Date of this Version
Erforschung biologischer Ressourcen der Mongolei (2005) 9: 193-198.
Proceedings of the symposium ”Ecosystem Research in the Arid Environments of Central Asia: Results, Challenges, and Perspectives,” Ulaanbaatar, Mongolia, June 23-24, 2004.
This paper presents the results of our studies on the ecological adaptations and geographical distribution of plants with C4-photosynthesis in Mongolia using 13C isotope discrimination.
Previous studies identified about 80 C4-species in 8 families in the Mongolian flora. Our investigations lead to the identification of four additional species, which can be regarded as C4-plants. Orostachys spinosa (-16.26‰ 13C), O. thyrsiflora (-16.86‰ 13C), O. fimbriata (-16.15‰ 13C), and Euphorbia humifusa (-23.29‰ 13C). However, as the discrimination level for Euphorbia humifusa is very similar to that of C3-plants it may be switching between C3 and C4 types of photosynthesis according to the environmental conditions.
C4-plants become more important in the Mongolian vegetation along a gradient of decreasing precipitation and increasing temperature from northern Mongolia to southern Mongolia. Along this gradient also soil salinity increases, vegetation cover decreases, and the relief changes from mountains to hilly steppes and finally to the relatively flat Gobi desert. The decreasing importance of C4-plants towards southern Mongolia is also reflected in the 13C-levels from herbivores.