Wednesday, July 30, 2008

Mysterious Dark Energy detected

There are mysteries in the universe—troubling behaviors of the stars that make no sense unless you assume forces you can't see.

Enter Dark Matter and Dark Energy. Can't see them. Can't measure them. But the most accepted models of the universe only make sense if they exist.

(Image: A University of Hawai'i team compared the strength of the Cosmic Microwave Background with sections of the sky where they located superclusters (red circles) and supervoids (blue circles). Microwaves tended to be stronger in the red and orange areas, and weaker in the blue areas. Credit: UH Institute for Astronomy.)

Now, for the first time, researchers at the University of Hawai'i's Institute for Astronomy may have actually measured the effects of one of them: Dark Energy.

A team led by Dr. István Szapudi believes it has been able to find direct evidence for the existence of Dark Energy, by measuring changes in microwaves that have moved through superclusters and supervoids.

(Okay. Some definitions:

(The universe has unimaginably vast areas that are dense with galaxies and also has areas that have comparatively few galaxies. The first are called superclusters and the second supervoids.

(Dark Matter: Based on theoretical calculations of the universe and how it works, there ought to be far more matter than we can actually find and measure. Astronomers assume it's there, but we just can't detect it. The missing stuff is called Dark Matter.

(Dark Energy: The universe is expanding, and something appears to be accelerating the expansion. What's causing the acceleration? The experts don't know, but some of them have a name for it. Astronomers call this mysterious—and until now theoretical—force Dark Energy.)

“We were able to image dark energy in action, as it stretches huge supervoids and superclusters of galaxies,” Szapudi said, in a press release from the Institute for Astronomy. His co-authors were Benjamin Granett and Mark Neyrinck. Their paper will be published within the next two months in the Astrophysical Journal Letters.

How it works is this, as Szapudi's team explains: If a microwave enters a supercluster, it gains energy. When it leaves the supercluster, it should lose that energy again. But if the supercluster is being affected by Dark Energy, being flattened in the 500 million years it takes for the microwave to cross it, then the microwave will actually retain some of the supercluster's energy.

“Dark energy sort of gives microwaves a memory of where they’ve been recently,” Neyrinck said.

The team looked at the 50 largest superclusters and at the 50 biggest supervoids in a region representing galaxies across about a quarter of the sky.

The team found that microwaves that had passed through superclusters appeared to have gained energy, while ones that had passed through supervoids lost energy. The distinctions were extremely small, but detectable.

See the Institute for Astronomy release on the paper here:

© 2008 Jan W. TenBruggencate

Monday, July 28, 2008

Polynesian chickens in Chile? New furor, but they still look Polynesian.

A towering scientific furor has arisen over...chickens.

Specifically, whether Polynesian voyagers introduced chickens to South America before the first Europeans showed up...carrying their own chickens.

(Image: Red jungle fowl, the chicken of the Polynesians--in this case, a rooster. Credit: U.S. Fish and Wildlife Service.)

We'll get into some detail later, but the short version is this:

It still looks clear that voyaging canoes from the Polynesian culture of the Pacific carried chickens to the Americas well before Christopher Columbus, despite a great deal of rancorous comment and competing scientific papers in the esteemed journal, Proceedings of the National Academy of Scientists (PNAS).

Here's the longer version.

In 2007, researchers led by Alice Storey of New Zealand published a paper on the dating and DNA analysis of chicken bones found at the El Arenal archaeological site in southern Chile.

They found that 1) the bones dated to before Europeans first arrived in the Americas, and 2) the chickens were closely related genetically to early chickens found in Hawai'i and elsewhere in the Polynesian Pacific.

The inescapable conclusion was that the El Arenal chickens came from Polynesia, and since Polynesians, not South Americans, were a voyaging culture, that those chickens arrived on Polynesian voyaging canoes.

This helps resolve a couple of great anthropological mysteries.

  1. How could the amazing Polynesian voyaging culture have populated virtually every isolated island in the vast Pacific and missed the Americas? Answer, of course: It didn't. The Polynesians simply failed to settle in the Americas, perhaps because there were
    already people there.

  2. Throughout Polynesia, there are sweet potatoes. Sweet potatoes come from the Americas. How did they get into the Pacific? There have been suggestions, such as Thor Heyerdahl's drift raft theory, that somehow South Americans carried the potato through the Pacific. But it seems much more likely that voyaging canoes from the Pacific touched on the coast of South America and either did some swapping or some inspired botanical exploration.

