Fungal community and functional responses to land management in a tallgrass prairie ecosystem

Jacob Hopkins, Ecology and Evolutionary Biology, University of Kansas/Kansas Biological Station, Lawrence, KS, Tatiana Semenova-Nelsen and Benjamin Sikes, Ecology & Evolutionary Biology, University of Kansas, Lawrence, KS

Background/Question/Methods
Soil fungi are key components of terrestrial ecosystems that influence plant growth and are major contributors to carbon and nutrient cycles. Fungal communities and their functions are altered by disturbance, including the land management necessary to maintain many ecosystems. It is unclear however, how management driven shifts to fungal community structure are related to altered function, and how long these effects persist following management activities. Here we tested how different land management techniques altered fungal community composition and influenced hydrolytic enzyme activity in a tallgrass prairie ecosystem. We hypothesized that fire or mowing would drive differences in fungal community structure directly via disturbance, and indirectly through changes to the soil environment. We further hypothesized that changes to fungal community composition would be associated with altered C, N, and P acquiring enzyme activity. We assessed fungal community composition, enzyme activity, and soil environmental variables just prior to management and at regular intervals throughout the following season in pairs of mowed and burned tallgrass prairie plots. Using ordination, indicator species analysis, and structural equation modeling, we quantified how management activities influence the fungal communities and functions that sustain tallgrass prairie ecosystems.
Results/Conclusions
Land management treatments drove differences in fungal community composition that acted on top of seasonal variations in fungal communities. Fungal community shifts were primarily due to compositional turnover rather than loss/gain of diversity, and reflected management driven changes to the soil environment such as post-management increases in soil moisture, nitrogen, and phosphorous. Prior to land management, soil fungi were associated with C acquiring enzyme activity (BGase) and soil carbon storage. Following burning or mowing, however, fungal community structure shifted in response to increases in N and P availability. These changes were correlated with increased N (NAGase) and P (APase) acquiring enzyme activity, while being largely decoupled from BGase activity and soil carbon storage. One month after management actions however, NAGase and APase activities remained elevated, but they were no longer associated with fungal community structure, which again became linked to BGase activity and carbon storage. This suggests fungal community and functional shifts following land management reflect rapid responses to changes in N and P availability, and that fungal carbon cycle roles may be resilient to short-term shifts in fungal community structure and function. In summary, tallgrass prairie fungal communities and their function appear resilient and adapted to recurrent management disturbance, and may contribute to the long-term persistence of prairie ecosystems.