Barrier islands of the central Georgia coast: Formation, function, and future

ABSTRACT Georgia’s coastline is composed of a series of short, wide, mixed-energy (tide-dominated) barrier islands, each backed by extensive marsh, topped with mobile dunes, and flanked by deep inlets. Many of the islands, particularly those along the southern Georgia coast, consist of Pleistocene cores surrounded by mobile deposits that attached during the Holocene sea-level transgression. Positioned within the head of the funnel-shaped South Atlantic Bight, tidal ranges here commonly reach ~2–3 m. As a result, inlets are numerous and the back-barrier environment hosts nearly 400,000 acres of salt marsh. Today, many of the barriers are transgressive, and hard structures such as revetments and groins are becoming increasingly more common to stabilize shorelines along the four developed islands. This field guide presents evidence of island formation, modern ecologic function, and likely future changes for three island groups: (1) Blackbeard, Cabretta, and Sapelo Islands; (2) Sea Island and St. Simons Island; and (3) Jekyll Island. The field trip provides evidence of the Pleistocene-age island cores, the natural southward migration of the mobile Holocene-age sandy shorelines, and the impacts of storm erosion and hard structures built to combat that erosion. This field guide serves as the static, print companion to an online virtual field trip (https://storymaps.arcgis.com/stories/0aa3fd921cc4458da0a19a928e5fa87c).

Temporal and Spatial Variations in NDVI and Analysis of the Driving Factors in the Desertified Areas of Northern China From 1998 to 2015

China faces some of the most serious desertification in the world, leading to many problems. To solve them, large-scale ecological restoration projects were implemented. To assess their effectiveness, we analyzed normalized-difference vegetation index (NDVI) data derived from SPOT VEGETATION and gridded climate datasets from 1998 to 2015 to detect the degrees of desertification and the effects of human and climate drivers on vegetation dynamics. We found that NDVI of desertified areas generally decreased before 2000, then increased. The annual increase in NDVI was fixed dunes (0.0013) = semi-fixed dunes (0.0013) > semi-mobile dunes (0.0012) > gobi (gravel) desert (0.0011) > mobile dunes (0.0003) > saline–alkali land (0.0000). The proportions of the area of each desert type in which NDVI increased were fixed dunes (43.4%) > semi-mobile dunes (39.7%) > semi-fixed dunes (26.7%) > saline–alkali land (23.1%) > gobi desert (14.4%) > mobile dunes (12.5%). Thus, the vegetation response to the restoration efforts increased as the initial dune stability increased. The proportion of the area where desertification was dominated by temperature (1.8%) was far less than the area dominated by precipitation (14.1%). However, 67.6% of the change was driven by non-climatic factors. The effectiveness of the ecological restoration projects was significant in the Loess Plateau and in the Mu Us, Horqin, and Hulunbuir sandy lands. In contrast, there was little effect in the Badain Jaran, Ulan Buh, and Tengger deserts; in particular, vegetation cover has declined seriously in the Hunshandake Sandy Land and Alkin Desert Grassland. Thus, more or different ecological restoration must be implemented in these areas.

Dune Systems’ Characterization and Evolution in the Andalusia Mediterranean Coast (Spain)

This paper deals with the characterization and evolution of dune systems along the Mediterranean coast of Andalusia, in the South of Spain, a first step to assess their relevant value in coastal flood protection and in the determination of sound management strategies to protect such valuable ecological systems. Different dune types were mapped as well as dune toe position and fragmentation, which favors dune sensitivity to storms’ impacts, and human occupation and evolution from 1977 to 2001 and from 2001 to 2016. Within a GIS (Geographic Information System) project, 53 dune systems were mapped that summed a total length of ca. 106 km in 1977, differentiating three dune environments: (i) Embryo and mobile dunes (Type I), (ii) grass-fixed dunes (Type II) and (iii) stabilized dunes (Type III). A general decrease in dunes’ surfaces was recorded in the 1977–2001 period (−7.5 × 106 m2), especially in Málaga and Almería provinces, and linked to dunes’ fragmentation and the increase of anthropic occupation (+2.3 × 106 m2). During the 2001–2016 period, smaller changes in the level of fragmentation and in dunes’ surfaces were observed. An increase of dunes’ surfaces was only observed on stable or accreting beaches, both in natural and anthropic areas (usually updrift of ports).

