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Central Ranges

Biodiversity:  Controlling environmental weeds

Medium Priority

What is this issue

Environmental  weeds (such as boxthorn, gorse, grass weeds, ash trees).

Impacts of the issue

Competition with native flora; resulting in declines in biodiversity and production values; reduction in quality of appropriate habitat for native species.  


  • High rainfall areas = rapid spread
  • Nutrient enrichment, disturbance, overgrazing = increased susceptibility
  • Garden escapes
  • Difficulty of control (terrain, poor access)
  • Low landholder knowledge and capacity, increase in 'lifestyle' blocks
  • Climate change (shifts in weed species distributions and ecosystem health)


  • Gaining voluntary compliance with Natural Resources Management Act 2004
  • Engaging landholders to control weeds on their properties 
  • Capacity of individuals to identify weeds
  • Insufficient resources, time and personnel to tackle on a largescale
  • Different perceived impacts of weeds, i.e. organic farming, broad acre, lifestyle
  • Regular new weed incursions   
  • Lack of follow up treatment in successive years
  • Difficult terrain
  • Reinfestation likely when neighbours are not coordinating their efforts
  • Continued spread and reinfestation by stock
  • Human movement and transport
  • Industry hygiene and movement from businesses outside of farming, i.e. earthmoving, construction, transport

Climate impacts and adaptation needs

  • Identify areas that will be more susceptible to weed invasion under future climate change models
  • Identify ALERT weeds to prevent incursion of under climate change scenarios
  • Potential changes to weed behaviour, i.e. flowering time, spread, survival

Who plays a role

  • Department of Environment, Water and Natural Resources (particularly Parks staff)
  • Landholders
  • Local Action Planning and Landcare groups
  • Local Government (Mid Murray Council, Barossa Council, Adelaide Hills Council)
  • Primary Industries and Regions SA
  • SA Murray-Darling Basin Natural Resources Management Board 

Strategies and Actions

Contain spread of weed populations

  • Regular monitoring of areas with known weed populations
  • Promote and support landholders to undertake early and regular containment works, to minimise further spread
  • Support landholders to coordinate with neighbouring properties for weed management
  • Support quarantine measures, i.e. Control movement and sale from infested properties, holding pens and plant hygiene
  • Promote good biosecurity hygiene practices to prevent further infestations

Protect sites of high value within the region

  • Map key assets/ sites of the region and their weed threats
  • Support control of infestations in close proximity to key assets/ sites, aiming for a significant reduction in density
  • Monitor change in distribution within and in close proximity of key assets/ sites
  • Prevent incursion of weeds by encouraging natural regeneration and/or planting native species
  • Prevent incursion of weeds by managing total grazing pressure

Manage weeds using a landscape approach

  • Research, trial and develop integrated weed management packages - using both biological and herbicide treatments where possible
  • Promote integrated weed management techniques to land managers
  • Support the collaboration of neighbours on control campaigns as a landscape approach
  • Recognise and reward land manager efforts at best practise weed control