Coastal Dune Systems Research Articles

Reprint of Changes in coastal dune systems on the Catalan shoreline (Spain, NW Mediterranean Sea). Comparing dune landscapes between 1890 and 1960 with their current status

The aim of this paper is to assess the changes that have occurred in coastal dune landscapes in Catalonia (Spain, NW Mediterranean Sea) over the last decades. Data from photographic, cartographic, and documentary sources between 1890 and 1960 have been examined and contrasted with the current status of dunes. Our analysis measures the historical transformation of the coastal dune system according to type of transformation (disappeared dunes, dunes smaller in size and dunes that have undergone few changes) and land cover changes surrounding the beaches.At this time in Catalonia, the most extensive coastal dune systems are located in Empordà county (Roses Bay and Baix Ter Bay) and the Ebro Delta. The results reflect that the loss of dune habitat during recent decades has affected more than 90% of the Catalan beaches assessed, 60% of which have disappeared and 30% reduced in size. The most affected province is Barcelona, where disappearance of dunes has affected over 80% of beaches and no beaches present almost untouched dunes; Girona and Tarragona have also been seriously affected, with dunes disappearing from 60% to 40% of the beaches assessed, respectively. However, on a minority of beaches along the Catalan shoreline, a few dunes remain almost untouched (10%).Land cover changes surrounding the beaches show that dune habitats have been drastically reduced due to human pressure, especially urbanization and tourism-related processes. A multiple correspondence analysis (MCA) has shown that the dune systems that have disappeared are located in non-protected areas and low-lying coastal zones, whereas dunes that have become smaller in size or undergone few changes are located in protected natural areas and on cliffed coasts.

Sedimentological analysis of a Late Quaternary coastal dune system: An example from Gopnath, south‐east Saurashtra, Western India

AbstractCoastal dune systems consisting of allochemical grains are important sedimentary archives of Pleistocene age in both of the hemispheres between the latitudes of 20° to 40°. The south Saurashtra coast in western India exhibits a large section of Middle Pleistocene aeolianites in the form of coastal cliffs, which is famous as ‘Miliolite’. Miliolites of Gopnath in south‐east Saurashtra are the oldest known coastal aeolianite deposits (age >156 ka which corresponds to Marine Isotope Stage 6) in western India. Aeolian deposits of similar ages have also been reported from the Thar Desert in north‐west India and from Southern Arabia which were largely controlled by the south‐west monsoon wind system that affects the entire belt corresponding to Sahara–Sahel, the Arabian Peninsula and north‐western India. Miliolite deposits in Gopnath are characterized by grainfall, grainflow and wind ripple laminations. At least three types of aeolian bounding surfaces have been identified. Five major facies have been identified which represent the dune and interdune relationship within the coastal aeolian system. The major dune bodies are identified as transverse dune types. The Gopnath aeolianites were deposited under dominantly dry aeolian conditions. Facies association reveals two different phases of aeolian accumulation, namely initiation of aeolian sedimentation after a prolonged hiatus and the establishment of a regularized aeolian sedimentation system. While initiation of aeolian sedimentation is marked by vast stretches of sheet sand with occasional dune bodies, the overlying thick, tabular, laterally extensive cross‐stratified units manifest regular aeolian sedimentation. However, the dune building events in Gopnath were interrupted by development of laterally extensive palaeosol horizons. Eustasy and climate exerted the major allogenic controls on the aeolian sedimentation by affecting the sediment budget as well as influencing the sedimentation pattern.

