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4.1 Weeds

Summary points

• Weeds are reported by park managers as the most common threat to park values in NSW parks.
• The NSW Invasive Species Plan outlines the management of invasive species in NSW and Industry & Investment NSW leads the implementation of this plan.
• There are a range of strategies to control or reduce the impacts of weed species that are most effective at various stages in their cycle of incursion and establishment.
• Strategic prioritisation of weed management occurs for all parks through regional pest management strategies.
• Park managers report they are stopping weed impacts from increasing in almost 90 per cent of the park system.
• All parks have examined which weeds pose the greatest threat to park biological values and have determined priority sites where management will lead to the greatest conservation outcomes for the values at risk.
• Major programs, such as the Bitou Bush Threat Abatement Plan, are delivering positive outcomes.

Introduction

To ensure better outcomes for native vegetation, biodiversity, land and waterways (State Plan priorities), DECCW is focussing on: 1. weeds that pose a threat to biodiversity on a regional scale; 2. identifying biodiversity at risk and needing urgent protection; and 3. managing areas where weeds are likely to affect neighbouring lands. More details of DECCW's approach to weed management are provided in Protecting our national parks from pests and weeds (2006).

Management of weeds within the park system also helps to address the threat at a landscape scale. For example, DECCW's weed control activities assist the 13 Catchment Management Authorities (CMAs) to address the state-wide target to reduce the impact of invasive species by 2015 established by the Natural Resource Commission.

Status and trends

Over 1650 weed species have established in NSW and more than 300 of them are likely to have significant impacts on the environment. Research estimates that 70 per cent of these weeds are 'garden escapees' (Coutts-Smith & Downey 2006).

Within NSW parks, weeds are reported by park managers as the most common threat to park values. The extent varies from local incursions to broader incursions. However, weeds are not uniformly distributed across any given park. Park managers estimate that only 18 per cent of the total area of the parks system is threatened by weeds, with the severity of threats varying from mild to high.

Note that a threat does not necessarily mean there is a problem, but that there is potential for problems and that the causes need to be managed.

Some of the most commonly found weeds across NSW are lantana, bitou bush, blackberry and Crofton weed. For some weed species such as lantana and bitou bush, strategic management plans have been developed to identify priorities for control and outline actions to manage the weeds. They also explain how the success of these actions will be measured. These are resulting in some very positive outcomes. For example, removal of bitou bush is resulting in recovery of littoral rainforest species in Cape Byron SCA and coastal wattle and native grass species in Bundjalung National Park (see more information on bitou bush case studies).

DECCW undertakes extensive planning across the NSW park system to prioritise and manage weed impacts. All parks within the system are covered by regional pest management strategies, which consider both pest animal and weed management issues. Regional pest management strategies aim to prioritise activities and maximise the effectiveness of weed management through cooperative approaches with neighbours and regional programs. Monitoring is an important component of DECCW's weed management programs to ensure they are delivering the desired outcomes. Monitoring protocols have been developed to assist staff assess the effectiveness of their programs.

There are a range of strategies to control or reduce the impacts of weed species that are most effective at various stages in their cycle of incursion and establishment. As set out in the NSW Invasive Species Plan 2008 - 2015, the strategies include prevention (preventing new species from establishing); eradication (removing new species before they can establish as a self sustaining population); containment (restricting the spread of established or emerging species); and protection (reducing the impacts from widespread invasive species). The Department of Industry and Investment NSW leads the implementation of this plan.

The impact of weeds in NSW parks are being minimised through the application of these approaches and park managers report they are stopping weed impacts from increasing in almost 90 per cent of the park system. As part of ongoing works to improve the management of weeds, all park managers have examined which weeds pose the greatest threat to park biological values and have determined priority sites where management will lead to the greatest conservation outcomes for the values at risk. This in-depth assessment provides data as well as decision-making processes for weed management and will lead to greater conservation outcomes.

DECCW is working with Catchment Management Authorities to identify priorities for weed control based on where the impacts on biodiversity are greatest. Other planning processes, such as regional pest management strategies and regional operations plans, support park managers in systematically identifying where weed impacts are greatest within the park system so that action can be taken to address problems.

Future direction

• Work in partnership with other land managers and land holders to implement practical solutions to manage weed threats to biodiversity and native vegetation.
• Work with other Government agencies to manage weeds. For example, a range of projects are being undertaken by the NSW Department of Industry and Investment including biological control, community awareness and involvement, education and training, legislation and policy and research projects.
• Contribute to research to improve understanding of the interactions between climate change, biodiversity and weeds.
• Implement weed management actions under the Threatened Species Priorities Action Statement to promote the recovery of threatened species, populations and ecological communities.

Further information

• The NSW DECCW website has extensive information on weeds in NSW including information on identification and control and management priority setting within each Catchment Management Authority. Species specific information is also available for bitou bush, blackberry, introduced grasses, lantana, scotch broom and willows.
• See the "Conserving and managing natural and cultural values across the landscape" chapter of our DECCW Annual reports for examples of recent pest animal and weed management actions.
• Protecting our national parks from pest and weeds (2006)
• The NSW State of the Environment Report: Section 7.3 'Reserves and Conservation'
• NSW Invasive Species Plan, which provides actions that aim to prevent and effectively manage the introduction and spread of invasive species so that this significant threat is minimised.
• Coutts-Smith, A.J. & Downey, P.O. (2006). Impact of Weeds on Threatened Biodiversity in New South Wales, Technical Series no.11, CRC for Australian Weed Management, Adelaide.