Erin Rogers

Candidature

PhD Candidate

Thesis title

Phosphorus-adaptive traits linking soil phosphorus specialisation and species distribution across Australia

Research project

Phosphorus (P) is an important nutrient for plant growth and reproduction. Alongside nitrogen (N), it is considered to limit instantaneous photosynthesis at the leaf and ecosystem level, with implications for global productivity and carbon sequestration. Much of the southern hemisphere’s land contains moderately to strongly P-limited ecosystems, where soils tend to have low concentrations of P (both total [P] and available [P]) compared with those in the northern hemisphere. Plants need adequate supplies of P in leaves to fuel the biochemical processes behind photosynthesis such as the cycling of the precursors ATP and NADP and as a component of RuBP, PGA, and PGAL sugars. The importance of P for plant growth and cellular function has led to the evolution of a suite of functional traits to facilitate access and use of available P. Adaptations to specific soil P concentrations may also limit species distributions, resulting in spatial structuring of plant communities in response to soil P. Phosphorus-related functional traits may play a role in linking the edaphic component of plant physiology with species occurrence and distribution. The role of P in shaping plant distribution is particularly relevant in Australia where much of the continent’s soils have undergone extensive weathering and thus P-leaching, with the exception of past volcanism along the east coast creating pockets of high P basaltic soils.

The key scientific question driving my thesis will be asking which P-adaptive traits delineate low-P specialist plants (beyond our iconic P-specialist Proteaceae) and explores whether P-adaptive traits associate with a plants’ soil P-niche across the Australian continent. To address this question, I have designed three separate studies. Chapter One will focus on quantifying the variation in photosynthesis that is influenced by soil P by measuring the photosynthetic biochemistry and leaf nutrients of Australian plants (i.e., the ‘photosynthetic phenotype’ of P-limited plants) along climate and soil fertility gradients across the continent. Chapter Two will ask at what concentration of soil P do distinct P-adaptive traits emerge? I will focus on quantifying at what soil P concentration plants substitute lipid-P in their leaves for non-phospholipid compounds such as galactolipids and sulfolipids (a trait important for low-P specialist), I will do this across a broad range of taxa along the natural P gradient of the Cooloola soil chronosequence. Chapter Three will focus on a suite of whole plant functional traits, including root and leaf physiological traits that are adaptive to P, to ask which traits contribute to a species being associated with a soil P-niche, and thus species distributions, taking an Australia-wide approach.

Australia is not the only continent containing P-poor soils. Some estimate approximately 43% of natural terrestrial land is significantly limited by P. Most terrestrial P-limitation occurs within tropical, subtropical and temperate biomes all of which are highly productive on a ground area basis and contain some of the highest levels of species diversity, despite being nutrient-poor. Broadly, my thesis will link species taxonomic grouping, plant traits and P-specialisation across the globally significant P-poor landscape that is Australia. By contributing insights to the key question of why some species can survive where, my thesis may provide a framework to investigate the interplay between species co-occurrence and distribution, P-adaptive and whole plant functional traits, and soil fertility across P-poor landscapes outside of Australia.

Publications

Rogers, E. I E., Mehnaz, K. R., Ellsworth, D. S. (2024) Stimulated photosynthesis of regrowth after fire in coastal scrub vegetation: increased water or nutrient availability? Tree Physiology. https://doi.org/10.1093/treephys/tpae079

Crous, K. Y., Cheesman, A., Middleby, K., Rogers, E. I. E., Wujeska-Klause, A., Bouet, A., Ellsworth, D. S., Liddell, M., Cernusak, L., Barton, C. V. M. (2023) Similar patterns of leaf temperatures and thermal acclimation to higher leaf temperatures in a temperate and tropical tree canopy. Tree Physiology. https://doi.org/10.1093/treephys/tpad054

Wallach, A.D., Ramp, D., Benitez-Lopez, A., Wooster, E. I. F., Carroll, S., Carthey, A. J. R., Rogers, E. I. E., Middleton, O., Zawada, K. J. A., Svenning, J., Avidor, E., Lundgren, E. (2022) Savviness of prey to introduced predators. Conservation Biology. 10.1111/cobi.14012

Douglas, A. N. J., Morgan, A. L., Rogers, E. I. E., Irga, P. J., Torpy, F. R. (2021) Evaluating and comparing the green wall retrofit suitability across major Australian cities. Journal of Environmental Management. https://doi.org/10.1016/j.jenvman.2021.113417
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Supervisor

David Ellsworth