Ectomycorrhizal fungi and pinaceae invasions

NUÑEZ MARTIN A.; HORTON THOMAS R.; HAYWARD JEREMY; DIMARCO ROMINA D.; SIMBERLOFF DANIEL

Conferencia; VIII SOUTHERN CONNECTION CONGRESS; 2016

Belowground interactions are complex and important to plant invasions. Here we describe research on Isla Victoria in Nahuel Huapi National Park and in other parts of the southern hemisphere on mycorrhizal fungal invasion, and their role on pine invasions. Pinaceae invasion is a major problem in the southern hemisphere, with millions of hectares invaded. We used a series of greenhouse, field and lab studies to investigate the role of mycorrhizal fungi in pine invasion. We found that mycorrhizal fungi can limit Pinaceae invasion, with seedling establishment and growth far from plantations hindered by a lack of mycorrhizal inoculum. Different communities of mycorrhizal fungi occur inside plantations than in the natural regeneration areas. Also, results from inoculation studies with feces showed that animals are the main dispersal vectors of mycorrhizal fungi in the area, since field experiments showed that wind dispersal of propagules from sporocarps is limited. With large field experiments, we found that mycelial networks associated with exotic Pinaceae promote invasion fronts of Pinaceae. When seedlings were connected to a network of exotic trees, they grew significantly bigger than when isolated from such networks. However, in native forest areas distant from any exotic trees, isolation from the native networks was an advantage. This suggests a new mechanism for biotic resistance, where fungal network of native trees can reduce the establishment of exotic trees. It is clear from these results that studying Pinaceae invasion without studying their mycorrhizal symbionts can lead to an incomplete understanding of the invasion process.