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

Accurate measurements of atmospheric CO2 concentrations are performed routi nely in a variety of experimental settings including open fields and forest s, leaf gas-exchange chambers, phytotrons and specialized growth chambers. However, the accurate monitoring of large scale structurally and biological ly complex experimental systems, operating as materially closed systems, is not widely reported. Here we report the design elements, material specific ations and other details for high precision monitoring of CO2 in Biosphere 2, a large scale ecologically diverse experimental facility located in Orac le, AZ. The results are used to illustrate how carbon balance in a temporar ily isolated sub-system of the facility is used to assess carbon dynamics u nder different environmental conditions such as variable atmospheric CO2 le vels, temperature, light, and soil moisture. The analytical system describe d here should be applicable for any settings in which continuous, high accu racy measurements of CO2 in a complex system are needed for quantitative re search. (C) 1999 Elsevier Science B.V. All rights reserved.