Introduction: geoethics goes beyond the geoscience profession

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Data from: Spatial patterns of plant litter in a tidal freshwater marsh and implications for marsh persistence

The maintenance of marsh platform elevation under conditions of sea level rise is dependent on mineral sediment supply to marsh surfaces and conversion of above- and below-ground plant biomass to soil organic material. These physical and biological processes interact within the tidal zone, resulting in elevation-dependent processes contributing to marsh accretion. Here we explore spatial pattern in a variable related to above-ground biomass, plant litter, to reveal its role in the maintenance of marsh surfaces. Plant litter persisting through the dormant season represents the more recalcitrant portion of plant biomass, and as such has an extended period of influence on ecosystem processes. We conducted a field and remote sensing analysis of plant litter height, above-ground biomass, vertical cover, and stem density (collectively termed plant litter structure) at a tidal freshwater marsh located within the Potomac River estuary. LiDAR and field observations show that plant litter structure becomes more prominent with increasing elevation. Spatial patterns in litter structure exhibit stability from year to year and correlate with patterns in soil organic matter content, revealed by measuring the loss on ignition of surface sediments. The amount of mineral material embedded within plant litter decreases with increasing elevation, representing an important trade-off with litter structure. Therefore, at low elevations where litter structure is short and sparse, the role of plant litter is to capture sediment; at high elevations where litter structure is tall and dense, above-ground litter contributes organic matter to soil development. This organic matter contribution has the potential to eclipse that of below-ground biomass as the root to shoot ratio of dominant species at high elevations is low compared to that of dominant species at low elevations. Because of these tradeoffs in mineral and organic matter incorporation into soil across elevation gradients, the rate of marsh surface elevation change is remarkably consistent across elevation. Because of the role of plant litter in marsh ecosystem processes, monitoring and assessment of these dynamic geomorphic marsh landscapes might be streamlined through the measurement of plant litter structure, either via LiDAR technologies or field observation

LiDAR and field data for Dyke Marsh

LiDAR point files (Ground and All Points) collected in 2012; RTK GPS point files collected in 2012 and 2013; Field data on plant litter and surface soils; and some derived data from the LiDAR survey at the locations of plots and RTK elevations

Innovations in Coastline Management With Natural and Nature-Based Features (NNBF): Lessons Learned From Three Case Studies

Coastal communities around the world are facing increased coastal flooding and shoreline erosion from factors such as sea-level rise and unsustainable development practices. Coastal engineers and managers often rely on gray infrastructure such as seawalls, levees and breakwaters, but are increasingly seeking to incorporate more sustainable natural and nature-based features (NNBF). While coastal restoration projects have been happening for decades, NNBF projects go above and beyond coastal restoration. They seek to provide communities with coastal protection from storms, erosion, and/or flooding while also providing some of the other natural benefits that restored habitats provide. Yet there remain many unknowns about how to design and implement these projects. This study examines three innovative coastal resilience projects that use NNBF approaches to improve coastal community resilience to flooding while providing a host of other benefits: 1) Living Breakwaters in New York Harbor; 2) the Coastal Texas Protection and Restoration Study; and 3) the South Bay Salt Pond Restoration Project in San Francisco Bay. We synthesize findings from these case studies to report areas of progress and illustrate remaining challenges. All three case studies began with innovative project funding and framing that enabled expansion beyond a sole focus on flood risk reduction to include multiple functions and benefits. Each project involved stakeholder engagement and incorporated feedback into the design process. In the Texas case study this dramatically shifted one part of the project design from a more traditional, gray approach to a more natural hybrid solution. We also identified common challenges related to permitting and funding, which often arise as a consequence of uncertainties in performance and long-term sustainability for diverse NNBF approaches. The Living Breakwaters project is helping to address these uncertainties by using detailed computational and physical modeling and a variety of experimental morphologies to help facilitate learning while monitoring future performance. This paper informs and improves future sustainable coastal resilience projects by learning from these past innovations, highlighting the need for integrated and robust monitoring plans for projects after implementation, and emphasizing the critical role of stakeholder engagement.Coastal Engineerin