Rhodes>Botany>Staff>Brad Ripley

Prof Brad Ripley

I am a plant ecophysiologist, specialising in the response of natural vegetation and crop systems to climate change. This includes understanding the role of climate and increasing atmospheric CO2 concentrations on the ecophysiology and ecology of C3 and C4 grasses, woody thickening of savanna systems, and climate change effects on invasive plants, plant food value and biological control. In crop systems I am interested in how elevated CO2 mitigates effects of increased temperature and drought on plant productivity and yield. I am also interested in the implications of these eCO2 and climate induced changes on the management of systems and the use of tools such as fire and biological control agents.


Response of natural vegetation to climate change and eCO2:

Savana systems depend on interactions between C3 trees and C4 grasses. The differences in photosynthetic physiology between these functional groups results in fundamental differences in the way in which they respond to climate and eCO2. This has the potential to alter trees-grass interactions and savanna function. These differences have been used to explain current observations of woody thickening of savanna globally. However, woody thickening and bush encroachment show a high degree of variability geographically and in response to differences in abiotic and biotic interactions. My work aims to understand this complexity and differences in responses to eCO2. I am also interested in how changes to historic CO2 concentrations and climate have driven plant evolution, vegetation change and the performance of plants.


Response of crop and applied systems to climate change and eCO2:

Future prediction are for a warmer, drier world for much of the Worlds crop growing regions. Both drought and increased temperatures are detrimental to crop production and yield. eCO2 can offset these negative effects, the magnitude of which depends on species and genotypic differences and the magnitude timing of climate stress. My work aims to quantify these effects and help to develop efficient system of screening genotypes suitable for a future world. Change climate and eCO2 also effects plant response to herbivory with important consequences for the use of biological control agents.


Recent publications:


BS Ripley, P Mavindidza, CS Mutengwa (In submission) Can response of wheat genotypes to elevated temperature, atmospheric CO2 concentration and drought can be predicted by the response patterns to current ambient conditions? Agronomy Journal.



SL Raubenheimer, BS Ripley (2022) CO2-stimulation of savanna tree seedling growth depends on interactions with local drivers. J. Ecol, in press.

BS Ripley, TM Bopape, S Vetter (2022) A doubling of atmospheric CO2 mitigates the effects of severe drought on maize through the preservation of soil water. Annals of Botany, in press.

SL Raubenheimer, K Simpson, R Carkeek, BS Ripley (2021) Could CO2-induced changes to C4 grass flammability aggravate savanna woody encroachment? African Journal of Range & Forage Science, 1-14.

NC Baso, JA Coetzee, BS Ripley, MP Hill (2021) The effects of elevated atmospheric CO2 concentration on the biological control of invasive aquatic weeds. Aquatic Botany 170, 103348, 5.

Z Faltein, KJ Esler, GF Midgley, BS Ripley (2020) Atmospheric CO2 concentrations restrict the growth of Oxalis pes-caprae bulbs used by human inhabitants of the Paleo-Agulhas plain during the Pleistocene glacials. Quaternary Science Reviews 235, 105731, 7.

BS Ripley, A Edwardes, MW Rossouw, VR Smith, GF Midgley (2020) Invasive grasses of sub-Antarctic Marion Island respond to increasing temperatures at the expense of chilling tolerance. Annals of botany 125 (5), 765-773, 3.

R Mathakutha, C Steyn, PC le Roux, IJ Blom, SL Chown, BH Daru, BS Ripley...(2019) Invasive species differ in key functional traits from native and non‐invasive alien plant species. Journal of Vegetation Science 30 (5), 994-1006, 35. 

KJ Simpson, JK Olofsson, BS Ripley, CP Osborne (2019) Frequent fires prime plant developmental responses to burning. Proceedings of the Royal Society B 286 (1909), 20191315, 9.

MR Lundgren, LT Dunning, JK Olofsson, JJ Moreno‐Villena, JW Bouvier, BS Ripley, ...(2019) C4 anatomy can evolve via a single developmental change. Ecology letters 22 (2), 302-312, 31.

LL Nackley, A Betzelberger, A Skowno, AG West, BS Ripley, WJ Bond (2018)CO2 enrichment does not entirely ameliorate Vachellia karroo drought inhibition: A missing mechanism explaining savanna bush encroachment. Environmental and Experimental Botany 155, 98-106,     10.

S Archibald, CER Lehmann, CM Belcher, WJ Bond, RA Bradstock, BS Ripley ...(2018) Biological and geophysical feedbacks with fire in the Earth system. Environmental Research Letters 13 (3), 033003, 113.

O Nokelainen, E van Bergen, BS Ripley, PM Brakefield (2018) Adaptation of a tropical butterfly to a temperate climate. Biological Journal of the Linnean Society 123 (2), 279-289, 10.

AL Skowno, MW Thompson, J Hiestermann, BS Ripley, AG West, WJ Bond (2017) Woodland expansion in South African grassy biomes based on satellite observations (1990–2013): general patterns and potential drivers. Global change biology 23 (6), 2358-2369, 86.


Graduated Students and Post-Doctoral Fellows:

Postdoctoral Fellows: Gillian Dolnald, Sam Taylor, Ossi Nokelainen. PhDs: Sarah Raubenheimer, Andrew Skowno, Matthew Gilbert, Doug Ibrahim. MScs: Peter Mavindidze, Tebadi Bopape, Nompumelelo Baso, Kervin Prayag, Maurice Anderson, Claire Adams, Lavinia Perumal, Nicole Moore, Nic Venter, Christna Klopper, Tarryn Martin, Kirsten Frole, Andrew White, Trevor Abraham, Claire Fraser, Seranne Howis, Lilian Kiguli, Craig Peter.

Last Modified: Tue, 15 Feb 2022 17:38:05 SAST