Determining high risk vegetation communities and plant species in relation to climate change in the Australian alpine region
Adaptation Research Grants Program
To use plant functional traits in combination with existing long-term data sets to assess the risk associated with different threats to the flora of the Australian Alps, including directly from climate change (reduced snow cover, warmer summers), and indirectly (increased fires, grazing by feral animals, and summer tourism). Managers will be able to use these results to prioritize resilience adaptation strategies to climate change such as fire management, weed and feral animal control and summer tourism. In addition, native and weed species will be classified into high, moderate and low risk/invasive species so key refugia for native species can be identified, and species for rehabilitation programs, weed control and for ex situ conservation in seed banks selected.
The alpine region around Australia’s highest mountain, Mt Kosciuszko, is part of one of the three most at risk ecosystems in Australia from climate change. With higher temperatures and decreased precipitation, snow cover is already declining with even greater reductions predicted in the short to medium term (2020 to 2050). Consequently the distribution of many native plants and animals may contract, while the distribution of weeds and feral animals may expand. Wildfires in the region are also likely to be more frequent and intense.
To contribute to our understanding of how changes in the environment alter plant composition and ecological process, we conducted a series of functional trait analyses of existing composition datasets. We collected trait data in the field for 220 species including canopy height, leaf area, leaf dry matter content and specific leaf area (SLA). Variation in traits among the alpine flora was not related to species distributional ranges. Traits were strongly associated with growth forms, with shrubs often taller than herbs and graminoids, but often had small, tough, long-lasting leaves.
Species traits were combined with relative cover values to calculate community trait weighted means, a commonly used measure of functional diversity. Functional diversity varied with altitude/duration of snow cover. For example, shrubs which are taller with small tough leaves dominated lower altitude summits, while at higher altitude summits, large, soft leaved herbs and graminoids dominated. Late lying snowpatches areas with short growing seasons were dominated by low growing herbs and graminoids with small leaves while areas with longer growing seasons were dominated by herbs and graminoids that were taller and had larger leaves.
Recovery from fire differed among plant communities. The composition and functional diversity of recovering tall alpine herbfield is trending towards that of equivalent unburnt sites, while burnt windswept feldmark was colonised by graminoids and herbs that are often found in tall alpine herbfield species, with limited shrub recovery in the first nine years post fire.
Grazing by feral hares had no effect on composition or functional diversity, while vegetation recovering from cattle grazing showed clear changes in composition and functional diversity even 43 years later. Prioritising management for this high value conservation region, therefore, involves enhancing resilience by minimising existing threats, particularly those from fire, weeds and hard-hooved grazing animals which will be exacerbate by climate change.
Please cite as: Pickering, C, & Venn, S, 2013 Increasing the resilience of the Australian flora to climate change and associated threats: a plant functional traits approach National Climate Change Adaptation Research Facility, Gold Coast, pp. 94
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