Mapping the Future: Spatial Models of Decadal-Scale Landscape Change in Northern Australia

Repeated sequences of digitised and georeferenced historical aerial photography provide a powerful means of understanding landscape change over time scales beyond conventional ecological monitoring, especially in remote areas. We use this method to develop spatially explicit models of vegetation change at five sites in the Australian monsoon tropics, and assess the goodness-of-fit of the model to observed change. Models were derived by (i) converting the landscape into cells using a grid-overlay method and classifying vegetation as either closed forest (CF) or savanna (SV); (ii) examining repeat sequences of aerial photographs (taken in 1947, 1972 and 1997) to determine the temporal sequence of vegetation change in each cell (i.e., stasis versus change to different vegetation class); (iii) using thematic layers to derive cell-based measures of elevation, slope angle and drainage distance; (iv) counting the number of like-habitat points in the area surrounding each cell, with the fractal dimension of this area also calculated; and (v) using a bootstrapped generalised linear modelling approach (which controls for potential spatial autocorrelation) to derive a cell-based probability map of change based on the landscape features from (iii) and (iv) fitted to (ii) (an example is given in Figure 1).