Open top chambers for exposing plant canopies to elevated CO2 concentration and for measuring net gas exchange
Open top chamber design and function are reviewed. All of the chambers described maintain CO2 concentrations measured at a central location within ±30 ppm of a desired target when averaged over the growing season, but the spatial and temporal range within any chamber may be closer to 100 ppm. Compared with unchambered companion plots, open top chambers modify the microenvironment in the following ways: temperatures are increased up to 3°C depending on the chamber design and location of the measurement; light intensity is typically diminished by as much as 20%; wind velocity is lower and constant; and relative humidity is higher. The chamber environment may significantly alter plant growth when compared with unchambered controls, but the chamber effect on growth has not been clearly attributed to a single or even a few environmental factors.
A method for modifying an open top chamber for tracking gas exchange between natural vegetation and the ambient air is described. This modification consists of the addition of a top with exit chimney to reduce dilution of chamber CO2 by external ambient air, is quickly made and permits estimation of the effects of elevated CO2 and water vapor exchange.
The relatively simple design and construction of open top chambers make them the most likely method to be used in the near future for long-term elevated CO2 exposure of small trees, crops and grassland ecosystems. Improvements in the basic geometry to improve control of temperature, reduce the variation of CO2 concentrations, and increase the turbulence and wind speed in the canopy boundary layer are desirable objectives. Similarly, modifications for measuring water vapor and carbon dioxide gas exchange will extend the usefulness of open top chambers to include non-destructive monitoring of the responses of ecosystems to rising atmospheric CO2.
KeywordsOpen top chamber Gas exchange Photosynthesis Elevated CO2
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- Arp, W. J. 1991. Vegetation of a North American salt marsh and elevated carbon dioxide. Doctoral Thesis. Vrije Universiteit Amsterdam, The Netherlands.Google Scholar
- Curtis, P. S., Drake, B. G., Leadley, P. W., Arp, W. J. & Whigham, D. F. 1989. Growth and senescence in plant communities exposed to elevated CO2 concentrations on an estuarine marsh. Oecologia 78: 20–26.Google Scholar
- Curtis, P. S., Balduman, L. M., Drake, B. G. & Whigham, D. F. 1990. Elevated atmospheric CO2 effects on below ground processes in C3 and C4 estuarine marsh communities. Ecology 71: 2001–2006.Google Scholar
- Davis, J. M., Riordan, A. J. & LawsonJr., R. E. 1983. Wind tunnel study of the flow field within and around open-top chambers used for air pollution studies. Bound. Layer Meteor. 25: 193–214.Google Scholar
- Drake, B. G. & Leadley, P. W. 1991. Canopy photosynthesis of C3 and C4 plant communities exposed to longterm elevated CO2 treatment. Plant Cell Environ. 14: 853–860.Google Scholar
- Drake, B. G., Leadley, P. W., Arp, W. J., Nassiry, D. & Curtis, P. S. 1989. An open top chamber for field studies of elevated atmospheric CO2 concentration on salt marsh vegetation. Funct. Ecol. 3: 363–371.Google Scholar
- Drake, B. G., Rogers, H. H., & AllenJr., L. H. 1985. Methods of exposing plants to elevated carbon dioxide. In: B. R., Strain and J. D., Cure (eds). Direct Effects of Increasing Carbon Dioxide on Vegetation, pp. 11–31. United States Department of Energy, Carbon Dioxide Research Division, DOE/ER-0238, Office of Energy Research, Washington, DC.Google Scholar
- Grulke, N. E., Reichers, G. H., Oechel, W. C., Hjelm, U. & Jaeger, C. 1990. Carbon balance in tussock tundra under ambient and elevated atmospheric CO2. Oecologia 83: 485–494.Google Scholar
