Coordination of photosynthetic traits across soil and climate gradients |
| |
| Authors: | Andrea C. Westerband Ian J. Wright Vincent Maire Jennifer Paillassa Iain Colin Prentice Owen K. Atkin Keith J. Bloomfield Lucas A. Cernusak Ning Dong Sean M. Gleason Caio Guilherme Pereira Hans Lambers Michelle R. Leishman Yadvinder Malhi Rachael H. Nolan |
| |
| Affiliation: | 1. Faculty of Science and Engineering, School of Natural Sciences, Macquarie University, North Ryde, New South Wales, Australia;2. Hawkesbury Institute for the Environment, Western Sydney University, Penrith, New South Wales, Australia;3. Département des Sciences de l'environnement, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada;4. Australian Research Council Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia;5. Georgina Mace Centre for the Living Planet, Imperial College London, Ascot, UK;6. College of Science and Engineering, James Cook University, Cairns, Queensland, Australia;7. USDA-ARS Water Management and Systems Research Unit, Fort Collins, Colorado, USA;8. Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA;9. School of Biological Sciences, University of Western Australia, Perth, Western Australia, Australia;10. School of Geography and the Environment, Environmental Change Institute, University of Oxford, Oxford, UK |
| |
| Abstract: | “Least-cost theory” posits that C3 plants should balance rates of photosynthetic water loss and carboxylation in relation to the relative acquisition and maintenance costs of resources required for these activities. Here we investigated the dependency of photosynthetic traits on climate and soil properties using a new Australia-wide trait dataset spanning 528 species from 67 sites. We tested the hypotheses that plants on relatively cold or dry sites, or on relatively more fertile sites, would typically operate at greater CO2 drawdown (lower ratio of leaf internal to ambient CO2, Ci:Ca) during light-saturated photosynthesis, and at higher leaf N per area (Narea) and higher carboxylation capacity (Vcmax 25) for a given rate of stomatal conductance to water vapour, gsw. These results would be indicative of plants having relatively higher water costs than nutrient costs. In general, our hypotheses were supported. Soil total phosphorus (P) concentration and (more weakly) soil pH exerted positive effects on the Narea–gsw and Vcmax 25–gsw slopes, and negative effects on Ci:Ca. The P effect strengthened when the effect of climate was removed via partial regression. We observed similar trends with increasing soil cation exchange capacity and clay content, which affect soil nutrient availability, and found that soil properties explained similar amounts of variation in the focal traits as climate did. Although climate typically explained more trait variation than soil did, together they explained up to 52% of variation in the slope relationships and soil properties explained up to 30% of the variation in individual traits. Soils influenced photosynthetic traits as well as their coordination. In particular, the influence of soil P likely reflects the Australia's geologically ancient low-relief landscapes with highly leached soils. Least-cost theory provides a valuable framework for understanding trade-offs between resource costs and use in plants, including limiting soil nutrients. |
| |
| Keywords: | Australia least-cost theory of photosynthesis nutrient-use efficiency optimality theory plant functional traits soil nutrients soil phosphorus trait coordination water-use efficiency |
|
|
