Spatial structuring of arbuscular mycorrhizal communities in benchmark and modified temperate eucalypt woodlands
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Arbuscular mycorrhizal fungi (AMF) are crucial to the functioning of the plant–soil system, but little is known about the spatial structuring of AMF communities across landscapes modified by agriculture. AMF community composition was characterized across four sites in the highly cleared south-western Australian wheatbelt that were originally dominated by forb-rich eucalypt woodlands. Environmentally induced spatial structuring in AMF composition was examined at four scales: the regional scale associated with location, the site scale associated with past management (benchmark woodlands with no agricultural management history, livestock grazing, recent revegetation), the patch scale associated with trees and canopy gaps, and the fine scale associated with the herbaceous plant species beneath which soils were sourced. Field-collected soils were cultured in trap pots; then, AMF composition was determined by identifying spores and through ITS1 sequencing. Structuring was strongest at site scales, where composition was strongly related to prior management and associated changes in soil phosphorus. The two fields were dominated by the genera Funneliformis and Paraglomus, with little convergence back to woodland composition after revegetation. The two benchmark woodlands were characterized by Ambispora gerdemannii and taxa from Gigasporaceae. Their AMF communities were strongly structured at patch scales associated with trees and gaps, in turn most strongly related to soil N. By contrast, there were few patterns at fine scales related to different herbaceous plant species, or at regional scales associated with the 175 km distance between benchmark woodlands. Important areas for future investigation are to identify the circumstances in which recolonization by woodland AMF may be limited by fungal propagule availability, reduced plant diversity and/or altered chemistry in agricultural soils.
KeywordsAgricultural landscapes Ecological restoration Glomeromycota Land use Nitrogen Phosphorus Soil fungi
We thank the Department of Parks and Wildlife WA, Tom and Lyn Cooke and Neil and Wendy Whyte for allowing us to sample their sites, Khalil Kariman for preparing fertilizer solutions and Jon Leff and Jane Speijers for advice on data analysis. This study was supported through the CSIRO Building Resilient Australian Biodiversity Assets theme and the Great Western Woodlands Supersite, part of the Australian government’s Terrestrial Ecosystems Research Network.
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