Effects of temperature on photosynthesis of two morphologically contrasting plant species along an altitudinal gradient in the tropical high Andes

• Published in: Oecologia Vol. 114; no. 2; pp. 145 - 152
• Main Authors: Cabrera, H.M, Rada, F, Cavieres, L
• Format: Journal Article
• Language: English
• Published: Berlin Springer-Verlag 01-04-1998; Springer
• Subjects: Acaena; acaena cylindrostachya; Altitude; Animal and plant ecology; Animal, plant and microbial ecology; Autoecology; Biological and medical sciences; Ecophysiology; Fundamental and applied biological sciences. Psychology; High temperature; highlands; Leaves; mountains; Photosynthesis; Photosynthetically active radiation; plant morphology; Plants; Plants and fungi; Senecio; senecio formosus; Soil temperature; Soil temperature regimes; temperature; Temperature control; Temperature gradients; Venezuela; South America; Andes; America; Temperature; Interspecific comparison; Tropical zone; Rosaceae; Environmental factor; Compositae; Energy balance; Mountain; Dicotyledones; Morphology; Angiospermae; Spermatophyta; Photosynthesis; Senecio; Altitude; Plant morphology; Key words Energy balance; Tropical mountain; Leaf temperature
• ISSN: 0029-8549; 1432-1939
• DOI: 10.1007/s004420050430

The effects of temperature on photosynthesis of a rosette plant growing at ground level, Acaena cylindrostachya R. et P., and an herb that grows 20-50 cm above ground level, Senecio formosus H.B.K., were studied along an altitudinal gradient in the Venezuelan Andes. These species were chosen in order to determine -- in the field and in the laboratory -- how differences in leaf temperature, determined by plant form and micro-environmental conditions, affect their photosynthetic capacity. CO₂ assimilation rates (A) for both species decreased with increasing altitude. For Acaena leaves at 2900 m, A reached maximum values above 9 μmol m-2s-1, nearly twice as high as maximum A found at 3550 m (5.2) or at 4200 m (3.9). For Senecio leaves, maximum rates of CO₂ uptake were 7.5, 5.8 and 3.6 μmol m-2s-1for plants at 2900, 3550 and 4200 m, respectively. Net photosynthesis-leaf temperature relations showed differences in optimum temperature for photosynthesis ($A_{\text{o}.\text{t}.}$) for both species along the altitudinal gradient. Acaena showed similar$A_{\text{o}.\text{t}.}$for the two lower altitudes, with 19.1°C at 2900 m and 19.6°C at 3550 m, while it increased to 21.7°C at 4200 m. Maximum A for this species at each altitude was similar, between 5.5 and 6.0 μmol m-2s-1. For the taller Senecio,$A_{\text{o}.\text{t}.}$was more closely related to air temperatures and decreased from 21.7°C at 2900 m, to 19.7°C at 3550 m and 15.5°C at 4200 m. In this species, maximum A was lower with increasing altitude (from 6.0 at 2900 m to 3.5 μmol m-2s-1at 4200 m). High temperature compensation points for Acaena were similar at the three altitudes, c. 35°C, but varied in Senecio from 37°C at 2900 m, to 39°C at 3550 m and 28°C at 4200 m. Our results show how photosynthetic characteristics change along the altitudinal gradient for two morphologically contrasting species influenced by soil or air temperatures.