- Ham, J. & Owensby, C. 1991. Simulating confounding CO2 and chamber effects in open to field chambers for CO2 enrichment studies. Agronomy abstracts. American Society of Agronomists, Madison, Wisconsin 53711 USA, p. 18.Google Scholar
- Hardy, R. W. F. & Havelka, V. D. 1975. Photosynthate as a major factor limiting N2 fixation by field grown legumes with emphasis on soybeans. In: P. S., Nutman (ed). International Biological Programme. 7. Symbiotic Nitrogen Fixation in Plants. Cambridge University Press, Cambridge, United Kingdom.Google Scholar
- Heagle, A. S., Body, D. E. & W. W., Heck. 1973. An open top field chamber to assess the impact of air pollution on plants. Environ. Qual. 2: 365–368.Google Scholar
- Heagle, A. S., Philbeck, R. B., Rogers, H. H. & Letchworth, M. B. 1979. Dispensing and monitoring ozone in open-top field chambers for plant-effects studies. Phytopath. 69: 15–20.Google Scholar
- Hileman, D. R., Ghosh, P. P., Bhattacharya, N. C., Biswas, P. K., Allen, Jr., L. H., Peresta, G., and Kimball, B.A. In press. A comparison of the uniformity of an elevated CO2 environment in three different types of open top chambers. In: G. R. Hendrey (ed). Free Air CO2 Enrichment for Plant Research in the Field. Springer Verlag.Google Scholar
- Jones, P. H., AllenJr., L. H., Jones, J. W., Boote, K. J. & Campbell, W. J. 1984. Soybean canopy growth, photosynthesis and transpiration responses to whole season carbon dioxide enrichment. Agron. J. 76: 633–637.Google Scholar
- Leuning, R. & Foster, L.J. 1990. Estimation of transpiration by single trees: Comparison of a ventilated chamber, leaf energy budgets and a combination equation. Agr. and For. Meteorol. 51: 63–68.Google Scholar
- Long, S. P. 1991. Modification of the response of photosynthetic productivity to rising temperature by atmospheric CO2 concentrations. Has its importance been underestimated?—Opinion Plant Cell Environ. 14: 729–739.Google Scholar
- Mooney, H. A., Drake, B. G., Luxmoore, R. J., Oechel, W. C. & Pitelka, L.F. 1991. Predicting ecosystem responses to elevated atmospheric CO2 concentrations. BioScience 41: 96–104.Google Scholar
- Oechel, W. C. & Strain, B. R. 1985. Native species responses to increased atmospheric carbon dioxide concentration. In: B. R., Strain and J. D., Cure (eds). Direct Effects of Increasing Carbon Dioxide on Vegetation. United States Department of Energy, Carbon Dioxide Research Division, DOE/ER-0238, Office of Energy Research, Washington, DC, pp. 117–154.Google Scholar
- Olszyk, D. M., Tibbitts, T. W. & Hertzberg, W. M. 1980. Environment in open top field chambers utilized for air pollution studies. Environ. Qual. 9: 610–615.Google Scholar
- Owensby, C. E., Coyne, P. I. & Auen, L. M. 1989. Responses of Vegetation to Carbon Dioxide. Part II: Large Chamber System. US Department of Energy Atmospheric and Climate Research Division.Google Scholar
- Rogers, H. H., Cure, J. D., Thomas, J. F. & Smith, J. M. 1984a. Influence of elevated CO2 on growth of soybean plants. Crop Sci. 24: 361–366.Google Scholar
- Rogers, H. H., Heck, W. W. & Heagle, A. S. 1983. A field technique for the study of plant responses to elevated carbon dioxide concentrations. Air Poll. Contr. Ass. 33: 42–44.Google Scholar
- Rogers, H. H., Sionit, N., Cure, J. D., Smith, J. M. & Bingham, G. E. 1984b. Influence of elevated carbon dioxide on water relations of soybeans. Plant Physiol. 74: 233–238.Google Scholar
- Sanders, G. E., Clark, A. G., & Colls, J. J. 1991. The influence of open top chambers on the growth and development of field bean. New Phytol. 117: 439–447.Google Scholar
- Unsworth, M. H., Heagle, A. S. & Heck, W. W. 1984. Gas exchange in open top field chambers. I. Measurement and analysis of atmospheric resistances. Atmosph. Environ. 18: 373–380.Google Scholar
- Weinstock, L., Kender, W. J. & Musselman, R. C. 1982. Microclimate within open-top air pollution chambers and its relation to grapevine physiology. Am. Soc. Hort. Sci. 107: 923–929.Google Scholar