Relationships between C3 plant foliar carbon isotope composition and element contents of grassland species at high altitudes on the Qinghai-Tibet Plateau, China

PLoS One. 2013;8(4):e60794. doi: 10.1371/journal.pone.0060794. Epub 2013 Apr 2.

Abstract

Relationships of foliar carbon isotope composition (δ(13)C) with foliar C, N, P, K, Ca, Mg contents and their ratios of 219 C3 species leaf samples, obtained in August in 2004 to 2007 from 82 high altitude grassland sites on the Qinghai-Tibet Plateau China, were examined. This was done with reference to the proposition that foliar δ(13)C increases with altitude and separately for the life-form groups of graminoids, forbs and shrubs and for the genera Stipa and Kobresia. For all samples, foliar δ(13)C was negatively related to foliar K, P and ∑K+ Ca+ Mg, and positively correlated to foliar C, C/N and C/P. The significance of these correlations differed for the taxonomic and life-form groups. Lack of a relationship of foliar δ(13)C with foliar N was inconsistent with the majority of studies that have shown foliar δ(13)C to be positively related to foliar N due to a decrease of Ci/Ca (the ratio between intercellular and atmospheric concentration of CO2) and explained as a result of greater photosynthetic capacity at higher foliar N concentration. However this inconsistency relates to other high altitude studies that have found that photosynthetic capacity remains constant as foliar N increases. After accounting for the altitudinal relationship with foliar δ(13)C, of the elements only the K effect was significant and was most strongly expressed for Kobresia. It is concluded that factors critical to plant survival and growth at very high altitudes, such as low atmospheric pressure and low temperatures, may preclude expression of relationships between foliar δ(13)C and foliar elements that have been observed at lower altitudes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Altitude*
  • Carbon / chemistry
  • Carbon Isotopes / chemistry*
  • China
  • Cyperaceae / chemistry
  • Nitrogen / chemistry
  • Plant Leaves / chemistry*
  • Plants / chemistry*
  • Tibet

Substances

  • Carbon Isotopes
  • Carbon
  • Nitrogen

Grants and funding

The research was funded by the National Key Basic Research Program of China (2010CB950902), the National Natural Science Foundation of China (grant no. 31070427) and National Key Technologies R&D Program of Ministry of Science and Technology of the People's Republic of China (grant no. 2009BAC61B01). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.