Soil properties and floristic community distribution within a deeply weathered landscape within a biodiversity hotspot of Western Australia

Aims: This study aims to identify some of the key soil-related factors that underpin the distribution of plant communities and provide a more comprehensive understanding of an old, climatically buffered infertile landscape including kwongkan habitats. We investigate the pedological, topographical and hydrological correlates of abundance and floristic community distribution within the Alison Baird Reserve, a floristically diverse, old and climatically weathered landscape in south-west Western Australia. Methods: Fifty-four soil samples were collected across 0.165 km² and analysed for a range of physical and chemical properties. Samples were taken from the topsoil and subsurface, and a combination of statistical and geostatistical methods were used to examine soil–plant community distribution relationships. Results: Elevation, sub-surface moisture, electrical conductivity and clay content were the most important factors in determining vegetation composition and distribution; with sub-surface properties varying more between floristic communities and correlating more strongly than topsoil factors. Associations between soil nutrients (Phosphorus, Nitrogen, Carbon) and community distributions were not as significant as expected, likely due to the depleted nature of the soil system. Conclusion: The significance of soil parameters including particle size, moisture, elevation, water repellence and depth to water table suggests that water availability and retention within the soil is a key correlate of the distribution of floristic communities at the site and may act as a pathway to explain large scale variation in plant communities across the south-west of Western Australia. This understanding will help conservation and management of areas with such high biodiversity including relocation of endangered flora.