Vernal herbs are an understudied component of the forest flora, possibly due to life-history traits that make them difficult subjects to study. Vernal herbs play a role in nutrient cycling and influence floral and faunal community composition through competition and food provisioning. We designed this experiment, now in its ninth year, to assess whether site conditions or dispersal prevents spring-flowering herbs from colonizing previously disturbed forest sites. We investigated the efficacy of different methods of introduction in order to develop simple and cost-effective management strategies. We chose four mesic forests on formerly cut and grazed sites. We wild-harvested and transplanted a limited number of flowering adults and hand sowed propagules of five spring-flowering species, Dicentra canadensis, D. cucullaria, Jeffersonia diphylla, Polemonium reptans, and Stylophorum diphyllum.
Results/Conclusions
Our restoration approach was largely successful. After seven years, all 20 introduced populations were still represented. Seventeen populations exhibited positive population growth, and offspring from 17 populations dispersed beyond initial transplant or sown quadrats. The wild-harvested, flowering adults survived and produced viable seeds for multiple years. Furthermore, we found that transplanting adults was more efficient and effective than sowing propagules. Our results provide clear experimental evidence that dispersal is a limiting factor to the development of diverse spring-flowering communities in disturbed forests. Particularly for vernal perennial forest herbs, assisted dispersal of wild adults from multiple local populations is an efficient way to restore depauperate sites.