Elevation-induced climate change as a dominant factor causing the late Miocene C 4 plant expansion in the Himalayan foreland

Haibin Wu , Zhengtang Guo , Joel Guiot (1) , Christine Hatté (2, 3) , Changhui Peng (2) , Yanyan Yu , Juyi Ge , Qin Li , Aizhi Sun , Deai Zhao

1 CEREGE - Centre européen de recherche et d'enseignement des géosciences de l'environnement
2 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]
3 GEOTRAC - Géochrononologie Traceurs Archéométrie

During the late Miocene, a dramatic global expansion of C 4 plant distribution occurred with broad spatial and temporal variations. Although the event is well documented, whether subsequent expansions were caused by a decreased atmospheric CO 2 concentration or climate change is a contentious issue. In this study, we used an improved inverse vegetation modeling approach that accounts for the physiological responses of C 3 and C 4 plants to quantitatively reconstruct the paleoclimate in the Siwalik of Nepal based on pollen and carbon isotope data. We also studied the sensitivity of the C 3 and C 4 plants to changes in the climate and the atmospheric CO 2 concentration. We suggest that the expansion of the C 4 plant distribution during the late Miocene may have been primarily triggered by regional ari-dification and temperature increases. The expansion was unlikely caused by reduced CO 2 levels alone. Our findings suggest that this abrupt ecological shift mainly resulted from climate changes related to the decreased elevation of the Himalayan foreland.

Keywords: inverse vegetation model; C 4 plant expansion; late Miocene; pollen biome; paleoclimate reconstruction

Domains: Continental interfaces, environment

Haibin Wu, Zhengtang Guo, Joel Guiot, Christine Hatté, Changhui Peng, et al.. Elevation-induced climate change as a dominant factor causing the late Miocene C 4 plant expansion in the Himalayan foreland. Global Change Biology, 2014, 20 (5), pp.1461-1472. ⟨10.1111/gcb.12426⟩. ⟨insu-02269748⟩