Australia: The Land Where Time Began

A biography of the Australian continent 

Semi-Arid Floodplain Soils - Impacts on Eukaryotic Diversity of Inundation and Drought

According to the authors¹ wet and dry phases characterise floodplain ecosystems, and their ecological character is defined by periodic inundation. Around the world natural flooding and drying regimes have been altered substantially by climate change, regulation of rivers and the construction of levees with consequences that are largely unknown on key biotic groups. The hypothesis of the authors¹ suggests that in areas of semi-arid floodplain affected by climate change in southern Australia communities of soil eukaryotic organisms would transition towards comprising mainly species that specialised in dry soils as the severity of droughts increased. In this study the authors¹ measured the composition of the eukaryote community, by the use of 18S rRNA amplicon pyrosequencing, in soil that had been depleted in water to varying degrees of drying, to confirm that transitional changes occurred, that were reproducible, in the biodiversity of eukaryotes in this floodplain. Three years after a flood the structures of inter-flood communities were dominated by persistent species, rather than species that specialised in either wet or dry conditions. By 8 years after a flood 2 % of taxa were unique to dry locations, and when inundated a year to 2 weeks after a flood 10 % were restricted to wet locations. In both these environments 48 % of the total soil biota were detected. The authors¹ suggest their discovery of a large suite of organisms that are capable of surviving almost 10 years of drought, and up to 1 years submerged supports the concept of inherent resilience of semi-arid soil communities in Australia under increasing pressure from changes in the availability of water that are induced by climate change.

Sources & Further reading

1. Baldwin, Darren S., Matthew J. Colloff, Gavin N. Rees, Anthony A. Chariton, Garth O. Watson, Leon N. Court, Diana M. Hartley, et al. "Impacts of Inundation and Drought on Eukaryote Biodiversity in Semi-Arid Floodplain Soils." Molecular Ecology 22, no. 6 (2013): 1746-58.