Can Vegetation Removal Successfully Restore Coastal Dune Biodiversity?

Coastal dune habitats have been declining globally over the last several decades due to rapid urbanization. Within remaining dune systems, dune fixation has resulted in further losses of mobile dunes with negative impacts on their associated species. Some studies suggest vegetation removal can initially promote habitat heterogeneity, and increase availability of suitable habitats for psammophile, xeric and endemic mobile dune species, but longer-term responses are generally unknown. We investigated the temporal trends of four taxonomic groups to determine the effect of vegetation removal on dune assemblages over a 12-year period at an LTER site. Three different forms of removal are investigated here—removal in a grid form on fixed dunes, removal of the wind-facing slope vegetation on semi-fixed dunes and opportunistic off-road driving on disturbed dunes. Results were varied across taxa, highlighting the need for multi-taxa monitoring in conservation and restoration management. Overall, fixed dune treatment had very little effect, while a stronger response was found in semi-fixed treatments in particular for mobile dune indicator species, which showed evidence of recolonization within a few years following treatment. Disturbed dunes were most similar to mobile dunes for animal taxa indicating that pulse removal may not be as effective as continuous press disturbance. Nevertheless, a less destructive form of disturbance such as re-introduction of grazing might be preferable and requires further investigation.

Landscape drivers of coastal dune mobility

<p>Coastal dunes are dynamic landforms whose morphology is governed primarily by climate and vegetation dynamics. Over the last 50 years, coastal sand dunes across the globe have dramatically ‘greened’ and wind speeds fallen (Pye et al., 2014; Delgado-Fernandez et al., 2019; Jackson et al., 2019), reducing aeolian transport of sediment and minimising dune reshaping by near-surface winds.  This rapid vegetation has also been attributed to a dramatic decline of several rare species of plants and invertebrates in several coastal dune systems (Howe et al., 2010; Pye et al., 2014). In an effort to increase habitat diversity, large-scale vegetation removal and dune re-profiling are becoming increasingly common interventions. However sustained aeolian activity following intervention appears to be rare (Arens et al., 2013).</p><p>In order to better understand the environmental drivers of long-term dune mobility, this work explores the landscape scale physical factors related to self-sustaining ‘natural’ mobile dunes across the United Kingdom. The analysis presented includes the use of geographically weighted regression, a spatial analysis technique that models the local relationships between predictors (e.g. wind speed, slope, elevation, aspect, surface roughness) and an outcome of interest (mobile dunes). It is hoped that the results of this work will help guide decision-making with regards the location, scale and morphology of future interventions in order to maximise their sustainability, minimising the need for maintenance and further intervention.</p><p>References</p><p>Arens, S.M., Slings, Q.L., Geelen, L.H. and Van der Hagen, H.G., 2013. Restoration of dune mobility in the Netherlands. In Restoration of coastal dunes (pp. 107-124). Springer, Berlin, Heidelberg.</p><p>Delgado-Fernandez, I., O'Keeffe, N., & Davidson-Arnott, R. G. (2019). Natural and human controls on dune vegetation cover and disturbance. Science of The Total Environment, 672, 643-656.</p><p>Howe, M. A., Knight, G. T., & Clee, C. (2010). The importance of coastal sand dunes for terrestrial invertebrates in Wales and the UK, with particular reference to aculeate Hymenoptera (bees, wasps & ants). Journal of Coastal Conservation, 14(2), 91-102.</p><p>Jackson, D. W., Costas, S., González-Villanueva, R., & Cooper, A. (2019). A global ‘greening’of coastal dunes: An integrated consequence of climate change?. Global and Planetary Change, 182, 103026.</p><p>Pye, K., Blott, S. J., & Howe, M. A. (2014). Coastal dune stabilization in Wales and requirements for rejuvenation. Journal of coastal conservation, 18(1), 27-54.</p>

