DGE Beacon, December 2003
Seminar Reports Special News

Dec. 16, Raphael Kudela, Assist. Prof., Ocean Sciences Dept., UC Santa Cruz presented a seminar titled "Light-Nutrient Interactions in a Not So Steady Ocean. Applications and Implications of Non-Redfield, Non-Steady State Phytoplankton Dynamics." After giving us some background in ocean dynamics, Rafe explained some of his recent research measuring the physical, chemical and biological (mainly diatoms) content of water samples at particular sites off the northern California coast. He showed how and why individual samples vary from the steady-state parameters often assumed in some models.

Holiday Celebration

On Sunday, Dec. 14, the Field Lab got together to share gourmet dishes prepared by members at Chris Field's home. It was a fun evening with holiday spirit shared by all. Even hostess Nona made us all feel welcome inspite of recent surgery on a broken foot.

The landscaping workparty originally scheduled for December has been postponed to January 10, 2004 because the site is not yet ready.

Dec. 15, Axel Kleidon, from the Department of Geography, University of Maryland, College Park presented a seminar titled
"Gaia and Beyond: Are there general principles of atmosphere-biosphere interactions?" He emphasized the special effect of oxygen in relation to life on earth and discussed the greenhouse effect and carbon cycle. He is attempting to apply theories of Entropy to Biological Systems.

Field Lab Meetings

On December 3, Lisa Moore presented some results from her studies of root biomass in the Jasper Ridge plots. She has observed that when the roots received more water than normal, both their diameter and depth of growth decreased. Hypotheses and implications of these results in relation to climate change were discussed.

On November 5th, first-year grad student Kim Nicholas Cahill gave a talk entitled "Assessment of a Prairie Restoration in Southwestern Wisconsin as a Carbon Sink: Don't Hold Your Breath! She sum-marized findings from work recently completed for her MS from the University of Wisconsin-Madison. The study investigated the carbon budget and ecosystem ecology of two 16 year-old prairie restorations and an agricultural system in south-western Wisconsin. While both types of prairie restorations (C3- and C4-grass dominated) had significantly higher soil carbon stocks than the agricultural site, the plant species found were not those expected based on initial seeding history, complicating efforts to design management of grasslands for carbon sequestration. Furthermore, the use of flux-based measurements contained significant uncertainties in the terms used for (1) aboveground plant productivity; (2) below-ground productivity; and (3) the microbial fraction of soil surface CO2 loss. Flux measurements of this type
did not provide good agreement with estimates of carbon stocks over the term of the study, highlighting the need to further refine the methodology for quantifying carbon sequestration.

Thursday, Dec. 11, Bess Ward, Professor of Geosciences, Princeton University, presented a talk titled "What Controls N Loss from Aquatic Systems? Diversity and Function in the Nitrogen Cycle." She described a glacial lake in Antarctica where the surface layer is permanently frozen, thus preventing mixing of the waters beneath. There is, however, a microbial nitrogen cycle. Her on-going studies are illucidating the genetics and physiology of these Marinobacter species.

On December 3, Ruth DeFries from the Dept. of Geography & ESSIC, Univ. Maryland, College Park, spoke on Land Use Change & Ecosystem Function. She has been correlating historical data on land use with remote sensing data in various local regions of the Amazon, East Africa, and India. The most common changes are from forest to pasture to crops. Each of these changes involve trade-offs between economic benefits, food production, water resources, biodiversity, etc. which she clearly illustrated with "spiderweb" diagrams. She also discussed broader ecosystem consequences with regard to Biodiversity and Climate Feedbacks (local vs global effects).

Editor Jan Brown