In some ways, understanding the effects of global warming comes down to measuring how microbes respond to warming soils. Through their incessant work in breaking down plant and animal matter, microorganisms drive the respiration of gases such as carbon dioxide from the planet’s thin “skin” of soil cover. These emissions account for more than 10 times the carbon dioxide produced by human activity.

It’s well known that as temperature increases, the rate of chemical reactions typically increases along with it. The same is true of the biochemical reactions carried out by microbes, which metabolize organic compounds in the soil and respire carbon dioxide as waste. Hence, higher temperature means more respiration, which means more carbon returned to the atmosphere.

Another, less-understood factor controlling the flow of carbon dioxide from the soil is the efficiency with which microbes use carbon — that is, the ratio of carbon incorporated into their cell structure and the amount respired as waste. Slight changes in microbial efficiency, brought on by changing soil temperatures, could potentially have a significant effect on the total release of soil carbon dioxide.

With this in mind, University of New Hampshire microbial ecologist Serita Frey and colleagues set out to measure the efficiency of microbial communities in soils in response to both short and long-term warming conditions. The study, published in the Jan. 20 edition of Nature Climate Change, contained two main findings.

The first finding was that for more complex, hard-to-break-down carbon compounds, microbial efficiency goes down as temperature increases, meaning that more carbon dioxide is respired as waste. This wasn’t unexpected. Theoretical predictions show that higher operating temperatures in the molecular machinery needed for metabolism reduce overall efficiency in microbes.

But the second result showed that in soils artificially warmed for 18 years, the drop in efficiency from further temperature increases was much lower than in controls. In other words, microbial communities shifted in response to long-term warming, becoming more efficient in their use of carbon. Since current climate models don’t account for this particular efficiency parameter, the study results could mitigate the long-term predicted increases of soil carbon dioxide emissions.

“It all depends on what timescale you’re looking at,” said co-author Johan Six, a professor in the UC Davis Department of Plant Sciences at the time of the study. “We’re finding more and more that there’s quite a bit of difference between what happens in the short-term versus the long-term. It might well be that many systems are a lot more resilient than we think at this point.”

To measure microbial efficiency, the researchers added four easy-to-track synthetic compounds to artificially warmed soils. The compounds roughly approximate the range of complexity found in natural soils, ranging from glucose, a simple sugar, to phenol, a component of the lignin found in wood. Each compound was “tagged” with a heavy isotope of carbon so that researchers could track how much of each compound was incorporated into microbial biomass, and how much was respired as carbon dioxide.

Using this method, the team showed that microbial efficiency is inversely related to temperature in some compounds but not others. Since glucose can be directly assimilated by most soil microbes, its utilization showed no sensitivity to changes in temperature. But phenol, which must be broken down by microbial enzymes into less complex molecules before it can be used, showed a 60 percent drop in efficiency as temperature was increased from five to 25 degrees Celsius.

“I think their key message about incorporating some critical elements of microbial physiology into soil organic models is spot on,” said Josh Schimel, a microbial ecologist at UC Santa Barbara. “Soil microbial communities are enormously complex. So the question is, how do we capture some of the dynamics of those communities that are really important in regulating global carbon cycling?”

In order to study how those dynamics might play out over the longer term — what Six called “the legacy effect” of warming on bacterial communities — the researchers conducted the same measurements on soils taken from plots warmed by underground coils at a research site in Harvard Forest.

For soils that had been continuously warmed five degrees Celsius above ambient temperatures for 18 years, further heating in the range of 10 to 25 degrees showed a much smaller decrease in microbial efficiency compared with the control soils which had not been previously warmed.

One of the remaining challenges is resolving the exact causes underlying this change in microbial efficiency. The study’s authors aren’t certain whether the change is due to physiological adaptations by existing microbes or a wholesale change in the species composition of the microbial community.

“You might imagine that you get a change in organisms living in the soil, maybe different species or maybe changing physiology in some way to deal with the change in resource availability,” Frey said.

OYANG TENG can be reached at science@theaggie.org.

Let’s all be honest with ourselves. Drinking is a reality of college and a lot of times, college students do not always make the best decisions. Driving after a long night of partying or hanging out at the bars may seem like a good idea, especially if you think you’ve sobered up in the early hours of the morning, but nothing beats a second opinion. Enter the pocket breathalyzer.

What is a pocket breathalyzer?
Pocket breathalyzers are portable devices that measure your blood alcohol content (BAC) level. They let you know how much you’ve had or if you’ve simply had too much.

