Understanding soil biodiversity using two orthogonal 1000km transects across New South Wales, Australia

The patterns of soil biodiversity across different soil gradients still require evaluation in different environments. A close relationship between soil biodiversity and soil physicochemical properties (e.g. soil pH) is evident in most studies, but a large unexplained residual variance is usually reported. This suggests that a deeper exploration into the multidimensional nature of these biotic-abiotic interactions will help develop our understanding of how a combination of soil properties drives soil biodiversity more than any one soil attribute. This was tested by analysing the multivariate associations between soil microbial diversity and soil physicochemical heterogeneity across different Australian soil landscapes. The study area involved two orthogonal transects each of ~1000 km across the state of New South Wales (NSW). A set of 33 abiotic attributes including soil properties and other key environmental covariates were correlated against a soil microbial DNA dataset (16S rRNA and ITS genes) to profile the soil bio-physicochemical relationships. This was undertaken for two land use archetypes representing natural and managed ecosystems. The study found that soil microbial communities were highly related to multiple soil attributes and vegetation. Even though the extent of these relationships varied depending on the environmental scenario and the structural microbial community component analysed, the multidimensional association with soil heterogeneity was evident beyond any single soil property, environmental gradient or land use.