Storey's paper was published in the PNAS in mid-2007. The same journal this week (July 28, 2008) published another chicken paper that challenges the Storey results. It is: “Indo-European and Asian origins for Chilean and Pacific chickens revealed by mtDNA,” by Jaime Gongora, Nicolas J. Rawlence, Victor A. Mobegi, Han Jianlin, Jose A. Alcalde, Jose T. Matus, Olivier Hanotte, Chris Moran, Jeremy J. Austin, Sean Ulm, Atholl J. Anderson, Greger Larson, and Alan Cooper.

In this one, Australian researcher Jaime Gongora argued that it might be premature to attribute those El Arenal chickens to a Polynesian voyager's introduction, in part because Gongora's team can't find Polynesian chicken DNA in modern South American chickens. Also because they argue it's possible the pre-European dates for the chicken bones were wrong.

Before we proceed further, a little chicken background. Chickens originated in Southeast Asia, and were so wildly popular as domestic fowl that they were carried around the world. Some went west to Europe, and some went east into Polynesia. They certainly got to the Americas from Europe, and the Storey work shows they may also have reached the Americas from Polynesia.

Gongora, in an emailed statement on his paper, said this:

“European chickens were introduced into the American continents by the Spanish after their arrival in the 15th century. However, there is ongoing debate about the presence of pre-Columbian chickens among Amerindians in South America, particularly in relation to Chilean breeds. This debate includes controversial claims that Polynesians introduced chickens into South America before the arrival of Europeans.”

Gongora said he conducted extensive surveys of the genetics of modern South American chickens, and found that they appear to be exclusively European in origin.

“This DNA study shows that modern Chilean chickens originated from European breeds, and the apparently pre-Columbian specimen provides no support for a Polynesian introduction of chickens to South America,” Gongora wrote.

He goes on to challenge the radiocarbon dates of the El Arenal site, suggesting that marine sediments might have contaminated them and made them seem older than they are.

“Definitive proof of Polynesian chicken introductions into the Americas will require further analyses of ancient DNA sequences and radiocarbon and stable isotope data from archaeological excavations within both Chile and Polynesia,” he wrote.

Anthropologist Elizabeth Matisoo-Smith, a co-author with Storey on the original paper, said their continued research has confirmed the original dates. They have already published work that shows that the diet of the El Arenal chickens was a land-based, not a marine-based diet.

“The Carbon and Nitrogen values show that the diet of the El Arenal chicken was terrestrial,” Matisoo-Smith said in an email.

“All the dates we have are consistent,” she said. The Storey and Matisoo-Smith team is in the process of getting its latest findings published.

The upshot of all this seems to be that, on balance, there is now more rather than less evidence of Polynesian chickens in Chile, and therefore Polynesian voyaging to the Americas.

© 2008 Jan W. TenBruggencate

Wednesday, July 23, 2008

Making cars seXy efficient

A car is a car is a car.

Clearly, that statement ain't true.

Sometimes a car is a sportster, and sometimes an SUV. Sometimes a van, sometimes a sedan.

But what counts is under the hood, you might hear.

Even that isn't necessarily a true statement these days.

Sometimes you'll find the power source for a car under the hood, but it might just as easily be in the trunk, or in the case of big battery packs, under the seats.

The world is in the heady process of redefining the family passenger vehicle.

In the liquid fuel category, there are gasoline cars, diesel cars and biodiesel cars, propane and liquefied petroleum gas (LPG) cars, cars that run on various combinations of gasoline and ethanol, hydrogen cars and so forth.

There's the compressed air car.

There are electric cars, and hybrids. But there are such variations, that you really need to pay attention.

There, for example, are plug-in hybrids, and extended range electrics, both of which have blends of traditional fuel engines and electric car capabilities. Like hybrids, but not like most hybrids.

Each new blend of transportation technologies seems to be getting its own name.

Click on the “efficient transportation” category in the right hand column of this blog for a number of stories on these issues. One is found at

The key to modern vehicle technology, in an age of astronomic liquid fuel prices, is efficiency. And one of the things expected to help move efficiency along is the Automotive X Prize, a $10 million contest to develop the most energy efficient automobile possible—and they need to be fast.

