An  Arctic LTER greenhouse in peak autumn. Credit: Sadie Iverson

Arctic LTER greenhouses in peak autumn. Credit: Sadie Iverson

In 1989, MBL Senior Scientist Gaius Shaver and his colleagues set up a series of small experimental greenhouses on a hillside above the Toolik Field Station at the National Science Foundation Arctic Long Term Ecological Research site in northern Alaska. The clear plastic-covered greenhouses increase ambient soil temperatures by up to 2°C and are used by Shaver and other scientists to observe the effects of sustained warming on the Arctic environment. Today, the test plots are the longest-running climate warming study in the tundra.

New research from Seeta Sistla, a doctoral student at the University of California, Santa Barbara and a graduate of the Brown-MBL Partnership and Graduate Program in Biological and Environmental Sciences, her adviser, Josh Schimel, Shaver, and their colleagues reports the results the long-term warming experiment at the site.

The study reveals that decades of slow and steady warming have not changed the amounts of carbon in the soil, despite changes in vegetation and even the soil food web. Whether or not this phenomenon—no net loss of soil carbon despite long-term warming—is a transient phase that will eventually give way to increased decomposition activity and more carbon release, remains to be seen.

 “This work demonstrates why long-term ecological research, and especially long-term whole-ecosystem experiments, are a good thing,” says Shaver. “The experiment on which this paper is based was set up in 1989, when Seeta Sistla was about 6 years old.  There is no way she could have produced such a nice thesis if we had not set up these experiments so many years ago, not always knowing exactly how they would be used.”

The paper appeared in the May 15, 2013 Advance Online Publication of the journal Nature.

Other researchers participating in this study include John C. Moore and Rodney T. Simpson from Colorado State University, Fort Collins and Laura Gough from the University of Texas at Arlington.

Funding came from the National Science Foundation Long Term Ecological Research (LTER) Program, DOE Global Change Education Program Graduate Fellowship, a Leal Anne Kerry Mertes scholarship, and Explorer’s Club.




The U.S. Global Change Research Program (USGCRP) last week delivered its annual report to Congress for fiscal year 2013: Our Changing Planet.

The report highlights recent activities by 13 federal agencies to strengthen our scientific understanding of global changes including climate change, the threats and opportunities they present, and how they are likely to evolve over time.

In addition, Our Changing Planet showcases tangible results of work carried out by USGCRP agencies, including, for example, some of the most detailed, data rich maps of Alaskan permafrost ever generated; the most precise map ever produced of carbon stored in Earth’s tropical forests; critical information about the number and magnitude of extreme weather events in the United States; and updated maps that help gardeners and growers plan for harvesting seasons.

This report anticipates the USGCRP’s comprehensive Third National Climate Assessement, which will be released in early 2014. MBL Distinguished Scientist Jerry Mellilo chairs the advisory group that is preparing the National Climate Assessment, which presents the latest science about the current and projected effects of climate change across the United States.


The National Oceanic and Atmospheric Administration is announcing preliminary information that the U.S. experienced 11 disasters each costing over a billion dollars in losses in 2012. Of these 11 events, seven were severe weather or tornado events, and two were related to hurricanes/post tropical cyclones. The remaining two were the year-long drought and associated wildfires.

From Kathiann M. Kowalski

The Environmental Fellows in the MBL’s Logan Science Journalism Program have returned to Woods Hole after two full and exhausting days of field work at the Harvard Forest. Besides being an incredible living laboratory for lots of ecological research, Harvard Forest is a place of great beauty. The view of the hemlock forest canopy was especially breathtaking.

Hemlocks in Harvard Forest. Photo by KM Kowalski

Sadly, Harvard Forest Director David Foster reports, most of the hemlocks there may be dead in as little as ten years. Hemlock wooly adelgid infestation will drastically change the face of the forest.

Closer to ground, our group took carbon dioxide readings from plots at the MBL’s heated soil experiment area. That experiment examines questions related to climate change.

We also took core samples from Black Gum Swamp. We want to see what organic material the sediments contain as we go deeper and further back in time.

Core sampling at Black Gum Swamp, Harvard Forest. Photo by KM Kowalski

Now we’re working with the core samples and data from our field work. We’ve heard the saying that even a bad day in the field beats a good day in the office, and I do miss the beauty and serenity of the majestic hemlocks and the rest of the trees.

