Print PageFungal species may approach the limits of their niches under global change, and therefore may need to migrate long distances to more suitable habitats. The ability of fungi to aerially disperse between distant sites is unknown. We sampled soils from 19 sites across Southern California at three time points (March, July and November, 2010) to understand the environmental, spatial and temporal variables affecting belowground fungal biomass and community composition. In addition, we continuously sampled airborne fungal assemblages at five of these sites to characterize their spatially and temporally explicit diversity and composition. We then linked soil and airborne fungal communities with prevailing wind patterns to determine potential sources of airborne fungal propagules. We hypothesized that soil temperature and moisture are the largest predictors of soil fungal biomass and composition leading to seasonal and spatial shifts in fungal communities. Airborne fungal communities were hypothesized to correlate significantly with soil fungal communities and therefore also exhibit spatial and temporal shifts in composition. Finally, we hypothesized that nearby soil fungal communities should be more similar than distant assemblages. Airborne fungal communities were expected to follow the same trend, although to a lesser extent, as the atmosphere is ostensibly more homogenous than soils.
Results/Conclusions
Soil fungal biomass was significantly correlated with soil moisture and shifted seasonally with significantly higher fungal biomass at the wettest sampling date (March, 2010) (P < 0.05). Soil fungal composition also correlated most significantly with soil moisture (r2 = 0.36, P < 0.01). Belowground fungal communities were more diverse in the wettest sites (Western sites) and during the wettest sampling time (March, 2010). Nearby fungal communities were more similar than distant fungal communities. Airborne fungal communities were also more similar in composition to nearby soil fungal communities. However diversity of fungi in the soil peaked in the spring while airborne diversity peaked during the summer sampling dates (May – July 2010), suggesting that while fungal biomass in the soil may respond quickly to moisture, spore production and dispersal may lag behind by up to three months. Since soil and air fungal biomass and composition are both affected by soil moisture, global climate change is expected to have a significant effect on fungal distributions. Furthermore, because fungal communities were spatially distinct in air and soil fungal samples, dispersal limitation may prevent fungi from migrating to suitable habitats in future climates.
