Supplementary Table 1: Topographic variables that were considered plausible correlates of
burnt area of four large fires in southwest Tasmania (Wood et al. 2011) and for change from
non-forest (NF) to forest (F) in this study. For Topographic Position, we trialled a range of
radius values (i.e. 100m, 200m, 500m, 1000m) and slope cut-off values and visually assessed
their relevance to fire spread and vegetation patterns. The 200m radius best represented the
spatial scale of these key processes and the four slope categories provided an appropriate
level of detail for the subsequent analyses in this study and Wood et al. (2011).
Variable
Data source
Topographic Position:
Topographic Position Index (Jenness 2006) determined for
A. Valley
each cell of a 25m Digital Elevation Model (DEM) by
B. Ridge
calculating the difference between the elevation of the cell
C. Flat (<5°)
and the mean elevation calculated from all cells in a circular
D. Gentle slope (5° to 15°)
window of radius 200m centred on the cell of interest.
E. Moderate slope (15° to 30°)
F. Steep slope (>30°)
Northness Index
Northness Index (Holden et al. 2009) was calculated as slope
x COS(aspect). Aspect (degrees) and slope (%) were
calculated from 25m DEM. Steep North ~ 1, Steep South ~ -1,
East and West and Flat ~ 0.
Elevation (m)
25m DEM.
References
Holden ZA Morgan P, Evans JS (2009) A predictive model of burn severity based on 20-year
satellite-inferred burn severity data in a large southwestern US wilderness area. For Ecol
Manag 258:2399-2406
Jenness J (2006) Topographic position index (tpi_jen.avx) extension for ArcView 3.1.
Jenness Enterprises. Available at: http//www.jennessent.com/arcview/tpi.htm (last accessed
October 2009).
Wood SW, Murphy BP, Bowman DMJS (2011) Firescape ecology: how topography
determines the contrasting distribution of fire and rain forest in the south west of the
Tasmanian Wilderness World Heritage Area. J Biogeogr 38:1807-1820