Nature-based solutions are increasingly recognized as effective and multifunctional components of climate-resilient flood protection. While tropical mangroves have received substantial attention, temperate riparian forests, particularly willow systems, offer comparable wave attenuation and biodiversity benefits, yet remain understudied. This study assesses the ecological and protective value of three types of willow floodplain forests: a so-called wild-grown willow forest, a pollard willow forest, and a willow plantation. Using field data from the Biesbosch National Park (the Netherlands), we quantified forest structure, ground-dwelling invertebrate diversity, and modelled wave attenuation under storm scenarios. Structural complexity and biodiversity were highest in the wild-grown forest, with significantly greater invertebrate order richness, larger body sizes, and more heterogeneous canopy architecture. The pollard forest showed the highest wave attenuation efficiency due to their dense, low-lying crown structures. The plantation forest showed lower values across both axes. We integrated these findings into a trade-off model evaluating ecological value, flood protection efficiency, and a 50-year simple cost analysis of each forest type as a hybrid solution alongside traditional dikes. While the pollard forest is the most spatially efficient for flood attenuation, the wild-grown system provides greater ecological value at lower lifecycle cost. Our results underscore the importance of tailoring hybrid flood defense strategies to local priorities - balancing biodiversity, spatial constraints, and economic feasibility. The framework developed here can inform ecosystem-based design in delta regions worldwide, supporting integrated climate adaptation that aligns safety with ecological resilience.

The restoration and creation of tidal freshwater wetlands is increasingly becoming important, yet the success of these efforts is limited by salt intrusion, a growing concern due to climate change and human activities. Key topographical features, such as (re)constructed channel network, might help mitigate salt intrusion in these areas. Using a hydrodynamic model and idealized topographies based on real-world data from natural marshes and various constructed wetlands, we analysed how topographies respond to saltwater intrusion events. Our findings reveal that, although wetland topographies based on natural marshes experience faster salinity increases at the onset of an event, they also achieve quicker salinity reductions at its conclusion, resulting in shorter overall periods of salinization compared to artificial wetland designs (e.g. up to 8.10 % in the drought simulations and 48.72 % in the storm surge simulations). The rapid reduction in salinity is driven by the distinct topography of natural marshes, particularly the creek system, which amplifies salt fluxes. Compared to the reference topography, the natural marsh topography exhibited 6.50 % higher salt fluxes in drought (S + W) simulations and up to 41.02 % higher in storm surge (S + W) simulations. These findings emphasize the importance of incorporating natural marsh characteristics, such as slope and channel network design, into tidal freshwater wetland restoration and creation projects to improve resilience against salt intrusion and ensure their long-term sustainability in the face of climate change.

The success of climate adaptation and nature conservation measures depends significantly on public support. Although the value of protecting iconic species is often easy to communicate to non-expert audiences, conveying the broader importance of ecosystem restoration and conservation for climate resilience is more challenging. To address this, we developed a method that combines spatially explicit models of complex, self-organizing ecosystems with state-of-the-art visualization techniques. This approach creates immersive, three-dimensional panoramic views of natural landscapes, illustrating how people live in and interact with these ecosystems. Our method showcases the inherent complexity of ecosystems, highlighting features such as spatial patterning and the dynamic processes that shape them, as well as the critical role of this complexity in supporting biodiversity. Additionally, it demonstrates the potential of restored or even constructed ecosystems as nature-based solutions to future climate challenges. Adaptable to various ecosystems and locations, with the optional addition of audio or text explanations, this visualization tool can be used in diverse contexts, from museum exhibits to on-site virtual experiences, effectively reaching broad audiences. We present our visualization approach through two case studies that bring to life past climate-adaptive ecosystems and envision future developments. The first case depicts a historic medieval village, now located within a low-lying polder, which was once founded on an expansive, climate-resilient marsh that naturally rose with sea levels due to continuous sediment deposition. The second case explores a planned nature restoration project in Biesbosch National Park, where an embanked meadow is planned to be converted into a tidal wetland.

The adaptive capacity of ecosystems, or their ability to function despite altered environmental conditions, is crucial for resilience to climate change. However, the role of landscape complexity or species traits on adaptive capacity remains unclear. Here, we combine field experiments and morphodynamic modelling to investigate how ecosystem complexity shapes the adaptive capacity of intertidal salt marshes. We focus on the importance of tidal channel network complexity for sediment accumulation, allowing vertical accretion to keep pace with sea-level rise. The model showed that landscape-scale ecosystem complexity, more than species traits, explained higher sediment accumulation rates, despite complexity arising from these traits. Landscape complexity, reflected in creek network morphology, also improved resilience to rising water levels. Comparing model outcomes with real-world tidal networks confirmed that flow concentration, sediment transport and deposition increase with drainage complexity. These findings emphasize that natural pattern development and persistence are crucial to preserve resilience to climate change.

