Conquering New Frontiers: The Effect of Vegetation Establishment and Environmental Interactions on the Expansion of Tidal Marsh Systems

Abstract

Tidal marshes are dynamic systems whose lateral expansion depends on various biologically, physically, and geomorphologically controlled small- and large-scale feedback networks. Due to the bimodal existence of two landscape states at the tidal marsh edge (vegetated tidal marsh flat and bare tidal flat), and the high wave energy affecting the foremost seaward (pioneer) zone of tidal marshes, plant seedlings face two challenges: 1) successful seed settling and germination or clonal expansion and establishment under non-optimal conditions, and 2) a variety of abiotic stresses after establishment. Modelling and laboratory studies have addressed the reciprocal relationship especially between hydrodynamic and sedimentary forces and vegetation traits and have revealed fundamental mechanisms and feedbacks. Nevertheless, validations of the findings from artificial environments in natural ecosystems are still lacking. In this review, we present the current state of literature to vegetation-abiotic interactions, focusing on the establishment and adaptation of seedlings and propagules and what effect they may have on the prospective evolution of tidal marshes.