Are invasive fungal species always the bad guys in human affected ecosystems?
Invasive species by definition are not native to a specific location -species that were introduced species, and that have a tendency to spread to a degree believed to cause damage to the environment, human economy, or human health. Ectomycorrhizal fungi are no exception and some fantastic examples have spread and successfully reproduced worldwide, such as fly agarics (Amanita muscaria), and waxy laccaria (Laccaria laccata). Although none of those two examples can be considered very damaging to human economy, both fit perfectly into the category of species that can easily spread in the target areas as co-invasive partners with alien plants as detailed in Dickie et al. 2016. Furthermore, the co-invasion of pathogenic fungi is a serious threat to the environment, with obvious and long-term negative effects on native ecosystems, but that is another story.
Studies focusing on intentional or accidental introduction of ectomycorrhizal fungi with the introduced ectomycorrhizal plants are rare. The introduction and potential invasive nature of fungi can be studied at various levels, with most pronounced effects at the ecosystem level. South America, despite having millions of hectares planted for decades with ectomycorrhizal trees such as pines, eucalypts, and acacias, has only a few published studies pointing out the problem of invasive ectomycorrhizal species. Ectomycorrhizal symbiosis is generally considered as positive for ecosystems, being involved in several ecological roles such as supporting survival of young plants, improvement of soil nutrient availability, and in stabilizing soils.
But are ectomycorrhizal fungi seen in human eyes as something directly useful or beneficial? Our research team has been investigating this question specifically in South America. We recently published a paper, revealing a range of non-native ectomycorrhizal fungi recorded in South America, focusing on fungi with fruiting bodies within the soil (hypogeous sequestrate fungi; Sulzbacher et al. 2017). A second project, currently in review, examined non-native fungi in the Brazilian Pampa biome. Both species lists of invasive fungi are fairly long, and mycologists might be enthusiastic to see commonly present co-invading species as Chondrogaster packysporus, Descolea alba, Hysterangium inflatum or Laccaria lateritia, while more economy-oriented mushroom lovers may notice species such as Boletus edulis, Lactarius deliciosus, Suillus luteus, Suillus granulatus, and even just recently described, the edible and aromatic truffle Tuber sp. nov. (Grupe et al., unpublished data).
How many and how much of these edible, co-invasive, non-human economy damaging species are used for culinary purposes or traded in the market? With an exception of several organized plantations dedicated to European truffle species production in Chile, Argentina, and Brazil, there are little available data on other invasive mushrooms and truffles species gaining tradition in South America. To overcome the lack of information on species being collected and consumed, and the lack of quantitative data, we are starting an initiative to collect data sources and data themselves.
Left: edible invasive ectomycorrhizal fungi Suillus sp. Right: North American truffle Tuber sp. (ectomycorrhizal fungi) invading Brazilian Pampa. Photo: Marcelo Aloisio Sulzbacher.