Jäger et al. 2003

Jäger HJ, Schmidt SW, Kammann C, Grünhage L, Müller C, Hanewald K. 2003. The University of Giessen free-air Carbon dioxide enrichment study: description of the experimental site and of a new enrichment system. Journal of Applied Botany – Angewandte Botanik 77: 117-127.

These authors describe the study site and technical details of the operation of a long-term experiment designed to study the impact of rising atmospheric Carbon dioxide concentrations, the GiFACE. In essence, this study system is unique and important, being the only such study currently ongoing in Europe, and is based on what appears to be the leading edge of relevant technology. At its heart, the system consists of a circular open-topped chamber into which CO2 is released under the control of a concentration monitor in the center. Release occurs at the upwind side of the ring, and consistently acheives the target enrichment of about 25% additional CO2 at 40cm above ground. Grassland canopy heights at this site and similar sites in Europe are almost never higher than 50cm.

Turbulence from the blowers disrupts microclimates in and near the rings during the ambient quiet at night, so the blowers are only run during daylight hours. Control plots without enrichment show the expected pattern of higher ambient CO2 concentrations at night, associated with nocturnal respiration and diurnal photosynthesis. These authors do not address the effects of this blower and enrichment schedule may have on a simulation of globally enriched atmospheric CO2.

This paper is the reference provided by Dr. Kammann to provide needed details for my application to the Canadian Food Inspection Agency to import soil samples from the GiFACE site to Canada.