Climate change is causing shifts in the global water cycle, resulting in episodes of drought and flooding which will become more frequent. These effects will be most pronounced in drylands, which cover more than a third of the Earth’s terrestrial surface. We found that increased precipitation variability decreased grass cover, increased shrub cover and overall, decreased aboveground net primary productivity. However, the effects on below-ground communities, and how that relates to aboveground responses, remain unknown. The objective of this study was to evaluate how the increase in precipitation variability influenced plant-associated soil fungi. To address this aim, we characterised the soil mycobiome from different precipitation treatments and host plants collected from a long-term experiment at Jornada Basin LTER over three years. This field study consisted of five levels of increased inter-annual precipitation variability that kept the same mean precipitation for 10 years. From these experimental plots, we collected soil samples, extracted DNA, sequenced samples using next generation sequencing techniques, assigned fungi to operational taxonomic units, and grouped fungi according to functional guilds.
Results/Conclusions
Fungal DNA concentrations ranged from 10–95.5 ng/µl with a mean of 36.59 ng/µl. There were no significant differences in DNA concentrations between the different sampling years nor among the different precipitation treatments. There was, however, a significant difference in DNA concentrations corresponding with host plant type. Soils sampled underneath shrubs had the highest DNA concentrations, followed by soils sampled underneath grass, and bare ground. Soil fungal community composition differed substantially between host vegetation type and different precipitation variability treatments. Increased rainfall variability caused a decrease in alpha diversity in the soil mycobiomes underneath grass and bare soil, whereas it had no significant effect underneath shrubs. These results suggest that soil mycobiomes that are associated with grasses may be more sensitive to increase in precipitation variability than soil mycobiomes associated with shrubs. Future greenhouse bioassay plant-soil feedback experiments will attempt to reveal the causality in the relationships between observed changes in the soil mycobiomes and its associated vegetation type.