Does plant size affect growth responses to water availability at glacial, modern and future CO2 concentrations?

• Published in: Ecological research Vol. 31; no. 2; pp. 213 - 227
• Main Authors: Liu, Jin-Chun, Temme, Andries A, Cornwell, William K, van Logtestijn, Richard S. P, Aerts, Rien, Cornelissen, Johannes H. C
• Format: Journal Article
• Language: English
• Published: Tokyo Springer Japan 01-03-2016; Blackwell Publishing Ltd
• Subjects: annuals; Atmosphere; Avena sativa; Behavioral Sciences; biomass; Biomass accumulation; Biomedical and Life Sciences; C3 plants; Carbon; Carbon dioxide; Chenopodium album; climate; CO2 concentration; Drought; Ecology; Evolutionary Biology; Flowers & plants; Forestry; Growth rate; leaf area; Leaves; Life Sciences; Moisture content; Original Article; Plant biomass; plant response; Plant Sciences; Relative growth rate; rooting; Soil water; soil water regimes; Transpiration; Water; Water availability; Water use efficiency; Zoology; Biomass accumulation; concentration; Water use efficiency; Drought; CO; Relative growth rate
• ISSN: 0912-3814; 1440-1703
• DOI: 10.1007/s11284-015-1330-y

Plant responses to carbon (C) and water availability are strongly connected. Thus, we can learn much about the responses of modern plants to rising atmospheric carbon dioxide (CO₂) by studying their performance under a range of carbon and water availabilities, including very low CO₂ as in past glacial periods. We hypothesized that, especially in shallow soils, the positive effects of high CO₂ and the negative effects of low CO₂ on growth response to drought are moderated by plant size-driven feedbacks through transpiration and soil water depletion. We grew two temperate annual C₃ species, Avena sativa and Chenopodium album, in glacial (180 ppm), modern (400 ppm) and future (700 ppm) CO₂ levels and five soil water regimes in climate chambers. In both species, low CO₂ resulted in a much lower relative growth rate, biomass and total leaf area than at ambient CO₂ with higher water availability, but this difference disappeared steadily towards severe drought conditions. Elevated CO₂ increased relative growth rate, plant biomass and total leaf area of both species slightly compared with ambient CO₂. These results were especially pronounced under drought. Our results support the hypothesis that, in annuals, plant size modulates the negative drought effect at low CO₂. However, plant size-mediated effects of high CO₂ on growth response to drought were inconclusive. Further experiments should reveal the interactive effects of CO₂ and water regimes in environments closer to a field setting, both in shallow and in deep soils with unconstrained rooting, as well as in mixed communities.