This dataset illustrates connectivity options for the fragmented landscapes of mainland Australia. It has been developed using a least cost paths method (LCP). Version 1 is a combination of analyses within the fragmented landscapes of south-western Western Australia (SWWA), and southern and eastern mainland Australia (SEA).
The LCP method identifies the shortest cumulative 'cost' route across a resistance surface. The resistance surface is based on the Euclidian distance from remaining natural areas, where higher costs were ascribed to increasing distances away from those areas. Natural areas were identified by combining the National Vegetation Information System Version 4.1 data, and the National Carbon Accounting Forest Cover Version 8 data (after removing areas of plantation forestry).
To favour ecologically important areas, the resistance values of this basic surface were halved for riparian areas and remnant vegetation greater than 10 hectares after a 100 metres edge had been removed. This has the effect of drawing the routes towards these features.
The LCP analysis requires begin and end points, which are connected by identifying the lowest resistance route. Landscape 'foundation stones' were used for this purpose. The foundation stones were the National Reserve System, World Heritage Areas, private conservation lands, Ramsar and important wetlands, and nationally significant remnants (those greater than 100 hectares after removing a 100 metre edge).
The foundation stone areas were converted to point features and the LCP analysis was develop to connect every point to every other point. To constrain the model, routes were identified only for points less than 50 kilometres from each other. Because each point is connected to all others (within 50 kilometres) lowest cost routes may be identified numerous times. This count is captured in an attribute field named 'popularity'.
Usage Notes:
The LCP analysis was developed on cost surfaces with a 250 metre cell size for SWWA, and 500 metres for the SEA region. The product described here has been delivered as a network of lines which actually represent potential connections much wider than the lines. As a consequence the product is indicative of the optimum route and should be used to identify potential connectivity options by expanding (buffering) the lines to represent at least 250 metre wide connections. Precise locations and widths of functional re-connections will require finer resolution local planning.
The basic cost surface has been developed as the distance from the edge of remnant natural areas. Routes within natural areas have no validity because there is no differentiation of costs within them. They remain in the dataset for completeness and recognising that users may have access to different remnant vegetation information to demonstrate connectivity options. It is suggested that when presenting the data that the connectivity network be obscured (overlayed) by a natural areas dataset.
The popularity of the routes between foundation stones (attribution field called 'popularity') may be useful for landscape prioritisation or for cartographic purposes by illustrating wider connections to more ‘popular’ routes.
Disclaimer:
While reasonable efforts have been made to ensure that the contents of this dataset are factually correct, the Commonwealth does not accept responsibility for the accuracy or completeness of the contents, and shall not be liable for any loss or damage that may be occasioned directly or indirectly through the use of, or reliance on, the contents of this dataset.CC - Attribution (CC BY)
Use is granted under the Creative Commons by Attribution model.
Use is granted under the Creative Commons by Attribution model.
© Commonwealth of Australia (Department of the Environment and Energy) 2014
