Dushan Kumarathunge

Candidature

PhD Candidate

Thesis title

Scaling the impact of temperature on overall plant growth: A modeling approach

Research Project

Dushan KumarathungePlant metabolic processes are directly affected by the thermal environment in which the plants are growing. Understanding how the effects of temperature on individual physiological processes combine to determine the overall effect on growth is of paramount importance in predicting plant growth responses in future climates. My PhD research is designed with the broad objective of modelling the impact of rising temperatures on plant growth by examining whole-plant eco-physiological responses. It will link temperature dependency of leaf level physiology to whole plant level followed by ecosystem scale. My focus is to understand the key processes contributing to the temperature effect on photosynthesis and growth and improve the temperature –growth relationship currently used in process-based forest growth models. Broadly, my research comprises the following components:

  1. A synthesis of plant photosynthetic temperature responses:
  2. Modelling temperature response of growth
  3. Modelling growth responses of Australian forests across temperature gradient

I use three models, MAESPA; model of canopy radiation interception and photosynthesis, GDAY (Generic Decomposition and Yield); a simple ecosystem model that simulates carbon, nitrogen, and water dynamics at the stand scale and a carbon balance model which utilizes leaf level net photosynthetic rates to allocate daily C assimilate towards biomass production of stems, leaves, fine roots and coarse roots. My fieldwork includes measurement of range of physiological parameters in Whole Tree Chamber (WTC) and glasshouse experiments.

Publications

Drake JE, Tjoelker MG, Varhammar A, Medlyn BE, Reich PB, Leigh A, Pfautsch S, Blackman CJ, Lopez R, Aspinwall MJ, Crous KY, Duursma RA, Kumarathunge D, De Kauwe MG, Jiang M, Nicotra AB, Tissue DT, Choat B, Atkin OK, Barton CVM, (2018) 'Trees tolerate an extreme heatwave via sustained transpirational cooling and increased leaf thermal tolerance', Global Change Biology, vol.24, no.6, pp 2390-2402

Drake JE, Varhammar A, Kumarathunge D, Medlyn BE, Pfautsch S, Reich PB, Tissue DT, Ghannoum O, Tjoelker MG, (2017) 'A common thermal niche among geographically diverse populations of the widely distributed tree species Eucalyptus tereticornis: No evidence for adaptation to climate-of-origin', Global Change Biology, vol.23, no.12, pp 5069-5082

Research Project Supervisors

Professor Belinda Medlyn, Professor Mark Tjoelker and Dr John Drake