Photosynthetic responses of Larrea tridentata to a step-increase in atmospheric CO2 at the Nevada Desert FACE Facility

Authors

Erik P. Hamerlynck, University of Nevada, Las VegasFollow
Travis E. Huxman, University of Nevada, Las VegasFollow
Robert S. Nowak, University of Nevada, RenoFollow
S. Redar, California State University - San Bernardino
Michael E. Loik, University of California - Santa CruzFollow
Dean N. Jordan, University of Nevada, Las VegasFollow
Stephen F. Zitzer, Desert Research InstituteFollow
James S. Coleman, Desert Research InstituteFollow
Jeffrey R. Seemann, University of Nevada, RenoFollow
S. D. Smith, University of Nevada, Las VegasFollow

Document Type

Article

Publication Date

2000

Publication Title

Journal of Arid Environments

Volume

44

Issue

4

First page number:

425

Last page number:

436

Abstract

Of all terrestrial ecosystems, the productivity of deserts has been suggested to be the most responsive to increasing atmospheric CO2. The extent to which this prediction holds will depend in part on plant responses to elevated CO2 under the highly variable conditions characteristic of arid regions. The photosynthetic responses of Larrea tridentata , an evergreen shrub, to a step-increase in atmospheric CO2(to 550 μmolmol−1) were examined in the field using Free-Air CO2 Enrichment (FACE) under seasonally varying moisture conditions. Elevated CO2 substantially increased net assimilation rate (A(net)) in Larrea during both moist and dry periods of the potential growing season, while stomatal conductance (gs) did not differ between elevated and ambient CO2 treatments. Seasonal and diurnal gas exchange dynamics in elevated CO2 mirrored patterns in ambient CO2, indicating that elevated CO2 did not extend photosynthetic activity longer into the dry season or during more stressful times of the day. Net assimilation vs. internal CO2 (A/Ci) responses showed no evidence of photosynthetic down-regulation during the dry season. In contrast, after significant autumn rains, A(max)(the CO2 saturated rate of photosynthesis) and CE (carboxylation efficiency) were lower in Larrea under elevated CO2. In situ chlorophyll fluorescence estimation of Larrea Photosystem II efficiency (Fv/Fm) responded more to water limitation than to elevated CO2. These findings suggest that predictions regarding desert plant responses to elevated CO2 should account for seasonal patterns of photosynthetic regulatory responses, which may vary across species and plant functional types.

Keywords

Creosote; Elevated CO2; FACE; Larrea; Mojave Desert; Nevada; Photosynthetic down-regulation; Stomatal conductance; Water stress

Disciplines

Desert Ecology | Environmental Indicators and Impact Assessment | Plant Biology

Language

English

Publisher Citation

E.P Hamerlynck, T.E Huxman, R.S Nowak, S Redar, M.E Loik, D.N Jordan, S.F Zitzer, J.S Coleman, J.R Seemann, S.D Smith Photosynthetic responses of Larrea tridentata to a step-increase in atmospheric CO2at the Nevada Desert FACE Facility Journal of Arid Environments, Volume 44, Issue 4, April 2000, Pages 425–436 http://dx.doi.org/10.1006/jare.1999.0615

Repository Citation

Hamerlynck, E. P., Huxman, T. E., Nowak, R. S., Redar, S., Loik, M. E., Jordan, D. N., Zitzer, S. F., Coleman, J. S., Seemann, J. R., Smith, S. D. (2000). Photosynthetic responses of Larrea tridentata to a step-increase in atmospheric CO2 at the Nevada Desert FACE Facility. Journal of Arid Environments, 44(4), 425-436.
http://dx.doi.org/10.1006/jare.1999.0615