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Refugia are key environments in biogeography and conservation. Because of their unique eco‐evolutionary formation and functioning, they should display distinct functional trait signatures. However, comparative trait‐based studies of plants in refugia and non‐refugia are lacking. Here, we provide a comparison between resource‐rich (putative microrefugia for species preferring mesic habitats under increasing aridity) and resource‐impoverished woodlands (non‐refugia) around two granite outcrops in south‐western Australia. We measured and compared six functional traits (bark thickness, foliar δ13C, foliar C:N, leaf dry matter content, plant height, specific leaf area) in four woody species. We performed multiple‐trait, multiple‐species and single‐trait, within‐species analyses to test whether plants in resource‐rich habitats were functionally distinct and more diverse than those in the surrounding resource‐impoverished woodlands. We found that species in resource‐rich woodlands occupied larger and distinct multiple‐trait functional spaces and showed distinct single‐trait values (for specific leaf area and bark thickness). This suggests that plants in resource‐rich woodlands can deploy unique and more diverse ecological strategies, potentially making these putative microrefugia more resilient to environmental changes. These findings suggest that species in microrefugia may be characterised by unique functional signatures, illustrating the utility of comparative trait‐based approaches to improve understanding of the functioning of refugia. [ABSTRACT FROM AUTHOR]

Abstract: Plants respond to changing environmental conditions, and their ability to adjust intra‐specifically to such shifts represents an ecological and evolutionary advantage. We studied seven plant traits for two common, rhizomatous granite outcrop species (the fern Cheilanthes austrotenuifolia, and the herb Stypandra glauca) with seasonal foliage during the cooler, wetter winter months at seven sites across an aridity gradient in southwestern Australia. We investigated trait patterns at regional and habitat scale, by investigating changes in trait values along the aridity gradient, and by comparing two different habitats types (sun‐exposed and sheltered). We expected plants occurring in more arid sites and highly irradiated, shallow‐soil (sun‐exposed) habitats, to exhibit traits indicative of more conservative resource acquisition, retention and use strategies. At the habitat scale, we found support for our prediction, with plants in more stressful, sun‐exposed habitats showing traits’ values associated with more conservative strategies (especially for water), such as smaller plants, denser leaves, higher foliar δ13C and C/N. However, at the regional scale many traits displayed the opposite pattern, suggesting less conservative resource acquisition in more arid sites. This evidence was particularly pronounced for specific leaf area (SLA), which exhibited a significant, positive relationship with increasing aridity. We suggest that the unexpected regional trends in foliar traits relate to shorter lived, faster growing leaves linked to highly efficient resource acquisition and use strategies during the shorter growing season in the more arid regions. These highly exploitative strategies may enable plants to avoid climate extremes, that is, hot and dry periods in the more arid sites. Our findings of contrasting foliar traits responses at different scales support the importance of multi‐scale approaches to quantify the role of intraspecific trait variability. [ABSTRACT FROM AUTHOR]

Microsites are created by abiotic and biotic features of the landscape and may provide essential habitats for the persistence of biota. Forest canopies and understorey plants may moderate wind and solar radiation to create microclimatic conditions that differ considerably from regional climates. Skirt‐forming plants, where senescent leaves create hut‐like cavities around the stem, create microsites that are sheltered from ambient conditions and extreme weather events, constituting potential refuges for wildlife. We investigate day and night temperatures and humidity for four locations (grass tree cavities, soil, 20 cm above‐ground, 1 m above‐ground) in a South Australian forest with relatively open canopy of stringybark eucalypts (Eucalyptus baxteri, E. obliqua) and an understorey of skirt‐forming grass trees (Xanthorrhoea semiplana) at 5, 10, 20, and 40 m from the forest edge. We also measured the percentage of canopy and understorey covers. Generally, temperature and humidity differed significantly between more sheltered (grass tree cavities, soil) and open‐air microsites, with the former being cooler during the day and warmer and more humid during the night. Furthermore, our results suggest that canopy cover tends to decrease, and understorey cover tends to increase, the temperature of microsites. Distance to the edge was not significantly related to temperature for any microsite, suggesting that the edge effect did not extend beyond 10 m from the edge. Overall, grass trees influenced microclimatic conditions by forming a dense understorey and providing cavities that are relatively insulated. The capacity of grass tree cavities to buffer external conditions increased linearly with ambient temperatures, by 0.46°C per degree increase in maximum and 0.25°C per degree decrease in minimum temperatures, potentially offsetting climate warming and enabling persistence of fauna within their thermal limits. These climate moderation properties will make grass trees increasingly important refuges as extreme weather events become more common under anthropogenic climate change. [ABSTRACT FROM AUTHOR]

Identifying refugia is a critical component of effective conservation of biodiversity under anthropogenic climate change. However, despite a surge in conceptual and practical interest, identifying refugia remains a significant challenge across diverse continental landscapes. We provide an overview of the key properties of refugia that promote species' persistence under climate change, including their capacity to (i) buffer species from climate change; (ii) sustain long-term population viability and evolutionary processes; (iii) minimize the potential for deleterious species interactions, provided that the refugia are (iv) available and accessible to species under threat. Further, we classify refugia in terms of the environmental and biotic stressors that they provide protection from (i.e. thermal, hydric, cyclonic, pyric and biotic refugia), but ideally refugia should provide protection from a multitude of stressors. Our systematic characterization of refugia facilitates the identification of refugia in the Australian landscape. Challenges remain, however, specifically with respect to how to assess the quality of refugia at the level of individual species and whole species assemblages. It is essential that these challenges are overcome before refugia can live up to their acclaim as useful targets for conservation and management in the context of climate change. [ABSTRACT FROM AUTHOR]