Free Air Carbon Dioxide Enrichment (FACE)
A method and infrastructure used to experimentally enrich the atmosphere enveloping portions of a terrestrial ecosystem with controlled amounts of carbon dioxide (and in some cases, other gases), without using chambers or walls.
Glossary. M.S. Ashton et al. (eds.), Managing Forest Carbon in a Changing Climate,DOI 10.1007/978-94-007-2232-3, © Springer Science + Business Media B.V. 2012
Free-air carbon dioxide enrichment (FACE) provides an experimental technique for studying the effects of elevated p CO2 on vegetation and other ecosystem components in large unenclosed plots (>20 m diameter). FACE avoids many modifications to the microclimate imposed by chamber methods and therefore provides some of the most reliable estimates of plant response to elevated p CO2.
Advances in Ecological Research. Volume 28, 1999, Pages 1-56. https://doi.org/10.1016/S0065-2504(08)60028-8