ANÁLISE DA EVOLUÇÃO TEMPORAL E DA DINÂMICA SEDIMENTAR DA DUNA DO PÔR DO SOL, JERICOACOARA, CEARÁ – BRASIL

No presente trabalho voltamos nossa atenção para as dunas móveis que são interfaces litorâneas, áreas continuamente modeladas pelas ações dos ventos e das ondas, importantes reservatórios de sedimentos que atuam na manutenção do fluxo sedimentar da faixa praial. Partindo deste universo, concentramos nossos estudos na Praia de Jericoacoara, município de Jijoca de Jericoacoara-CE, tendo como objetivo analisar a dinâmica morfossedimentar da Duna do Pôr do Sol na Praia de Jericoacoara, a partir da análise temporal de imagens de satélites; realização de perfis de praia, cálculo do grau de declividade da face de avalanche da duna, da área e do volume sedimentar da duna; e da observação da evolução dos tipos de uso e de ocupação. Os resultados desta pesquisa possibilitaram a elaboração de diagnósticos e prognósticos evolutivos para a área estudada, fornecendo dados e informações que podem vir a subsidiar os gestores públicos na gestão adequada da zona costeira e na compreensão dos riscos ambientais.Palavras-chave: Dinâmica Costeira; Duna; Jericoacoara/CE. ABSTRACTIn the present work we turn our attention to the mobile dunes that are coastal interfaces and represent areas continuously modeled by the action of the winds and the waves, important reservoirs of sediments for the maintenance of the sedimentary flow of the praial band. Starting from this universe, we concentrated our studies in the Beach of Jericoacoara, municipality of Jijoca of Jericoacoara-CE, aiming to analyze the morphosedimentary dynamics of the Dune of the Sunset on the Beach of Jericoacoara, based on the temporal analysis of satellite images; the realization of beach profiles, the calculation of the degree of slope of the slip face, the area and the sedimentary volume of the dune; and the observation of the evolution of types of use and occupation. The results of this research enabled the elaboration of diagnoses and evolutionary prognoses for the studied area, providing data and information that can subsidize the public managers in the adequate management of the coastal zone and in the understanding of the environmental risks.Keywords: Coastal Dynamics; Dune; Jericoacoara / CE. RESUMENEn el presente trabajo dirigimos nuestra atención a las dunas móviles que son interfaces costeras, áreas continuamente modeladas por las acciones de vientos y olas, importantes depósitos de sedimentos que actúan para mantener el flujo sedimentario de la playa. Desde este universo, enfocamos nuestros estudios en Jericoacoara Beach, Jijoca de Jericoacoara-CE, con el objetivo de analizar la dinámica morfosedimentaria de Sunset Dune en Jericoacoara Beach, a partir del análisis temporal de imágenes de satélite; haciendo perfiles de playa, calculando la pendiente de la cara de avalancha de dunas, el área y el volumen sedimentario de la duna; y observando la evolución de los tipos de uso y ocupación. Los resultados de esta investigación permitieron la elaboración de diagnósticos y pronósticos evolutivos para el área estudiada, proporcionando datos e información que pueden ayudar a los administradores públicos en el manejo adecuado de la zona costera y en la comprensión de los riesgos ambientales.Palabras clave: Dinámica costera; Duna; Jericoacoara / CE.

