Australian native plants are remarkably tolerant to a wide range of environmental conditions in which they grow. However, as the climate changes, background warming and extreme climatic events are pushing even the toughest plants closer to their limits. We have developed and applied new approaches to assess the tolerance of photosystems using chlorophyll fluorescence to evaluate the sensitivity of plants to increasing heat load. We then conducted a broad botanical garden survey to test how intrinsic heat tolerance of photosynthetic tissue differs among phylogenetically and morphologically diverse species. These sensitivity data combined with functional traits and environmental variables allowed us to explore the standing variation in tolerance of Australian flora. Preliminary analyses show that soil temperature, seed source environment, and growth form play roles in describing diversity in tolerance and sensitivity of photosynthetic tissue. Plants that have higher leaf water content, lower leaf density, and higher leaf mass per area generally were more sensitive to heat load, but substantial variation in heat tolerance remained unexplained by leaf traits. Using our recently established Thermal Load Sensitivity framework that integrates heat exposure with damage and repair processes, we also simulated scenarios parameterised by these data to identify conditions that could lead to photosystem damage. Our current research builds upon this study to investigate the capacity for plants to repair damage, restore function, and to determine how different life stages and tissue types are affected by heat, to better understand impacts of heat across the life cycle of native plants.

Under global climate change, heatwaves are occurring more frequently and becoming more severe. In high-elevation regions, where warming temperatures are further exacerbated, extreme heat events will likely push species beyond their tipping points, forcing community and distribution change. As well as warmer days, heatwaves also manifest warmer nights. The photosystems in the leaves of plants typically undergo physiological recovery overnight, allowing them to cope with moderate daytime heat stress. Without cool overnight temperatures and limited capacity for recovery, chronic heat stress in plants may compound. In alpine regions, where growing seasons are characteristically mild and short, elevated overnight temperatures may actually promote growth and hence be beneficial. To resolve whether warm nights will help or hinder alpine vegetation communities, it is vital to understand how different species respond under natural conditions. However, simulating warming at night in situ (under field conditions) has been methodologically challenging as ambient night-time temperatures are often too cool to maintain passive heating, particularly in alpine systems. Here, we simulated combinations of acute diurnal and nocturnal heating in a sub-alpine grassland using bespoke heatwave chambers that combine passive warming and active convective heating. Following a four-day heatwave, photosystem heat tolerance of in situ vegetation was measured using chlorophyll fluorometry. We were able to effectively increase air temperature in overnight treatment chambers despite subzero ambient temperatures. Warm nights did not always hinder plant heat responses as anticipated. For some species, cumulative day/night heating was associated with an increase in heat tolerance in response to the compounding stress treatment. This result raises questions surrounding the trade-off of upregulating heat tolerance. Future studies should seek to understand the downstream effects of short-term stress responses, particularly under compounding and repeated heat events.

Western Australia's unique biodiversity is increasingly threatened by the impacts of anthropogenic climate change, compounding existing pressures such as habitat loss and altered fire regimes. Banksia menziesii and B. ilicifolia, foundation species of several threatened ecological communities, exemplify the vulnerability of native flora to these intensifying environmental changes.
This project investigates the capacity for local adaptation and the movement of advantageous alleles in these two keystone species, whose natural distributions span strong climate gradients across southwest Western Australia. Through population genomics and genotype-environment association analyses, the study aims to uncover the genetic basis of adaptation to local climates and identify climate-associated alleles.
In addition to landscape genomic analyses, controlled-environment experiments are being used to test fitness and stress responses of individuals from different climatic origins. These combined approaches will reveal how existing genetic variation may support resilience, and whether gene flow between populations could enhance adaptive capacity in the face of ongoing climate shifts.
Outcomes of this research will inform science-based conservation strategies, including the potential for targeted genetic rescue, assisted gene migration, and climate-ready restoration planning. As climate change increasingly threatens the viability of locally adapted populations, this work will provide critical evidence to guide adaptive management and preserve the evolutionary potential of iconic Banksia species and the ecological communities they support.

Energy is a fundamental currency in food web ecology, needed for metabolic maintenance, growth, and reproduction. Prey energy content and nutritional value, rather than purely organism abundance, is important for determining food web functioning in coastal ecosystems vulnerable to climate extremes including droughts and floods. The Coorong estuary and hypersaline lagoon at the terminus of the Murray-Darling River system is exposed to altered flow regimes due to river regulation, water extraction, and climate change. We aimed to determine the energy content (kJ/g biomass) of key prey (benthic macroinvertebrates and fishes) to determine how energy density (kJ/m2) changes through time and space. Macroinvertebrates and fishes were sampled throughout the estuary and lagoon with their energy content measured by bomb calorimetry. Combining energy content with biomass data from annual monitoring surveys allowed calculation of energy density from 2018–2023, a period encompassing dry years and the largest Murray River flood since 1956. Energy density decreased significantly between the estuary and lagoon, driven by reduced freshwater flows and increased salinities outside flooding periods. One fish species, the salt-tolerant small-mouth hardyhead, dominated energy density in the hypersaline lagoon. The region of highest energy densities contracted during low flow periods and expanded under higher flows. The flood event initially decreased energy densities in the estuary but allowed prey to expand into previously inhospitable regions. After the flood, energy densities of both macroinvertebrates and fish increased substantially in the South Coorong, a region where ecological condition had deteriorated, particularly since the Millennium Drought. The spatial and temporal patterns of prey energy density in relation to flow enhanced our understanding of trophic dynamics in temperate estuaries exposed to climatic extremes, and demonstrated that increasing environmental flows could enhance energy provisioning for predators such as large fish and birds in the southern expanse of the ecosystem.

Many organisms are shifting their ranges uphill, toward the poles, or to deeper waters in response to climate change, tracking their optimal niches. However, 20-37% of the recoded species are shifting toward the equator, downhill, or to shallower waters, that is, range shifts counterintuitive to what is expected under climate change. Despite the prevalence and potential importance of counterintuitive shifts, they are seldom predicted by the species distribution models on which conservation decisions often rely, and we have remarkably few hypotheses as to why species might exhibit counterintuitive shifts. We propose the ‘Interaction Opportunists Hypothesis’, which formalises the idea that counterintuitive shifts could arise from climate change-induced alterations in biotic interactions at the warm edge of species’ distributions. Reductions in antagonistic interactions, increases in positive interactions, or changes in the type or outcome of biotic interactions could make previously unsuitable habitats viable parts of a species’ range. Our hypothesis provides a generalisable framework to explain counterintuitive shifts across diverse systems.