Invasive golden oyster mushrooms are disrupting native fungal communities as they spread throughout North America

Earth's biodiversity is in decline, and invasive species are among the greatest threats to local ecosystems.¹ While the impacts of invasive plants, animals, and pathogens are increasingly well documented, the impacts of invasive nonpathogenic microbes are not.^2,3,4 The golden oyster mushroom (GOM; Pleurotus citrinopileatus) is a white-rot wood decay fungus and grows primarily on hardwoods.^5,6,7 GOM is a widely cultivated and prized edible fungus native to eastern Asia. GOM was imported into North America in the early 2000s and is now sold in popular mushroom-growing kits. GOM escaped into North American forests around 2010^7,8 and is now rapidly expanding its range. We predicted GOM is changing fungal community composition and lowering species richness in the wood it colonizes. We conducted a field survey of fungal communities from dead elm trees in south-central Wisconsin, USA, and generated metabarcoding data to determine whether fungal communities and species richness differ when GOM is present. To contextualize GOM's impacts, we used community science observations of GOM in North America to map GOM's range expansion and modeled its potential future distribution. When GOM is present, fungal community composition significantly changes, and fungal species richness significantly decreases. GOM has spread quickly and widely in just 8 years, and it is now found in 25 states and 1 Canadian province. While GOM currently grows in middle and northeastern North America, our model predicts climate change will make many other parts of the continent climatically suitable, and GOM will likely continue its range expansion.