Knowledge of disturbance interactions is fundamental to improved understanding of plant community dynamics and the development of management practices aimed at increasing resilience of grassland ecosystems. In this study, we evaluated grassland responses to multiple disturbance interactions in a series of 2-year, randomized complete block experiments repeated in 2016 and 2017 in the Nebraska Sandhills, mixed-grass prairie. Soil type was a Valentine fine sand (mixed, mesic Ustipsamments). Each experiment contained a 3 × 2 × 2 factorial arrangement of soil disturbance (no soil disturbance, soil disturbance with no seed, and soil disturbance with forb seeding), water addition (water, no water), and fire treatments (fire, no fire). In both experiments, fire had the most prominent impact on plant community composition and biomass. Fire increased bare ground and reduced canopy cover of annual plants in the first year. However, annual plants recovered in the second year. Forbs, especially marestail (Conyza canadensis), were most significantly affected by fire. Other plant groups, including warm- and cool-season grasses, natives and exotics, and so on, varied in cover and biomass in response to interacting disturbances and temporal variability. Forb seedling establishment was negatively affected by temporal variability in weather patterns. Differences in plant community response between experiments were likely due to drought in 2017. Overall, the plant community showed resilience to the multiple disturbance interactions. We did not see evidence of large or non-linear changes in plant community structure over the short term in these grasslands.