Natural risks and vulnerabilities of dynamic coastal dune landscapes

Set in the Habitats Directive as priority habitat, fixed dunes with herbaceous vegetation (grey dunes) occur around the coasts of Europe. As a part of many coastal dune systems these habitats are especially complex and low resilience and need special attention from the conservation and management perspectives. Nearly a decade we have studied representative examples of fixed dunes in Estonia. Due to growing anthropogenic pressure and ongoing global changes it is vital to distinguish the changes and analyse general trends of development of grey dunes. The selected sites Keibu (located on the NW coast of mainland Estonia) and Ruhnu (located on the eastern coast of Ruhnu Island) are representative examples in Estonia, with a coverage of a geographical range and ecological variation. Both sites are part of conservation and monitoring areas. In each site, we have compiled a landscape profile to visualize the topography, vegetation and soils. he study was carried out on perpendicular to shoreline landscape profiles in order to express the full spectrum of coastal dune plant communities and surface deposits from shores towards inland. Both, natural and human impacts have been considered in the assessment of changes in the structure and functioning of the grey dunes in Estonia. The results show that changes in dune landscapes can be rapid, especially on sandy beaches due to stronger storm surges in recent decades. The inland areas are more affected by human activity and the changes there are well reflected. The gradual loss of open sandy habitats on the sites is evident during the last 100 years and show the overall development trends of dynamic coastal dune landscapes. This study has proven that these areas need permanent observation to assess the level of changes. It is vital to contribute to the decision making processes concerning their optimal use and conservation needs to maintain their resilience.

Changes in coastal dune systems on the Catalan shoreline (Spain, NW Mediterranean Sea). Comparing dune landscapes between 1890 and 1960 with their current status

The aim of this paper is to assess the changes that have occurred in coastal dune landscapes in Catalonia (Spain, NW Mediterranean Sea) over the last decades. Data from photographic, cartographic, and documentary sources between 1890 and 1960 have been examined and contrasted with the current status of dunes. Our analysis measures the historical transformation of the coastal dune system according to type of transformation (disappeared dunes, dunes smaller in size and dunes that have undergone few changes) and land cover changes surrounding the beaches.At this time in Catalonia, the most extensive coastal dune systems are located in Empordà county (Roses Bay and Baix Ter Bay) and the Ebro Delta. The results reflect that the loss of dune habitat during recent decades has affected more than 90% of the Catalan beaches assessed, 60% of which have disappeared and 30% reduced in size. The most affected province is Barcelona, where disappearance of dunes has affected over 80% of beaches and no beaches present almost untouched dunes; Girona and Tarragona have also been seriously affected, with dunes disappearing from 60% to 40% of the beaches assessed, respectively. However, on a minority of beaches along the Catalan shoreline, a few dunes remain almost untouched (10%).Land cover changes surrounding the beaches show that dune habitats have been drastically reduced due to human pressure, especially urbanization and tourism-related processes. A multiple correspondence analysis (MCA) has shown that the dune systems that have disappeared are located in non-protected areas and low-lying coastal zones, whereas dunes that have become smaller in size or undergone few changes are located in protected natural areas and on cliffed coasts.

UAV monitoring of 3-year Foredune Partial Recovery from a Severe Winter: Truc Vert Beach, SW France

Guillot, B., Castelle, B., Marieu, V., Bujan, S., and Rosebery, D., 2018. UAV Monitoring of 3-year foredune partial recovery from a severe winter: Truc Vert beach, SW France. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 276–280. Coconut Creek (Florida), ISSN 0749-0208.The recent development of ultra-light civil UAVs and photogrammetric techniques provides new and efficient means to remotely sense the coastal topography at high spatial and temporal resolutions along spatially extensive areas. Truc Vert, SW France, is a high-energy meso-macrotidal beach backed by a preserved high and wide coastal dune system. This coastal dune system, which had been relatively stable over the last 70 years, was severely eroded during the winter of 2013/2014 with 800-m long and up to 8-m high cuspate erosion scarps. Since then, the foredune has been slowly recovering. This 3-year period was characterized, at the early stage, by the destabilisation of the scarped dune by trough blowouts, scarp slumping and filling and seasonal beach berm dynamics. The onset of foredune recovery occurred subsequently, and was characterized by the development of a dune ramp. This ramp provided efficient conduit for beach-dune delivery/exchange of sediment by the end of the study despite the high-energy winter of 2015/2016 drove localized dune erosion. The coastal dune did not fully recover with an approximately 60% average recovery within 3 years, an overall accretion due primarily to incipient foredune formation and foredune growth in height. The timing and magnitude of the incomplete recovery sequence from the UAV surveys provide an outstanding measure of coastal dune resilience to severe storms in this region of the world.