“The technology-neutral competition, a project of the X PRIZE Foundation, is open to teams from around the world that can design and build production-capable, 100 MPGe (miles per gallon energy equivalent) vehicles that people will want to buy and that meet market needs for price, size, capability, safety and performance. Winners of the $10 million prize purse will need to exceed 100 MPG equivalent fuel economy, fall under strict emissions caps and finish in the fastest time,” says the X Prize website,

The latest news on the prize is that there are 94 teams that have signed letters of intent to participate. They come from 14 countries and 24 states. They'll close the entry list sometime in the next few months.

To win the prize, car makers not only have to come up with an efficient car. They have to prove that the thing works. For that, there will be racing, and U.S. cities are now competing for their own piece of the prize—to be the site where the races are held.

“The cross country stage race will begin in New York City in September 2009, and will continue in up to nine other major markets throughout the U.S. Each stage race will feature a driving competition over city, suburban and rural roads between 30 and 200 miles in length. The Progressive Automotive X PRIZE is interested in offering diverse geographic and driving “real world” conditions, including the potential for slick and snowy roads, mountainous conditions and downtown city streets,” the X-folks say.

So far, there's been a lot of interest.

“Cities representing a diverse geographic and demographic mix – such as Albuquerque, Boston, Cleveland, Dallas, Detroit, Denver, Indianapolis, New York, Las Vegas, Long Beach, Pasadena, Portland, San Francisco, Seattle, and St. Louis – have all expressed interest in the competition,” says X.

With the average American car getting mileage in the 20-30 mile per gallon range, the X Prize pushes the envelope with a minimum requirement that achieves four times that efficiency.

It's gotta help.

© 2008 Jan W. TenBruggencate

Monday, July 21, 2008

The lasagne forests of Hawai'i

The key value to forests is their ability, according to a new federal report, is to manage water, and the native lasagne forests of Hawai'i are a key example.

That's lasagne in the sense of layered, not food, since much of the Hawaiian forest is not particularly edible.

(Image: The native Kaua'i forest shrub, mokihana, whose berries are collected and woven into lei that have a distinct anise scent. But you wouldn't want to eat them.)

A new federal study is saying that water is perhaps the most product of a forest. The online journal Science Daily today (July 21) issued a report under the title “Greatest Value Of Forests Is Sustainable Water Supply.”

"Historically, forest managers have not focused much of their attention on water, and water managers have not focused on forests. But today's water problems demand that these groups work together closely," said Oregon State geosciencies professor Julia Jones, vice chair of a committee of the National Research Council, which released the report. She was quoted in Science Daily.

Hawai'i resarchers have figured this out, and water departments work alongside wildlife managers and conservation groups on watershed management teams across the state, to protect native forests.

What's special about Hawaiian native forests as opposed to, for instance, woodlands of non-native species?

One way to determine this is to walk through a woodland in Hawai'i. The planted loblolly pine forests of Kōke'e on Kaua'i have very little other growth under them. Eucaluptus stands in Maui's Upcountry area prevent other species from coming up in their shade. Miconia forests on the Big Island are often nearly entirely miconia, with very little other vegetation able to survive.

When a heavy rain pounds these woodlands, muddy water can flow from them, as the rain erodes the unprotected soil below.

By contrast, a healthy native Hawaiian forest can be layered like a dish of lasagne.

As a raindrop is driven by gravity toward the ground, it first encounters an upper layer of canopy trees, like koa and 'ōhi'a. And then it encounters the shorter trees growing below, the mehame and 'āla'a. And then the ferns like hāpu'u and shrubs like 'a'ali'i. And then the ground ferns, mosses and the dense layers of roots, leaves, rotting branches and the rest.

The upshot, according to botanists, is that all the gravity-fed power of that raindrop to slam into the ground and break up soil particles is gone. Instead of muddy water seeping into streams, the water drips clear from springs and saturated mosses. Those dense forests also inhibit the ground-level winds that suck moisture out of the landscape, and block the evaporative powers of the sunshine.

Here is a list of findings from the report cited in Science Daily:

  • Forests provide natural filtration and storage systems that process nearly two-thirds of the water supply in the U.S.

  • Demand for water continues to rise due to population growth, while forest acreage is declining and remaining forest lands are threatened by climate change, disease epidemics, fire and global climate change.

  • Forest vegetation and soils, if healthy and intact, can benefit human water supplies by controlling water yield, peak flows, low flows, sediment levels, water chemistry and quality.

  • Increases in water yield after forest harvesting are transitory; they decrease over time as forests re-grow, and in the meantime water quality may be reduced.

