We are in the process of developing a state-of-the art free-air carbon dioxide enrichment(FACE) facility in northern Wisconsin to examine the interacting effects of elevated CO2 and O3 on a Populus tremuloides forest ecosystem. The FACE system will allow study of community level forest responses to elevated CO2 and O3 under natural, nonchambered conditions. We have assembled a multidisciplinary team of scientists to examine responses from the molecular to the ecosystem levels. Our long-term goal is to examine the interacting effects of elevated CO2 and O3, alone and in combination, on the productivity, competitive interactions, and carbon and nitrogen fluxes in a regenerating aspen ecosystem. Three replicate FACE rings will be established in each of four treatments (CO2, O3, CO2 + O3 control) in a randomized complete block design. Rooted cuttings from nine P. tremuloides clones previously characterized for their O3 and/or CO2 sensitivities will be planted at 0.5 m x 0.5 m spacing across each FACE ring. The close spacing will simulate a naturally regenerating aspen forest. Fumigation with elevated CO2 (550 ppm) and O3 (50 ppb above background during photosynthetically active daylight hours to a target of 80 ppm-hr seasonal exposure) will be conducted over the approximately 100-day growing season. Growth measurements (height, diameter, biomass, leaf area, root production and root mortality), physiological measurements (photosynthesis, respiration, stomatal conductance, chlorophyll content), plant nutrient status (nitrogen), foliar biochemistry (carbohydrates, phenolic glycosides, and antioxidants), litter decomposition rates, and soil respiration will be made throughout each growing season. The establishment and operation of this FACE system is an expensive, capital-intensive research project. Therefore, we will encourage multiple use of the research site by researchers and their students. We currently have some 14 in vestigators and their graduate students involved. Thus far, we have three years' support from the U.S. Department of Energy, the U.S. Forest Service Northern Station's Global Change Program, the National Council for Air and Stream Improvement of the Pulp and Paper Industry, and Michigan Technological University. In addition, we have significant in-kind contributions by the U.S. Forest Service and Brookhaven National Laboratory. However, we are still short of capital for critical air and meteorological monitoring equipment, the related data acquisition systems, and ozone generation. This proposal seeks support for high resolution, rapid-response instrumentation for the ozone, CO2, and meteorological monitoring, and for the ozone generation needed for the facility. We seek $251,671 from the National Science Foundation Academic Research Infrastructure (ARI) Program; we have matching contributions of $59,955 from the National Council for Air and Stream Improvement of the Pulp and Paper Industry (NCASI) and $44,896 from the host institution, Michigan Technological University.
