DGE Beacon, November 2003
Seminar Reports Special News
Ken Caldeira gave what he described as his "job interview talk" in the Carnegie Seminar Room on Nov. 24. He is currently a member of the Climate & Carbon Cycle Modeling Group, Energy & Environment Directorate, Lawrence Livermore National Laboratory. Although the title of his talk was Calcareous Plankton & Global Climate, he covered a wide range of subjects and model systems in which he has been involved. We are now emitting sixty times the natural amount of CO2 from volcanos and making a very large impact on marine ecosystems. Ken draws on his background in Physics and Atmospheric Science for his modeling studies.

Our own Jeff Dukes has made a coast-to-coast splash in the news media with his recent study, “Burning Buried Sunshine: Human Consumption of Ancient Solar Energy,” about to be published in the November issue of Climatic Change. He made some impressive estimates of how much buried plant material it takes to produce one gallon of gasoline — 196,000 pounds. This ratio can be expressed in several ways. For example, it would take 40 acres worth of wheat — stalks, roots and all— into the tank of your car every 20 miles; more than 1000 tons of ancient plant matter to fill the average gas tank; all the green plants grown in 400 years wouldn’t quite produce the fossil fuels we burn in one year; and the amount of plants that went into the fossil fuels we burned since the Industrial Revolution began (in 1751) is equal to all the plants grown on Earth over 13,300 years. Jeff also addressed the question of using more plant biomass to provide energy. He found that we would need to harvest 22% of all land plants just to equal the fossil fuel energy used in 1997 (the year used in the study). “Biomass burning can be part of the solution if we use agricultural wastes, but other technologies have to be a major part of the solution as well — things like wind and solar power.” Dukes began this study while a postdoc in the University of Utah lab of Jim Ehleringer, himself a former Carnegie Fellow in Plant Biology. In January, he’ll leave us for a position at the University of Massachusetts, Boston.

On November 20, Brian Popp from the School of Earth Science & Technology at the Univ. of Hawaii talked about Alkenone Biogeochemistry. His thesis was about using ratios of alkenones in sea floor, core samples to determine the sea surface temperature (SST) and pCO2 through geologic time scales. It has been found that the major source of these alkenones is from certain common diatoms, in particular, the Coccolithophore, Emilia huxleyi. And, furthermore, the ratios of certain alkenones are a function of the growth temperature of the algae. However, studies have also revealed that E. huxleyi may grow at different elevations in the water column depending on light intensity and nutrient availability. Therefore, the alkenone concentration does not necessarily indicate SST.

The Seminar on November 19 was given by Michael Goulden from Earth System Science, Univ. Calif., Irvine. Michael was Chris Field's first graduate student at Carnegie after which he broadened his experience at Harvard before joining UCI in September 1997.  He is collaborating on ecological research at sites in Canada (boreal forest), Brazil (tropical rain forest), and a part of the campus wetland at Irvine. His research shows that in addition to biogeochemical and physical factors, the physiology of the plants themselves play a role in land-atmosphere gas exchange and should be accounted for in model systems.

The Seminar on October 22 was given by Ralph Keeling of the Scripps Institution of Oceanography, Univ. Calif., San Diego. His topic was the Perspectives on the Fate of Anthropogenic
CO2 and the Changing Biogeochemistry of the Oceans.
Field Lab Meetings
The Nov. 19 Lab. Meeting featured first-year, Grad. Student, Claire Lunch. Her talk was labeled "Eddy covariance in arid ecosystems: Is it possible, and what can we learn from it?" She described the on-going study at the Univ. of Utah, of which she has been a part, having to do with CO2 uptake in arid sites. The importance of precipitation was emphasized, but also the very large, negative effect of cattle grazing.

Stanford Prof. Peter Vitousek initiated the fall DGE Seminar Series to an overflow audience in Carnegie’s Seminar room on Wednesday, October 1. Peter’s lecture was titled “Sources of Elements over 4 Million Years of Soil and Ecosystem Development.” He described his on-going studies in the Hawaiian Islands which offer unique ecosystems, in part, because of their volcanic origins over millions of years from lava flumes in the ocean floor. One startling finding (for me at least) was that dust blown in from the Gobi Desert has been a primary source of phosphorus for the growth of native vegetation.
On Nov. 12, Jeff Dukes presented two papers:
l. Nitrogen and Climate Change soon to be published in Science. The paper shows that some models which suggest that land ecosystems can sequester carbon fast enough to affect policy options for curbing anthropogenic CO2 emissions, fail to recognize that nitrogen will be limiting CO2 uptake.
2. Effect of climate change on the success of invasive plants. When invasive, annual grasses die, they are tinder (fuel) for large fires. Native species lose their adaptive advantage when climate change is relatively rapid. When the climate changes, plants race to the best habitat, and invasive species have the advantage. Also there may be a disruption of the plant-pollinator relationship. As a practical experiment, Star Thistle is being introduced to some of the plots at Jasper Ridge.
Editor Jan Brown
e-mail: jbrown@globalecology.stanford.edu