Natural ecosystems: Pattern and process in relation to local and landscape diversity in southwestern Australian woodlands

Natural woodland ecosystems in southwestern Australia are examined in terms of their spatial structure at three different scales. Fine-scale structure of the vegetation and soil surface has a strong influence on water capture and retention, resulting in mostly localised infiltration and use. Stand-scale structure results from the patchy distribution of canopy trees, regeneration patches and a diversity of understorey shrubs which provides a diverse above- and below-ground structure. At the landscape scale, broad vegetation patterns are related to soil and landform changes along catenas, but there are also finer-scale mosaics resulting from disturbance history, individualistic species distributions and more subtle physical/chemical changes. Complex patterns at all these scales confer resilience to the woodland system. Most of this complexity has been lost in the current agricultural system, and it can be hypothesised that many current degradation problems can be related to this. The challenge for the future is to develop complexity and resilience in agricultural systems while maintaining an acceptable level of production.