Season of prescribed fire determines grassland restoration outcomes after fire exclusion and overgrazing

Fire exclusion and mismanaged grazing are globally important drivers of environmental change in mesic C4 grasslands savannas. Although interest is growing prescribed fire for grassland restoration, we have little long-term experimental evidence the influence burn season on recovery herbaceous plant communities, encroachment by trees shrubs, invasion exotic grasses. We conducted a experiment (seven burns between 2001 2019) historically fire-excluded overgrazed central Texas. Sites were assigned to one four treatments: summer (warm season, lightning season), fall (early cool winter (late or unburned (fire exclusion). To assess restoration outcomes experiment, 2019, identified old-growth serve as reference sites. Herbaceous-layer communities all sites compositionally functionally distinct from grasslands, with perennial grasses long-lived forbs. Unburned characterized several species tree, shrub, vine; certain C3 forbs; intermediate composition Despite compositional differences, treatments had comparable plot-level richness (range 89–95 species/1000 m2). At local-scale, (23 species/m2) (20 supported greater than (15 species/m2), but did not differ significantly Among treatments, most consistently produced vegetation structure (e.g., mean woody canopy cover 9%). But whereas promoted invasive grass Bothriochloa ischaemum maintaining areas low cover, simultaneously limited controlled B. invasion. Our results support body literature that shows alone, without introduction propagules, cannot necessarily restore community composition. Nonetheless, this demonstrates implemented can benefit preventing while also controlling an grass. suggest deserves attention planning ecological research.