Grazing and the Coupling of Biodiversity in Vascular Plant and Soil Microbial Communities

This study sought to ascertain how different grazing management protocols affect the coupling between soil microbial and vascular plant communities. Changes in microbial and plant communities were observed over a grazing season (Spring 2013-Spring 2014) at 2 previously ungrazed agricultural sites-a moist lowland (Longfield Farm) and a drier upland (Normanskill Farm)-near Albany, NY. Each landscape was divided into 6 fenced enclosures (paddocks). One paddock at each farm was managed by a management-intensive grazing (MIG) protocol, which employs high stock density and frequent rotations. A second paddock was managed by continuous grazing (CG) at lower (conventional) stock density. A third paddock at each site was left ungrazed (U). Three "simulation" paddocks were used to explore the underlying dynamics of grazer-microbe-plant interactions. By spring 2014, plant species richness (S) was significantly higher (t-tests: P < 0.05) in the MIG paddocks at both farms. At Normanskill Farm, S was correlated with both microbial diversity and biomass, while at Longfield Farm, S was independent of microbial diversity and biomass but varied directly with soil moisture. Our findings suggest that while MIG leads to increased S relative to CG, different forcing factors may be responsible for the enhancements in upland and lowland systems.