Coastal dunes arise from feedbacks between vegetation and sediment supply. Species-specific differences in plant functional morphology affect sand capture and dune shape. In this study, we build on research showing a relationship between dune grass species and dune geomorphology on the US central Atlantic Coast. This study seeks to determine the ways in which four co-occurring dune grass species (Ammophila breviligulata, Panicum amarum, Spartina patens, Uniola paniculata) differ in their functional morphology and sand accretion. We surveyed the biogeography, functional morphology, and associated change in sand elevation of the four dune grass species along a 320-kilometer distance across the Outer Banks. We found that A. breviligulata had dense and clumped shoots, which correlated with the greatest sand accretion. Coupled with fast lateral spread, it tends to build tall and wide foredunes. Uniola paniculata had fewer but taller shoots and was associated with ~42% lower sand accretion. Coupled with slow lateral spread, it tends to build steeper and narrower dunes. Panicum amarum had similar shoot densities and associated sand accretion to U. paniculata despite its shorter shoots, suggesting that shoot density is more important than morphology. Finally, we hypothesize, given the distributions of the grass species, that foredunes may be taller and wider and have better coastal protection properties in the north where A. breviligulata is dominant. If under a warming climate A. breviligulata experiences a range shift to the north, as appears to be occurring with U. paniculata, changes in grass dominance and foredune morphology could make for more vulnerable coastlines.

Previous work on the US Atlantic coast has generally shown that coastal foredunes are dominated by two dune grass species, Ammophila breviligulata (American beachgrass) and Uniola paniculata (sea oats). From Virginia northward, A. breviligulata dominates, while U. paniculata is the dominant grass south of Virginia. Previous work suggests that these grasses influence the shape of coastal foredunes in species-specific ways, and that they respond differently to environmental stressors; thus, it is important to know which species dominates a given dune system. The range boundaries of these two species remains unclear given the lack of comprehensive surveys. In an attempt to determine these boundaries, we conducted a literature survey of 98 studies that either stated the range limits and/or included field-based studies/observations of the two grass species. We then produced an interactive map that summarizes the locations of the surveyed papers and books. The literature review suggests that the current southern range limit for A. breviligulata is Cape Fear, NC, and the northern range limit for U. paniculata is Assateague Island, on the Maryland and Virginia border. Our data suggest a northward expansion of U. paniculata, possibly associated with warming trends observed near the northern range limit in Painter, VA. In contrast, the data regarding a range shift for A. breviligulata remain inconclusive. We also compare our literature-based map with geolocated records from the Global Biodiversity Information Facility and iNaturalist research grade crowd-sourced observations. We intend for our literature-based map to aid coastal researchers who are interested in the dynamics of these two species and the potential for their ranges to shift as a result of climate change.

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The genus Austropurcellia is a lineage of tiny leaf-litter arachnids that inhabit tropical rainforests throughout the eastern coast of Queensland, Australia. The majority of their diversity is found within the Wet Tropics rainforests of northeast Queensland, an area known for its exceptionally high levels of biodiversity and endemism. Studying the biogeographic history of limited-dispersal invertebrates in the Wet Tropics can provide insight into the role of climatic changes such as rainforest contraction in shaping rainforest biodiversity patterns. Here we describe six new species of mite harvestmen from the Wet Tropics rainforests, identified using morphological data, and discuss the biogeography of Austropurcellia with distributions of all known species. With this taxonomic contribution, the majority of the known diversity of the genus has been documented.

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Coastal foredunes form via biophysical feedbacks between sand accretion and burial‐tolerant vegetation and can protect coastlines from hazards such as extreme storms and sea level rise. Predicting how coastal dunes, and the services they provide, will change in the future requires an understanding of the relative roles of the physical and ecological processes that shape their structure and function. Here we assess the relative roles of sand supply, beach morphology, and vegetation in determining foredune morphology, and its change, along a 300‐km stretch of the US Central Atlantic coast. In particular, we used the spatial variability inherent in beaches and dunes of this region to determine the relative importance of shoreline change rate (SCR; a proxy for sand supply to the beach), beach morphology, and grass density of four widespread dune grasses (Uniola paniculata, Ammophila breviligulata, Panicum amarum, and Spartina patens) to foredune morphology metrics (height, width, and aspect ratio) along the North Carolina Outer Banks barrier islands. Foredune morphology and change metrics are correlated with three main factors: multidecadal SCR (1997–2016), beach slope, and dune grass density and species identity. Multidecadal SCR and beach width explained the most variation in, and were positively correlated with, foredune height and width, and were negatively correlated with foredune aspect ratio (height divided by width). In addition, grass density and changes in grass density contributed significantly to foredune morphology change. We found a positive relationship between change in A. breviligulata density and foredune width, which aligns with previous studies on the US Atlantic and Pacific Northwest coasts. Our results demonstrate the interactive roles of beach sand supply and dune grass functional morphology in dune building processes on highly vulnerable coastlines.

Coastal dunes are often the first and primary form of defense against destructive surge and waves that accompany extreme storm events. Beach grasses are known to affect dune height, width, and stability, contributing to the dune’s ability to protect the hinterland from wave and flooding hazards (Hacker et al. 2012). However, the interaction and feedbacks between dune development and properties of beach grasses (e.g., species, density) is not fully understood. In particular, our knowledge of the ecomorphodynamic processes controlling the recovery of coastal dunes following storms and the long-term ability of dunes to adapt to changes in climate remains inadequate. The objective of this interdisciplinary research is to characterize the temporal and spatial variability of coastal foredune recovery following major storm events and the subsequent impact of this recovery on future vulnerability. The study region consists of three low-lying barrier islands within the Cape Lookout National Seashore (CALO) along the central coast of North Carolina. The 90 km stretch of coast exhibits spatial variability in dominant dune grass species, grass cover density, coast orientation, beach slope, and wave energy. Using physical and ecological field datasets and process-based numerical modeling, post-storm dune recovery is assessed following Hurricane Matthew (2016).