Gas exchange and hydraulic strategies of pasture species under climate change
High temperature and drought are two of the major environmental factors constraining plant growth and distribution across the globe. Model predicted increases in global surface temperatures and drought are set to exacerbate these limitations, particularly in ecosystems which are highly sensitive to climate change, such as grasslands. Grasslands are major terrestrial ecosystems covering ~70% of Australia’s and more than 40% of all land surfaces (McIvor, 2005), they support a wealth of biodiversity and are responsible for storing more than one-third of global terrestrial carbon stocks (Trumper et al. 2009). Grasslands also have significant economic importance and underpin forage production, with the livestock and dairy industries relying primarily on grasslands for feed. Hence, understanding the response of grasslands to climate change induced warming and drought is of considerable environmental and economic importance.
Plant traits associated with the exchange of carbon and the transport of water are key determinants of plant survival and growth (Boyer 1996), and the analysis of these traits in response to future climatic conditions can provide a quantitative tool for determining the capacity of species to respond to shifts in climate (Creek et al. 2018; Li et al. 2015; Mitchell et al. 2014). Carbon assimilation rates, xylem hydraulic function and primary production are intimately linked as carbon assimilation rates dictate biomass production, and much of the variation in assimilation under nominal and stressed conditions is accounted for by hydraulic limitation due to the shared stomatal pathway that exists for water and carbon exchange (Brodribb 2009).
My PhD project aims to investigate species-specific differences in key plant functional traits associated with gas exchange and hydraulic function in a variety of widely cultivated pasture species, and identify the response of these traits to predicted increases in temperature and drought.
My research will help provide a mechanistic understanding for species and ecosystem level responses to abiotic stress and allow for the identification of more resilient cultivars. Ultimately, my research will provide insight into how species widely used in pastures will perform under future climate scenarios and help evaluate species selection strategies that may mitigate the effects of climatic changes, contributing to a more sustainable and profitable livestock and dairy industry.
Professor David Tissue, A/Professor Brendan Choat, Professor Sally Power, Professor Belinda Medlyn
Churchill AC, Zhang H, Fuller KJ, Amiji B, Anderson IC, Barton CVM, Carrillo Y, Catunda KLM, Chandregowda MH, Igwenagu C, Jacob V, Kim GW, Macdonald CA, Medlyn BE, Moore BD, Pendall E, Plett JM, Post AK, Powell JR, Tissue DT, Tjoelker MG, Power SA, (2022) 'Pastures and Climate Extremes: Impacts of Cool Season Warming and Drought on the Productivity of Key Pasture Species in a Field Experiment', Frontiers in Plant Science, vol.13, Article no.836968
Zhang H, Powell JR, Plett JM, Churchill AC, Power SA, Macdonald CA, Jacob V, Kim GW, Pendall E, Tissue D, Catunda KM, Igwenagu C, Carrillo Y, Moore BD, Anderson IC, (2021) 'Climate warming negates arbuscular mycorrhizal fungal reductions in soil phosphorus leaching with tall fescue but not lucerne', Soil Biology and Biochemistry, vol.152, Article no.108075
Zhang H, Powell JR, Power SA, Churchill AC, Plett JM, Macdonald CA, Jacob V, Kim GW, Pendall E, Tissue DT, Catunda KLM, Igwenagu C, Carrillo Y, Moore BD, Anderson IC, (2021) 'Arbuscular mycorrhizal fungal-mediated reductions in N2O emissions were not impacted by experimental warming for two common pasture species', Pedobiologia, vol.s 87-88, Article no.150744
Jacob V, Zhang H, Churchill AC, Yang J, Choat B, Medlyn BE, Power SA, Tissue DT, (2020) 'Warming reduces net carbon gain and productivity in medicago sativa l. And festuca arundinacea', Agronomy, vol.10, no.10, Article no.1601
Aspinwall MJ, Jacob VK, Blackman CJ, Smith RA, Tjoelker MG, Tissue DT, (2017) 'The temperature response of leaf dark respiration in 15 provenances of Eucalyptus grandis grown in ambient and elevated CO2', Functional Plant Biology, vol.44, no.11, pp 1075-1086