Salt marsh vegetation recovery on the Bay of Fundy

Abstract

Beginning in the 17th century many Bay of Fundy marshes were diked and drained for agricultural use, but storm breaching of dikes and failure of tidal gates has returned tidal flooding to some marshes. We investigated two breached and undiked salt marsh pairs in the Bay of Fundy to assess the potential for recovery of these reclaimed lands and improve our knowledge about salt marsh restoration. We examined the distribution of major species with respect to elevation and compared plant cover and production of reference and recovering marshes. The vertical range of both Spartina alterniflora and Spartina patens increased with tidal range - a condition recognized for S. alterniflora, but not previously reported for S. patens. Our results reveal that S. alterniflora and S. patens are inundated less frequently than in microtidal marshes and tolerate a large variation in inundation frequency and depth. The upper portions of the S. patens zone may not be submerged by tidal waters in some years, so hydroperiod (and its associated stresses) may play less of a role in limiting the lower elevation of a species' distribution in the high marsh. Our comparisons of reference and recovering diked marshes inform not only restoration activities on the Bay of Fundy, but also give a perspective on recovery trajectories of reclaimed salt marshes in general. Regionally, the broad elevation range of S. alterniflora and high sediment deposition rates impart Bay of Fundy marshes with a high resilience and prospects for success of deliberate restoration efforts are promising, without the addition of fill required for marsh restoration in some regions. While marsh loss occurs in other areas the Bay of Fundy provides an opportunity to regain this resource.