Landscapes and seascapes at the edge: boundary zones under global environmental change

Coastal lagoons and dunes are highly valuable but vulnerable systems, impacted by sea-level rise, storms and intense human pressures, including tourism and infrastructure development. Robust multi-temporal shoreline mapping is essential for understanding coastal evolution and supporting effective protection and management strategies. This study investigates shoreline evolution at the Naxos Airport Lagoon, located along the western coast of Naxos, within the Cyclades, one of the Mediterranean regions most vulnerable to climate change impacts. The analysis combines historical aerial imagery (1960–1989) with recent high-precision RTK-GNSS shoreline surveys conducted between 2022 and 2024. Historical shorelines are digitized from georeferenced aerial photographs following established photointerpretation approaches. Contemporary shoreline positions are measured using RTK-GNSS techniques. All shoreline datasets are integrated in a GIS environment and analyzed with the Digital Shoreline Analysis System (DSAS), using standard metrics such as End Point Rate (EPR), Net Shoreline Movement (NSM), and Linear/Weighted Linear Regression Rates to quantify erosion and accretion trends over both long (multi-decadal) and short (2022–2024) periods. The combined analysis clarifies how natural processes and human interventions have reshaped the lagoon’s fringe over ~60 years. The results support identification of critical stretches requiring protection or restoration of dunes and wetlands and offer a quantitative baseline for future monitoring, coastal hazard assessment and integrated management of the Naxos Airport Lagoon system.

Greek islands are coastal boundary environments where terrestrial, coastal, and marine processes interact under increasing pressure from sea-level rise, erosion, extreme events, tourism development, and other forms of global environmental change. While these island “edge-scapes” are highly exposed, they host habitats such as dunes, wetlands and seagrass meadows that act as a natural defense against coastal flooding and erosion through wave attenuation, storm surge reduction and sediment stabilization. However, coastal protection assessments often represent habitats mainly through their presence or extent, without considering whether their spatial configuration enhances or limits their protective function. Here we present a workflow that embeds habitat connectivity and fragmentation metrics into an established coastal protection model to better capture where coastal habitats provide effective protection. Habitat distribution data are combined with biophysical and socio‑economic variables describing (i) protection capacity (e.g., geomorphology, slope, sediment accretion, seabed and emerged habitats), (ii) exposure (e.g., wave climate, storm surge, sea‑level change, winds and currents), and (iii) societal demand (e.g., population density, infrastructure and cultural assets). Configuration is quantified using spatial pattern metrics derived from FRAGSTATS to capture patch density, shape, aggregation, and fragmentation of the habitats. Configuration effects are most apparent for seagrass habitats dominated by Posidonia oceanica and Cymodocea nodosa; island coastlines characterized by dense, aggregated, and well‑connected seagrass seascapes are associated with higher modelled capacity, whereas fragmented or sparse patterns correspond to reduced capacity even where habitat presence is recorded. Terrestrial coastal habitats further modulate capacity locally, particularly where dunes and wetlands occur adjacent to high‑exposure shorelines. The approach supports island‑focused marine spatial planning and nature‑based solutions by accounting for both habitat extent and seascape–landscape structure. Keywords: islands; coastal protection; Posidonia oceanica; connectivity; fragmentation

Treeline ecotones constitute dynamic transitional landscapes that have exhibited global upward altitudinal shifts in recent years, a phenomenon closely linked to climate change. The climatic signal of these dynamics has triggered an explosion of research interest over the last two decades. Changes in forest limits represent complex processes with profound ecological consequences, including changes in biodiversity and carbon storage dynamics. Despite the general global trend of treeline advancement, the literature frequently documents divergent responses to climate change, including stability or even recession. These discrepancies highlight a prevailing "climate bias," as ecotone dynamics rarely follow climatic warming in a linear manner. Factors such as time lags in tree response, water stress, biotic interactions, and disturbances decisively shape their evolution. Overlooking these processes, combined with short-term time series, often leads to the misinterpretation of transient fluctuations as permanent trends. This complexity is particularly evident in the Mediterranean basin, a climate change "hotspot," where rising temperatures are accompanied by intensifying aridity that potentially constrains growth in forests at their ecological margins. Despite its significance, the region remains underrepresented in research. Furthermore, in Mediterranean mountain landscapes, distinguishing between climate-driven shifts and secondary forest succession—related to historical land-use changes (e.g., grazing abandonment)—further complicates the interpretation of observed range shift patterns. Understanding the natural processes of treeline dynamics requires moving beyond single-factor approaches toward multifactorial analytical frameworks, with a particular emphasis on complex and understudied environments.

Coastal lagoons are unique ecosystems that provide a wide range of environmental services. However, they are prone to sea-level rise (SLR), due to both human activities and climate change. The Greek coastline is characterized by several coastal lagoons. In this work, we digitized all coastal lagoons along the Greek coastline (a total of 152 lagoons), using satellite images. We calculated their dimensions and physiographical characteristics, such as such as lagoon length, width, area, perimeter and sandspit morphology. We further conducted a multi-temporal analysis using Sentinel-2 imagery (2015–2025) to assess water surface extent and water quality trends for the five largest lagoons. In order to highlight their vulnerability to sea level rise, we considered two Shared Socioeconomic Pathways (SSP1-2.6 and SSP5-8.5) scenarios for future sea-level rise in the Mediterranean context. Where there were available projections also considering Vertical Land Motion (VLM), we used those instead. All lagoons, their computed parameters and projections have been integrated into a freely accessible WebGIS application. Our results show that 8 to 25% of the Greek lagoons will be fully inundated, depending on the scenario considered, while a substantially larger number are expected to experience partial breaching. Regarding the five largest lagoons, remote sensing analysis revealed predominantly stable conditions. However, Tsoukali lagoon exhibited a significant expansion trend; likely linked to sediment starvation caused by dam construction. In terms of water quality, all lagoons remain eutrophic, with Vistonis as the most ecologically stressed with recorded anoxia events. Collectively, these findings underscore the critical susceptibility of Greek coastal lagoons to both climatic and anthropogenic stressors.

