45. Invasive Plants in Tropics

Organised by Denise Hardesty, CSIRO. First meeting held 9-12 December, 2008 at Macquarie U. Second meeting 5-9 October, 2009 at Moreton Bay Research Station, Qld

PARTICIPANTS INCLUDE Denise Hardesty - CSIRO Sustainable Ecosystems (Leader) David Westcott - CSIRO Sustainable Ecosystems Saara DeWalt - Clemson U (USA) Carol Horvitz - U Miami (USA) Helen Murphy - CSIRO Sustainable Ecosystems Curtis Daehler - University of Hawai'i (USA) Marcel Rejmanek - University of California, Davis (USA) Jan Pergl - Institute of Botany, Academy of Sciences (Czech Republic) Brad Murray - University of Technology, Sydney Philip Hulme - Lincoln University (NZ) Peter Bellingham - Landcare Research (NZ) Andy Sheppard - CSIRO Entomology Ray Callaway - University of Montana (USA) Jane Catford - U Melbourne Participants at second meeting Hardesty, Westcott, Murphy, Sheppard, Daehler, Catford, Pergl

Dec 08 > Oct 09 >

BACKGROUND

While well recognised in temperate environments, it is only recently that the importance of plant invasions in tropical rainforests has gained attention. The ecological processes that drive invasions can also shed light on processes structuring and maintaining tropical forest ecosystems. Invasions represent perturbations of ecosystems and the responses of the invader and the invaded communities can provide clues to the nature of the interactions and processes driving ecosystem function on ecological and evolutionary timeframes.

An important feature of the global epidemic of biological invasions is that they are replicated events. The same or a closely related species invades on different continents or in geographically distinct regions within a continent and these events can also be compared with population dynamics and patterns of movement across the landscape within the native range. This phenomenon provides an opportunity to examine the processes and outcomes of the invasion by a single species under differing circumstances. Comparisons of continentally replicated invasion experiments provide opportunities to test hypotheses about the mechanisms underpinning invasion and the functioning and maintenance of the ecosystems in which they occur.

The first meeting of this working group was held 9-12 December 2008. During this workshop we agreed upon the following steps and we are:

• Preparing a manuscript to address ecological processes that drive invasion. We are specifically addressing several of the hypotheses (neutrality and niche-based appoaches) to understand whether alien plant species are rule-breakers or law abiders in tropical forest communities.
  
• Developing a Janzen-Connell based model for comparing the role of dispersal and recruitment between species in native and introduced ranges, to test the impact of differences in dispersal and survival curves, or a combination of both.
  
• Compiling key findings to date from geographic comparisons of invasives at the single species and communities levels. Given the paucity of data in tropical systems, we are drawing lessons from the temperate literature.
  
• Developing a research proposal based upon large-scale biogeographic comparisons of species in native and introduced ranges to test hypotheses about mechanisms underpinning invasion in tropical systems.
  

The 2nd working group was held 5-9 October 2009 at Moreton Bay Research Station on Stradbroke Island. The smaller group comprised 7 participants including 2 from overseas and 2 from Australia/NZ.

During this workshop we focused on two main projects with the group and we are:

• Progressing a manuscript around the intermediate disturbance and the role disturbance plays in plant invasion processes.
• Completing the compilation of key findings to date for geographic comparisons of tropical plant invasives at the single species and communities levels. In the initial scan of the first 20% of ca. 3,000 papers that fit the key terms we identified finds some interesting trends that will form the basis of an overview paper on invasion ecology.
• Preparing an oral presentation for the upcoming 1 th Australian weeds conference to be held in Christchurch, NZ in 2010.

Last updated February 2010