Numerical Simulation and Large-Scale Physical Modelling of Coastal Sand Dune Erosion

Do, K.; Shin, S.; Cox, D., and Yoo, J., 2018. An international comparison of drowning in South Korea. In: Shim, J.- S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 196–200. Coconut Creek (Florida), ISSN 0749-0208.Coastal sand dune system is important in the nearshore environment for sand supply, ecosystem, and hazard mitigation. In this study, a process-based morphological model was performed and the results were compared with large-scale laboratory experimental data. Two-dimensional large-scale laboratory experiments were conducted with 1:6 geometric scale in the large wave flume (104m (L) × 3.7 m (W) × 4.6 m (D)) of the Hinsdale Wave Research Laboratory at Oregon State University (Maddux et al, 2006). Several different wave conditions were used with different water levels in this experiment including pre-storm, storm, and post storm based on random wave time series by using TMA spectrum. The data set included cross-shore Wave heights, fluid velocities, and the profile changes of the beach and dune. The process based model, XBeach (Roelvink et al., 2009) was used to simulate the nearshore hydrodynamics and bed level change during storm wave condition. Several semi-empirical parameters were used in the XBeach model to predict morphodynamic process (Roelvink et al., 2009) and recently the updated parameters (WTI settings) were suggested based on the results of field observations. The present study ran the XBeach model by using both default and WTI settings and compared with the results from the experiments. The results showed that the model results with WTI settings showed good agreement with the measured beach profile while the model results with default settings over-predicted the offshore sediment transport and dune erosion. Especially, the wave skewness (facSk) and asymmetry (facAs) gave the highest contribution to predict dune erosion.

Contrasting plant water‐use responses to groundwater depth in coastal dune ecosystems

AbstractGroundwater lowering can produce dramatic changes in the physiological performance and survival of plant species. The impact of decreasing water availability due to climate change and anthropogenic groundwater extraction on coastal dune ecosystems has become of increasing concern, with uncertainties about how vegetation will respond in both the short and long terms.We aimed to evaluate the water‐use responses of different plant functional types to increasing groundwater table depth and how this would affect their physiology in Mediterranean coastal dune systems differing in aridity.We modelled water‐table depth, quantified the contribution of different soil layers to plant water through Bayesian isotope mixing models and used a combination of spectral and isotope data to characterize plant ecophysiology. We found that increasing depth to groundwater triggered water uptake adjustments towards deeper soil layers only in the dry season. These adjustments in water source use were made by conifer trees (Pinus pinea,P. pinaster) and hygrophytic shrubs (Erica scoparia, Salix repens) but not by the xerophytic shrubCorema album. Moreover, we observed a greater use of groundwater under semi‐arid conditions. Accompanying the greater use of water from deep soil layers as a response to increasing groundwater depth, the semi‐arid dimorphic‐rooted conifer treeP. pineaand hygrophytic shrubE. scopariadeclined their water content (WI), without implications on photosynthetic parameters, such as chlorophyll content (CHL), photochemical index (PRI) and δ13C. Unexpectedly, under semi‐arid conditions, the shallow‐rooted xerophytic shrubC. album, associated with an absence of water source use adjustments, showed a decline inWI,CHLandPRIwith groundwater table lowering.We provide insight into how different species, belonging to different functional types, are acclimating to groundwater changes in a region experiencing climatic drought and a scarcity in groundwater due to anthropogenic exploitation. Greater depth to groundwater combined with limited precipitation can have a significant effect on plants’ water source use and ecophysiology in semi‐arid coastal dune ecosystems.Aplain language summaryis available for this article.

