Prairie plant communities and their associated phyllosphere fungal communities change across the steep precipitation gradient in Kansas USA, though individual plant species’ phyllosphere communities may not

Abstract

Tallgrass prairies in North America have endured substantial losses in diversity along with compositional shifts due to anthropogenic environmental change. One largely overlooked aspect of diversity in prairie systems is phyllosphere fungi. Many environmental drivers impact the composition and diversity of phyllosphere fungal communities including plant hosts and surrounding plant communities, precipitation, and land use history. Studies have mainly focused on the changes in foliar fungal communities associated with specific plant species. Few, however, have addressed the association between whole plant communities and their phyllosphere fungi. Additionally, though it is well documented that plant communities shift along precipitation gradients, the impact on phyllosphere fungi in prairies has yet to be explored. Further, little is known about how prairie plant phyllosphere fungi in post-agricultural fields differ from those in native prairie remnants or if they respond differently to environmental change. To determine how plant communities and their phyllosphere fungal communities respond to changes in precipitation and between land use histories, we sampled plant communities and associated phyllosphere fungal communities in native prairie remnants and post-agricultural prairie sites across the steep precipitation gradient (456 mm yr⁻¹ – 1040 mm yr⁻¹) in the central plains in Kansas, USA. In addition, we sampled leaves of big bluestem (Andropogon gerardii, Poaceae) and leadplant (Amorpha canescens, Fabaceae) in five native prairie remnants across a shorter span of the same gradient (615 mm yr⁻¹ – 1038 mm yr⁻¹) to dissect the response of phyllosphere fungi in individual prairie plant species across this precipitation gradient. Plant community cover data and MiSeq ITS2 metabarcode data of the phyllosphere fungal communities indicated that both plant and fungal community composition respond strongly to mean annual precipitation (MAP), but less so to land use (native prairie remnants vs. post-agricultural sites). Plant and fungal diversity were greater in the native remnant prairies than in post-agricultural sites and both plant diversity and the diversity of fungi in their phyllospheres increased with MAP. Additionally, communities in the arid and mesic parts of the precipitation gradient were distinct. We also found that A. canescens and A. gerardii, harbored comparable phyllosphere fungal communities which did not significantly change along the precipitation gradient. Similarly, the diversity of the phyllosphere fungi neither differed between these two plant hosts nor changed with increasing precipitation. Although decoupling the drivers of fungal communities and their composition – whether abiotic or host-dependent – remains a challenge, our research highlights the distinct community responses to precipitation and the tight tracking of the plant communities by their associated fungal symbionts – though individual prairie plants may not show significant distinctions.