Site 28 Johnson Swamp

Description
Located east of Kerang off the Pyramid Creek, this wetland supports Open Woodland dominated by Eucalyptus largiflorens (Black Box). The adjacent land uses include cropping and grazing. Changes to flooding regimes have created dense areas of Phragmites australis (Common Reed) and areas of Muehlenbeckia florulenta (Tangled Lignum). The wetland has been dry since March 2002.

Vegetation Description and Composition
The water level has dropped over the past two years and the swamp is now dry. In Quadrat A, around 90% of the species are introduced whereas in Quadrat B the only two species present are native. The level of species abundance has declined at both quadrats. Three salt indicator species are still present. Tree health appears stable in Quadrat A but there are borers present in three of the four trees next to Quadrat B and these four trees have also been burnt. There has been substantial change in the vegetation survey results when recent data is compared with 1997 and 1998 vegetation data. The increase in species present is mainly due to introduced plants establishing after slashing of a large section of Quadrat A in 1998 and again in 1999. In addition, the long period of dry seasonal conditions has also had an influence.

Johnson Swamp

Water Quality
Generally water quality within this wetland is good, rarely exceeding 5 000 EC.

Groundwater and Salinity
The water table around this swamp is fairly shallow - coming within 2.5 metres of the surface around the edge of the swamp with salinity levels up near 50 000 EC.

Threats to the site continue to be:

possible rising salinity levels.
heavy infestation of rabbits.
possible inappropriate water regime through irrigation tail water disposal.
large numbers of the introduced mosquito fish.

Monitoring Survey Dates
December 1997, December 1998, December 1999, December 200, November 2001, December 2002.

Page top