Photosynthesis and Microclimate of Camissonia Claviformis, A Desert Winter Annual
1979
Ehleringer, J. | Mooney, H. A. | Berry, J. A.
The photosynthetic characteristics of the C₃ desert winter annual Camissonia claviformis and the microclimate of the Camissonia habitat in Death Valley, California on 21 March 1976 are presented. This species has one of the highest photosynthetic capacities of any higher plant, with rates exceeding 6 nmoled CO₂ cm— ² sec— ¹ at midday irradiances and optimum leaf temperatures. The photosynthetic temperature optimum is at 20°C, in concert with the prevailing cool winter temperatures of this desert habitat. The daily totals of primary production and water loss for Camissonia on 21 March are calculated using leaf energy budget and CO₂ diffusion photosynthetic equations. Measured and predicted leaf temperatures were 2—4°C below air temperatures during the day. The rate of primary production is predicted to be 68.1 g CO₂ m— ² day— ¹ under high stomatal conductances, while daily transpiration at these stomatal conductances, will be 5.54 kg m— ¹ day — ¹. The effects of decreases in stomatal conductance on daily primary production, transpiration, and water—use efficiency are calculated and show that the values of these 3 parameters diminish rapidly with decreasing stomatal conductance.
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