Impact of grassland management intensity on associations between bacterial, fungal and plant communities

Abstract

Understanding co-occurrences of different taxa is of both fundamental and applied relevance, for example, to understand ecosystem processes and to design monitoring programs for above- and belowground biodiversity. Plants and microorganisms form complex, interdependent relationships, which are exposed to and may be compromised by agricultural management. Here we assessed the effect of grassland management intensities on bacterial, fungal and plant communities and their associations. We further analyzed the potential of inferring information from taxa of one community on structural changes of the other communities with the aim of potentially enhancing the efficiency of biodiversity assessments by finding common indicator taxa. For that, bacterial, fungal and plant communities as well as environmental factors were assessed in 89 grassland sites of either extensive type (no fertilization, late and infrequent cuttings) or intensive type (fertilization, early and frequent cuttings) of management in the Swiss lowlands.

Bacterial, fungal and plant community structures as well as plant indicator values for soil nutrients and moisture differed between management types. Also, community homogeneity was significantly higher for all communities in the intensively managed grassland. For bacterial community structures, this was likely related to a smaller soil pH range in intensively managed grassland, while a lower fungal and plant richness may have caused more homogenous fungal and plant community structures in intensively managed grassland. Further, correlation strength among community structures dropped by 25–66 % from extensively to intensively managed grassland. Finally, indicator analysis suggested that future monitoring programs may use plant taxa to estimate expected effects on fungal communities and vice versa, but bacterial communities require additional assessment. Our results revealed a multifaceted and profound effect of management on bacterial, fungal and plant communities, which reinforces the conservation value of extensively managed grassland.