How much does it cost?
The cheapest kind attach to key chains and are about $8. The kind that you can install in your car cost quite a bit more. Those range from a few hundred dollars to over $1,000, but add the benefit of preventing your car from starting if your BAC is over the legal limit.

How does it work?
Portable breathalyzers work just like police breathalyzers. You blow on the mouthpiece and wait for the results. Usually a light will indicate whether you are under the legal limit or not. Some have red, yellow and green lights to let you know where you stand.

For college students who do not have a lot of money, the small cost of a pocket breathalyzer may be well worth it to prevent the huge expense, pain and inconvenience of an accident, a DUI or, especially in Davis, a BUI.

NICOLE NOGA can be reached at science@theaggie.org.

Even if you don’t believe in evolution, you can’t deny that there are some truly amazing organisms that populate our planet. And if you don’t believe in evolution, I have some choice words for you … another time perhaps. When you ask someone to think of the most majestic creature on earth, perhaps they will say the lion, or the Bengal tiger, or maybe the orca.

If you ask this same person about the smartest organism on earth, maybe they will say the dolphin, an ant colony, or in rare cases, they might say humans. The pattern I have noticed is that when anyone is asked about the most amazing organisms on earth, no one ever thinks to mention the plants.

I can name three plants off the top of my head that are as beautiful as a tiger, as strong and resilient as an orca and as well adapted to their environments as humans. And one of these in particular, is my personal all time favorite … but I’ll save that surprise for later.

The saguaro cactus. It inhabits one of the harshest regions on earth, the Sonoran Desert in Arizona. Nighttime temperatures can reach freezing, sometimes dropping below 32 degrees Fahrenheit. During the day, temperatures can reach 135 degrees … in the shade. Only about 100 animal species call this place home, yet the saguaro cactus thrives here, often growing to heights of 60 feet.

Harsh climates are often indicative of very small plant and animal species. Small size allows better temperature regulation and less water consumption, so it’s strange that a plant can reach such a size here. It has developed a slew of defenses to protect it from the weather and other interested parties. Sharp spines and a thick wax coating prevent water loss and prevent birds from poking holes that would dry the plant out.

Yet this plant also has to reproduce, and so once a year, it produces hundreds of small, highly sugary fruits to entice birds to eat them and carry the seeds far away, preventing competition between parent and offspring.

Some people think that cockroaches are the most resilient of all terrestrial life on earth. But drop that cockroach into a bucket of salt water and see how long it lasts. Even the most hearty of trees wither and die when exposed to salt water, but not so for the the red mangrove.

While most trees require fresh water to survive, the red mangrove makes its home on the sandy shores of tropical regions across the planet. This habitat results in the the mangrove roots being completely submerged in salt water every high tide. While this would kill any other terrestrial plant, pores on the roots, along with a specialized vascular system, transfer all of the salt within the plant to a few sacrificial leaves. These leaves then turn yellow, die and fall off, leaving the rest of the plant salt-free. This is comparable to a pack-a-day smoker growing special arteries that transport all the smoke harmlessly to a few strands of sacrificial hair. Scoreboard: hypothetical evolution, 1. Emphysema, 0.

And now for my personal favorite, the plant of nightmares (of flies), the Venus flytrap. The flytrap occupies one of the deadest environments on the planet — the salty, hot, humid, oxygen-deprived, nitrogen-deficient, stagnant bogs of the Everglades. There are only a few species of plant that have evolved to live here, and most of them are carnivorous.

The Venus flytrap is the casino of the plant world. It provides enough enticing reward to keep the flies coming back for more, but on a long enough timeline, the house always wins. The plant has developed such a precise and exact method of feeding that even after millions of years, its primary prey, the fly, has still not evolved to avoid the flytrap’s deadly allure.

Let’s take this casino metaphor a little further. Flytraps produce nectar inside their traps, which entices insects to come feed … the promise of a sugary payout is more than enough to bring insects through the door. Unfortunately for the insect, this is often a one-way trip. Should the fly escape with its life, it will be none the wiser that it has had a close brush with death. When the fly returns time and again, the odds begin stacking in the plants’ favor.

Enough flies escape that future generations are not wary of the plant’s scent, but the plant takes more than enough victims to sustain itself … much like a casino.

The flytrap, like the casino, is so successful not because it wins every time, but because it loses strategically and often enough that the flies keep playing the game. We humans like to believe that we animals make the rules, but the reality of the situation is that plants have been around far far longer than we have, and will still be here long after the strongest tiger, the biggest orca and the smartest dolphin are all gone.

HUDSON LOFCHIE dreams of having an army of flytraps at his disposal. Until then, he can be reached at science@theaggie.org.