Monitoring the coastal zone using earth observation: application of linear spectral unmixing to coastal dune systems in Wales

AbstractCoastal sand dune systems across temperate Europe are presently characterized by a high level of ecological stabilization and a subsequent loss of biological diversity. The use of continuous monitoring within these systems is vital to the preservation of species richness, particularly with regard to the persistence of early stage pioneer species dependent on a strong sediment supply. Linear spectral unmixing was applied to archived Landsat data (1975–2014) and historical aerial photography (1941–1962) for monitoring bare sand (BS) cover dynamics as a proxy for ecological dune stabilization. Using this approach, a time series of change was calculated for Kenfig Burrows, a 6‐km2 stabilized dune system in South Wales, during 1941–2014. The time series indicated that a rapid level of stabilization had occurred within the study area over a period of 75 years. Accuracy assessment of the data indicated the suitability of medium‐resolution imagery with an RMSE of <10% across all images and a difference of <3% between observed and predicted BS area. Temporal resolution was found to be a significant factor in the representation of BS cover with fluctuations occurring on a sub‐decadal scale, outside of the margin of error introduced through the use of medium‐resolution Landsat imagery. This study demonstrates a tractable approach for mapping and monitoring ecologically sensitive regions at a sub‐Landsat pixel level.

Chronology of the Late Pleistocene archaeological sequence at Vanguard Cave, Gibraltar: Insights from quartz single and multiple grain luminescence dating

Vanguard Cave is an archaeological site located on the shoreline of the Rock of Gibraltar at the south-western extreme of the Iberian Peninsula. It is part of a limestone cave system facing the adjacent Governor's Beach on the south-eastern coast of Gibraltar and has been filled to the roof with more than 17 m of sedimentary deposits. Due to its long stratified sequence, comprising rich palaeoenvironmental and faunal records as well as multiple Palaeolithic occupation layers, Vanguard Cave provides valuable information for our understanding of human behaviour and dispersal across south-eastern Iberia in general and particularly about the strategic role of the promontory of Gibraltar for past human populations. The development of a reliable absolute chronology for the sedimentary sequence at Vanguard Cave is therefore of great importance in this context.In this study, we applied optically-stimulated luminescence dating to sand-sized quartz grains from the uppermost ∼4 m of the Vanguard Cave deposits, as well as from the Hyaena Cave sediments – a small niche adjacent to the main cave chamber. We use single-grain and multiple-grain dating to clarify the depositional history of the sedimentary sequence, as well as to assess the reliability of the two dating approaches and their potential for future chronological studies at the site. The single-grain and multi-grain ages are consistent with one another and indicate no partial bleaching or post-depositional mixing of the sediments. Our results suggest that Vanguard Cave experienced continuous sediment accumulation probably since the last sea-level highstand in MIS 5, and was completely filled by ∼43 ka (MIS 3). The eastern side of the Rock of Gibraltar faced an exposed coastal shelf covered with savannah and an active coastal dune system during MIS 3. Our results indicate that similar environmental conditions are likely to have persisted also during MIS 4 and large parts of MIS 5.

Vegetation change on an urban coastal dune system

Coastal environments, not directly transformed by urbanisation but within an urban matrix, can be transformed by changes in climate, invasive species and plantings. We assess changes in vegetation structure since European settlement and changes in native species abundance since 2003 on the cuspate dune complex at Lower Sandy Bay, Tasmania. The pre-European vegetation of the cuspate forehead seems likely to have been grassland dominated by Spinifex sericeus and Austrofestuca littoralis on the foredunes and Eucalyptus viminalis open-forest with a shrubby to grassy understorey on the older dunes. Some trees of E. viminalis still occur on the dune system, together with many elements of the original understorey. The foredune native vegetation had been replaced by Ammophila arenaria closed-grassland by 2003. Much of this grassland was invaded by the native shrub, Acacia longifolia, by 2017. Between 2003 and 2017 almost all native shrub species increased in abundance. Succulent, grass and herb species suffered decline. Increased competition with exotic species, changes in disturbance regimes and decreases in fire frequency in the coastal area are most likely to have influenced the changes in native species distributions.

