Energy balance and temperature relations of Azorella compacta, a high-elevation cushion plant of the central Andes |
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Authors: | C Kleier & P Rundel |
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Institution: | Department of Biology, Regis University, Denver, CO, USA; Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA, USA |
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Abstract: | The environmental relationships and ecophysiology of Azorella compacta, a giant cushion plant, were investigated in Parque Nacional Lauca, Chile (18°10'–18°25' S and 69°16' W, 4400 m asl). The diurnal temperature range can reach 42 °C on some days of the year. The surface temperature of A. compacta was 13 °C below that of the air temperature of −7 °C at dawn, but from midmorning to late afternoon, the plant surface temperature remained within a few degrees of the air temperature. Soil surface temperatures did not differ between north- and south-facing slopes, but a model showed an increase in radiation reception by north-facing slopes throughout most of the year. Gas exchange measurements of A. compacta measured at the onset of the wet season ranged from −0.6662 to 11.4 μmol·m−2·s−1, and maximum stomatal conductance (Gs) was 410 mmol·m−2·s−1. The estimated light compensation point was 89 μmol·m−2·s−1 and estimated light saturation occurred at about 1280 μmol·m−2·s−1. Diurnal water potential measurements for A. compacta ranged from −1.67 to −2.65 MPa. This is one of the first ecophysiological studies of a tropical alpine cushion plant. |
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Keywords: | Ecophysiology parinacota Parque Nacional Lauca Puna tropical alpine |
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