BER Research Highlights

Search Date: December 13, 2017

7 Records match the search term(s):


December 08, 2008

Novel Relationship Between Nitrogen and Albedo (Solar Radiation Reflectance) in Forests

A positive correlation between the uptake of nitrogen and carbon by leaves has been recognized for some time. However, in a study published this week in the Proceedings of the National Academy of Sciences, scientists report that this relationship also holds for whole forest canopies and that both variables are strongly related to canopy albedo (the fraction of solar radiation that is reflected). This suggests that nitrogen levels in forests can influence Earth's climate in ways that have not previously been recognized. The article reports that forests with high levels of foliar nitrogen reflect more solar radiation and absorb more CO2 than forest with lower nitrogen levels. They also discovered that variation in forest canopy nitrogen can be accurately detected using satellites, making it possible to continuously track these global-scale effects of forests on the Earth's climate system. Significant data for these analyses was provided by DOE-funded AmeriFlux sites.

Reference:  S.V. Ollinger, A.D. Richardson, M.E. Martin, D.Y. Hollinger, S. Frolking, P. B. Reich, L.C. Plourde, G.G. Katul, J.W. Munger, R. Oren, M-L. Smith, K.T. Paw U, P. V. Bolstad, B.D. Cook, M.C. Day, T.A. Martin, R.K. Monson, and H.P. Schmid (2008) Canopy nitrogen, carbon assimilation, and albedo in temperate and boreal forests: Functional relations and potential climate feedbacks. ww.pnas.org/cgi/doi/10.1073/pnas.0810021105

Contact: Mike Kuperberg/Jeff Amthor/Roger Dahlman, SC-23.1, (301) 903-3281
Topic Areas:

Division: SC-23.1 Climate and Environmental Sciences Division, BER


September 15, 2008

New, Surprising Insights into Potential Effects of Ozone Pollution on Forest Growth

Fossil fuel use is causing an increase in the concentrations of both carbon dioxide and ozone in the atmosphere. The increasing carbon dioxide concentration is expected to stimulate tree growth, while available data indicate that increasing ozone can counteract the beneficial effects of increasing carbon dioxide on tree growth. Recently published measurements from the longest running field experiment exposing trees to elevated carbon dioxide and ozone, research sponsored by DOE, surprisingly indicate that the combination of elevated carbon dioxide and ozone stimulated root growth in some tree communities. The scientists conducting the research suggested that the death of ozone-sensitive trees followed by increased growth of ozone-tolerant trees made possible by access to space and soil nutrients that would have been used by ozone-sensitive trees might be the explanation for the increased root growth. But whatever the mechanism might be, these new results indicate a possible long term response to increasing concentrations of carbon dioxide and ozone that is not generally considered in assessments of potential effects of the changing composition of the atmosphere on forest tree growth.

Contact: Jeffrey S. Amthor, SC-23.1, (301) 903-2507
Topic Areas:

Division: SC-23.1 Climate and Environmental Sciences Division, BER


July 21, 2008

The Changing Atmosphere Could Drive Forests to Use More Water

Fossil fuel use is causing an increase in the atmospheric concentrations of both carbon dioxide and ozone. In principle, an increase in the concentration of either gas can reduce the amount of water used by plants in transpiration (evaporation of water from plants), but a group of SC-sponsored scientists recently discovered that this was not the case in a unique and large-scale field experiment. The scientists directly measured effects of elevated carbon dioxide and ozone concentrations on forest-tree transpiration in the SC Program for Ecosystem Research's ecosystem-scale elevated-carbon-dioxide and elevated-ozone field experiment in northern Wisconsin forest stands (the world's largest long-term study of ecological effects of changes in atmospheric composition). They found that increasing the concentration of the gases 40-50% above ambient concentrations caused an increase in transpiration of about 14%. The results indicate that, if other factors remain constant, increasing atmospheric concentrations of carbon dioxide and ozone might cause an increase in water use by temperate forests. These findings alter our basic understanding of interactions between atmospheric composition and water cycling in forests. The research was recently reported in the journal Tree Physiology.

