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Sushmita Dhakal

Candidature

PhD Candidate

Thesis title

How do Australian Native Plants stay Productive under Phosphorus-limited soils?

Research Project

Sushmita DhakalPhosphorus (P) is a key constituent of many macromolecules and is central to formation of ATP, an energy currency of cells that drives plant metabolism, growth and reproduction. If P is the lifeblood for plant growth and energy, how do plants stay productive in low-P environments? This is the very question that drives my Ph. D Research. My interest particularly centres on a phenomenon called “resorption” by which plant internally recycle and redistribute nutrients such as, P from aging old tissues to actively growing new growth. In a low nutrient environment, resorption serves as a keystone process minimizing plant’s reliance on external P supply and conserving P within the plants that is otherwise lost to the soil via leaf fall. Resorbed nutrients are readily available for plant growth and it affects important ecosystem processes such as nutrient uptake, nutrient loss rate, nutrient decomposition, plant competition and overall plant fitness. Despite the critical role of P resorption across natural ecosystems, its general pattern and underlying influences are unclear. By studying diverse array of plant species across different locations in Australia, I intend to investigate how leaf phosphorus resorption efficiency varies with soil type, geology and soil nutrient status. Initially, I will examine the pattern of P resorption efficiency (PRE) amongst species in a community and relate it with important plant traits such as, leaf lifespan. Additionally, I will explore the influence of site geology, N and P availability on P resorption efficiency. Finally, I will compare P resorption patterns among different P acquisition strategy-groups to gain insights on how plants regulate their P-uptake and P-use within and across sites with varying soil P status. My research will integrate various biological, soil and geological information in relation to plant P use which in turn will shed light on ecological trade-offs and compromises inherent to plants adaptation to P-poor environments. Such data will provide valuable insights to modelers to understand plant trait syndromes, a fundamental component of global ecological models.

Supervisors

Prof. David Ellsworth, Prof. Ian Wright, Dr Catriona Macdonald