Shrub Encroachment Effects on Habitat Heterogeneity and Beetle Diversity in a Mediterranean Coastal Dune System

AbstractCoastal dunes are fragile dynamic environments characterised by low productivity and high levels of bare and shifting sands. They are highly threatened by urbanisation and human development. The dunes in Nizzanim Dunes Nature Reserve, Israel, have additionally incurred shrub encroachment following exclusion of grazing and wood extraction from the area.The temporal changes over the last few decades have been monitored in the Nizzanim Long‐Term Ecological Research project and are reflected by spatial heterogeneity. Some dunes are fixed with high plant cover and associated characteristics, while other dunes are still in semi‐fixed and mobile states.Measures of beetle abundance, richness and diversity showed significant differences, among dune states. Cluster analysis and ordination of species composition revealed distinct assemblages for three different states, with more psammophilous species found in mobile dunes than in other dune states. Variation within a dune state was not significant for any dune state, while among states species composition was significantly different, demonstrating high β‐diversity between dune states.Landscape heterogeneity contributes to high β‐diversity and γ‐diversity in the coastal dunes and continued shrub encroachment, and the associated fixation of mobile dunes will lead to habitat homogenisation and a decline in γ‐diversity. This finding highlights the importance of disturbance in dynamic Mediterranean coastal dunes. We recommend a restorative intervention that promotes disturbance and heterogeneity at the landscape level by conserving all three dune states. Copyright © 2017 John Wiley & Sons, Ltd.

The impact of fire on sand dune stability: Surface coverage and biomass recovery after fires on Western Australian coastal dune systems from 1988 to 2016

This study aims to determine the common response of coastal sand dunes in Western Australia (WA) to fire on decadal time-scales, in terms of ecological-geomorphic-climatic interactions to test the hypothesis that fire plays a role in coastal dune destabilisation. Fires are commonly suggested to have contributed to widespread dune reactivation in Australia and globally, a hypothesis that is relatively untested. We used data from the Landsat Thematic Mapper, Enhanced Thematic Mapper Plus, and Operational Land Imager missions to monitor changes in surface coverage on coastal sand dunes in south-west WA after fires. We analysed 31 fire scars from 1988 to 2016 in two Landsat scenes on the west and south coast of WA. Recovery ratios derived from the Normalised Difference Vegetation Index (NDVI) were used to monitor patterns in post-fire biomass and surface cover. Recovery ratios are correlated with indices of burn severity, and meteorological data to investigate relationships. We also used Maximum Likelihood Classification to monitor changes in bare sand area. Results suggest that recovery followed a strongly consistent pattern, and is characterised by rapid vegetation cover re-establishment within six to twelve months. Prior to this, some aeolian activity may have occurred but without substantial surface changes. Initial germination and/or resprouting were followed by steady growth up to seven years, where NDVI typically neared pre-fire values. Some variation in early recovery occurred between the west and south coast, possibly owing to relative proportions of reseeding and resprouting plants. A log regression explained 75% of the recovery pattern (79% on the south coast). Precipitation had some ability to explain recovery up to nine months post-fire (r2=0.29 to 0.54). No relationships were observed between estimates of burn severity and recovery. After nine months, the biggest cause of spatial variation in recovery was the pre-fire community composition and related seedbank or resprouting density. Image classification did not identify any new blowout features except where fires were not the primary cause. Results suggest that fires are not presently contributing to the destabilisation of coastal dunes in south-west WA.

Sedimentary evidence of extreme storm surge or tsunami events in the southern Baltic Sea (Rogowo area, NW Poland)

