A global survey of carbon isotope discrimination in plants from high altitude |
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Authors: | Ch Körner G D Farquhar Z Roksandic |
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Institution: | (1) Institut für Botanik, Sternwartestraße 15, A-6020 Innsbruck, Austria;(2) Plant Environmental Biology, Research School of Biological Sciences, Australian National University, G.P.O. Box 475, 2601 Canberra, A.C.T., Australia;(3) Present address: Bureau of Mineral Resources, Geology and Geophysics, Department of Resources and Energy, G. P.O. Box 378, 2601 Canberra, A.C.T., Australia |
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Abstract: | Summary Carbon 13/12 isotope ratios have been determined from leaves of a hundred C3 plant species (or ecotypes) from all major mountain ranges of the globe, avoiding drought stressed areas. A general increase in 13C content was found with increasing altitude, i.e. overall discrimination against the heavy isotope is reduced at high elevation. The steepest decline of discrimination is observed in taxa typically ranging to highest elevations (e.g. the genus Ranunculus). Mean 13C for all samples collected between 2500 and 5600 m altitude is-26.15 compared to the lowland average of-28.80 (P<0.001). Forbs from highest elevations reach-24. According to theory of 13C discrimination this indicates decreasing relative limitation of carbon uptake by carboxylation. In other words, we estimate that the ratio of internal to external partial pressure of CO2 (p
i
/p
a
)in leaves of high elevation plants is lower than in leaves of low altitude. These results confirm recent gas exchange analyses in high and low elevation plants. |
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Keywords: | Photosynthesis 13C" target="_blank">gif" alt="delta" align="BASELINE" BORDER="0"> 13C Alpine ecology Atmospheric CO2 |
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