On the other hand, it’s also fun trying to sift through the data so we can see what it tells us. And we’re looking forward to preparing our presentations for the end of the week. Now we just need Excel, PowerPoint, and the rest of our computer programs to cooperate.

The Environmental Fellows in the MBL’s Logan Science Journalism Program spent the weekend gathering data at Harvard Forest in Petersham, Mass. Here’s how one day went down:

By Kathiann M. Kowalski

Our first full day of field work was both exhausting and fascinating. During the morning, we sampled meter-square plots to determine how moose and deer grazing affect trees in Harvard Forest. Highstead ecologist Ed Faison explained his research in this area. Then we counted species, took measurements, and noted any signs of grazing. In other words, “Eaten, or not eaten?”

As with any good science experiment, we had a control area. Within the control area, deer and moose are free to wander at will. Although none came near us, we saw evidence of lots of grazing. At least one moose also left some scat for us to observe.

We then took measurements in two experimental areas. One was fenced in to keep moose and deer out entirely. The other had an opening two feet up from the ground. Deer could scoot under, but moose were out of luck. The complete exclosure showed almost no signs of grazing. The partial exclosure had some evidence of grazing, but still less than the control area. We’ll wait for data analysis back at the lab to see if more specific conclusions can be drawn.

After lunch back at Shaner Hall, we headed out into the field again—this time to observe and examine evidence of the hemlock wooly adelgid and its impacts on the forest. Forest ecologist David Orwig described his research and the spread of this Asian pest across the Eastern seaboard. Then we counted wooly adelgid egg sacks on the undersides of marked leaves. The highest count I got on one branch was 317; yet another branch on the same tree had only 3.

Again, we measured the types, height, and diameters of trees in one-meter plots for a control area. Afterward, we took similar measurements in an experimental area where researchers had run cuts along the trunks of Eastern hemlocks. The resulting “girdling” mimicked the effects of the wooly adelgid by causing the trees to starve. While there were far fewer Eastern hemlocks in the experimental area, there was a surprising amount of understory growth going on. One of our one-meter plots had a whopping ten trees in it!

In addition to the sampling and protocols, we learned some important things about doing science in the field. For one thing, there’s lots of preparation and staging. Once our transects were finally laid out, doing observations and taking measurements took way more time than any of us anticipated. You have to do the work carefully and methodically. Working with a buddy helps—not just to share work but also to remind each other to follow each step exactly. Like many other professions, doing a good job means taking the time to do it carefully and to do it right.

The hike in and out of the hemlock forest followed a beautiful trail, complete with babbling brook. It’s scary to think that a pest like the wooly adelgid could kill those majestic trees and transform the area.

Scampering around the hills without trails was more challenging, especially when carrying tape measures, meter sticks, meter frames, and other paraphernalia. I did fall on my butt twice—fortunately suffering just a bruise. And the bugs were indeed biting—despite multiple applications of spray, long clothing, and so forth. Chris Neill and Rich McHorney say we’re just not used to the exertion. In any case, none of us felt the least bit guilty about the delicious blueberry pie at dinner.

All in all, though, it was a good day. I know I’ll sleep well tonight!

The much-anticipated National Ecological Observatory Network (NEON), which will collect data across the United States on the impacts of climate change, land use change, and invasive species on natural resources and biodiversity, is becoming a reality. The National Science Foundation is funding the $434 million construction of NEON, starting with $18 million in FY 2011. NEON plans to build 62 sites across the U.S., including two in locations familiar to MBL Ecosystems Center scientists: at Toolik Field Station in Arctic Alaska and at Harvard Forest in Massachusetts.

“There will be lots of opportunities for collaboration and interaction with NEON,” says MBL Senior Scientist Gaius Shaver, who directs the NSF’s Long-Term Ecological Research project at Toolik Field Station. MBL Distinguished Scientist Jerry Mellilo, who performs research at Harvard Forest, just rotated off the board of NEON.

For more information:

Toolik Field Station on the North Slope of Alaska. Toolik is one of the new NEON (National Ecological Observatory Network) sites. Credit: Courtesy of Jim Laundre, MBL

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