BERAC subcommittee review of F ree A ir C O 2 E nrichment (FACE) & O pen T op C hamber (OTC) elevated CO 2 pro

1. BERAC subcommittee review of Free Air CO2Enrichment (FACE) & Open Top Chamber (OTC) elevated CO2 projects in the DOE Program October 8-9, 2006 Richard Birdsey, USFS Reinhart Ceulemans, Antwerp, Belgium James Ehleringer, Univ Utah, Chair Jerry Melillo, Marine Biology Lab Josef Nösberger, ETH, Switzerland Walter Oechel, San Diego State Univ Susan Trumbore, UC Irvine

2. What is an open top chamber (OTC) experiment? • smaller size • altered microclimate • requires less CO2

3. What is a free air CO2-enrichment experiment (FACE)? • larger size • realistic microclimate • uses much more CO2

4. Rhinelander, deciduous forest Duke, coniferous forest Oak Ridge, deciduous forest Nevada, desert shrub

5. Where are the DOE-sponsored OTC experiments? SI, salt marsh, MD SI, scrub oak, FL

6. There are additional FACE and OTC experiments nationally that receive partial support from DOE, but that were not part of this review. DOE funds can be broadly divided into several categories: • Infrastructure support • Carbon dioxide gas • Site management • Research

7. The distribution of FACE sites globally (> 8 m ring) http://www.bnl.gov/face/Research_Sites.asp

8. BERAC Subcommittee Review of DOE-Funded FACE and Related Experiments Context for review: • DOE is funding trace gas enrichment experiments in two separate programs (Terrestrial Carbon Processes Program and Ecosystem Functioning and Response Program) • Recent BERAC review of DOE’s Terrestrial Carbon Processes Program did not review FACE experiments but raised questions about them: How long should current sites/experiments remain operational? Where might new sites/experiments best be established? • Recommended that: 1) review be undertaken to assess existing scientific information and potential for new findings at each DOE FACE experiment 2) DOE periodically evaluate when a site has reached a point of diminishing scientific return • Use review procedure to produce recommendations concerning which current DOE FACE sites/experiments should be either maintained or phased out, and where new ones should or might be established.

9. BERAC Subcommittee Review of DOE-Funded FACE and Related Experiments Specifics of Charge: Focused review on the charges in the letter • Review/assess information from existing DOE experiments (What has been learned?) • Assess their potential to yield new findings, if continued • Provide recommendations on whether existing experiments have reached or are reaching point of diminishing scientific return • Provide recommendations on which experiments should be maintained or discontinued, and where new ones might be established to address programmatic goals requiring such experiments

10. BERAC Subcommittee Review of DOE-Funded FACE and Related Experiments Specifics of charge (cont.): Assess • Escalating costs of FACE experiments and how such costs might be reduced • Scientific need and technical feasibility of modifying FACE experimental approaches to consider other greenhouse gases or climatic influences on carbon cycle processes, and functioning and response of terrestrial ecosystems • Alternative approaches for conducting FACE-type experiments that offer significant cost advantages

11. The review of FACE/OTC projects in DOE is based on presentations and documents from DOE managers responses from DOE managers on specific questions related to the charge of the subcommittee responses from project PIs on specific questions related to the charge of the subcommittee (transmitted via DOE managers) open scientific literature previous BERAC reports

12. The subcommittee consisted of individuals with expertise in carbon cycle science and policy physiology to ecosystems scales agriculture, forestry, and ecology temperate, tropical, and arid lands soil carbon global change experimental to modeling FACE experience (operating and decommissioning) Richard Birdsey, USFS, PA Reinhart Ceulemans, Antwerp James Ehleringer, Univ Utah, Chair Jerry Melillo, Marine Biology Lab Josef Nösberger, ETH, Zurich Walter Oechel, San Diego State Susan Trumbore, UC Irvine

13. Findings The DOE has been the lead federal agency in ecosystem climate change experiments, pioneering the required technology necessary to predict how ecosystems will respond to future CO2 environments. The continued DOE role as the leader in this area is absolutely critical if we are to develop the knowledge base and models of how ecosystems will respond to future environments and to the release of anthropogenic CO2. FACE studies have achieved the most realistic elevated CO2 (eCO2) environment for ecosystem studies of all experimental approaches to date. FACE-scale studies of ecosystem processes have been quite productive by any metric, and have produced fundamental new insights into carbon dynamics that were not predictable from pot- and greenhouse-scale studies. In many cases, generalities about processes relevant to the ecosystem scale have emerged, allowing for progress in the development of models to predict carbon dynamics at multiple scales. Applications of the models are important to forming climate policy at national and global scales.

14. Examples from cross-site comparisons Elevated CO2 did not have a detectable effect on N mineralization, suggesting progressive N limitation on ecosystems. Net primary production enhanced across sites, with the effect greatest in high-productivity ecosystems

15. Findings (continued) “Surprises” from FACE studies have also emerged, such as the importance of belowground processes, their influence on the carbon cycle, and on turnover processes under elevated CO2. Fine root turnover (3-9 yr) is far slower than earlier predictions (1 yr), with clear implications for carbon sequestration. The stable isotope tracer associated with the eCO2 is used to follow carbon.

16. Findings (continued) Another “surprise” is the interactive importance other factors, such as moisture, trace gases, and nutrients in moderating, enhancing, or diminishing the effects of eCO2 on enhancing carbon fixation. Elevated O3 concentration (partly) counteracts benefits of elevated CO2 concentration. Standing biomass after 6 years (% differences relative to ambient plots) "CO2, ozone, and species" interactions were part of the design of the Rhinelander FACE, whereas other eCO2 experiments appear to have incorporated additional factors subsequently.

