Effects of restoration strategies on vegetation establishment in retired cranberry bogs

The wetlands of the New Jersey Pine Barrens (USA) have historically been utilized for large-scale cranberry ( Vaccinium macrocarpon ) farming. In 2003, 3800 hectares of retired cranberry farm became the focus of restoration efforts by the New Jersey Conservation Foundation with the goal of returning much of its 2000 hectares of wetlands to the previous condition as Atlantic white cedar ( Chamaecyparis thoides) swamp. Two different agricultural strategies had previously been employed throughout the farm: traditional- minimal soil and hydrological modification, and modernized- intensive management with soil replacement and major hydrological modification. During restoration, three different strategies were employed: hydrological restoration only, hydrological restoration with microtopographic modification, and hydrological restoration with microtopographic modification and planting of C. thyoides . The purpose of our study was to examine the effects of these strategies on vegetation establishment a decade after restoration was initiated. Replicate nested quadrats were established at each study site, and vegetation was surveyed in both June and August of 2017. All restoration strategies produced robust plant assemblages with similar diversity and quality to each other and to the reference sites. However, the assemblages were set apart by their unique indicator species. Our results also suggest that planting C. thyoides seedlings may give the species selective advantage in a competitive successional setting. According to NMDS ordination, plant assemblages at restored sites were significantly different from reference sites; only continued monitoring will allow us to determine where their successional paths will lead. This study has important implications for future restoration projects in the New Jersey Pine Barrens and similar ecosystems, especially because the results suggest that as long as hydrological restoration occurs, this can promote the establishment of robust, diverse, and relatively high-quality plant assemblages.