Planting techniques and abiotic variation at two salt marsh restoration sites in the Bay of Fundy

• Published in: Restoration ecology 2023-03, Vol.31 (3), p.n/a
• Main Authors: Rabinowitz, Tasha R. M., Lundholm, Jeremy T., Graham, Jennie M., Bowron, Tony M., Proosdij, Danika
• Format: Article
• Language: English
• Subjects: Aquatic plants; Climate change; Ecosystem services; Growth rate; Halophytes; Indigenous species; managed realignment; Maritime Canada; Native organisms; Nutrients; Plant communities; Planting; Plugs; Restoration; Revegetation; Salt marshes; Saltmarshes; Soil nutrients; Soil salinity; Soils; Spartina; Survival; Tidal currents; Tidal flow; tidal wetland restoration; Transplants; vegetation restoration; Winter
• ISSN: 1061-2971; 1526-100X
• DOI: 10.1111/rec.13707

Salt marshes provide many important ecosystem services, and interest in their restoration is growing in response to climate change. In Maritime Canada, salt marsh restoration projects have focused on restoring tidal flow without planting. Over time, these sites can show persistent deficits in vegetation diversity. We evaluated six techniques for encouraging revegetation (plugs, field transplants, seed, wrack, tilling, and no planting) with eight native species (Carex paleacea, Juncus gerardii, Limonium carolinianum, Plantago maritima, Poa palustris, Solidago sempervirens, Sporobolus alterniflorus, and Sporobolus michauxianus) at two Bay of Fundy salt marsh restoration sites. Community recovery and plant performance (growth rate, summer and winter survival, and health) were monitored over 2 years. Planting plugs produced the highest abundance of perennial halophytes over both years with high survival rates (76.4% ± 0.02 SE), whereas plants transplanted from adjacent sites had higher mortality and slightly lower cover. All planted species survived and grew. Growth rate, health, and winter survival were all more strongly related to site than planting technique, indicating that location was more important to success than technique. We found evidence that differences in elevation, inundation, soil salinity, and soil nutrients at each site may explain these differences in performance. Plugs and field transplants may both be useful for restoration in the future and mixing methods to capitalize on respective strengths may produce best results when planting. Our results also highlight the need to tailor planting plans to individual sites as plants may respond uniquely in different situations.