  • Impervious surfaces such as roads and road drainage systems increase overland flow, deliver water directly to stream channels, and can increase surface erosion.

  • Forest chemicals, including those used to fight fire, can adversely affect aquatic ecosystems, especially if they are applied directly to water bodies or wet soil.

  • One of the biggest threats to forests, and the water that derives from them, is the permanent conversion of forested land to residential, industrial and commercial uses.

The Science Daily report is found at

© 2008 Jan W. TenBruggencate

Friday, July 18, 2008

Symbionts starve reef corals

Some corals may carry within them the seeds of their own destruction.

Reef-building corals are understood to be a combined biological creature, made up of coral animals that contain plants known as dinoflagellates. The coral can feed off the waste products of its symbiotic tenant, while the plant gains a range of benefits, including protection, from the coral.

(Image:Disease spreading across a coral. Credit: Michael Stat, HIMB/SOEST.)

But researchers have found that not all the symbionts—the plants contained within reef corals—are created equal.

“Symbioses are widespread in nature and occur along a continuum from parasitism to mutualism,” write Michael Stat, Emily Morris and Ruth Gates, of the University of Hawai'i's Hawai'i Institute of Marine Biology in the School of Ocean and Earth Science and Technology.

Their report, Functional diversity in coral-dinoflagellate symbiosis, was published in the Proceedings of the National Academy of Sciences.

In essence, they found that some of the single-celled plants that live within corals are excellent tenants and great partners.

But others are not, and can in fact are so dangerous to their hosts that they can be used to identify corals that will soon be in trouble from disease. It appears that by not providing nearly as much food to the corals as other such plants, they may weaken the corals and make them susceptible to diseases that healthy corals can avoid.

“The relationship between these dinoflagellates and corals has long been considered mutually beneficial, with the dinoflagellates supplying the coral with food via photosynthesis in return for recycled nutrients and shelter. Over the last 20 years it has been made clear that there are many different types of dinoflagellates in corals and that the unions or symbiosis between a given coral and their dinoflagellates can be very specific,” Stat said in a press release.

In work on the coral reefs of the Northwestern Hawaiian Islands at French Frigate Shoals, the researchers found that healthy corals often had a different variety, or clade, of dinoflagellate than diseased corals.

When they conducted laboratory tests, they found that the type found on diseased corals produced far fewer nutrients than the ones found in healthy corals.

“We have discovered that a group of diseased corals in the Northwestern Hawaiian Islands associate with a type of endosymbiotic algae that has never been found in Hawaiian corals before. Our analyses suggest that these endosymbiotic algae are not providing the coral with nutrition and that the corals may be starving, making them more susceptible to disease,” Gates said.

“This work shows for the first time that different types of coral dinoflagellates are not equally beneficial, and that there is a link between the type of dinoflagellate and coral disease,” Stat said.

The work suggests that reef researchers may be able to recognize a reef's susceptibility to disease by looking at the microscopic plantlife in its corals.

“Just as we have tests for human diseases such as cancer and tuberculosis, we now have the ability to screen corals for disease susceptibility. This discovery is a key finding that will contribute to the conservation and protection of ecologically important corals in Hawaii and elsewhere, Gates said.

© 2008 Jan W. TenBruggencate

Wednesday, July 16, 2008

Jets on diets: less weight, less fuel

Aircraft manufacturers are pulling out the stops to improve fuel efficiency in jets, and they're seeing success in those efforts.

That's a key issue in Hawai'i, where close to a third of the imported petroleum goes to fuel aircraft.

(Image: Bombardier's new energy-efficient CSeries jet. Credit: Bombardier.)

The European aircraft manufacturer Airbus says aircraft fuel use has dropped 70 percent in the past 40 years, and continues to decline, with a target of another 50 percent by 2020. The planes are also decreasing noise and emissions.

“"Aircraft will only be accepted if they are efficient in terms of the environment. We have to keep technology at the heart of our programme to improve our performance,” said Airbus sustainable development chief Philippe Fonta.

At this point, improvements are coming incrementally, and with small changes that won't be immediately apparent to most passengers.

Bombardier says its new CSeries jets will cut the fuel use by 20 percent. The five-across seating jets hold 110 to 130 passengers and are scheduled to be in service by 2013.

