Large scale riparian revegetation

Article by Kenneth McClymont, catchment project officer, Sunshine Coast Council

Waterways and wetlands are the living arteries of our natural environment that support a range of habitats and diverse and specialised wildlife. The Sunshine Coast comprises of 5 catchments that drain from the Blackall and D’Aguilar ranges in the west – eastward to the coast via a network of streams, creeks and rivers. Maintaining the good health of these waterways and their habitats is reliant upon the condition of the adjoining riparian areas (the land that fringes a waterway) and its vegetation. In addition to supporting habitats, riparian areas contribute to water quality by stabilising banks to limit erosion and filtering pollutants from water.

Through an integrated catchment approach the waterways and catchment management unit within Sunshine Coast Council are investing council environment levy funds into large scale riparian restoration projects in the Maroochy River, Mary River and Mooloolah River catchments to increase riparian habitat and improve water quality.

The Maroochy River floodplain has been extensively cleared since European settlement with much of the area being used for growing sugar cane and other crops. Since the demise of the local sugar industry other industries such as turf farming and grazing have been pursued with a gradual increase in rural residential blocks.

Areas of fringing riparian vegetation are extremely limited within the middle to lower reaches of the Maroochy River catchment so any existing areas are critical for maintaining connectivity for native fauna and flora as well as maintaining ongoing river health. The Maroochy River rehabilitation project is a restoration project which has been targeted to protect, enhance and expand riparian vegetation within this part of the Maroochy River catchment.

This four year project incorporates integrated weed control, assisted regeneration and revegetation goals to manage about 3.5 kilometres of river bank. The project which began in 2015 is located at the confluence of the North and South Maroochy rivers east of the Bruce Highway in the locality of Yandina. The project area includes cleared pasture/cropping land and riparian zones consisting of woody weeds with some regrowth and significant remnant native vegetation.

Approximately 4.2 hectares were planted with 11,000 native plants broadly corresponding to pre-clearing Regional Ecosystem (RE) vegetation types. In addition nine hectares have been rehabilitated through weed control and assisted regeneration techniques. Several kilometres of electric fencing were installed to exclude stock from neighbouring properties.

The areas that were treated include several council managed esplanade areas and two private landholder properties. The project has had some challenges from several dry spells and minor damage from stray cattle browsing and breaking of plants.

Since European settlement the upper Mary River floodplain has been heavily cleared for grazing and agriculture and the river itself has been significantly sand mined. As a result of these historical impacts, large destructive floods and resultant high to extreme erosion have been a regular event. More recent major flooding occurred in the Mary River catchment in January 2011, January 2013 and February 2015. These large flows also caused substantial erosion of the bed, banks and floodplain of the river resulting in significant sediment loss in addition to damage to agricultural land and public infrastructure. Subsequently, council undertook a hydrological study of the river reach from Moy Pocket Road bridge to the confluence of Walli Creek and the Mary River just upstream of Kenilworth to identify appropriate techniques and possible sites for riparian restoration.

The Mary River restoration project resulted and was designed as a three year ecological restoration project with aims to use revegetation with local native plant species to eventually stabilise a 2 kilometre reach of the Mary River in the vicinity of the Kenilworth township. Approximately 6 hectares were planted with around 46,000 plants in a planting design broadly corresponding to the pre-clearing regional ecosystem (RE) vegetation types. Additionally, approximately 4,000m2 of riparian forest was rehabilitated via selective weed control and assisted regeneration techniques. The areas being rehabilitated are on 6 private landholder sites and 2 council managed sites with the project area predominately in the degraded riparian zone which consisted of mainly woody and other weeds with very little remnant native vegetation. The flow on benefits of the project include protection of several nesting sites of the endangered Mary River turtle (Elusor macrurus).

Ongoing challenges for the project have included minor flooding damage, rampant ongoing leguminous vine weed regrowth, frost damage and persistent damage to plants from local feral rusa deer.

The Mooloolah River corridors 2 project which began in 2017 is a three year ecological restoration project that aims to protect and enhance a 2.5 m reach of the Mooloolah River between Old Gympie Rd and Scarffe Rd, Glenview, (located in the middle catchment of the river, west of the Bruce Highway). The Mooloolah River has narrow but significant fringing regionally endangered lowland subtropical rainforest containing a number of threatened flora and fauna species.

The areas being rehabilitated are on 19 land parcels owned and managed by private landholders and three council managed land parcels. Project outcomes include 6.5 hectares of revegetation (37,500 plants) and 12.5 hectares of selective weed control in the remnant riparian rainforest.

The current project is a follow up to the first Mooloolah River Corridors restoration project which ran from 2009 - 2012. The original project involved revegetation and remnant weed control along the Mooloolah River corridor mostly on council managed riparian reserves upstream of Old Gympie Road. The current stage two works will directly link to past efforts. The current project has been targeted to cover an entire reach of the river in an area that has a combination of mainly private landholdings but also significant portions of council managed riparian reserve linkages along the main river channel. Council negotiated with landholders to get them involved and is undertaking revegetation, weeding and stock exclusion fencing along the river as part of the project.