Increased soil N availability may often facilitate plant invasions. Therefore, lowering N availability might reduce these invasions and favor desired species. Here, we review the potential efficacy of several commonly proposed management approaches for lowering N availability to control invasion, including soil C addition, burning, grazing, topsoil removal, and biomass removal, as well as a less frequently proposed management approach for lowering N availability, establishment of plant species adapted to low N availability. We conclude that many of these approaches may be promising for lowering N availability by stimulating N immobilization, even though most are generally ineffective for removing N from ecosystems (excepting topsoil removal). C addition and topsoil removal are the most reliable approaches for lowering N availability, and often favor desired species over invasive species, but are too expensive or destructive, respectively, for most management applications. Less intensive approaches, such as establishing low-N plant species, burning, grazing and biomass removal, are less expensive than C addition and may lower N availability if they favor plant species that are adapted to low N availability, produce high C:N tissue, and thus stimulate N immobilization. Regardless of the method used, lowering N availability sufficiently to reduce invasion will be difficult, particularly in sites with high atmospheric N deposition or agricultural runoff. Therefore, where feasible, the disturbances that result in high N availability should be limited in order to reduce invasions by nitrophilic weeds.

Revegetation by seeding is an important tool in restoration. Seeding practices for restoration often rely on standard prescriptions for seed mix diversity and seeding rates. Seed mix diversity and rates are generally low within restoration projects and these practices are typically not informed by research. The objective of this study was to explore a new method for determining an optimal seed mix diversity and seeding rate for restoration of a semiarid grassland. We examined restoration success associated with differing seed mix diversity levels (5–50 species) and seeding rates (400–1,600 pure live seeds [PLS]/m²) using a response surface regression (RSR) experimental design at 12 disturbed sites in northeastern Colorado. Overall restoration success was evaluated based on optimizing desirability across nine individual responses: biomass and diversity of seeded, volunteer native, noxious, non‐native species, and the density of seeded species. Greatest restoration success after four growing seasons occurred at a seed mix diversity of 35 species and a seeding rate of 1,366PLS/m².RSRexperimental design and analysis has seldom been used to answer ecological questions. This novel approach to address a pressing restoration challenge provided unique insight into how seed mix diversity and seeding rate, singly or in combination, influence the first 4 years of plant community development and overall restoration success. These results suggest that including more native species and seeding at higher rates than current practice could lead to greater restoration success in grasslands.