Global change amplifies coastal flood risks and motivates a paradigm shift towards nature-based coastal defence, where engineered structures are supplemented with coastal wetlands such as saltmarshes. Although experiments and models indicate that such natural defences can attenuate storm waves, there is still limited field evidence on how much they add safety to engineered structures during severe storms. Using well-documented historic data from the 1717 and 1953 flood disasters in Northwest Europe, we show that saltmarshes can reduce both the chance and impact of the breaching of engineered defences. Historic lessons also reveal a key but unrecognized natural flood defence mechanism: saltmarshes lower flood magnitude by confining breach size when engineered defences have failed, which is shown to be highly effective even with long-term sea level rise. These findings provide new insights into the mechanisms and benefits of nature-based mitigation of flood hazards, and should stimulate the development of novel safety designs that smartly harness different natural coastal defence functions.

Current techniques for the creation and exploration of virtual worlds are largely unable to generate sound natural environments from ecological data and to provide interactive web-based visualizations of such detailed environments. We tackle this challenge and propose a novel framework that (i) explores the advantages of landscape maps and ecological statistical data, translating them to an ecologically sound plant distribution, and (ii) creates a visually convincing 3D representation of the natural environment suitable for its interactive visualization over the web. Our vegetation model improves techniques from procedural ecosystem generation and neutral landscape modeling. It is able to generate diverse ecological sound plant distributions directly from landscape maps with statistical ecological data. Our visualization model integrates existing level of detail and illumination techniques to achieve interactive frame rates and improve realism. We validated with ecology experts the outcome of our framework using two case studies and concluded that it provides convincing interactive visualizations of large natural environments.

Thorough understanding of the potential for threshold dynamics and catastrophic shifts to occur in natural systems is of great importance for ecosystem conservation and restoration. However, verifying the presence of alternative stable states, one of the theoretical explanations for sudden shifts in natural systems, has proven to be a major challenge. We examine processes on local and landscape scales in salt-marsh pioneer zones, to assess the presence of alternative stable states in this system. To that end, we investigated the presence of typical characteristics of alternative stable states: bimodality and threshold dynamics. We also studied whether vegetation patches remained stable over long time periods. Analysis of false-color aerial photographs revealed clear bimodality in plant biomass distribution. By transplanting Spartina anglica plants of three different biomass classes on three geographically different marshes, we showed that a biomass threshold limits the establishment of Spartina patches, potentially explaining their patchy distribution. The presence of bimodality and biomass thresholds points to the presence of alternative stable states and the potential for sudden shifts, at small, within-patch scales and on short time scales. However, overlay analysis of aerial photographs from a salt marsh in The Netherlands, covering a time span of 22 years, revealed that there was little long-term stability of patches, as vegetation cover in this area is slowly increasing. Our results suggest that the concept of alternative stable states is applicable to the salt-marsh pioneer vegetation on small spatio-temporal scales. However, the concept does not apply to long-term dynamics of decades or centuries of heterogeneous salt-marsh pioneer zones, as landscape-scale processes may determine the large-scale dynamics of salt marshes. Hence, our results provide the interesting perspective that threshold dynamics may occur in systems with, on the long term, only a single stable state.

Complexity theory highlights scale-dependent feedback mechanisms as an explanation for regular spatial patterning in ecosystems. To what extent scale-dependent feedback clarifies spatial structure in more complex, non-regular systems remains unexplored so far. We report on a scale-dependent feedback process generating patchy landscapes at the interface of intertidal flats and salt marshes. Here, vegetation was characterized by Spartina anglica tussocks, surrounded by erosion gullies. To demonstrate the presence of a scale-dependent feedback, we determined if vegetation induced habitat modification resulted in local facilitation and large scale-inhibition of plant growth. Field surveys revealed that larger tussocks have deeper gullies, suggesting that gully erosion is caused by increased water flow around tussocks. This was confirmed by flume experiments, showing that feedback effects vary with current velocity and water depth. Transplantation of small Spartina units inside and just outside present tussocks revealed that the growth of Spartina transplants compared to transplant growth on bare sediment was higher within the raised Spartina tussocks, but lower in the gully just outside Spartina tussocks, providing clear evidence of scale-dependent feedback. Our results emphasize that scale-dependent feedback is a more general explanation for spatial complexity in ecosystems than previously considered.