Arbuscular mycorrhizal fungal communities along an soil age and fertility gradient on an arid sand dune chronosequence
Teste, F., Krüger, M., Laliberté, E., Lambers, H. and Bunce, M. (2013) Arbuscular mycorrhizal fungal communities along an soil age and fertility gradient on an arid sand dune chronosequence. In: 5th joint conference of New Zealand Ecological Society and Ecological Society of Australia, 24 - 29 November, Auckland, New Zealand.
Arbuscular mycorrhizal fungi (AMF) are known to enhance phosphorus (P) acquisition by plants, but it has been suggested that AM strategy becomes ineffective in strongly weathered soils, where P availability is extremely low. Using high-throughput DNA sequencing, we determined changes in the diversity and composition of AMF communities along a 2 M year old sand dune chronosequence in the south-western Australia global biodiversity hotspot. AMF have thus far been largely ignored in biodiversity hotspots, and it is unknown how these communities vary during long-term ecosystem development. We show that AMF spore density decreased from 90,000 spores m-³ in the young dunes to 55,000 spores m-³ in the old dunes. Mycorrhizal colonisation was dominated by Rhizophagus species where it peaked to 24% in 120,000 year old dunes and then dropped again to 9% in 2 M year old dunes. This reduction in colonisation was perhaps due to antagonistic effects of non-mycorrhizal, cluster-rooted Proteaceae plants that dominate on the oldest soils, or to the very low P levels in the soil (<10 ppm total P). Multivariate analyses of the operational taxonomic units (OTUs) show that richness and diversity of the AMF communities are the greatest in the 120,000 year old dunes. A sharp 50% loss of OTUs richness was found in the oldest dunes. The AMF community structure in the mid-aged dunes also differ from the younger and older dunes. Our results are consistent with the view that the AM strategy becomes less effective when P availability declines to very low levels.
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|Murdoch Affiliation:||School of Biological Sciences and Biotechnology|
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