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Physiological and Ecological Studies on an Arctic Vegetation: III. Observations on Carbon Assimilation, Carbohydrate Storage and Stomal Movement in Relation to the Growth of Plants on Jan Mayen Island

R. Scott Russell
Journal of Ecology
Vol. 28, No. 2 (Aug., 1940), pp. 289-309
DOI: 10.2307/2256231
Stable URL: http://www.jstor.org/stable/2256231
Page Count: 21
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Physiological and Ecological Studies on an Arctic Vegetation: III. Observations on Carbon Assimilation, Carbohydrate Storage and Stomal Movement in Relation to the Growth of Plants on Jan Mayen Island
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Abstract

1. Measurement of the assimilation rate were made and the level of sugars and starch determined, by analytical methods, in plant material collected on Jan Mayen Island. 2. The net assimilation rate of Oxyria digyna was found to be 0.30 gm. per sq. dm. per week towards the end of the growing season. 3. Considerable reserves of sugars and starch were present in the leaves and roots of Oxyria digyna and Polygonum viviparum as well as in the leaves of Ranunculus glacialis. Changes during the growing season and also the ratios between the various carbohydrate fractions were examined. 4. Significant diurnal changes in the starch and sugar levels were shown to take place in the leaves of Oxyria digyna during mid-August; the variation in the starch level being particularly marked. 5. Observations on the stomatal movements of Oxyria digyna and Taraxacum croceum showed that, although the stomata were continuously open, the aperture tended to be greater at the time of day when light intensity and temperature were highest. 6. The effect of the arctic environment on carbohydrate metabolism and growth is discussed. 7. It is concluded that, in the arctic, carbon assimilation proceeds at a rate sufficient to supply the requirements of growth and that the low growth rate of arctic plants is controlled by other factors; in this connexion the importance of exposure, temperature and nitrogen deficiency is emphasized.

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