Dataset Information

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

ABSTRACT: 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.

SUBMITTER: Ecker M

PROVIDER: S-EPMC7530989 | biostudies-literature | 2020 Oct

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

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

Ecker Michaela M Kelley Douglas D Sato Hiromitsu H

Scientific reports 20201001 1

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. ...[more]

PMID: 33004831

Similar Datasets

Project description:Haasgat is a primate-rich fossil locality in the northeastern part of the Fossil Hominid Sites of South Africa UNESCO World Heritage Site. Here we report the first hominin identified from Haasgat, a partial maxillary molar (HGT 500), that was recovered from an ex situ calcified sediment block sampled from the locality. The in situ fossil bearing deposits of the Haasgat paleokarstic deposits are estimated to date to slightly older than 1.95 Ma based on magnetobiostratigraphy. This places the hominin specimen at a critical time period in South Africa that marks the last occurrence of Australopithecus around 1.98 Ma and the first evidence of Paranthropus and Homo in the region between ?2.0 and 1.8 Ma. A comprehensive morphological evaluation of the Haasgat hominin molar was conducted against the current South African catalogue of hominin dental remains and imaging analyses using micro-CT, electron and confocal microscopy. The preserved occlusal morphology is most similar to Australopithecus africanus or early Homo specimens but different from Paranthropus. Occlusal linear enamel thickness measured from micro-CT scans provides an average of ?2.0 mm consistent with Australopithecus and early Homo. Analysis of the enamel microstructure suggests an estimated periodicity of 7-9 days. Hunter-Schreger bands appear long and straight as in some Paranthropus, but contrast with this genus in the short shape of the striae of Retzius. Taken together, these data suggests that the maxillary fragment recovered from Haasgat best fits within the Australopithecus-early Homo hypodigms to the exclusion of the genus Paranthropus. At ?1.95 Ma this specimen would either represent another example of late occurring Australopithecus or one of the earliest examples of Homo in the region. While the identification of this first hominin specimen from Haasgat is not unexpected given the composition of other South African penecontemporaneous site deposits, it represents one of the few hominin localities in the topographically-distinct northern World Heritage Site. When coupled with the substantial differences in the mammalian faunal communities between the northern localities (e.g., Haasgat, Gondolin) and well-sampled Bloubank Valley sites (e.g., Sterkfontein, Swartkrans, Kromdraai), the recovery of the HGT 500 specimen highlights the potential for further research at the Haasgat locality for understanding the distribution and interactions of hominin populations across the landscape, ecosystems and fossil mammalian communities of early Pleistocene South Africa. Such contextual data from sites like Haasgat is critical for understanding the transition in hominin representation at ?2 Ma sites in the region from Australopithecus to Paranthropus and early Homo.

Dataset Information

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

Publications

Modelling the effects of CO<sub>2</sub> on C<sub>3</sub> and C<sub>4</sub> grass competition during the mid-Pleistocene transition in South Africa.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets