Vegetation Clearance Detection

Multi-temporal satellite imagery can be used to detect vegetation clearance over large areas. Vegetation clearance can be attributed to either human induced clearance (eg. clearing for agriculture, drainage, arson) or natural causes (bushfire caused by lightning strikes, natural disaster). The land cover classification described above also had a temporal component to determine what changes in landcover had occurred between 1990 and 1995 in order to quantify gain or loss of carbon fixing material. This information was collated with other data from the rest of Australia by the Bureau of Rural Sciences in Canberra to determine how clearance has affected Greenhouse Gas emissions on an Australia-wide basis.

In 2001, the Department for Environment and Heritage initiated a project that would map and quantify illegal vegetation across the agricultural areas of South Australia. The benefits of using aerial photography and satellite imagery for vegetation change detection are their broad area coverage, availability of many epochs of data, and the ability to detect change where it normally could not be seen by standard car observations. One example of this is what has been termed "doughnut clearance" where an area of vegetation is cleared, but a ring of vegetation is left around the clearance to disguise it from standard ground based surveys.

Click on the images below for a more detailed view.
Before	After	Red = Vegetation Clearance Blue = Vegetation (no change) Cream = Pasture Orange = Pasture to bare Cyan = Water/Dams

Using the same methodologies, vegetation clearance due to bush fire can also be mapped and quantified. The images below illustrate the vegetation clearance due to bushfire (the dark red scar in the below image) at Tulka on the Eyre Peninsula.

Tulka on the Eyre Peninsula 10/01/2000	Tulka on the Eyre Peninsula 28/06/2001