Coastal landscapes represent highly dynamic socio-ecological systems where terrestrial and marine processes interact, generating complex spatial patterns that strongly influence biodiversity and ecosystem service (ES) provision. Despite their ecological importance, coastal zones are among the most heavily impacted environments globally, experiencing increasing pressure from land-use change, habitat degradation, and cumulative anthropogenic stressors. Understanding how landscape structure shapes ecological processes and multifunctionality is therefore critical for effective ecosystem management. This study examines the relationship between landscape structure, biodiversity, and ecosystem service provision across European coastal zones. Biodiversity–Ecosystem Services (BES) bundles were identified using an unsupervised clustering approach (k-means) applied to harmonized European datasets, incorporating indicators of species and habitat richness alongside provisioning, regulating, and cultural services. Four distinct BES bundles were derived, representing characteristic combinations of biodiversity and ecosystem service supply. To explore how landscape structure influences the spatial distribution of these bundles, a suite of landscape metrics describing composition and configuration was calculated at multiple scales. The relationship between landscape metrics and BES bundle membership was modelled using Geographical Random Forest (GRF), a spatially explicit machine learning approach that accounts for spatial heterogeneity by calibrating local models. Results reveal clear spatial patterns in BES bundle distribution, ranging from low-functioning landscapes to multifunctional systems characterized by high biodiversity and service provision. Landscape metrics related to fragmentation, connectivity, and heterogeneity emerge as key influencing factors, although their importance varies spatially. This highlights the non-stationary nature of landscape–function relationships in coastal environments. The findings demonstrate the potential of landscape metrics as proxies for biodiversity and ecosystem service patterns, while emphasizing the importance of spatially explicit approaches. The proposed framework supports large-scale ecological assessment and provides insights for ecosystem-based management, conservation planning, and restoration across European coastal zones.

Tidal notches are among the most reliable geomorphological indicators of past sea levels, providing high-resolution data on the interaction between eustatic changes and regional tectonics. This study presents a comprehensive spatial analysis of a newly developed database comprising over 650 tidal notch sites across the Mediterranean basin, including Greece, Italy, Malta, Croatia, France, Spain and Turkey. The research employs a multi-proxy approach, integrating morphological parameters such as notch height, vertex depth, and profile geometry with lithological data and bioerosion rates. A key component of this study is the application of a rigorous chronological framework, utilizing calibrated carbon-14 dating and biological markers to establish a precise timeline for Holocene relative sea-level (RSL) changes. Preliminary results indicate that tidal notches are a widespread geomorphological feature found throughout the Mediterranean basin. The presence of tidal notches throughout the basin, regardless of local tectonic movements, underscores their value as a fundamental tool for understanding the evolution of Mediterranean coasts. Despite the abundance of these landforms, a lot of them remain undated due to the destructive effects of bioerosion on biological markers. The findings offer a refined model for Mediterranean coastal evolution, distinguishing between climate-driven sea-level rise and geodynamic land movements. This work provides essential baseline data for assessing the future vulnerability of coasts in the context of accelerating global sea-level rise.

Under conditions of ongoing global environmental change, coastal cities operate as critical boundary zones where climatic, ecological, and socio-spatial processes intersect. This paper examines Kalamata, a medium-sized coastal city in southern Greece, as an urban “edge-scape” where heat exposure is shaped by the interaction of coastal microclimates, built environments, and seasonal population dynamics. While heat vulnerability assessments have largely focused on metropolitan areas, smaller coastal cities remain underexplored despite experiencing compound pressures. In Kalamata, elevated humidity, proximity to the sea, and limited urban ventilation interact with densely built structures and tourism-driven seasonal intensification, amplifying perceived heat stress and everyday exposure. Methodologically, the paper develops a composite spatial framework and mapping approach using openly available datasets, integrating population distribution, built-up intensity, and relative access to green infrastructure. By operationalizing green space as a proportion of total urban area, the cartographic analysis captures and visualizes unequal access to cooling resources across the city. This approach enables the identification of spatial patterns of vulnerability beyond conventional surface temperature assessments. The paper introduces the concept of coastal amplification of heat vulnerability, arguing that edge conditions, such as humidity, seasonal population fluctuations, and coastal spatial configurations, mediate and intensify the impacts of extreme heat. In this sense, Kalamata functions as a sensitive indicator of emerging socio-environmental pressures in Mediterranean coastal systems. By situating urban heat within a boundary landscape perspective, the study contributes to interdisciplinary discussions on environmental transformation at the edge, highlighting the need to integrate spatial representation, coastal dynamics and socio-spatial inequalities into climate adaptation and spatial planning strategies.