Project 5 - Sytematics of Environmental Weeds

5.2: Dispersal mechanisms of willows in South Eastern Australia

Challenges

Willows are widespread invasive riverine exotic weeds through southeastern Victoria. Willow invasion effects water flow, chemistry and local native vegetation dynamics.

Current control efforts are extensive, but could be improved with a thorough understanding of the dispersal dynamics of willows.

Seeking solutions

The fundamental scientific and environmental management question that needs to be addressed is: "On what geographical scale must willow eradication and post eradication monitoring be conducted to ensure that these efforts will be effective over the long term?" To answer this question it is necessary to know the extent and pattern of seed and pollen movement across catchments as this will allow removal efforts to be targeted at spatial scales that will minimise the risk of reinfestation – which is currently quite common. Knowledge of the distances that willow seeds and pollen move across landscapes will also allow more realistic risk assessment and management with regard to predicting which native plant communities that are currently willow free have a significant chance of being colonized by willows species in the future.

Approaches

This project will use high-throughput DNA analysis of adult and seedling willow genotypes to:

  1. examine historical patterns of willow movement across Victorian catchments through the analysis of the geographical genetic structure of established populations of these species and;
  2. determine current patterns of seed dispersal and pollen movement by using parentage and paternity analysis to ascertain the origin of invading seedlings and thus directly measure dispersal distances.

Collaboration

Melbourne Water, Goulburn Broken Catchment Management Authority, Corangamite CMA, West Gippsland CMA, North East CMA, North Central CMA, Department of Sustainability and Environment (Victoria).

Tools for Decision Makers

Our results will be published in scientific journal articles.

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