MORFOGÊNESE E GEODINÂMICA DAS DUNAS COSTEIRAS DE CANOA QUEBRADA, CEARÁ, BRAZIL

Este trabalho apresenta uma análise da geodinâmica e morfogênese do campo de dunas na região de Canoa Quebrada, localizada no município do Aracati, inserido no Estado do Ceará. Abrange a área formada pela planície flúvio-marinha, faixa de praia e campo de dunas localizados na margem direita da foz do rio Jaguaribe. O recorte temporal avaliado corresponde à análise da dinâmica do campo de dunas com base nas taxas de migração no período de 1988 a 2013. Os objetivos dessa pesquisa foram analisar a dinâmica ambiental do campo de dunas móveis em direção ao ecossistema manguezal localizado na foz do rio Jaguaribe. Associado à abordagem metodológica, realizou-se geoprocessamento de fotografias aéreas da década de 80 na escala de 1:25.000 e imagens de satélites Quickbird dos anos de 2004, 2010 e 2013. Foram identificadas dunas móveis do tipo longitudinais, barcanóides e lençóis de areias. Do ponto de vista de cobertura vegetal, foram identificadas dunas semi-fixas no contato com o ecossistema manguezal. Quanto às gerações dunares, domina a geração D1, caracterizada pela ocorrência de dunas atuais, móveis. No contato com o ecossistema manguezal, as dunas semi-fixas se combinam com a geração de dunas anteriores às atuais, do tipo sub-atuais, definindo a existência de dunas de geração D2. A taxa média de migração no campo de dunas durante todo esse período de 40 anos foi de 7m/ano. Nos anos de 2010 a 2013 praticamente não ocorreu migração, mas as dunas continuam se deslocando em direção ao ecossistema manguezal.Palavras chaves: Dunas costeiras, geodinâmica; morfogênese de dunas.ABSTRACTThis paper presents an analysis of geodynamic and morphogenesis of the dune field in the Canoa Quebrada region, located in the municipality of Aracati, inserted in the state of Ceará. It covers the area formed by fluvial-marine plain, the strip of beach and dune field located on the right bank of the mouth of the river Jaguaribe. The estimated period corresponds to the dynamic analysis of the dune field based on migration rates from 1988 to 2013. The objectives are to analyze the environmental dynamics of the mobile dune field towards the mangrove ecosystem located at the mouth of the river Jaguaribe. Associated with the methodological approach, we analyzed through GIS aerial photographs of the 80 on the scale of 1: 25,000 and 2004, 2010 and 2013 years of Quickbird satellite images. We find mobile dunes of the longitudinal type, barcanoids and sand sheets. Semi-fixed dunes were identified in the contact with the mangrove ecosystem. As for dune generations, we can say that dominates the generation D1, characterized by the occurrence of present-day dunes. In the contact with the mangrove ecosystem, the semi-fixed dunes combine with older dunes to define the existence of D2 generation. The average migration of the dune field during that period of 40 years was 7m / year. In the years 2010-2013, virtually no migration occurred, but the dunes continue to move towards the mangrove ecosystem.Keywords: Coastal dunes, geodynamics; dune morphogenesis.

ANÁLISE E IDENTIFICAÇÃO DOS COMPARTIMENTOS GEOAMBIENTAIS DA REGIÃO DE “PORTO DOS BARCOS” NO MUNICÍPIO DE ITAREMA-CEARÁ

A área de análise é a costa oeste do Estado do Ceará, tendo como enfoque a praia de Porto dos Barcos no município de Itarema. Foi elaborada e compartimentada geoambiental, sendo identificadas as seguintes unidades: a planície litorânea (com subunidades de faixa praial, campo de dunas móveis; campo de dunas fixas e paleodunas); a planícies flúvio-marinhas (desembocaduras fluviais revestidas por manguezais); as planícies fluviais (matas ciliares; lagoas freáticas; e tabuleiros pré-litorâneos ou costeiros. Essa compartimentação é a do Diagnóstico da Zona Costeira e da Gestão Integrada. O artigo tem como objetivo analisar os compartimentos geoambientais presentes na área de estudo, a fim de obter dados quantitativos quanto as áreas de cada setor geoambiental da região. Essa quantificação será importante para investigar os processos geomorfológicos que se apresentam em uma área dinâmica, que sofre modificações em curto espaço de tempo, devido à aceleração dos intensos processos naturais e as ações antrópicas. A metodologia se baseou em pesquisas bibliográficas e levantamentos de campo e análise de imagens de satélite. Podemos concluir que os processos dinâmicos atuantes transformam a paisagem rapidamente, em espaço de tempo de poucos meses, fato que dificulta a análise ambiental e o planejamento de uso sustentável da região.Palavras-chave: Compartimentação geoambiental; Itarema; Porto dos Barcos; Praia do Porto. ABSTRACTThe area of analysis is the west coast of the state of Ceará, focusing on the beach of Porto dos Barco in the municipality of Itarema. It was elaborated and compartmentalized geoenvironmental, being identified the following units: the coastal plain (with subunits of beach strip, field of mobile dunes; field of fixed dunes and paleodunas); Fluvio-marine plains (mangrove-lined river mouths); fluvial plains (riparian forests; groundwater lagoons; and pre-coastal or coastal trays. This compartmentalization is the Coastal Zone Diagnosis and Integrated Management. to obtain quantitative data on the areas of each geoenvironmental sector in the region.This quantification will be important to investigate the geomorphological processes that present themselves in a dynamic area, which undergoes changes in a short time, due to the acceleration of intense natural processes and anthropic actions. The methodology was based on bibliographic research and field surveys and satellite image analysis.We can conclude that the dynamic processes acting quickly transform the landscape, within a few months, a fact that hinders the environmental analysis and the planning of use. sustainable development of the region.Keywords: Geoenvironmental subdivision; Itarema; Porto dos Barcos; Porto Beach. RESUMENEl área de análisis es la costa oeste del estado de Ceará, centrándose en la playa de Porto dos Barco en el municipio de Itarema. Fue elaborado y compartimentado geoambientalmente, identificándose las siguientes unidades: la llanura costera (con subunidades de franja de playa, campo de dunas móviles; campo de dunas fijas y paleodunas); Llanuras fluvio-marinas (desembocaduras de los ríos con manglares); llanuras fluviales (bosques ribereños; lagunas de aguas subterráneas; y bandejas pre-costeras o costeras. Esta compartimentación es el Diagnóstico y Manejo Integrado de la Zona Costera. para obtener datos cuantitativos sobre las áreas de cada sector geoambiental en la región. Esta cuantificación será importante para investigar los procesos geomorfológicos que se presentan en un área dinámica, que sufre cambios en poco tiempo, debido a la aceleración de procesos naturales intensos y acciones antrópicas. La metodología se basó en investigaciones bibliográficas y estudios de campo y análisis de imágenes satelitales. Podemos concluir que los procesos dinámicos que actúan rápidamente transforman el paisaje, en unos pocos meses, un hecho que dificulta el análisis ambiental y la planificación del uso. Desarrollo sostenible de la región.Palabras clave: Compartimentación geoambiental; Itarema; Puerto de los Barcos; Playa de Oporto.

