High quality, continuous measurements of CO2 in Biosphere 2 to assess whole mesocosm carbon cycling

Accurate measurements of atmospheric CO2 concentrations are performed routinely in a variety of experimental settings including open fields and forests, leaf gas-exchange chambers, phytotrons and specialized growth chambers. However, the accurate monitoring of large scale structurally and biologically complex experimental systems, operating as materially closed systems, is not widely reported. Here we report the design elements, material specifications and other details for high precision monitoring of CO2 in Biosphere 2, a large scale ecologically diverse experimental facility located in Oracle, AZ. The results are used to illustrate how carbon balance in a temporarily isolated sub-system of the facility is used to assess carbon dynamics under different environmental conditions such as variable atmospheric CO2 levels, temperature, light, and soil moisture. The analytical system described here should be applicable for any settings in which continuous, high accuracy measurements of CO2 in a complex system are needed for quantitative research. (C) 1999 Elsevier Science B.V. All rights reserved.