Contact: Jeffrey S. Amthor, SC-23.1, (301) 903-2507
Topic Areas:

Division: SC-23.2 Biological Systems Science Division, BER
      (formerly SC-23.1 Life Sciences Division, OBER)


July 21, 2008

University of Tennessee Field Day Includes DOEs Program on Carbon Sequestration in Terrestrial Ecosystems (CSiTE)

The University of Tennessee is holding its 2008 Field Day on July 24, 2008, with 19 different tours being offered. Three of this years tours will include the production of switchgrass, bioenergy, and storage of carbon in soils of the switchgrass system. DOEs CSiTE program will participate at the Milan, Tennessee, site. CSiTE is a joint Laboratory Program that investigates properties and processes of terrestrial carbon sequestration. A part of their field research is carried out at the Milan Switchgrass site. The Field Day draws visitors from around the country, and over 3,000 visitors attended previous events. Chuck Garten and Robin Graham of ORNL will present results on CSiTE research, discussing how switchgrass production as a feedstock for biofuel can provide a double dividend, since it also increases soil carbon sequestration, reducing the rate of CO2 increase in the atmosphere.

Contact: Roger C. Dahlman, SC-23.1, (301) 903-4951
Topic Areas:

Division: SC-23.2 Biological Systems Science Division, BER
      (formerly SC-23.1 Life Sciences Division, OBER)


July 21, 2008

Will Changes in Atmospheric Composition Caused by Fossil Fuel use Affect Pulpwood Quality?

Fossil fuel use is causing an increase in the concentrations of both carbon dioxide and ozone in the atmosphere. Both gases can affect the physiology of trees, so they might affect the quality of wood grown for pulp, i.e., tree stems grown principally to make wood pulp used in paper production and for some other wood products such as oriented strand board. Trees grown as part of the SC Program for Ecosystem Research's large-scale elevated-carbon-dioxide and elevated-ozone ecosystem experiment in northern Wisconsin provide a unique opportunity to experimentally determine whether future increases in carbon dioxide and ozone concentration might affect pulpwood quality. Using those trees, a team of scientists from Europe and the United States determined that the quality of wood from aspen trees was unaffected by elevated carbon dioxide and ozone concentrations, but that increased carbon dioxide and ozone increased the fraction of undesirable "extractives" in paper birch trees. This result indicates the possibility that the byproducts of fossil-fuel use might have a modestly negative effect on the economically important pulpwood industry. The research was reported earlier this year in the international journal Tree Physiology.

Contact: Jeffrey S. Amthor, SC-23.1, (301) 903-2507
Topic Areas:

Division: SC-23.2 Biological Systems Science Division, BER
      (formerly SC-23.1 Life Sciences Division, OBER)


April 07, 2008

Dioxide Concentration May Not be All Good News for Crops

It has been widely recognized for decades that the marketable yield of most crops is increased when they are grown in an elevated CO2 concentration, but a recent field experiment found that attack on soybeans by western corn rootworm, and by Japanese beetle, was increased with elevated CO2. A BER-sponsored research project investigating the underlying cause of this increased insect attack in elevated CO2 recently reported (April 1, 2008, Proc. Nat. Acad. Sci.) that elevated CO2 reduced the effectiveness of normal biochemical systems that plants use to help defend themselves against insects. The researchers concluded that changes in the plant’s natural defense systems caused by the ongoing increase in atmospheric CO2 concentration (which is caused mainly by energy production from fossil fuels) has the potential to exacerbate pest problems in crops of the future.

Contact: Jeffrey S. Amthor, SC-23.3, (301) 903-2507
Topic Areas:

Division: SC-23.1 Climate and Environmental Sciences Division, BER
      (formerly SC-23.3 Climate Change Research Division, OBER)


April 07, 2008

Increased Cold Damage to Plants With Warmer Springs?

Plant ecologists have long been concerned that global warming (caused in large part by energy production from fossil fuels) may actually increase the risk of plant frost damage. The underlying hypothesis is that mild winters and warm, early springs, which are expected to occur as warming continues, may induce "premature" leaf growth in many ecosystems, resulting in exposure of young leaves to subsequent late-spring frosts. The 2007 spring freeze in the eastern United States provided an excellent opportunity to evaluate this hypothesis and assess its potential consequences. A group of BER-sponsored researchers at Oak Ridge National Laboratory (collaborating with NASA, NOAA, and university scientists) analyzed the course of events over a period of early spring leaf growth, caused by unusually warm conditions, followed by a dramatic (and unusual) regional-scale late-spring freeze. The freeze resulted in regional-scale leaf damage and death, with extensive defoliation at many locations, which was observed from the ground and in satellite data. The researchers concluded that the possibility of future increased fluctuations in spring temperatures pose a real threat to some plants in temperate climates. The results were published in the March issue of BioScience.

Contact: Jeffrey S. Amthor, SC-23.3, (301) 903-2507
Topic Areas:

Division: SC-23.1 Climate and Environmental Sciences Division, BER
      (formerly SC-23.3 Climate Change Research Division, OBER)