Biocrusts are recognised for numerous beneficial functions in dryland environments including the promotion of surface stability, moisture retention, and sequestration of carbon and nitrogen from the air which enriches the soil. In microbial biocrusts these benefits are delivered as a consequence of the microbial community adaptations for survival. The biocrust community is not fixed, but is subject to flux and succession like any other ecological community. It has generally been observed that biocrust development is a slow process leading to more ecosystem benefits as crusts gradually mature. The possible reversal of this direction of development, or biotic hindrance of development is rarely considered as a natural component of biocrust life-history.
In this research we identified biocrust community microbes associated with soil stability in sand dune biocrusts of central Australia. A portable wind tunnel was used to subject the biocrust to wind, and a filter in the system was used to collect liberated particles. The microbial community composition in source soil and liberated dust was determined by DNA sequencing. Comparisons revealed that some microbes are preferentially released from biocrusts by wind erosion whilst others resist becoming detached from the soil.
The organisms which resist detachment from soil fit with the established narrative that biocrust succession is always leading to greater stability and “maturity” of the crust. Many of these taxa were cyanobacteria as expected, and identifying them has potential applications for monitoring and managing landscape stability. Easy removal of other microbes from biocrusts by light wind suggests that some microbes present in the biocrust community are not contributing to stability, and may even be adapted to exploit the biocrust – leading to a reduction in soil stability. In this presentation we explore the taxonomy and ecology of microbes in biocrusts which are easily liberated by the wind.