Franklin Wetland, Vasse ▶

The Brief

As part of the development of the Vasse LIA, it was a development condition that the Franklin Wetland was rehabilitated to a self-sustaining state. Works were undertaken by others in 2009/2010 with limited success. Tranen were engaged in 2013 to develop an Action Plan for the wetland and then implement the plan in 2014.

Constraints & Issues

• Failure of previous revegetation attempts.
• Unauthorised off-road vehicle activity, contributing to degradation of wetland area.
• Large weed infestations of pasture and wetland weeds dominated by Kikuyu (Pennisetum clandestinum), Couch (Cynodon dactylon) and Cotton Bush (Gomphocarpus fruticosus).
• A significant volume of dead organic weed matter from ongoing weed control undertaken by others for the three years prior.
• Construction of Vasse Bypass leading to changes in the hydrology halfway through the rehabilitation works.
• A small kangaroo population living within the wetland and the surrounding area.

Our Management Approach

The proposed rehabilitation works were split into three main areas, Wetland, Transitional and Upland Zones. The primary management strategy for the three areas involved an intensive weed control program and the re-establishment of natural vegetation to screen the wetland from the LIA. The Upland and Transition zones were highly compacted and waterlogged, so these areas were ripped and mounded.

The management actions undertaken included:

1. Undertaking a controlled burn to remove dead organic weed matter and encourage natural recruitment;
2. Control of re-growth and new weed infestations through herbicide application, manual removal and brush cutting;
3. Ripping and mounding of compacted areas to promote better root penetration and to raise the seedlings above the waterlogged soils;
4. Installation of over 72,600 native wetland seedlings and 36,300 tree guards in Wetland, Transition and Upland areas;
5. Staged planting of particular species in the Wetland Zone as the peak water levels receded.

The Outcome

The implementation of the project commenced in autumn 2014 and was completed and handed over to the City of Busselton in December 2016 six months ahead of schedule and within budget.

Problematic weed levels have been significantly reduced, which has allowed native vegetation to re-establish. Seedling survival in spring 2016 was 85% and had an average density of 3 plants / m². Ongoing minor weed control maintenance is currently occurring and is being managed by Tranen through the City.