Plants with crassulacean acid metabolism (CAM) are increasing in distribution and abundance in drylands worldwide, but the underlying drivers remain unknown. We investigate the impacts of extreme drought and CO2 enrichment on the competitive relationships between seedlings of Cylindropuntia imbricata (CAM species) and Bouteloua eriopoda (C-4 grass), which coexist in semiarid ecosystems across the Southwestern United States. Our experiments under altered water and CO2 water conditions show that C. imbricata positively responded to CO2 enrichment under extreme drought conditions, while B. eriopoda declined from drought stress and did not recover after the drought ended. Conversely, in well-watered conditions B. eriopoda had a strong competitive advantage on C. imbricata such that the photosynthetic rate and biomass (per individual) of C. imbricata grown with B. eriopoda were lower relative to when growing alone. A meta-analysis examining multiple plant families across global drylands shows a positive response of CAM photosynthesis and productivity to CO2 enrichment. Collectively, our results suggest that under drought and elevated CO2 concentrations, projected with climate change, the competitive advantage of plant functional groups may shift and the dominance of CAM plants may increase in semiarid ecosystems.
1.Univ Virginia, Dept Environm Sci, Charlottesville, VA 22904 USA 2.Univ Calif Berkeley, Dept Environm Sci Policy & Management, Berkeley, CA 94710 USA 3.Univ New Mexico, Dept Biol, Albuquerque, NM 87131 USA 4.Duke Univ, Dept Civil & Environm Engn, Durham, NC 27708 USA 5.Univ Utah, Dept Biol, Salt Lake City, UT 84112 USA 6.Indiana Univ Purdue Univ, Dept Earth Sci, Indianapolis, IN 46202 USA 7.North Carolina State Univ, Dept Forestry & Environm Resources, Raleigh, NC 27607 USA 8.Lanzhou Univ, Key Lab Semiarid Climate Change, Minist Educ, Coll Atmospher Sci, Lanzhou 730000, Gansu, Peoples R China 9.Northwest A&F Univ, State Key Lab Soil Eros & Dryland Farming Loess P, Yangling 712100, Shaanxi, Peoples R China 10.Penn State Univ, Dept Meteorol, 503 Walker Bldg, University Pk, PA 16802 USA
Recommended Citation:
Yu, Kailiang,D',Odorico, Paolo,et al. The competitive advantage of a constitutive CAM species over a C-4 grass species under drought and CO2 enrichment[J]. ECOSPHERE,2019-01-01,10(5)