Higher capability of C3 than C4 plants to use nitrogen inferred from nitrogen stable isotopes along an aridity gradient
- 384 Downloads
Background and aims
The nitrogen isotope composition (δ15N) of plants in arid and semiarid grasslands is affected by environmental factors, especially water availability. Nevertheless, it is unclear whether the response of δ15N to water availability differs between C3 and C4 photosynthetic pathways.
We investigated plant δ15N of coexisting C3 and C4 species as a function of aridity along a 3200 km aridity gradient across the arid and semi-arid grasslands of northern China.
Aridity was positively correlated with plant δ15N values in both C3 and C4 plants and also in the entire plant community, whereas soil bulk δ15N values increased first and then decreased along the aridity gradient. The N uptake by C4 plants appeared to be more affected by competition pressure of neighboring plants and soil microbes than for C3 plants along the transect.
The decoupled relationship between plant and soil δ15N values indicated that variations in vegetation and soil δ15N values were driven by differential biogeochemical processes, while different soil N sources were used for plant growth along the climatic gradient. The advantage of C3 plants in the use of N may counteract the competitive advantage that C4 plants have over C3 plants due to their higher water use efficiency under drier conditions. These findings can help understand why C4 plants do not completely replace C3 plants in drier environments despite their higher water use efficiency.
KeywordsCompetition Grassland transect Photosynthetic pathway Precipitation Trade-off
We thank all members of the Field Expedition Team from the Institute of Applied Ecology, Chinese Academy of Sciences, for assistance with the collection of the field data. We thank three anonymous referees as well as the Handling Editor for constructive comments on the manuscript. This work was supported by the National Basic Research Program of China (2016YFC0500601, 2016YFC0500700 and 2015CB150802), National Natural Science Foundation of China (41600302, 3231470505 and 41273094), Strategic Priority Research Program of the Chinese Academy of Sciences (XDB15010403), Youth Innovation Promotion Association CAS (2014174), and the Key Research Program from CAS (KFZD-SW-305-002). JP and JS were funded by the European Research Council Synergy grant ERC-SyG-2013-610028, IMBALANCE-P, the Spanish Government grant CGL2013-48074-P and the Catalan Government grant SGR 2014-274.
- Craine JM, Elmore AJ, Aidar MPM, Bustamante M, Dawson TE, Hobbie EA, Kahmen A, Mack MC, McLauchlan KK, Michelsen A, Nardoto GB, Pardo LH, Peñuelas J, Reich PB, Schuur EAG, Stock WD, Templer PH, Virginia RA, Welker JM, Wright IJ (2009) Global patterns of foliar nitrogen isotopes and their relationships with climate, mycorrhizal fungi, foliar nutrient concentrations, and nitrogen availability. New Phytol 183:980–992CrossRefPubMedGoogle Scholar
- Hilbig W (1995) The vegetation of Mongolia. SPB Academic Publishing, AmsterdamGoogle Scholar
- Watson L, Dallwitz MJ (1992) Grass genera of the world: descriptions, illustrations, identification, and information retrieval; including synonyms, morphology, anatomy, physiology, phytochemistry, cytology, classification, pathogens, world and local distribution, and references. http://delta-intkey.com/grass/www/index.htm