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Technischen Universitat Munchen (2010)

Carbon and nitrogen isotope composition of Inner Mongolia grassland : spatio-temporal variations at multiple scales

Wittmer, Maximilian

Titre : Carbon and nitrogen isotope composition of Inner Mongolia grassland : spatio-temporal variations at multiple scales

Kohlenstoff- und Stickstoffisotopie des Graslands der Inneren Mongolei : raum-zeitliche Veränderung auf verschiedenen Skalen

Auteur : Wittmer, Maximilian

Université de soutenance : Technischen Universitat Munchen

Grade : Doctoral Thesis 2010

Résumé
Carbon (δ13C) and nitrogen (δ15N) stable isotope compositions were used to elaborate the influences of changes in biotic and abiotic environmental parameters on the vegetation in the Mongolia-Manchurian grassland. The stomatal conductance of C3 vegetation depended on the water availability during the growing period and could be predicted. The isotopic information of the vegetation could be derived from grazers’ tissue (sheep wool & faeces) by taking the fractionation into account. The fraction was not influenced by selective grazing, grazing pressure or differential digestibility. Soil also reflected the isotopic composition of the vegetation but differed in its temporal integration. The modern and former times ratio of the C3 and C4 photosynthetic types was then reconstructed. Despite a distinct increase in ambient CO2 concentration, the abundance of C4 plants increased. This was related to the global warming, as grazing pressure exhibited no influence.

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Page publiée le 25 janvier 2016, mise à jour le 10 janvier 2019