An initial assessment of changes to Melaleuca distribution on a selected area of the Magela floodplain using aerial photography

2002

Internal Report 394
Riley J & Lowry J
Supervising Scientist Division
Department of the Environment, Water, Heritage and the Arts

About the report

Concerns have periodically been raised about the possible encroachment of Melaleuca spp. into previously unoccupied areas in Kakadu National Park. Recent examples were ABC Radio and TV news bulletins of the 6th and 7th of September 2001 (ABC 2001), respectively, which linked recent research findings on the spread of Melaleuca in Papua New Guinea, and the Mary River floodplain in the Northern Territory with the concern that woody vegetation communities – as represented by Melaleuca spp. – may change the wildlife habitats and environments in the wetland areas of Kakadu National Park.

While studies have been undertaken in the past which looked at the distribution of Melaleuca in selected areas of Kakadu (eg Williams 1984), there is presently not an established method for monitoring the spread or distribution of Melaleuca within Park boundaries.

The temporal analysis of remotely sensed imagery – such as aerial photographs – provide one means by which vegetation cover may be mapped and monitored. Williams (1984) used aerial photography from 1950 and 1975 to perform a temporal analysis of changes to Melaleuca distribution on the Magela floodplain. His study found that within the 25-year time period between air photos, while there been no increase in the area occupied by Melaleuca, 38% of the forested area had suffered a significant decrease in tree density.

In response to the concerns recently aired, and after consultation with members of Parks Australia North, it was decided that eriss would initiate a preliminary analysis of changes in melaleuca distribution on a section of the Magela floodplain.