How does it get the improved fuel performance? Cutting weight and improving wing design, Bombardier says on its website:

“Key technologies are at the heart of the CSeries advantage. Composite materials are part of the center and rear fuselages, tail cone and empennage (tail assembly) and wings. Overall, 20 per cent of the aircraft weight is in composite materials,” the manufacturer says. That, plus what it calls “its fourth-generation transonic wing design.”

Boeing is saying the latest model of its 777 has a number of design features that are cutting the cost of tanking up.

Some of the changes are small, but significant.

Boeing says its 777-200ER aircraft initially attained a 2 percent increase in fuel efficiency, and then since then, it has been able to add another 1.4 percent. For an aircaft in normal use, that 1.4 percent saves 200,000 gallons a year.

Boeing says three key things improved its plane's performance. One was modified GE engines. Another was reducing the plane's drag. And a third was cutting weight of things like the internal structure, and floor panels.

In many ways, the technologies being used for planes are the same ones being used to make cars more efficient—lighter weight, more efficient engines and aerodynamic design.

There's also an argument that in some applications, turboprop planes make more energy sense than pure jets. See:

For more on fuel prices, see:

© 2008 Jan W. TenBruggencate

Sunday, July 13, 2008

Global energy and global limits

We've come to an interesting zero-sum kind of place on the planet.

That is to say, interesting, in the sense of the purported Chinese curse: “May you live in interesting times.”

Opportunities for extracting resources are no longer limitless, and the planet's various reserve capacities appear in many cases to be tapped out.


Natural systems at one time presumably had a capacity for handling short term changes in inputs. A pulse of carbon dioxide could be absorbed by plants and marine life, as an example. Today, the absorption seems at capacity, and a pure chemical relationship has taken over—as we dump more carbon dioxide in, increasing levels of carbon dioxide dwell in the atmosphere; oceans grow more acid.


Humans don't have much opportunity for pioneering, for leaving civilization and going to never-inhabited places and tilling never-tilled soil. Polynesian voyagers ran out of new islands a millenium ago. American pioneers ran into a western ocean within the last few centuries. Virtually all the habitable lands on the planet are inhabited. It means that in many cases, if you're gonna do something new, you've got to shove something old out of the way.


The global food budget that suddenly seems limited. Where once we were assured that the American farmer had reserve capacity to feed the world. Now, take some acreage out of food grains for fuel, and there are shortages, price hikes.

Which leads to a thought about the carbon-neutrality of biofuels.

In theory if you sequester carbon dioxide in a corn plant or oil palm, and then convert it into fuel, and then release the same carbon dioxide in burning the fuel—well then, it's a balance. As much carbon in as out. No net impact on the atmosphere.

In practice, if you hadn't converted that land to grow fuel plants, the land would still have been growing other plants. The carbon would still have been sequestered in those plants, and it would arguably have been released considerably more slowly if you'd used them for food, or for timber, or even for a dedicated natural area.

Arguably, using biofuels is only preferable to using fossil fuels if no other fuel source is available.

It was interesting to see this article promoting non-carbon fuel sources: Interesting, in this case, because the website is sponsored by the oil giant Shell, which is actively pursuing biofuels—including participating in research in Hawai'i on algae-based biodiesel.

The article by Solomon Hsiang argues that there may be geopolitical and economic reasons for moving from fossil fuel oil to biofuels, but that ultimately, they're not the best answer.

“Biofuels seem unwise,” he said, and he argued for non-fossil-based energy sources, like the sun, wind, ocean cycles of various kinds, including waves, currents, tidal flows and potentially, although he doesn't cite it specifically, ocean thermal energy conversion.

“The quantities of energy available from these sources are mind-boggling (they're often measured in petawatts), all we need to do is find the political maturity, will-power and cooperation needed to tap into them,” Hsiang writes.

None of this is intended to make negative judgments about Hawai'i biofuel efforts, which in many ways appear far more environmentally friendly than efforts elswhere on the planet.

If you're growing guinea grass on abandoned cane fields, it might be more appropriate to employ that property to grow a local fuel source using jatropha, kukui or even oil palm.

If global sugar prices are so low that a local sugar company can't survive on them, ethanol appears an appropriate alternative end product, particularly since sugar is so dramatically more efficient at producing ethanol than is corn.

And if the various efforts statewide to produce an algae-based diesel substitute are successful, they will do wonderful things for the Hawaiian economy and local self-sufficiency, though not much for the carbon dioxide balance in the atmosphere.

