Abstract

Unassisted recovery of plant diversity after reductions in nutrient inputs can be slow and incomplete. Increased nutrient availability, light limitation and recruitment limitation are thought to be primary barriers to diversity recovery. In a full-factorial experiment, we tested whether removing these obstacles promoted recovery of plant diversity in a previously cultivated and fertilized old-field. Results immediately following manipulations demonstrated that these factors increased diversity to varying degrees, but it was unknown whether these restorative processes would continue or diminish over time. Here, we examine long-term responses 13 years after these manipulations and find that seed addition was the only treatment that continued to increase plant diversity and productivity. Seed addition also reduced the biomass of two invasive species that become co-dominant in this grassland after sufficient nutrient inputs. Our results suggest that alleviating recruitment limitation can accelerate the recovery of plant diversity, and ecosystem functions that depend on plant diversity.