Hydropedology and ecohydrology of the Brigalow Belt, Australia; opportunities for ecosystem rehabilitation in semiarid environments

The Brigalow Belt Bioregion--located between the subtropical coastline and semiarid interior of eastern Australia--is a unique ecological area characterized by noncracking clay soils that have high water-holding capacities, and rainfall patterns that are spatiotemporally erratic and unpredictable. These attributes have resulted in highly variable water-supply conditions defined by alternating periods of intense rainfall and prolonged drought to which open-forests and woodlands dominated by endemic Brigalow (Acacia harpophylla F. Muell. ex Benth.) plant communities are best adapted. Since the 1950s, most of the Brigalow woodland has been cleared for agriculture and now coal mining developments, therefore very little of the predisturbance vegetation today remains. The primary goal of landscape rehabilitation currently targets the re-establishment of native Brigalow plant communities in hopes of achieving stable and self-sustaining ecosystems. However, very few reference ecosystems exist from which to determine essential ecological structure and function. Therefore, restoration practitioners are faced with the daunting task of reconstructing landforms and ecosystems that are characteristic of the bioregion's distinct environmental conditions. Here, we examine the fundamental hydropedological and ecohydrological relationships that define the function of natural Brigalow ecosystems. We propose these relationships as the cornerstone for rehabilitation of semiarid environments and suggest applying investigative methods of related disciplines within a unifying modeling framework (gray-box) to promote the development of native plants in the Brigalow Belt. This is particularly critical where model parameterization may span a broad ecological organizational scale or where there are knowledge gaps within the model framework.