Compensatory photosynthesis of Sporobolus flexuosus (Thurb.) Rydb. following simulated herbivory in the northern Chihuahuan Desert
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Authors: R. S. Senock, W. B. Sisson, and G. B. Donart
Date: 1991
Journal: Botanical Gazette
Volume: 152
Number: 3
Pages: 275-281
Summary of Methods: Leaf net photosynthesis (Pn), conductance to water vapor, water potential, solar radiation penetration within the leaf canopy, and biomass production of mesa dropseed (Sporobolus flexuosus) was measured 4-, 18-, and 34-days following removal of one-half of all shoots. Pn rates of defoliated plants were 35% higher than leaves of similar aged leaves on control plants after 18 and 34 days. Daily integrated radiation penetration within the canopy of defoliated and control plants averaged 66 and 32 percent, respectively, of the total irradiance received in the open. Compensatory photosynthesis evident in this study was not due to changes in conductance or improvements in plant water status. There were no differences between treatments in leaf conductance, but on all three sample days, leaf water potential of partially defoliated plants were 20-30% more negative than those of control plants. In conclusion, compensatory photosynthesis may be a common response in defoliated range grasses despite the suboptimal environmental conditions common in the field.
Article Summary / Main Points: None
Vegetation Types:
MLRA Ecoregions:
Agrovoc Control Words: Riparian zones Rangelands Wildlife
Article Review Type: Peer Reviewed
Article Type: Experimental Research
Keywords: compensatory photosynthesis, mesa dropseed, sporobolus flexuosus, simulated herbivory, chihuahuan desert
Annotation: Plants used in the study were located within an exclosure that had not been grazed by livestock for 17 years but was freely accessible to rodents and rabbits. 24 plants were defoliated on August 14. The defoliation treatment consisted of determining the total number of shoots on each plant and removing one-half by clipping at the base. There was a control number with an equal number of plants that were not defoliated.
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