Belowground invasions: Effects of non-native ectomycorrhizal communities on non-native and native tree species

HORTON, THOMAS R; PAUCHARD, ANÍBAL; POLICELLI NAHUEL; NUÑEZ MARTIN A

Valdivia

Congreso; International workshop: mycorrhizal symbiosis in the southern cone of South America; 2017

Universidad Austral de Chile

Increasing evidence shows that belowground interactions are key in determining invasive plants success or failure. However, less is known about the changes that plant invasion produce in local soil biota and how non-native and native plants are affected. We measured the effect of exotic ectomycorrhizal fungi (EMF) on native communities in two ecosystems in southern Chile (Malalcahuello and Coyhaique). To determine how EMF community changes across the invasion and whether fungal species can switch hosts, we used the non-native invasive Pinus contorta and the dominant native Nothofagus antarctica as focal species. We sampled root tips from both species in stands with increasing pine density. We then used ITS-RFLP and sequencing to identify fungal species. To further analyse plant-fungal interactions, we conducted a greenhouse experiment. We took soil cores from native and invaded stands and planted seeds from the native and the invasive plants. We also planted a native non-mycorrhizal plant (Embothrium coccineum) to control for changes in abiotic soil conditions and we used sterilized soil as general control. Preliminary results from the DNA analyses showed a predominance of non-native suilloid fungi in field samples, which have been previously described as decisive for pine invasion. In the greenhouse experiment, native and exotic plants showed similar growth and root colonization percentage in all treatments, but a higher shoot/root ratio in both soil origins compared with sterile soil in which they grew less and invested more biomass in roots. Hence, the role of belowground mutualists seems crucial for both the native and the invasive plant, even in the presence of soil pathogens. Despite similar plants growth, invasive fungal community might be replacing native ECM species. Future molecular analysis will determine the possibility of novel interactions, together with a wide-ranging understanding of the role of ECM species in plant invasions and their belowground impact.