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Abstract Salt marshes are vital but vulnerable ecosystems. However, our understanding of disturbance‐induced dieback and recovery processes in multi‐specific marshes remains limited. This study utilized remote sensing data (2001–2021) to analyze a dieback event and subsequent recovery in the multi‐specific San Felice marsh within the Venice lagoon, Italy. A significant dieback ofSpartina maritima(Spartina) was identified in 2003, likely triggered by a drought event and heat stress. This resulted in a conversion of 4.6 ha of marsh predominantly colonized bySpartina(fractional cover ofSpartina> 50%) in 2001 to bare soil in 2003. These bare areas were then gradually encroached by vegetation, indicating the occurrence of the recovery. Despite gradually gaining ground,Spartinaonly dominated 6.4 ha marshes in 2021, significantly lower than its pre‐dieback area (21.3 ha). However, other species also encroached on the dieback area, such that the aboveground biomass returned to pre‐dieback levels, indicating that the shift in marsh species composition that occurred as a consequence of the event compensated for this ecosystem service. Vegetation recovery, spanning from 1 yr to more than 18 yr, was found to be slowest in areas of lowest elevation. This study provides evidence that dieback and recovery can modify the species composition of multi‐specific marshes over decades. These insights contribute to a better understanding of marsh resilience to drought and elevated temperature, both of which are likely to increase in the future. 

Abstract. The presence of bare patches within otherwise vegetated coastal marshes is sometimes considered to be a symptom of marsh dieback and the subsequent loss of important ecosystem services. Here we studied the topographical conditions determining the presence and revegetation of bare patches in three marsh sites with contrasting tidal range, sediment supply, and plant species: the Scheldt estuary (the Netherlands), Venice lagoon (Italy), and Blackwater marshes (Maryland, USA). Based on GIS (geographic information system) analyses of aerial photos and lidar imagery of high resolution (≤2×2 m pixels), we analyzed the topographic conditions under which bare patches occur, including their surface elevation, size, distance from channels, and whether they are connected or not to channels. Our results demonstrate that, for the different marsh sites, bare patches can be connected or unconnected to the channel network and that there is a positive relationship between the width of the connecting channels and the size of the bare patches, in each of the three marsh sites. Further, pixels located in bare patches connected to channels occur most frequently at the lowest elevations and farthest distance from the channels. Pixels in bare patches disconnected from channels occur most frequently at intermediate elevations and distances from channels, and vegetated marshes dominate at highest elevations and shortest distances from channels. In line with previous studies, revegetation in bare patches is observed in only one site with the highest tidal range and highest sediment availability, and it preferentially occurs from the edges of small unconnected bare patches at intermediate elevations and intermediate distances from channels. Although our study is only for three different marsh sites with large variations in local conditions, such as tidal range, sediment availability, and plant species, it suggests that similar topographic conditions determine the occurrence of bare patches. Such insights may inform decision makers on coastal marsh management on where to focus monitoring of early signatures of marsh degradation.