question whether or not M. dacus was actually a dwarf or not.

More recently, these bones were examined for their microstructure, particularly the rebuilding that happens to bones as an animal ages. This analysis indicated that M. dacus had bone microstructure identical to that of a fully mature sauropod. The diminutive dino also had an extremely reduced growth rate but maintained the high metabolic rates typical of other sauropod species. Based on this research, they were able to show, conclusively, that M. dacus was indeed an island dwarf species. The other sauropod bones at the site were also shown to belong to a different sauropod species.

Here's the article:
Stein, K. et al. (2010) Small body size and extreme cortical bone remodeling indicate phyletic dwarfism in Magyarosaurus dacus (Sauropoda: Titanosauria). Proceedings of the National Academy of Sciences: published online. (DOI: 10.1073/pnas.1000781107)
and http://www.sciencedaily.com/releases/2010/05/100503111513.htm

Under Cover

While working on my masters thesis I got really interested in the rates of forest and species loss. As a result, articles relating to these topics still catch my eye. So when I saw this article published online in PNAS I knew I couldn't pass it up.

If you are reading this blog then you are probably aware of the massive forest loss in the topics and other places around the world. Forests that aren't completely cut down are fragmented into ever smaller islands and refugia. We can see this happening, but putting a rate to it can be difficult. Typically, rates are calculated by such methods as putting together a large meta-analysis or collecting lots of satellite images. This study does the latter in that the researchers took data from the MODIS sensor to look at stratification for forest cover loss. MODIS (Moderate Resolution Imaging Spectroradiometer) is an instrument aboard the Terra (EOS AM) and Aqua (EOS PM) satellites that orbit around the Earth. Terra passes from north to south across the equator in the morning, and Aqua passes in the afternoon. This allows the satellites to view the entire surface of the Earth every 1-2 days. The authors also used the Landsat ETM+ to quantify gross forest cover loss (GFCL) for the entire planet. With these data they were able to compare GFCL among biomes, continents, and countries. Note that "GFCL is defined as the area of forest cover removed because of any disturbance, including both natural and human-induced causes."

"GFCL was estimated to be 1,011,000 km2 from 2000 to 2005, representing 3.1% (0.6% per year) of the year 2000 estimated total forest area of 32,688,000 km2." The results showed that Russia had the most extensive forest loss. Next in line were Brazil, Canada and the USA. If you break it down by type then you see the most loss in boreal forests, Russia being the biggest offender again - 60% of boreal forest loss can be blamed on them. Tsk tsk. Humid tropical forests rank next, especially in the countries of Brazil, Indonesia and Malaysia. Although, in terms of smallest proportion lost they actually rank pretty well. Mweh, still not exactly a comforting figure. Sticking with the tropics, dry tropical forests rank next, especially in the countries of Australia, Brazil, Argentina and Paraguay. Temperate forests have been hacked at for hundreds of years and, as of this study, still managed to have the second higest proportional loss (after boreal forests, which I mentioned above), with North America being the biggest offender -- 30% of the blame for global loss (5.1% proportional loss) lies there. Also, I would be remiss if I did not mention that the processes driving GFCL, and rates of recovery from it, vary regionally. If you look at the boreal system you will find that naturally induced fire is important, and in other systems additonal factors are key. But all in all, everybody needs to step back -- to a global scale, as in the picture at the top -- and see what this fragmentation is doing to these regions. (insert finger waggle and head shaking here)

Here's the article:
Hansen, M.C., S.V. Stehman, and P.V. Potapov (2010) Quantification of global gross forest cover loss. Proceedings of the National Academy of Sciences: published online. (DOI: 10.1073/pnas.0912668107)

(Both images are credited to NASA's MODIS website: http://modis.gsfc.nasa.gov/gallery/ and more spectactular images can be found there. Check it out!)

Bull City Locovores

Living in Durham, North Carolina I can tell you, there is some yummy yummy food in this city.

"... hundreds of outlying acres of rich Piedmont soil have 'transitioned' from tobacco, and now sprout peas, strawberries, fennel, artichokes and lettuce. Animals also thrive in the gentle climate, giving chefs access to local milk, cheese, eggs, pigs, chickens, quail, lambs and rabbits."

"... a drive around town might yield the smell of clams from the coastal town of Snead’s Ferry, steaming in white wine, mustard and shallots at Piedmont restaurant; pungent spice and sweet fennel from the 'lamby joe' sandwich at Six Plates; and seared mushrooms and fresh asparagus turned in a pan with spring garlic at Watts Grocery."

A lot of that food is obtained locally by many of the most popular restaurants in the area. A new(ish) article in The New York Times highlighted Durham's shift to local foods. This shift is particularly intriguing considering that not all that long ago the area and its farms was focused on the growing, harvesting, selling, and manufacture of tobacco. Many of those tobacco farms have switched to produce or livestock such as cattle and sheep.

"There are still plenty of good places for a barbecue plate, excellent French bistros like Vin Rouge and Rue Cler, and some white-tablecloth dining rooms, both traditional and modern."

"But the most intriguing cooks here have a few things in common: an understanding of how to give a menu a sense of place; a true love of pork and greens in all their forms; and a lack of interest in linens and glassware. Watts Grocery, for example, looks like an upscale sports bar, but it tastes like a Southern-artisanal Union Square Cafe."

Chefs take advantage of the locally grown products by visiting farms and farmers markets. This allows the restaurants and chefs to serve fresh, often organic, foods at very affordable prices.

"The food at Neal’s Deli is resolutely everyday and American — like breakfast biscuits stuffed with egg and sausage — but the eggs are steamed tender with a touch of pepper and parsley, and the wide, crisp biscuits are mixed from high-fat local buttermilk and organic flour from a nearby mill that’s been held by the same family for nine generations. The sausage patty is from Cane Creek
Farm in Alamance County, where Eliza MacLean, an owner of the farm and a former veterinarian, advises farmers across the state on the transition from tobacco to pork. Every bit of that care comes through in the flavor of the finished product, a stunning bargain at $3.25."

Farmers are also benefiting from this local food movement:

"Mr. Brinkley, [a] farmer, says that his family’s farm, and many others, might not have made it through the loss of the tobacco cash crop without the lucky coincidence of the rise in the local food movement. Now, chefs compete over his lady peas, pink-eyed peas and butternut squash — a relatively exotic vegetable here, he said, where the sweet potato was once the king of the winter table."

Read more here: http://www.nytimes.com/2010/04/21/dining/21carolina.html?8dpc

(image from visitsouth.com)