Introduction

Condition

Pressure

Response

Introduction

The Kermandie River has a catchment area of just over 14,000 ha. Altitudes range from 600 m along the western ridges of the catchment to sea level where the Kermandie drains into the Huon River estuary. The average annual rainfall at Geeveston is 880 mm (Bureau of Meteorology 2002) but up to 80 mm has been known to fall in one day. Temperatures range from -5.9 to 39.5°C.

Approximately 60% of the catchment is native forest, 15% is native vegetation other than forest (e.g. woodlands, alpine scrub, buttongrass plains and wetlands) and 25% of the catchment has been developed. Forestry, pome fruit production and beef cattle provide the major source of income for the 800 residents within the catchment.

Riparian vegetation in the catchment is valued for its:

• hydrologic and hydraulic function especially associated with flood attenuation and the dissipation of the energy associated with heavy flows following intense rainfall;
   


• role in channel stability especially in the developed lowland reaches;
   


• role in wildlife habitat - in particular, the role that woody vegetation has as a source of in-stream woody debris; and
   


• recreation and aesthetic qualities. Fishing and walking are the favourite pastimes of the local community.
   

Condition

In the early 1920s, native riparian vegetation was cleared throughout the agricultural and urban reaches of the Kermandie River and the river banks were replanted with an English 'crack' willow (Salix fragilis). By the mid-1990s, over 15 km of the river and its tributaries had become choked with dense stands of the willow and its understorey of blackberry (Rubus fruticosus) and gorse (Ulex europeus).

The riparian issues that required urgent consideration and action from the community were:

• extent and height of exotic vegetation cover. Dense stands of willow and blackberry towered up to six metres above the banks and extended for approximately 17 km. Masses of woody, weedy debris were piled over a metre high through the township, across the floodplains and caused major blockages to river flow following the 1996 floods;
   


• the river had become inaccessible for fishing and recreation;
   


• loss of biodiversity. The large range of native trees, shrubs, understorey plants that were once common in riparian zone were absent. Native fish and platypus once common in the river, were no longer present;
   


• frequent flooding. After low to moderate rainfall events, the river would frequently overflow its banks because of the expansive rooting and branching habit of the willow;
   


• water quality. In many places, cattle had unrestricted access to the river; and
   


• sedimentation. Large-scale forest activities combined with loss of bank integrity and vegetation changes in the riparian zone caused increased in-stream and riparian sedimentation.
   

Pressure

The main pressures impacting on the riparian vegetation of the Kermandie River are:

Vigorous regrowth of exotic species. Crack willow, blackberry and gorse have a range of reproductive mechanisms that make them difficult to eradicate.

High nutrient inputs. Phosphorus and nitrogen loads in the Kermandie River are very high compared with other rivers in Tasmania (Bobbi 1998).

Commercial uses of riparian zone. The floodplains of the lower Kermandie River are more fertile than upper slopes and are favoured areas for growing fruit trees and grazing stock.

Climatic variability. The frequency and intensity of rainfall in the catchment can be highly variable. In January 1996, around 120 mm of rain fell in just a few days resulting in massive floods in the lower reaches of the Kermandie River.

Lack of physical, human and economic resources. The Kermandie community is a small rural community in a region of Tasmania with low weekly household incomes (ABS 2001). Considerable time, energy and resources are required to achieve and maintain successful rehabilitation of riparian vegetation. Persistent and consistent effort over many years, possibly decades, is required to achieve a sustainable outcome.

Increasing demands for time, skills and matching funds that have become mandatory requirements for Rivercare planning and on-ground processes are exhausting volunteers in small communities.

Response

Following the 1996 floods, concerned members of the community met and formed the Kermandie Landcare Group to improve the condition of the river. The major milestones that have been achieved so far are as follows:

Integrated catchment management and planning. In 1996, the Landcare group prepared a brief plan for the restoration and rehabilitation of riparian vegetation to a more natural condition. Soon after, a Landcare grant from the Commonwealth government was received and on-ground work commenced. Since 1996, the Kermandie Landcare group has become affiliated with other Landcare, Coastcare, Bushcare and Waterwatch groups throughout the Huon region through the Huon healthy rivers project. Riparian rehabilitation of the Kermandie River is incorporated under the Huon catchment healthy rivers project catchment management plan (Huon Valley Council 1997).

The Geeveston community is committed to integrated catchment management and recognises that healthy native riparian vegetation is critical to good water quality, maintaining riverbank integrity and providing a healthy environment for the community and aquatic animals.

Removal of exotic species. To date, over 8 km of the Kermandie River has been cleared of willows, blackberry and gorse. Where woody exotic species such as crack willow, blackberry and gorse are concerned, a sustainable outcome for the restoration of native riparian species can only be achieved if all the weed species are removed from the riparian zone. For the Kermandie community, this means the removal of the last stands of willow from one of the tributaries and monitoring and maintaining the rehabilitated stretches for many years to eliminate any regrowth of weedy species until native vegetation recovery is achieved.

Revegetation of the riparian zone with native species. Over 4,000 native trees and shrubs have been planted and a considerable number of native wattles and understorey species such as ferns, sedges and herbs have regenerated naturally. There has been some success with revegetation and regeneration of native riparian species. The community is proud of the transformation that has occurred along its watercourse.

Monitoring and maintenance of exotic regrowth. Monitoring and maintenance of the riparian zone occurs three times a year in December, February and April where regrowth of the weedy, woody species and other invading garden species are targeted for removal and walking tracks maintained.

Stock exclusion. In many areas, stock have been excluded from landslip and riparian areas as a result of fencing and off-stock watering alternatives have been provided.

Partnerships. Over the last six years, the Landcare group has formed successful partnerships with, and received financial and practical assistance from landholders, Forestry Tasmania, Huon Valley Council, the Department of Primary Industries, Water and Environment's regional Landcare officer, Bushcare officer and Rivercare Team, the Tasmanian Landcare Association, Natural Heritage Trust and local voluntary community groups such as the Green Jackets, Geeveston Streetscape and Mission Australia. Volunteers from the Australian Trust for Conservation Volunteers and Green Corps teams have also assisted with weed removal and revegetation.

River access. A walking track has been constructed along rehabilitated reaches of the river. Visitors and the community who stop on their way to the Hartz Mountains National Park and the newly constructed Airwalk in the Tahune Forest now enjoy a long riverside walk that extends along much of the rehabilitated stretches of river at Geeveston. Brown trout and platypus are frequently observed in the clear waters of the river and there is a hope that native fish will also return. The track also provides good access for fishing.