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Bree Laugier

Candidature

PhD Candidate

Thesis Title

Pushing the Envelope: Does Range Size Limit Eucalypt Tolerance to Warming?

Research Project

Bree LaugierThe climate envelopes that species have experienced for millennia are rapidly changing. For long-lived and sessile trees, such as eucalypts, survival relies on their physiological flexibility to adapt to a warming climate. In general, it is expected that climatically suitable conditions will continue to shift in relation to tree species’ current geographical ranges, causing them to contract at climate-defined range margins where they can no longer tolerate rapidly changing climatic conditions.
Geographic range size has long been analysed to determine global principles that explain patterns of diversity and distribution, however the link between range size and tolerance to climate warming is unclear. Due to exposure to more varying climates within their natural geographic boundaries, it is predicted that species with widespread ranges will have increased tolerance to climate warming than narrowly distributed species.
However, geographic boundaries may not necessarily represent physiological tolerance limits of species. Meaning that geographically narrow-ranged eucalypt species may be able to survive outside the enveloped temperature or rainfall limits of their geographic distributions and are otherwise constrained by non-climatic environmental conditions, dispersal limitations or biological interactions. To predict eucalypt species future distributions and extinction risk more accurately under a warming climate, it is imperative that correlations between geographically experienced thermal niches and physiological fundamental thermal niches are analysed.
Identifying whether narrow-ranged species have the capability to tolerate temperatures outside their current climatic envelopes could indicate a greater ability to tolerate climate warming. On the other hand, species with fundamental thermal niches that are narrower than predicted temperature increases are likely to have a reduced capacity to respond to climate warming and a greater extinction risk.
My project aims to investigate biogeographic patterns of eucalypt fundamental thermal tolerance limits through empirical tests of growth responses to wide-ranging and high temperatures of diverse eucalypt taxa to better understand how species can physiologically adapt and respond to temperatures outside of their current climatic envelopes.

Publication

Esperon-Rodriguez M, Tjoelker MG, Lenoir J, Laugier B, Gallagher RV, (2024) 'Wide climatic niche breadth and traits associated with climatic tolerance facilitate eucalypt occurrence in cities worldwide', Global Ecology and Biogeography, vol.33, no.6, e13833

Supervisors

Professor Mark Tjoelker, A/Professor Rachael Gallagher, Dr Manuel Esperon-Rodriguez, Dr Kristine Crous