Total focal annual cover and litter in treatments representing native, naturalized, or invasive annuals, and controls. Given is mean (+ SE) a total cover of focal annual species, 2016–2018 b litter cover, 2016-2018 and c litter biomass at the end of the experiment in 2019. Sown native and naturalized annuals were allowed to colonize plots where they were not seeded and are included in total focal species cover in all cases except the invasive treatment, where they were a minor component (Fig. 1). Photo shows a perennial forb (Balsamorhiza sagittata) seedling (circled) emerging from the thick litter layer in an invasive plot. Within-year patterns for each variable were evaluated with post-hoc comparisons when the treatment effect was significant (P < 0.05), and means that do not share letters are significantly different.