© 2008 Jan W. TenBruggencate

Saturday, July 12, 2008

Strawberry guava biocontrol possible

The introduced strawberry guava fruit is a tangy little morsel when you're on a hike in Hawai'i, and it makes tasty jam or jelly.

(Image: Strawberry guava (Psidium cattleianum) leaves and fruit. Credit: Forest and Kim Starr, USGS.)

A strawberry guava thicket—and they do tend to grow into thickets—is a dense maze of smooth vertical poles, difficult to move through. And very little other vegetation is able to survive in such an infestation.

“Areas of heavy infestation become biological deserts with few native 'ōhi'a or koa and few native birds,” says a press release from the U.S. Forest Service. Tens of thousands of acres on several islands in Hawai'i have been invaded by the plants.

There has been little to do about these pests, short of laboriously poisoning individual plants, and then either hoping native vegetation comes back, or replanting it.

Now conservation scientists believe they may have a partial answer—a scale insect that attacks strawberry guava in its native Brazil.

The Forest Service plans to hold a statewide series of meetings to talk about its proposal to release the scale insect as a biocontrol for strawberry guava.

One problem with this variety of guava is that they're packed with seeds, and those seeds sprout readily in Hawaiian conditions. Sometimes you'll find a place where a fruit has fallen, and see a dozen or more seedlings rising from a space the size of a quarter.

The scale insect is known to science as Tectococcus ovatus, and in its native Brazil, it doesn't kill off all the strawberry guava, but it keeps their numbers low. The insects feed on the young leaves of the guava plants, reducing the amount of vigor needed to aggressively produce fruit and seed.

Research underway for the past 15 years shows that the scale can only survive on strawberry guava and will not move on to other plants in Hawai'i. They don't even kill the plants they're feeding on. They simply reduce reproduction, the Forest Service said.

Tectococcus would reduce the growth and reproduction of strawberry guava, which would help prevent further destruction of native forests, and allow slower growing native plants like 'ōhi'a and koa a chance to compete,” biocontrol researcher Tracy Johnson of the U.S. Forest Service.

The Forest Service is preparing an environmental assessment for the biocontrol proposal. Details on the proposal, and a series of public meetings starting in September 2008, will be available at For more information, reach Johnson at USDA Forest Service, Institute of Pacific Islands Forestry, 60 Nowelo Street, Hilo, Hawaii 96720, phone 808-967-7122.

© 2008 Jan W. TenBruggencate

Science writing not so bad after all

Much of what you read on is science journalism.

So, what do the scientists themselves think of science journalism?

Not much, you might think.

But that would be wrong, according to a study whose results were published in the July 11 Science Magazine, under the title, Interactions with the mass media.”

“Our analysis shows that interactions between scientists and journalists are more frequent and smooth than previously thought,” wrote authors Hans Peter Peters, Dominique Brossard, Suzanne de Cheveigné, Sharon Dunwoody, Monika Kallfass, Steve Miller and Shoji Tsuchida. They surveyed 1,354 researchers in several countries, including the U.S., Japan, Germany, England and France.

The scientists in this case were epidemiologists and stem cell researchers who had recently published material in peer-reviewed journals, and nearly 70 percent of them had had contact with journalists in the previous three years.

Almost half said their experience with the media was “mostly positive” and only 3 percent said it was “mostly negative.” The rest reported either neutral or balanced responses, the latter meaning there were both positive and negative things but that they balanced each other out.

The authors of the paper cite the same experience of, which is that many folks in the scientific community have the perception that communication with journalists is a disaster zone. The authors of the paper concede that this is the common understanding. But it's one that needs to be gotten over, they said.

“Negative experiences with the media still dominate peer communication about science-media relations. On the basis of extensive survey data, we now challenge several of the negative impressions of science-media interactions that are still all too common,” they wrote.

© 2008 Jan W. TenBruggencate

Sunday, July 6, 2008

Where aliens dominate, natives retreat

It won't be a surprise for anyone who has wandered under a canopy of eucalyptus or clambered through a patch of strawberry guava that you won't find many native plants there.

(Image: Young leaves of 'ōhi'a, one of the overstory trees that can mark a native forest.)

Researchers confirm that in a paper in the journal Forest Ecology and Management, entitled, “Limited native plant regeneration in novel, exotic-dominated forests on Hawai'i.”

Interestingly, they say that in some locales, natives do okay under an alien canopy.

But not in Hawai'i.

