ECOGEOMORPHIC FEATURES OF SALT MARSHES ANALYSED THROUGH REMOTE SENSING AND FIELD OBSERVATIONS

Poised between vulnerability and vitality in the intertidal zone, salt marshes are rife with ecosystem services. Elaborate halophytic zonation mosaics are intertwined with blue carbon dynamics, thus deciphering how to account for multi-layered biogeomorphic characteristics when estimating biomass and carbon sequestration is crucial. This thesis aimed to clarify nebulous factors in these dynamics by examining seven species associations and focusing on (1) above- and belowground biomass (AGB, BGB) and soil organic carbon (OC) distribution; (2) influences on biomass generation at the Mediterranean scale; (3) interlinkages between AGB and point cloud characteristics in digital terrain and canopy models; and (4) relationships between Normalised Difference Vegetation Index (NDVI) and biomass from local to regional scales. The results highlighted that the volume and partitioning of biomass and its relation to OC are highly species-specific. Mean AGB was notably greater in the middle-high marsh, whereas BGB and OC values peaked in the lower-middle marsh. In addition, vegetation mosaics imprint patterns of inaccuracy in point cloud-derived terrain models which can be exploited to correct elevation estimates and reconstruct canopy properties. Also, vegetation zonation encompasses a conglomerate of different NDVI to biomass relationships which result in cascading impacts on the use of vegetation indices from local to regional scales. Sea Lavender combines intense photosynthetic activity per unit area of AGB with the highest BGB and OC levels in the marsh. Due to its extent and apparent nexus of unique attributes, Sea Lavender has remarkable potential as a keystone salt marsh umbrella genus, one that is adept at enhancing and maintaining blue carbon reservoirs in the face of climate change. Overall, this research enhances the understanding of and ability to monitor salt marsh biomass and carbon sequestration dynamics. Thus, strengthening underpinning factors of interdisciplinary frameworks focused on the intertwined mechanisms that dictate marsh evolutionary trajectories.