Clonal Vegetation Patterns Mediate Shoreline Erosion

Abstract

Understanding processes governing coastal erosion is becoming increasingly urgent because highly valued ecosystems like salt marshes are being lost at accelerating rates. Here we examine the role of biotic interactions in mediating marsh shoreline erosion under wind wave forces. We parameterized analytical and cellular automata models with field data to assess how soil heterogeneity among clonal patches of an ecosystem engineer mediates spatiotemporal patterns of marsh shoreline erosion. We found that spatial heterogeneity accelerates erosion, especially when it is organized in patches of intermediate size. Patch size also mediated interannual variability in erosion and strongly controlled shoreline roughness. Our results indicate that shoreline roughness can be diagnostic of internal biological structure and spatiotemporal variability in erosion. Hence, measures of shoreline roughness may inform the timeframe and spatial extent needed to accurately monitor erosion. These findings highlight how the physical response of marsh shorelines to wind wave erosion is a function of landscape ecology.

Intraspecific variation in landform engineering across a restored salt marsh shoreline

“…Evidence of morphological trait and tissue nutrient differences among cultivated, local, and nonlocal populations under common garden conditions corroborates prior findings of heritable phenotypic variation in S. alterniflora . Affirming our prior work (Bernik, Eppinga, et al., 2018), we found that plants from the different sources exhibited distinct combinations of trait differences (Tables , Figures 3–5). Pairwise comparisons elaborate overall patterns of multivariate phenotypic differentiation in canopy architecture, biomass production, and tissue recalcitrance (Lumibao et al., 2020).…”

“…Our findings illustrate that Earth surface processes and attributes are sensitive to intraspecific variation in a well-recognized, widely distributed, and widely used landform engineer. Our study offers further evidence that the stability and transport of Earth surface materials can be mediated by plants (Corenblit et al, 2011) and that plants exhibit intraspecific variation in their capacity to reduce surface erosion (Berendse et al, 2015;Bernik, Eppinga, et al, 2018;Bernik, Pardue, et al, 2018). Our results are consistent with prior work showing that soil shear strength varies according to plant provenance (Bernik, Pardue, et al, 2018).…”

“…Using a randomized block design to control for a gradient of wind‐driven wave action along the shoreline (Bernik, Eppinga, et al., 2018), we established five replicate 25‐m 2 plots with S. alterniflora from each source, except for the CP cultivar, which was only planted in two plots due to the scarcity of source material (Figure 1). The plots were established 5 m inland from the waterline (Figure ) to allow plants time to establish prior to experiencing erosion.…”

“…Thus to standardize across plots, we divided erosion measures by cos α j . Data from NOAA buoy station GISL1 were used to weight calculations by the cumulative speed of wind gusts for each direction, and satellite imagery was used to approximate α j for each plot (Bernik, Eppinga, et al., 2018).…”

Spatially explicit removal strategies increase the efficiency of invasive plant species control

“…A potential disadvantage of such detailed spatially explicit models, however, is that they typically provide limited means for analytical analyses, and therefore often constrain the analyses to specific questions or case studies (Higgins et al 2000, Grevstad 2005, Eppinga et al 2006, Baker 2017). On the other hand, empirical data may provide a means to constrain model parameters in a way that enables comprehensive analyses through simulation (Bernik et al 2018). Hence, spatially explicit simulation models, parameterized with data of the specific IAS population considered, provide a powerful means to study how spatial organization of control efforts may mediate the effectiveness of control strategies targeting a particular IAS within a specific location (Epanchin‐Niell and Hastings 2010).…”