Interactive effects of drought and shade on three arid zone chenopod shrubs with contrasting distributions in relation to tree canopies
Article first published online: 6 FEB 2004
Volume 18, Issue 1, pages 67–76, February 2004
How to Cite
Prider, J. N. and Facelli, J. M. (2004), Interactive effects of drought and shade on three arid zone chenopod shrubs with contrasting distributions in relation to tree canopies. Functional Ecology, 18: 67–76. doi: 10.1046/j.0269-8463.2004.00810.x
- Issue published online: 6 FEB 2004
- Article first published online: 6 FEB 2004
- Received 7 April 2003; revised 26 August 2003; accepted 23 September 2003
- Carbon assimilation;
- shade tolerance;
- water stress
- 1Plants that grow beneath trees in arid systems may frequently experience both water and light limitation, although protection from high radiation loads during drought may compensate for a loss of productivity due to reduced light availability when water is plentiful.
- 2We examined the effects of shading, during an imposed water deficit, on the carbon gain, stomatal conductance (gs) and shoot water potential (Ψs) of seedlings of three shrubs: Atriplex vesicaria (Heward ex Benth.), a C4 species, and Enchylaena tomentosa (R. Br.) and Rhagodia spinescens (R. Br.), which are restricted to shaded sites beneath trees.
- 3Under conditions of limiting water, photosynthetic rates measured at saturating light (Amax) were negative in high-light grown Enchylaena plants but remained positive in shade-grown plants. When water was not limiting, Amax was reduced in shade-grown Atriplex but shade did not affect carbon gain in the other two species.
- 4AtriplexΨs was higher in shaded than in unshaded plants, but in unshaded plants positive carbon gain was maintained at Ψs below −10 MPa. Stomatal conductance and Amax decreased more slowly with increasing water deficit in shaded conditions in all species.
- 5Atriplex was tolerant of a broader range of light and soil moisture conditions than Enchylaena, with Rhagodia intermediate between these two species. The interactive effect between drought and shade and the ecophysiological tolerances of these three species have consequences for their field distributions.