Projects
Feast or famine
How Australian plants stay productive under low phosphorus. Phosphorus (P) is in low supply in soils around the nation, and limits plant production in the Australian landscape, as well as for many tropical forests worldwide. How scarce P restricts photosynthetic capacity has remained elusive. We will determine how Australian plants achieve high phosphorus-use efficiency despite low P concentrations in leaves and soils. We will synthesise knowledge of how plants maintain productivity with low P availability, and inform global models how to represent P biogeochemistry and photosynthesis to improve C-cycle estimates. The understanding of plant photosynthetic and P-saving mechanisms that emerge should provide benefits through improved ecological models and enhanced management of primary production.
Pushing the envelope
Does range size limit eucalypt tolerance to warming? This project aims to characterise the biogeographic constraints on the physiological flexibility of eucalypts to accommodate climate warming. Do temperature tolerances of diverse taxa vary predictably with native geographic range sizes and climate of origin? In addressing this question, the project expects to generate new knowledge on the comparative physiological responses of diverse eucalypt taxa to warming and heat waves using controlled-environment studies and a unique facility at Western Sydney University for heat wave studies of large trees. Expected outcomes include an enhanced capacity to predict carbon exchange and growth responses of native trees to climate warming over large geographic scales.
Seasonality of carbon uptake
Prof Elise Pendall
In a four-year study at the Cumberland Plain TERN site, we found that daily net C uptake was always detected during the cooler, drier winter months (June through August), while net C loss occurred during the warmer, wetter summer months (December through February). Gross primary productivity (GPP) seasonality was low, despite longer days with higher light intensity in summer, because vapour pressure deficit (D) and air temperature (Ta) restricted surface conductance during summer while winter temperatures were still high enough to support photosynthesis. Because summer carbon uptake may become increasingly limited by atmospheric demand and high temperature, and because ecosystem respiration could be enhanced by rising temperatures, our results suggest the potential for large-scale seasonal shifts in NEE in sclerophyll vegetation under climate change. (Renchon et al., Biogeosciences, 15, 3703–3716, 2018).
In a four-year study at the Cumberland Plain TERN site, we found that daily net C uptake was always detected during the cooler, drier winter months (June through August), while net C loss occurred during the warmer, wetter summer months (December through February). Gross primary productivity (GPP) seasonality was low, despite longer days with higher light intensity in summer, because vapour pressure deficit (D) and air temperature (Ta) restricted surface conductance during summer while winter temperatures were still high enough to support photosynthesis. Because summer carbon uptake may become increasingly limited by atmospheric demand and high temperature, and because ecosystem respiration could be enhanced by rising temperatures, our results suggest the potential for large-scale seasonal shifts in NEE in sclerophyll vegetation under climate change. (Renchon et al., Biogeosciences, 15, 3703–3716, 2018).
Soil carbon climate feedbacks
Prof Elise Pendall
Greenhouse gas exchange between soils and the atmosphere can mitigate or exacerbate climate change. We have conducted several projects at the Cumberland Plain TERN site on soils spanning a hydrologic gradient from wetland to grassland to forested upland. Our findings show that decomposition of carbon in deep soils is more strongly temperature sensitive than that in shallow soils, possibly because of strong protection of deep soil by high clay content. (Li et al. Soil Biology and Biochemistry 154 (2021) 108117)
Greenhouse gas exchange between soils and the atmosphere can mitigate or exacerbate climate change. We have conducted several projects at the Cumberland Plain TERN site on soils spanning a hydrologic gradient from wetland to grassland to forested upland. Our findings show that decomposition of carbon in deep soils is more strongly temperature sensitive than that in shallow soils, possibly because of strong protection of deep soil by high clay content. (Li et al. Soil Biology and Biochemistry 154 (2021) 108117)