Ecosystems


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One barometer of the weather is a plant’s seasonal cycles, such as the date when its leaves sprout in spring or drop off in fall. What these cyclic events, called plant phenology, might reveal about climate change is the focus of a long-term Brown-MBL study in a Martha’s Vineyard, Mass., forest.

An automated camera on a tower can record seasonal changes in overall leaf color, but photos might not always correspond to seasonal biochemical changes within leaves themselves. Credit: Marc Mayes/Brown University

An automated camera on a tower records seasonal changes in leaf color in a Martha’s Vineyard forest. Credit: Marc Mayes/Brown University

“Our overall goal is to understand the phenology of trees in a temperate, deciduous forest, and how it responds to climate change,” says MBL Ecosystems Center scientist Jianwu (Jim) Tang.

Tang and his collaborators have placed digital cameras on meteorological towers in the Vineyard’s Manuel F. Correllus State Forest, at the Nature Conservancy Hoft Farm Preserve, and in a private forest, and have been continuously capturing images of the trees and leaves since 2000.

They discovered recently that forest “greenness,” as captured by the digital images, does not necessarily correspond to direct measures of peak chlorophyll content in the leaves, which is an indicator of photosynthesis. (Photosynthesis levels, in turn, indicate rates of carbon absorption by the leaves, which is important information for modeling the impacts of climate change.) Their results are published online in the Journal of Geophysical Research: Biogeosciences.

“While color of leaves is important information, we found it is not sufficient to derive the real phenology change,” says Tang. They needed to supplement the imaging data by collecting leaves on a weekly basis and measuring chlorophyll levels in the lab. “This is a warning for future study,” says Xi Yang, a graduate student in the Brown-MBL Partnership and Graduate Program and lead author on the new paper. Yi’s advisors are Tang and John F. Mustard, professor of geological sciences at Brown University.

For more information, please see this press release issued by Brown University.

Citation:

Yang X, Tang J, Mustard J (2014) Beyond leaf color: comparing camera-based phenological metrics with leaf biochemical, biophysical and spectral properties throughout the growing season of a temperate deciduous forest. J. Geophys. Res. DOI: 10.1002/2013JG002460

 

 

The first annual Northeast Climate Science Center (NE CSC) Fellows Retreat is being held this week at MBL’s Marshview Field Station near Plum Island, off the North Shore coast of Massachusetts.  Sixteen graduate and postdoctoral fellows from eight states are learning about climate challenges to coastal and salt marsh habitats and meeting with federal and state managers, including stakeholders from the nearby Parker River National Wildlife Refuge, the State of Massachusetts Coastal Zone Management office, and Division of Ecological Restoration.

NE CSC Consortium leaders, including Jimmy Nelson and Christopher Neill from the MBL Ecosystems Center,  are facilitating interactive exercises in which Fellows practice science communication and engaging stakeholders in the research design process. The MBL is a founding member of the NE CSC consortium.

Jimmy Nelson of the Ecosystems Center explains results from a Plum Island, Mass., marsh nutrient enrichment experiment to Northeast Climate Science Center fellows at a retreat at MBL's Marshview Farm field station. Credit: Chris Neill

Jimmy Nelson of the Ecosystems Center explains results from a Plum Island, Mass., marsh nutrient enrichment experiment to Northeast Climate Science Center fellows at a retreat at MBL’s Marshview Farm field station. Credit: Chris Neill

The NE CSC, established in 2012, is part of a network of eight regional CSCs created to provide scientific information, tools, and techniques that managers and other parties interested in land, water, wildlife and cultural resources can use to anticipate, monitor, and adapt to climate change.  It is hosted by the University of Massachusetts, Amherst and also works with a consortium of institutions: the College of Menominee Nation, Columbia University, Marine Biological Laboratory, University of Minnesota, University of Missouri, Columbia, and the University of Wisconsin, Madison. In addition to the host and consortium institutions, the NE CSC will also collaborate with other important partner institutions.

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.

billion-dollar-disaster-map-2012

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.

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