| dc.description.abstract | Soil bacterial and fungal communities change dramatically over seasons and across multiple climate and environmental gradients. Little work has tested if the impact of these gradients on soil communities depends on the season in which they are measured, or whether seasonal community dynamics differ predictably across gradients. Given close links between microbial community variation and microbial function, more knowledge of community changes across these gradients in a single season and across the growing season could allow for a better understanding of microbial function at the landscape scale. We used amplicon sequencing to determine how the diversity and structure of soil bacterial and fungal communities respond to broad differences in environment, including historical precipitation, land use, and soil depth. We examined communities in spring and fall separately, then assessed whether community change across seasons depended on these same factors. We found that within-season variation in bacterial and fungal communities responded similarly to precipitation, land use, and depth. In spring and fall, these factors had similar impacts on bacterial and fungal communities, with depth explaining the majority of variation in diversity and community structure. Strong shifts in diversity and community structure across seasons were observed only at the 0-5 cm depth, and differed solely based on annual precipitation (not land use). While soil depth plays an important role in structuring microbial communities in both seasons, our results indicate that across seasons, only microbial communities at the soil’s surface are sensitive to climate differences. Key edaphic variables that change with soil depth and precipitation (i.e., soil moisture, pH, and organic carbon content) may simultaneously predict landscape-scale community variation within and across seasons. As patterns of microbial function in individual seasons and across seasons may respond differently to environmental gradients, future work determining if community structure and function are equally linked across environmental gradients and seasons will be key to assessments of functional redundancy, and to better predict change in ecosystem function. | |
