Fungi are essential components of terrestrial ecosystems worldwide. Many fungi produce fruiting bodies in the form of mushrooms. These mushroom-forming fungi are key to forest nutrient cycling and, in association with plants, range from beneficial symbionts to pathogens. Yet, we know very little about how regional, landscape, and local factors such as fire combine to affect the distributions of mushroom-forming species, nor how such distributions may be changing with a shifting climate. Understanding mushroom distributions is particularly challenging because these fungi spend most of their lives as branching filaments of asexual cells (hyphae) below the soil, and there presence only becomes known if and when they produce a mushroom. Recent work has shown that some fungi may occur as hyphae inside plants thousands of kilometers outside their known ranges, which are based on their sexual reproduction (i.e., mushrooms). These extended ranges of fungal hyphae suggest that different factors drive the distributions of life stages of these fungi, complicating efforts to forecast how fungi will respond to changing environments. This research will examine the distributions of mushroom-forming fungi across the United States by combining mushroom collections with sampling of fungal DNA in soils, litter, plant tissues, and the air, at study locations in eight different states (AK, AZ, CO, FL, KS, NH, MN, OR). Information at each site such as climate, plant communities, fire and soils will then be used to determine the conditions under which particular fungi are able to sexually reproduce and where they can only live as hyphae. The project will connect scientists with more than a thousand community members from mushroom clubs, local schools, and museums who will be involved in collecting mushrooms and working with fungal DNA for scientific purposes. Using the extensive climatic and geographic scope of the study, containing diverse plant communities and fire disturbances, we will test how environmental variables at multiple scales influence distributions of sexual and asexual stages of fungi. We will also determine whether occurrence of a fungus in one stage (e.g., mushrooms) is predictive of its occurrence in other substrates at a site (e.g., soils, air, or plant tissues), allowing improved sampling schemes for fungi. Together, this study will build the most complete picture to date of how macrofungal communities and their relationships change across climate gradients, thus building capacity to predict changes in fungal distributions and ecosystem processes under changing climate. Further, unprecedented fires in recent years have placed fire ecology in the public eye like never before, such that expanding understanding of fire as a driver of cryptic aspects of biodiversity and ecosystem dynamics is timely and of broad interest. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.