The impact of Acacia saligna and the loss of mobile dunes on rodent populations: a case study in the Ashdod-Nizzanim sands in Israel

The Mediterranean coastal dune habitat of Israel is diminishing rapidly, mostly due to massive urbanization, changes in habitat characteristics caused by dune stabilization and the presence of Acacia saligna, an invasive species brought to Israel for the purpose of dune stabilization. In this study we document the effect of sand stabilization on the composition of small mammal communities in the Ashdod-Nizzanim sands, Israel. We analyzed differences in species diversity and abundance for species of rodents in four types of habitat: unstable (mobile) sand dune, semi-stabilized dune, inter-dune depression and a plot of the invasive Acacia saligna. Rodent communities were found to undergo gradual changes concurrently with the stabilization of the sands. The mobile dune was the only habitat in which the strict psammophiles Jaculus jaculus and Gerbillus pyramidum were captured in abundance. No species commensal with human were captured neither in the mobile nor in the semi-stabilized dunes. However, in the inter-dune depression there was quite a large representation of Mus musculus, a rodent commensal with humans. The Acacia saligna plot had the lowest number of captures and the lowest rodent biomass calculated, with Mus musculus composing nearly half of the captures. The results of this study demonstrate that stabilization of the sands in Ashdod-Nizzanim area is associated with the disappearance of psammophile rodents and the appearance of species commensal with humans. In order to preserve the habitat for psammophile rodents, measures should be taken to halt the spread of acacia and the continuing stabilization of the sands.

Key Aesthetic Appeal Concepts of Coastal Dunes and Forests on the Example of the Curonian Spit (Lithuania)

The main objective of the study was to elicit key concepts determining the aesthetic appeal of coastal dunes and forests using the example of the Curonian Spit (Lithuania). The mixed approach included three methods: (1) paired comparison survey of 45 coastal landscapes, (2) semi-structured interviews with local inhabitants, and (3) eliciting the key aesthetic appeal concepts by a panel of experts using the Delphi technique. The results of the paired comparison survey show that the most aesthetically appealing landscapes of the Curonian Spit are: (1) white mobile dunes, (2) white dunes with grey (grassland) dunes in the background, and (3) grey dunes with white dunes in the background. The local inhabitants considered the concept of visual coherence as the best, explaining the aesthetic appeal of the dune and the forest landscapes on the spit. The experts of the Delphi survey considered that the concepts of stewardship, naturalness, imageability, and visual scale best define the scenic appeal. The appeal of the least attractive landscapes, in their opinion, was shaped by the concepts of naturalness, disturbance, and complexity. We conclude that the notions of visitors, local inhabitants and experts differ on the aesthetic appeal concepts of coastal dunes and forests, suggesting potential management conflicts.