Managing widespread weeds

Threat abatement plans (TAP)

The former Office of Environment and Heritage developed the Threat Abatement Plan (TAP) for the invasion of native plant communities by Chrysanthemoides monilifera (bitou bush and boneseed) in NSW, known as the Bitou TAP, a process for identifying and prioritising biodiversity at risk from widespread weeds and sites for control. The TAP approach was also used to develop the national Plan to Protect Environmental Assets from Lantana (PDF 569 KB).

It is not feasible (or a good investment) to apply the TAP approach to every individual weed species impacting on biodiversity, as many have overlapping distributions, impacts and management requirements. We have developed a site-led approach that applies the TAP process to multiple weed species on a landscape scale.

To ensure that management of widespread weeds has clear conservation outcomes, the Department of Climate Change, Energy, the Environment and Water has established:

• which widespread weeds pose a threat to biodiversity on a regional scale
• what biodiversity is at risk and needs urgent protection
• the sites where control will be most beneficial
• the monitoring required to assess both the effectiveness of control and the response of biodiversity at risk.

Statewide strategy – Biodiversity priorities for widespread weeds

The Biodiversity priorities for widespread weeds (BPWW) – Statewide framework is a joint project between NSW Department of Primary Industries and Regional Development, the former Office of Environment and Heritage and the former 13 catchment management authorities (CMAs, now Local Land Services). It uses an adapted Threat Abatement Plan (TAP) approach to identify and prioritise widespread weeds impacting on biological assets and sites for weed control.

The BPWW complements the NSW Invasive Species Plan in managing widespread weeds.

NSW Invasive Species Plan 2023–2028

The BPWW complements the NSW Invasive Species Plan 2023–2028, which is an update of the NSW Invasive Species Plan 2008–2015. The former Office of Environment and Heritage contributed to the development of the plan, which supports the NSW Biosecurity Strategy 2013–2021.

The plan identifies ways to:

• prevent new incursions
• eliminate or contain existing populations
• effectively manage already widespread invasive species. 

Protecting and prioritising biodiversity at risk

Many weeds that threaten native plants, animals and ecosystems are widespread and beyond the scope of eradication programs developed to deal with new and emerging weeds. To reduce the impact of widespread weeds on biodiversity (biological assets), control programs need to be prioritised to have the maximum benefit. This is best achieved using a site-led threat abatement plan (TAP) approach.

Identifying the biodiversity at risk from widespread weeds is essential for effective weed management. We use the Weed Impacts to Native Species (WINS) system to identify native species at risk from plant invasions.

The WINS process involves 4 steps:

• review of the relevant literature
• collation of local knowledge
• evaluation of an interim list of species at risk 
• final ranking of the native species at risk.

This system was used effectively to identify species under threat from bitou bush and lantana invasion in New South Wales.

Implementing the strategy

The BPWW provides guidelines to aid decision-making and future investment in weed control for biodiversity conservation. Long-term investment in weed management at high priority sites offers the best chance of protecting biodiversity at risk from weeds, particularly threatened species, populations and ecological communities.

Long-term investment will:

• assist Local Land Services meet the targets within their Regional Strategic Weed Management Plans (RSWMP)
• reduce the impacts of widespread invasive species – addressing a key goal of the NSW Invasive Species Plan
• help reduce the impact of key threatening processes.

Site-specific management plan

Site-specific management plans should be developed before the commencement of weed control programs at priority sites. This will assist site managers to focus control on priority biodiversity at risk and help ensure conservation outcomes are achieved.

Site management plans should be developed in consultation with all relevant stakeholders. They should clearly identify and determine the roles and responsibilities for all stakeholders and the state the objectives of the plan.

Key principles of the site management plan are:

• a staged approach to weed control
• minimising off-target damage to native biota.

Monitoring

Monitoring is an important part of weed control programs to make sure that control is delivering desired outcomes. When the key objective is biodiversity conservation, monitoring programs must explicitly assess both the reduction in weed abundance and the recovery of biological assets at risk.

The monitoring guidelines proposed for use at high priority sites were initially developed for the Bitou Bush Threat Abatement Plan (TAP). These guidelines are effective for monitoring most weed control programs with the exception of vines and aquatic weeds, where other techniques would be required.