The authors are Joseph Mascaro and Kristen Becklund of the University of Wisconsin, at Milwaukee and Madison, respectively, and Stefan Schnitzer o the Institute for Pacific Islands Forestry of the U.S. Forest Service.

“Recent evidence from Puerto Rico suggests that exotic-dominated forests can provide suitable regeneration sites for native species and promote native species abundance, but this pattern has been little explored elsewhere,” they wrote in the article's abstract.

To test the concept in Hawai'i, they studied plants in 46 sites and found, essentially, that the opposite is true in these islands.

They found that small native trees were missing entirely from 28 sites and were rare in all the others.

“Natives were never the dominant understory species'; in fact, they accounted for less than 10 percent of understory basal area in all but six sites, and less than 4 percent on average,” they wrote.

Where they did find a few natives, it tended to be near native-dominated forests, and the plants tended to be remnants from before the invasion of aliens, rather than the “products of active recolonization by native species.”

It's bad news for Hawaiian wildlands, since it means that without human intervention, the outlook is grim for native forests under threat of invasion.

“Hawaii's exotic-dominated forests can emerge, via invasion, without human disturbance and native Hawaiian plants are largely unable to colonize them once they appear,” they write.

© 2008 Jan W. TenBruggencate

Thursday, July 3, 2008

Ocean acidification requires action; the science is clear

The science showing the increasing acidification of the oceans is clear and concise—and does not require reliance on complex computer models, a University of Hawai'i researcher reports.

(Image: Coastal Hawaiian coral reef at Nu'alolo, Kaua'i.)

The effects of that acidification on living things is less clear and requires more research, but is sufficient to require humans to limit carbon dioxide emissions, said Richard E. Zeebe, an oceanographer with the UH School of Ocean and Earth Science and Technology.

Zeebe published a paper, “Carbon Emissions and Acidification,” in the journal Science, with co-authors James Zachos of the Earth and Planetary Sciences Department at the University of California at Santa Cruz, Ken Caldeira of the Carnegie Institution's Department of Global Ecology and Toby Tyrell of Southampton University's National Oceanographic Centre in the United Kingdom.

A key message of the paper, is that no matter what happens with climate change, there will be powerful disruptions in the oceans as a result of increasing carbon dioxide in the atmosphere—and carbon dioxide reduction in the atmosphere needs to be an international priority, the authors say.

The subhead to their article said that if the planet expects to avoid environmental damage from acidification of the oceans, it will require “reductions in carbon dioxide emissions regardless of climate change.”

Forty percent of the carbon dioxide produced by humans over the past two centuries has ended up in the oceans. The result is that the oceans become more acid, as carbon dioxide combines with water to form carbonic acid. A more acid ocean is one in which many organisms will have a much more difficult time producing calcite and aragonite, the compounds that make up oyster shells and coral reefs.

The measurement of acidity is the pH scale. Lower means more acid, and higher means more alkaline.

“From experiments we know that small changes in the pH of seawater (0.2-0.3 units) can affect the ability of key marine organisms such as corals and some plankton to build their skeletons and shells. Large areas of the ocean are in danger of exceeding these levels of pH change by the mid 21st century, including reef habitats such as the Hawaiian Islands Coral Reef Reserve,” Zeebe said in an email.

That is a frightening prospect for Hawai'i, where many shorelines are protected by coral reefs and some are even made of old coral reef.

“If we continue with business as usual and don't cut carbon dioxide emissions, carbonate reefs will ultimately start to dissolve. This is basic chemistry,” he said.

There are lots of slings and arrows thrown at climate researchers for the accuracy and dependability of the computerized models they use to predict the impacts of changes in atmospheric chemistry, but the calculation for what happens to ocean chemistry is much simpler, he said.

“Future ocean chemistry projections are largely model-independent on a time scale of a few centuries, mainly because the chemistry of carbon dioxide in seawater is well known and changes in surface ocean carbonate chemistry closely track changes in atmospheric carbon dioxide,” he wrote.

That leaves the issue of how life forms react to the changes.

“The biology is a bit more tricky,” Zeebe wrote.

“Most lab and field experiments show that calcifying organisms struggle under high carbon dioxide conditions but it's very difficult to predict their long-term reaction, let alone responses of entire marine ecosystems.

“Reduced calcification will surely hurt shellfish such as oysters and mussels, with big effects on commercial aquaculture. Other organisms may flourish in the new conditions, but this may include undesirable 'weedy' species or disease organisms,” he wrote.

© 2008 Jan W. TenBruggencate