Alexis Renchon

Candidature

PhD Candidate

Thesis title

Constraints on Ecosystem Carbon and Water Flux Estimates in Temperate Australian Evergreen Brodleaf Forests

Research project

Alexis RenchonThe carbon cycle plays a primary role in climate change. Natural ecosystems mitigate the rise of atmospheric CO2 by sequestrating more carbon via photosynthesis than emitting carbon via respiration. To date, we can only directly measure the net exchange of CO2 between an ecosystem and the atmosphere (NEE) via the eddy-covariance method. We partition daytime NEE into gross ecosystem production and ecosystem respiration using climatic driver of nighttime NEE (when only respiration occur). These partitioning methods have been defined mostly by studying deciduous and boreal ecosystems, but their transferability to evergreen ecosystems may not be valid. I will test and modify standard partitioning methods in Australian temperate eucalypt forests. Gross ecosystem production will be compared with a mechanistic model which bridges the leaf to ecosystem scale. This will help to identify critical conditions where there is a lack of understanding of the underlying mechanisms governing gross ecosystem production that will aid directing future studies. Ultimately, my PhD will improve our understanding of ecosystem carbon budgets in Australian ecosystems.

Publication

Renchon AA, Griebel A, Metzen D, Williams CA, Medlyn B, Duursma RA, Barton CVM, Maier C, Boer MM, Isaac P, Tissue D, de Dios VR, Pendall E, (2018) 'Upside-down fluxes Down Under: CO2 net sink in winter and net source in summer in a temperate evergreen broadleaf forest', Biogeosciences, vol.15, no.12, pp 3703-3716

Leopold A, Marchand C, Renchon A, Deborde J, Quiniou T, Allenbach M, (2016) 'Net ecosystem CO2 exchange in the "Coeur de Voh" mangrove, New Caledonia: Effects of water stress on mangrove productivity in a semi-arid climate', Agricultural and Forest Meteorology, vol.223, pp 217-232

Supervisors

Professor Elise Pendall, Professor Belinda Medlyn and A/Professor Matthias Boer