17. Findings (continued) Another “surprise” is the interactive importance other factors, such as moisture, trace gases, and nutrients in moderating, enhancing, or diminishing the the effects of eCO2 on enhancing carbon fixation. After 7 years of experimental treatment Soil Treatment respiration Elevated [CO2] +26% Elevated [O3] –8% Elevated [CO2] and [O3] +39% Soil respiration "CO2, ozone, and species" interactions were part of the design of the Rhinelander FACE, whereas other eCO2 experiments appear to have incorporated additional factors subsequently.

18. Findings (continued) Given the significance of microbial processes under elevated CO2, FACE studies would benefit from more significant interactions between DOE's Terrestrial Carbon Processes and Genomics: GTL Programs. The current FACE design and plot sizes impose constraints on the experimental sampling of aboveground and belowground materials, leading to a useful life expectancy of only 10-12 years per experiment. Harvesting plans of an eCO2 project were not described nor explicitly defined in any of the provided documents for FACE or OTC projects. Harvesting of eCO2 sites is a critical and productive phase of an eCO2 experiment life cycle; harvesting of the above- and below-ground components will yield some of the most useful samples for future research, analyses, and insights. Earlier recommendations from the last review regarding data sharing policies and data archiving protocols should be more fully implemented.

20. Recommendations During FY07 enter into the harvesting phase of an eCO2 experiment life cycle for several current projects. For the remaining, existing eCO2 projects, enter into the harvesting phase by FY10 at the latest. Immediately plan and initiate a workshop(s) to plan the next generation eCO2 experiments, incorporating multiple interacting factors and potentially different eCO2 designs and/or technologies [elaborated on later slide] We recommend that no new eCO2 projects be initiated until after workshop decisions on the future design of eCO2 experiments to address multiple interacting factors. It is clear now that single factor approaches are limited. We recommend that funding for any new or renewal research proposals at FACE/OTC projects be considered in the context of the schedule for harvesting a site. As soon as harvesting is determined, we recommend workshops at FACE/OTC projects to plan for the harvesting phase of the project. We recommend that funding be provided after "turning off the eCO2" to allow publishing of original research, within-site syntheses, and cross-site syntheses.

21. What are the factors contributing to a limited lifetime for any eCO2 project? • original project objective(s) completed • technical constraints in continuing the operations at a site (e.g. pipe height limits, reduced-height buffer effects) • site trampling, oversampling of soil and vegetation

22. A decision flowchart for guidance on when existing FACE/OTC projects should enter the harvesting phase of their life cycle

23. A decision flowchart for guidance on when existing FACE/OTC projects should enter the harvesting phase of their life cycle

24. Recommended guidance on when existing FACE/OTC projects should enter the harvesting phase of their life cycle

25. What is the potential to yield new insights if continued? • The potential for multi-factorial eCO2 studies to yield new insights into the capacity of ecosystems to take up and sequester C is extremely high. • Regarding the specific proposals under consideration, this is a decision for the DOE and its external review process and guided by the principles outlined here • the subcommittee did not have access to individual proposals • the subcommittee was not asked to review individual proposals • the subcommittee was addressing programmatic issues and not specific proposals

26. Elements in the harvesting of an eCO2 experiment • As soon as the harvesting decision is determined, we recommend workshops at FACE/OTC projects to plan for the “turning off the eCO2”. • Model simulations to identify data gaps, and short-term experiments should be components of the pre- and post-harvesting process. • Short-term experiments should be identified that are to be conducted in the transition period associated with “turning off the eCO2”. • The harvesting of aboveground and belowground materials for analyses should be planned, with a portion of the materials archived for future investigations by all interested investigators. • A plan should be developed for the long-term archiving and public access to experimental treatment data, process data results, and other parameters measured and models produced in the experiment. • Consideration should be given to setting aside of a portion of the experimental plot for future studies (whether supported by DOE or other funding sources).

27. Planning now for future critically needed eCO2 experiments multi-factorial

28. operational CO2 savings beyond diurnal control (design) • site location as a factor in CO2 cost savings • larger plots sizes • replication • soil carbon sequestration considerations • subplot treatments Although this project will be expensive by current standards, the answers are required by policy makers in order to know how ecosystems will respond to the continued release of anthropogenic CO2. Elaboration of recommendation 3 Convene a workshop(s) to plan for the next generation of eCO2 ecosystem experiments that will incorporate multiple-level [CO2] treatments and multiple "drivers" (temperature, nutrients, moisture, and bio-complexity). Following the workshop(s), we recommend a pilot study(ies) of alternatives to the current FACE (ring) approach that would allow for consideration of

29. Sufficiently detailed information was not supplied by each of the PIs in order for the subcommittee to determine the costs of the eCO2 experiments. Thus, the committee was not able to respond to that point of the charge at this point in time. However, from the information provided it is clear that CO2 is an ever increasing component of the budget. For future eCO2 experiments We note that significant budgetary savings could be achieved simply through the sighting of new eCO2 experiments near CO2 production facilities, thereby reducing or possibly eliminating transportation costs and perhaps also assisting that industry with its CO2-disposal needs.

30. Restatement of recommendations During FY07 enter into the harvesting phase of several eCO2 projects. For the remaining, existing eCO2 projects, enter into the harvesting phase by FY10 at the latest. Immediately plan and initiate a workshop(s) to plan the next generation eCO2 experiments. We recommend that no new eCO2 projects be initiated until after workshop decisions on the future design of eCO2 experiments to address multiple interacting factors. We recommend that funding for any new or renewal research proposals at FACE/OTC projects be considered in the context of the schedule for harvesting a site. As soon as harvesting is determined, we recommend workshops at FACE/OTC projects to plan for the harvesting phase of the project. We recommend that funding be provided after "turning off the eCO2" to allow publishing of original research, within-site syntheses, and cross-site syntheses.