Northern Temperate Pastures Exhibit Divergent Plant Community Responses To Management And Disturbance Legacies Identified Through A Producer Survey

Questions Does plant composition differ among grasslands having divergent disturbance and management histories? Which vegetation attributes and disturbances specifically influence rangeland health?Location Northern temperate pastures in the Central Parkland and adjacent Boreal natural regions of central Alberta, Canada.Methods Plant composition and rangeland health data from 102 pastures were related to disturbance history acquired from retrospective producer surveys. Health assessments evaluated indicators such as vegetation composition, hydrologic function, and site stability. Producers were asked to identify pasture history (e.g., last cultivation date, whether fire had occurred), contemporary grazing actions (timing of use, grazing systems, type of livestock), and other management activities (i.e. herbicide application, manure spreading).Results Cultivation and burn history were the primary drivers of vegetation differences, where previously cultivated pastures were dominated by introduced, naturalized grasses, eliminating most native species. Remnant non-cultivated grasslands were occupied by a mix of native and invasive plant species. Grazing system had limited impact on vegetation composition due to uniformly high livestock stocking. Plant composition corresponded with gradients in rangeland health, where the latter declined with increased stocking rate and supplemental feeding on pasture. Greater health was characterized by increased cover of graminoids (primarily introduced forages), abundant litter, low plant richness, and reduced stocking rates. Other land management activities had comparatively less impact on the composition and health of these grasslands.Conclusions Conversion of native grassland and forest in this region has a strong legacy effect on vegetation. Management actions associated with high stocking rates and supplemental feeding lowered rangeland health.