Summary
The influence of leaf orientation on leaf temperature has been studied in an sclerophyll vegetation of the Amazon basin, which grows on white sandy soils of very low water retention capacity and variable depth of the water table.
Leaf size of the species studied is mainly mesophyllous (sensu Raunkiaer). The high degree of leaf inclination in all species is very characteristic; 55% of the leaves present inclination angles (relative to the vertical) smaller than 45°.
Water potential is generally high, not being lower than −14 bars. Leaf resistance increases toward noon during the course of sunny days, indicating either water stress at leaf level or the influence of low relative humidity on stomata opening.
Leaf temperature under sunny conditions reflects the influence of leaf orientation on the amount of radiation absorbed by the leaf. Temperature differences recorded range from 1.8–5.4° C. The difference depends on leaf angle, leaf color and leaf diffusion resistance during the period of measurement.
Analysis of the relationship between leaf angle and leaf temperature, using Gates leaf energy balance, shows that under the conditions prevailing at noon in sunny days, leaf angles smaller than 50° are effective in reducing leaf temperature within a wide range of leaf resistances to water vapor transfer.
Similar content being viewed by others
References
Beadle, N. C. W.: Soil phosphate and its role in molding segments of the Australian flora and vegetation with special reference with xeromorphology and sclerophylly. Ecology47, 991–1007 (1966)
Brünig, E., Herrera, R., Heuveldop, J., Jordan, C., Klinge, H., Medina, E.: The international Amazon Project coordinated by Centro de Ecologia, IVIC: Organization and recent advances. In: Transact. Internat. MAB-IUFRO Workshop (Brunig, E., Ed.). Spec. Report1, 104–120 (1977)
di Castri, F.: Climatographical comparisons between Chile and the western coast of North America. In: Mediterranean type of ecosystems (di Castri, F., Mooney, H., Eds.). Ecological Studies7, 21–36 (1973)
Dunn, E. L.: Environmental stresses and inherent limitations affecting CO2 exchange in evergreen sclerophylls in mediterranean climates. Ecological Studies12, 159–181 (1975) (ref. 6)
Gates, D. M., Alderfer, R., Taylor, S. E.: Leaf temperature of desert plants. Science151, 994–995 (1968)
Gates, D. M., Schmerl, R. B. (Eds.): Perspectives of biophysical ecology. Ecological Studies12 (1975)
Hall, A. E., Schulze, E.-D., Lange, O. L.: Current perspectives of steady-state stomatal responses to environment. In: Water and plant life (Lange, O. L., Kappen, L. A., Schulze, E.-D., Schulze, Eds.). Ecological Studies19, 169–188 (1976)
Herrera, R.: Soil and terrain conditions in the International Amazon Project at San Carlos de Rio Negro, Venezuela; correlation with vegetation types. In: Transact. Internat. MAB-IUFRO Workshop. (Brünig, E., Ed.). Spec. Report1, 182–188 (1977)
Klinge, H., Medina, E., Herrera, R.: Studies on the ecology of Amazon Caatinga forest in southern Venezuela. 1. General features. Acta cient. venez.28, 270–276 (1977)
Kriedeman, P. E., Neales, T. F., Ashton, D. H.: Photosynthesis in relation to leaf orientation and light interception. Aust. J. biol. Sci.17, 591–600 (1964)
Lange, O. L., Lange, R.: Untersuchungen über Blattemperaturen, Transpiration und Hitzeresistenz an Pflanzen mediterraner Standorte (Costa Brava, Spanien). Flora153, 387–425 (1963)
Loveless, A. R.: A nutritional interpretation of sclerophylly based on differences in the chemical composition of sclerophyllous and mesophytic leaves. Ann. Bot.25, 164–168 (1961)
Loveless, A. R.: Further evidences to support a nutritional interpretation of sclerophylly. Ann. Bot.26, 549–561 (1962)
Milthorpe, F. L., Moorby, J.: An introduction to crop physiology. Cambridge: Cambridge University Press 1974
Mooney, H., Dunn, L.: Convergent evolution of mediterranean-climate evergreen sclerophyll shrubs. Evolution24 (2), 292–303 (1970a)
Mooney, H., Dunn, L.: Photosynthetic systems of mediterranean-climate shrubs and trees of California and Chile. Amer. Naturalist104, 447–453 (1970b)
Nobel, P. S.: Introduction to biophysical plant physiology. San Francisco: Freeman and Co. 1974
Sobrado, M.: Aspectos eco-fisiológicos de la vegetación esclerofita de suelos arenosos, podsolizados e inundables de la cuenca del Rio Negro, Territorio Federal Amazonas. Tesis de Licenciatura. Universidad Central de Venezuela. Fac. de Ciencias 1977
Tageeva, S. V., Brandt, A. B.: Study of optical properties of leaves depending on the angle of light incidence. In: Progress in Photobiology, pp. 163–169 (Christensen, B. Chr., Buchmann, B., Eds.). Amsterdam: Elsevier Publ. Co. 1961
Taylor, S. E.: Optimal leaf size: Ecological Studies12, 76–86 (1975) (ref. 6)
Walter, H.: Die Vegetation der Erde. II. Die gemäßigten and arktischen Zonen. Jena: Fischer 1968
Author information
Authors and Affiliations
Additional information
Contribution from the Venezuela MAB-1 Programm, partially supported by the National Research Council (CONICIT) and the Organization of American States (OEA)
Rights and permissions
About this article
Cite this article
Medina, E., Sobrado, M. & Herrera, R. Significance of leaf orientation for leaf temperature in an amazonian sclerophyll vegetation. Radiat Environ Biophys 15, 131–140 (1978). https://doi.org/10.1007/BF01323262
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF01323262