The Baltic Sea is not typically considered as an area affected by tsunamis. However, during the Late Pleistocene and Holocene several tsunami events have been interpreted from the sedimentary record, mainly in Sweden and Estonia. Furthermore, on the southern coast of the Baltic Sea, there are historical accounts of catastrophical marine floodings called “der Seebar” (“the Sea Bear”). Their descriptions reveal many features typical for tsunami, but their genesis remained unknown and sedimentary evidence for such events has not been found. Here we provide evidence of sandy event layers from the area of Rogowo, NW Poland – the area of historical catastrophic storms as well as “der Seebar” events. The study area is a low-lying coastal plain with an average elevation of –0.5 to +0.5 m a.s.l., protected from the open sea by beach and coastal dune systems up to 5 m high. Sedimentological, micropalaeontological and geochemical analyses along with AMS 14 C dating were applied to sedimentary successions seen in 5 major trenches and 198 sediment cores up to 1.5 m long. Two sandy layers were identified in the peat deposits that developed on the plain during the last ~2000 years. They reveal a number of typical features of tsunami deposits (significant lateral extent and thickness, rip-up clasts, chemical and micropalaeontological evidence of marine origin), however, 14 C dating along with the historical accounts revealed that the major layer, extending at least 1.2 km from the modern coasts, was probably deposited by arguably the largest storm surge during the last 2000 years, which took place in 1497 AD. These storm deposits were likely formed during inundation of the low-lying coastal plain after major breaching of coastal dunes resulting in tsunami – like flow pattern and thus similar sedimentological effects. A discontinuous sand layer of younger age (18th century) and sharing similar properties to the previous one may be related to “der Seebar” event or another storm surge. The study revealed that the southern Baltic Sea coast may be affected by much greater coastal flooding than known from more recent accounts and observations. Thus, the presented geological record should be taken as an example of a worst-case scenario in coastal zone risk assessment from natural hazards. These events left sedimentary deposits that resemble tsunami deposits. It is likely that, in similar settings where storm surges cause unidirectional inundation of a coastal plain, it may not be possible to establish whether the resulting deposits were laid down from storms or tsunamis.

Modelling small groundwater systems: experiences from the Braunton Burrows and Ainsdale coastal dune systems, UK

Coastal dunes are delicate systems that are under threat from a variety of human and natural influences. Groundwater modelling can provide a better understanding of how these systems operate and can be a useful tool towards the effective management of a coastal dune system, e.g. by identifying strategically important locations for flora and fauna and guiding the planning of management operations through predicting impacts from climatic change, sea level rise and land use management. Most dune systems are small, typically of the size 10–100 km2, compared with inland groundwater systems. Applying conventional groundwater modelling approaches to these small systems presents a number of challenges due to the local scale of the system and the fact that the system boundaries (sea, drains, ponds etc.) are close to the main body of the aquifer. In this paper, two case studies will be presented using different modelling approaches to understand the groundwater balance in two dune systems in the UK. The studies demonstrate that, although conventional hydraulic models can describe the general system behaviour, a fuller understanding of the recharge mechanisms and system boundaries is needed to represent adequately system dynamics of small groundwater systems.

Coastal dune dynamics in response to excavated foredune notches

Abstract Dune management along developed coasts has traditionally focussed on the suppression of the geomorphic dynamics of the foredune to improve its role in sea defence. Because a stabilized foredune acts as an almost total barrier to aeolian transport from the beach, the habitat diversity in the more landward dunes has degraded. With the overarching objective to mitigate this undesirable loss in biodiversity, dune management projects nowadays increasingly intend to restore aeolian dynamics by reconnecting the beach-dune system with notches excavated through the foredune. Here, we use repeat topographic survey data to examine the geomorphic response of a coastal dune system in the Dutch National Park Zuid-Kennemerland to five notches excavated in 2012–2013 within an 850-m stretch of the 20-m high established foredune. The notches were dug in a V-shape (viewed onshore), with a width between approximately 50 and 100 m at the top, a (cross-dune) length between 100 and 200 m, and excavation depths between 9 and 12.5 m. The 1 × 1 m digital terrain models, acquired with airborne Lidar and UAV photogrammetry, illustrate that during the 3-year survey period the notches developed into a U-shape because of wall deflation, and that up to 8-m thick and 150-m long depositional lobes formed landward of the notches. Sand budget computations showed that the sand volume of the entire study area increased by about 22,750 m 3 /year, which, given the 850-m width of the study area, corresponds to an aeolian input from the beach of approximately 26.5 m 3 /m/year. Between 2006 and 2012 all wind-blown beach sand deposited on the seaward side of the foredune; since 2013, the notches have caused 75% of the sand to be deposited landward of the foredune. This highlights that the notches are highly effective conduits for aeolian transport into the back dunes. Future monitoring is required to determine for how long the notches will stimulate aeolian dynamics and if (and when) vegetation eventually starts to regrow and enforces the degeneration of the notches.

