OOS 20-1 - Australian acacias take on the world: Lessons for management from a global translocation experiment

Wednesday, August 10, 2011: 8:00 AM
16B, Austin Convention Center
David M. Richardson1, Cang Hui2, Johannes J. Le Roux1 and John. R.U. Wilson3, (1)Centre for Invasion Biology, Stellenbosch University, Stellenbosch, South Africa, (2)Centre for Invasion Biology, Stellenbosch University, (3)South African National Biodiversity Institute, Kirstenbosch, South Africa

Climate change affects plant species in many ways.  Plants may adapt to the new conditions, shift their range, or go extinct.  In the face of rapid climate change, ecologists are challenged to provide guidelines for management, including radical interventions such as managed relocation.  We explores whether lessons from the widespread movement of a group of closely related plants to foreign environments can help to formulate strategies for managing native plants in the face of global change.

Australian acacias (Acacia subspecies Phyllodinae) are dominant over large parts of Australia and have been distributed around the world for many purposes.  At least 23 species are currently invasive in foreign environments.  Detailed data exist on the distribution ranges of Australian acacias, history of translocation(s), their invasive performance, and on key facets of human perceptions of different species.  This creates a valuable natural experiment for exploring factors that mediate responses of different species to various types of translocation, how they affect the ecosystems to which they are moved, and the options that exist in different environmental/ecological and socio-political settings to influence their occurrence and influence.

We explore the relative role of propagule pressure and a range of biological traits in shaping current distribution patterns, using data on introduction pathways, native and non-native distribution, and phylogeny.  Interactions between biological traits responsible for growth, fecundity, dispersal, and competitive ability are analysed to explain the macroecological patterns of the geographical ranges of species. We explore whether results from this natural experiment can inform strategies for managing these species in their native ranges.


Invasive Australian acacias are randomly distributed in the phylogeny; no taxonomic characters delineate invasive taxa. Life-history traits such as plant height, leaf area and seed mass do add explanatory power in predictive models, but the causal mechanisms appear complex and may be more closely related with factors linked to human usage (and thus propagule pressure) than with any mechanistic benefit they afford invasive species.  There is also strong evidence that macroecological patterns of Australian acacias in their natural native range can explain their performance in foreign environments.  Both range size and percolation metrics that are relevant to abundance and population growth rate are positively correlated with various measures of invasion success. The introduced-naturalised-invasive continuum evident in foreign environments can serve as basis for categorizing species for conservation attention under climate change.

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