Modelling the effects of CO2 on C3 and C4 grass competition during the mid-Pleistocene transition in South Africa

Ecker, Michaela; Kelley, Douglas; Sato, Hiromitsu. 2020 Modelling the effects of CO2 on C3 and C4 grass competition during the mid-Pleistocene transition in South Africa. Scientific Reports, 10, 16234. 8, pp. https://doi.org/10.1038/s41598-020-72614-2

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Abstract/Summary

Palaeoenvironmental reconstructions of the interior of South Africa show a wetter environment than today and a non-analogous vegetation structure in the Early Pleistocene. This includes the presence of grasses following both C3 and C4 photosynthetic pathways, whereas C3 grasses decline after the mid-Pleistocene transition (MPT, c. 1.2–0.8 Ma). However, the local terrestrial proxy record cannot distinguish between the potential drivers of these vegetation changes. In this study we show that low glacial CO2 levels, similar to those at the MPT, lead to the local decline of C3 grasses under conditions of decreased water availability, using a vegetation model (LPX) driven by Atmosphere–Ocean coupled General Climate Model climate reconstructions. We modelled vegetation for glacial climates under different levels of CO2 and fire regimes and find evidence that a combination of low CO2 and changed seasonality is driving the changes in grass cover, whereas fire has little influence on the ratio of C3:C4 grasses. Our results suggest the prevalence of a less vegetated landscape with limited, seasonal water availability, which could potentially explain the much sparser mid-Pleistocene archaeological record in the southern Kalahari.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1038/s41598-020-72614-2
UKCEH and CEH Sections/Science Areas:	Hydro-climate Risks (Science Area 2017-)
ISSN:	2045-2322
Additional Information. Not used in RCUK Gateway to Research.:	Open Access paper - full text available via Official URL link.
Additional Keywords:	environmental sciences, palaeoecology
NORA Subject Terms:	Ecology and Environment
Date made live:	04 Nov 2020 15:02 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/528837

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