Ecohydrological feedback as a land restoration tool in the semi-arid Brigalow Belt, QLD, Australia

In this study of native plant communities in the Brigalow Belt - a semi-arid bioregion of Queensland and New South Wales, Australia - an ecohydrological model was designed to investigate the complex feedback relationships existing between plant community traits and soil water dynamics among post-disturbance (i.e. mining and agricultural) landscapes. Two distinct locations (having similar composition and climatic environment, yet different soil water dynamics) were selected to compare the interaction and sensitivity of these traits towards water evaporation from soil or from plant transpiration. The model is constrained by soil physical attributes and climate data monitored at the Brigalow Catchment Study, and plant community parameters were derived using Latin hypercube sampling and pattern oriented modelling. Our findings indicate that, under the given soil-climate constraint, plant communities could only thrive if they were able to avoid prolonged periods of water stress (e.g., by minimising their physiological wilting point). Further, the influence of vegetation dynamics on evaporation from soil was deemed to be critical for the simulated soil water dynamics, whereas plant transpiration affected soil moisture only marginally. Moreover, both monitoring sites were dominated by the same species but co-dominated by different tree species, suggesting that evaporation from soil was probably influenced by the co-dominant species, whereas transpiration was probably controlled by the dominant species. For the re-establishment of native plant communities on post-mined landscapes and for agro-forestry and resource management in the Brigalow Belt, this implies that inherent ecosystem processes exist, which control plant community development and, hence, ecohydrological functions such as regulation of evapotranspiration. Therefore, restoration strategies should carefully reflect on species composition and their ecohydrological functions rather than attempting to re-establish the pre-disturbance ecosystem form and function - which could be less robust and even unsuccessful given post-disturbance conditions and under altered soil conditions of post-mined landscapes or the uncertainty of future climatic environments. (C) 2012 Elsevier B.V. All rights reserved.