Lead Investigator: Dr Hannah Carle (WSU)

Co-Investigators: Associate Professor Paul Rymer (WSU)

Project Summary: Restoration and conservation actions increasingly need to incorporate climate resilience planning. A preliminary step in addressing this need is to assess the sensitivity and resilience of species across floral diversity, so to better target interventions where most needed.

In a glasshouse experiment at HIE, we planted tube stock of 32 Cumberland Plains species representing the broad floral diversity of Cumberland Plain Woodlands and local wet and dry sclerophyll forests: different plant types (e.g. trees, C3/4 grasses), climate distributions, and degrees of commonness versus restrictedness in the landscape. Phase 1: These plants were grown in one of four temperatures (20-35°C) with daily maximum temperatures of 24-39°C. In each temperature bay, half the plants were well-watered, half were water-limited to emulate chronic, low-moderate water stress. Phase 2: After two months, two/four bays were retained, and plants from these bays were periodically moved into a 5-day heatwave at 35-39°C.

We tracked (weekly) canopy desiccation, mortality and reproduction. In Phase 1, stomatal conductance, chlorophyll fluorescence and leaf temperatures were measured. In Phase 2, heatwave and control plants were tracked in detail for stomatal conductance, fluorescence, leaf temperature, leaf water potentials (this project), and spectral signatures (PhD Zahra Emlaei). On Day 5 (peak heatwave exposure), plants were sampled for measurements of leaf critical temperature (Pieter Arnold, ANU). For a subset of plants from 8 diverse species, we logged leaf temperatures and soil moisture throughout heatwave exposure. All Phase 2 plants were destructively harvested for biomass measurements at the end of the experiment.

These detailed physiological, morphometric and demographic measurements will enable quantitative assessment of the thresholds of climate sensitivity for these 32 species, with statistical modelling to identify the mechanisms underpinning relative sensitivity and resilience at species level.