Using eDNA to Investigate Soil Fungal Trajectory and Mammal-Fungi Interactions at an Arid Australian Restoration Site

Abstract

Soil fungi regulate terrestrial ecosystem function and productivity. Native digging mammals influence soil physiochemistry, thus likely affect soil fungal communities; yet despite their re-establishment in many parts of arid Australia, the influence of digging mammals on soil fungi in reintroduction areas remains largely unknown. We used high-throughput DNA sequencing to characterise the soil fungal community at an arid mammal restoration site (Wild Deserts) and an adjacent area where digging mammals are extirpated, as well as to assess the fungal content of scat from a reintroduced digging mammal, the greater bilby (Macrotis lagotis). We assessed the richness, composition, spatial evenness and abundance of fungal functional guilds in soil samples taken inside and outside the reserve. Additionally, we assessed the composition of fungi and fungal functional guilds in bilby scat samples collected at several timepoints (pre- and post-reintroduction). Approximately 3 years after initial reintroductions, the soil fungal community did not differ in any of the assessed measures between digging mammal-present and –absent areas. In bilby scats, there were significant differences in fungal guilds detected between the sampling periods. Litter-saprotrophic fungus Chlorophyllum was more abundant in bilby scats collected three-years post release at Wild Deserts, compared to those collected pre-release and relatively high abundance of Chlorophyllum in several scats may point to opportunistic consumption of the fungus by bilbies. While we did not observe differences in the soil fungal community inside and outside the restoration area within the study period, the strong overlap between fungal taxa detected in soil samples and post-release scats is consistent with bilbies interacting with fungi in the environment at Wild Deserts. Our work highlights a need to improve knowledge of Australian arid-zone fungi, and for long-term monitoring regimes to establish benchmarks for fungal communities and elucidate the mechanisms and timescales by which digging mammals affect soil fungal restoration.