Within the Brigalow Belt Bioregion, less than 10 per cent of the 12 regional ecosystems dominated by brigalow (Acacia harpophylla) remain and hence all are considered to be endangered. Using the combination of Japan's Advanced Land Observing Satellite (ALOS) Phased Arrayed L-band Synthetic Aperture Radar (PALSAR) data and Landsat-derived Foliage Projective Cover (FPC), maps of the extent of three different stages of growth (early, intermediate and mature) have been discriminated across the region. To achieve this, the signatures of L-band HH and HV and FPC were extracted from remnant forests known to be located within the 12 regional ecosystems. These same data were then extracted from segments with woody vegetation across the landscape and the values relative to that of remnant forest were used to define the extent of mature forests. Early regrowth forests were associated with a low L-band HH backscatter (because of the lack of stems of sufficient size to evoke an L-band response). Those not mapped as mature or early regrowth were associated with an intermediate growth stage. The study indicates that substantive areas of brigalow-dominated forests are in the early stage of regrowth because of recover from recent clearing events (particularly those that occurred in the late 1990s and early 2000s. Through careful management of these forests (e.g., through thinning), these forests can be encouraged to develop into more substantive forests, thereby increasing carbon uptake but also improving capability for supporting biodiversity.