Energy balance and temperature relations of Azorella compacta, a high-elevation cushion plant of the central Andes.
The environmental relationships and ecophysiology of Azorella compacta, a giant cushion plant, were investigated in Parque Nacional Lauca, Chile (18 degrees 10'-18 degrees 25' S and 69 degrees 16' W, 4400 m asl). The diurnal temperature range can reach 42 degrees C on some days of the year. The surface temperature of A. compacta was 13 degrees C below that of the air temperature of -7 degrees 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 micromol.m(-2).s(-1), and maximum stomatal conductance (Gs) was 410 mmol.m(-2).s(-1). The estimated light compensation point was 89 micromol.m(-2).s(-1) and estimated light saturation occurred at about 1280 mumol.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.
Kleier
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Department of Biology, Regis University, Denver, CO, USA. ckleier@regis.edu
Rundel
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D000064:Acclimatization / Q000502:physiology*; D000388:Air; D019661:Apiaceae / Q000502:physiology*; D002245:Carbon Dioxide / Q000378:metabolism; D002677:Chile; D004463:Ecology; D017753:Ecosystem; D008027:Light; D010100:Oxygen / Q000378:metabolism; D010788:Photosynthesis / Q000502:physiology*; D054046:Plant Stomata; D012621:Seasons; D012987:Soil; D013472:Sunlight; D013696:Temperature; D014867:Water / Q000502:physiology
D012987:Soil; D014867:Water; D002245:Carbon Dioxide; D010100:Oxygen