Legumes are different: Leaf nitrogen, photosynthesis, and water use efficiency
- 30 March 2016
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences of the United States of America
- Vol. 113 (15), 4098-4103
- https://doi.org/10.1073/pnas.1523936113
Abstract
Using robust, pairwise comparisons and a global dataset, we show that nitrogen concentration per unit leaf mass for nitrogen-fixing plants (N2FP; mainly legumes plus some actinorhizal species) in nonagricultural ecosystems is universally greater (43–100%) than that for other plants (OP). This difference is maintained across Koppen climate zones and growth forms and strongest in the wet tropics and within deciduous angiosperms. N2FP mostly show a similar advantage over OP in nitrogen per leaf area (Narea), even in arid climates, despite diazotrophy being sensitive to drought. We also show that, for most N2FP, carbon fixation by photosynthesis (Asat) and stomatal conductance (gs) are not related to Narea—in distinct challenge to current theories that place the leaf nitrogen–Asat relationship at the center of explanations of plant fitness and competitive ability. Among N2FP, only forbs displayed an Narea–gs relationship similar to that for OP, whereas intrinsic water use efficiency (WUEi; Asat/gs) was positively related to Narea for woody N2FP. Enhanced foliar nitrogen (relative to OP) contributes strongly to other evolutionarily advantageous attributes of legumes, such as seed nitrogen and herbivore defense. These alternate explanations of clear differences in leaf N between N2FP and OP have significant implications (e.g., for global models of carbon fluxes based on relationships between leaf N and Asat). Combined, greater WUE and leaf nitrogen—in a variety of forms—enhance fitness and survival of genomes of N2FP, particularly in arid and semiarid climates.Keywords
This publication has 40 references indexed in Scilit:
- Biological nitrogen fixation: rates, patterns and ecological controls in terrestrial ecosystemsPhilosophical Transactions Of The Royal Society B-Biological Sciences, 2013
- The role of functional traits in species distributions revealed through a hierarchical modelEcography, 2011
- Legume Nitrogen Fixation and Soil Abiotic Stress: From Physiology to Genomics and BeyondPublished by Wiley ,2010
- The Nitrogen Paradox in Tropical Forest EcosystemsAnnual Review of Ecology, Evolution, and Systematics, 2009
- The evolution of antiherbivore defenses and their contribution to species coexistence in the tropical tree genusIngaProceedings of the National Academy of Sciences of the United States of America, 2009
- Evolutionary tradeoffs can select against nitrogen fixation and thereby maintain nitrogen limitationProceedings of the National Academy of Sciences of the United States of America, 2008
- World Map of the Köppen-Geiger climate classification updatedMeteorologische Zeitschrift, 2006
- A dynamic global vegetation model for studies of the coupled atmosphere‐biosphere systemGlobal Biogeochemical Cycles, 2005
- The worldwide leaf economics spectrumNature, 2004
- Photosynthesis and nitrogen relationships in leaves of C3 plantsOecologia, 1989