Characterization of photosynthetic pathway of plant species growing in the eastern Tibetan plateau using stable carbon isotope composition.

摘要

The photosynthetic pathway of plant species collected at Menyuan, Henan, and Maduo sites (3150, 3560 and 4210 m asl, respectively), east of Tibetan Plateau, China, during the growing season were studied using stable carbon isotopes in leaves. The study sites are dominated by alpine meadow, but there are also few semi-desert plants and cushion species. The 232 leaves analysed belonged to 161 species, 30 families and 94 genera. The delta 13C values (from -24.6 to -29.2 per mil) indicated that all the studied species had a photosynthetic C3 pathway. The absence of plant species with C4 photosynthetic pathway might be due to the extremely low air temperature characterizing the Tibetan Plateau. The average delta 13C value was significantly (p<0.05) different between annuals and perennials at the three study sites. Hence, the long-lived species had higher water use efficiency than short-lived species, that is, long-lived species are better adapted to the extreme environmental conditions of the Tibetan Plateau..