Free Air Carbon Dioxide Enrichment
Free Air Carbon Dioxide Enrichment, or FACE for short, is a technical test arrangement that makes it possible to simulate higher concentrations of carbon dioxide in the earth's atmosphere in the field and to investigate their influence on plants and ecosystems . By 2006 there were 32 FACE facilities worldwide, divided equally between natural and artificial ecosystems.
technology
Most FACE systems are based on a technology developed at Brookhaven National Laboratory (BNL): vertical tubes with nozzles, from which carbon dioxide can be emitted, are attached to the sample areas in a ring-shaped arrangement. These devices are small plastic pipes up to tall towers, as they are always a lot higher than the vegetation. They take up little space so that the microclimate (wind, solar radiation, evaporation) is not influenced. Depending on the direction and strength of the wind, carbon dioxide is blown out of the tubes. This results in a predefined carbon dioxide concentration within the test area. This can be a fixed amount above the normal concentration (usually + 200 ppm), but it is usually a fixed value that, depending on the experiment, lies between 475 and 660 ppm. These are values that prevailed at the end of the Carboniferous Age around 300 million years ago and, according to some calculations, are also expected for the end of the 21st century. The test areas have a diameter of 1 to 30 meters, but mostly over 10 m. In some systems, the ozone concentration is increased as an additional component .
The advantage of the FACE systems compared to the older technology of the open top chambers (CO 2 in plastic containers) is that they do not change the microclimate, which is massively influenced by OTCs (higher temperature, less wind, generally less stress for the Plants).
Technical disadvantages of the FACE system are: the increase in the carbon dioxide concentration occurs suddenly, which may lead to distortions compared to the actual, slow changes in the earth's atmosphere; the carbon dioxide concentration fluctuates with high frequency (seconds to minutes); the test area is a maximum of 450 square meters, which corresponds to about 100 pine trees, but is too small for the influence of larger herbivores or predators; FACE also changes the microclimate slightly under very stable and windless conditions.
In addition to the BNL type, there are a few different forms, such as a ring above the vegetation cover from which the CO 2 escapes, or a network of narrow tubes that run within the tree canopy (Web-FACE).
Results
The first FACE started in 1992 in Maricopa , Arizona, where cotton, wheat and sorghum were grown for 10 years . Other food crops that were examined in different FACE are soy, maize, rice, potato. In Switzerland, in a facility of the ETH Zurich , economic grasslands ( Lolium perenne and Trifolium repens ) were fumigated for 10 years , in the later FACE in New Zealand the grasslands were grazed with sheep.
In the mid-1990s, FACE systems were also built for forest plantations, for example for poplars (Italy) or the American sweetgum tree . The state of Hesse funded a project by the Geisenheim Research Institute , now the Geisenheim University , for special crops with one-off start-up funding of one million euros for the years 2009 to 2011.
A meta-analysis over 15 years showed an increase in production of 5–7% for rice and 8% for wheat . In Australia - depending on the plant - an increase in biomass of 20% to 49% was observed, although many other factors also play a role.
supporting documents
- George R. Hendrey, Francesco Miglietta: FACE Technology: Past, Present, and Future . In: J. Nösberger, SP Long, RJ Norby, M. Stitt, GR Hendrey, H. Blum (Eds.): Managed Ecosystems and CO 2 . Case Studies, Processes, and Perspectives . Ecological Studies, Volume 187. Springer-Verlag, Berlin, Heidelberg 2006, pp. 15–43. ISBN 3-540-31236-6
Web links
- Oak Ridge National Laboratory FACE page
- http://geb.uni-giessen.de/geb/volltexte/2003/1125/ Dissertation by Siegfried. W. Schmidt
- http://www.plumex.de
Individual evidence
- ↑ ( Page no longer available , search in web archives: Wiesbadener Kurier from July 30, 2009: Geisenheim research institute sets the course for an ambitious project )
- ↑ Elizabeth Ainsworth, Stephen Long: What Have We Learned from 15 Years of Free-Air CO2 Enrichment (FACE)? In: New Phytologist, 165 (2): 351-371. February 2005, accessed October 27, 2017 .
- ↑ http://www.regional.org.au/au/asa/2008/concurrent/crop-growth/5866_norton.htm