Current status and future restoration of coastal dune systems on the Catalan shoreline (Spain, NW Mediterranean Sea)

Coastal dunes are an essential part of beach-dune systems. Dunes systems have their own intrinsic values and provide a range of goods and services, including the protection of tangible goods located on the shoreline affected by waves, storms, and sea erosion. Dunes also act as repositories of biodiversity that have their exclusive habitat in dune communities, and the aesthetic value of dune landscapes derived from unique plant communities and landforms is also of great importance. Nevertheless, dune systems on developed coasts suffered a drastic decline in geomorphological and ecological quality throughout the last century. Catalonia (Spain, NW Mediterranean Sea) is no exception, and the coastal dune systems which were present in the early 20th century have now disappeared due to urbanization. The regeneration of dune systems is of crucial importance in this context. The aim of this study is to assess the current status of dune systems in Catalonia in order to determine their future prospects based on beach characteristics, those beaches likely to host dunes being determined according to their width and sediment type. The results of our study show that nowadays most dune systems in Catalonia are not developed due to human pressure on the beaches. Only those beaches located in the natural protected areas in Roses Bay, Baix Ter Bay, the Llobregat Delta, and especially the Ebro Delta, have the right characteristics to host well-developed dune systems. That said, 30% of sandy beaches in Catalonia have a width of over 35 metres; wide enough to host well-developed dune systems if appropriate integrated beach management is applied. The methodology used in this research also provide a tool to assess which are the beaches that can host dunes on other developed shores in the Mediterranean area.

Effects of clonal integration in the expansion of two alien Carpobrotus species into a coastal dune system – a field experiment

What makes a plant a successful invader is one of the most interesting questions in modern ecology. Comparative studies including congeners differing in invasiveness are a straightforward approach to detect potential traits explaining invasions. In this experiment we studied the importance of clonal integration and the capacity to buffer fragmentation in the expansion of two stoloniferous invaders, Carpobrotus edulis, considered more invasive, and Carpobrotus acinaciformis, considered less invasive. In particular we aim to determine whether differences in these clonal traits may explain differences in invasiveness between both species. We report evidence that clonal integration favour the expansion of the two exotic clonal species into a sand dune system. Benefit derived from clonal integration by itself does not explain differences in invasiveness between theses two exotic species. However, our result indicates that the greater invasiveness of C. edulis could be explained by a higher capacity to buffer the negative effect of fragmentation in comparison with C. acinaciformis. To elucidate the real contribution of clonal traits in plant invasions, new comparative studies should be conducted including more clonal species.

Development of a coastal dune vulnerability index for Mediterranean ecosystems: A useful tool for coastal managers?

Coastal dune ecosystems have been severely degraded as a result of excessive natural resource exploitation, urbanisation, industrial growth, and worldwide tourism. Coastal management often requires the use of vulnerability indices to facilitate the decision-making process. The main objective of this study was to develop a Mediterranean dune vulnerability index (MDVI) for sandy coasts, starting from the existing dune vulnerability index (DVI) proposed by Garcia-Mora et al. (2001) related to the oceanic coasts. Given that the Mediterranean sandy coasts are quite different from the Atlantic coasts, several adjustments and integrations were introduced. Our proposed index is based on the following five main group of factors: geomorphological conditions of the dune systems (GCD), marine influence (MI), aeolian effect (AE), vegetation condition (VC), and human effect (HE), for a total of 51 variables derived (and adapted) from the bibliography or proposed for the first time in this study. For each coastal site, a total vulnerability index, ranging from 0 (very low vulnerability) to 1 (very high vulnerability), was calculated as the unweighted average of the five partial vulnerability indices. Index computation was applied to 23 coastal dune systems of two different contexts in Italy, i.e. peninsular and continental island territories representative of the W-Mediterranean Basin, in order to compare the dune systems with different geomorphology, shoreline dynamics, and human pressure. In particular, our research addressed the following two questions: (1) Which variables are the most critical for the Italian coastal systems? (2) How can the coastal dune vulnerability index be used to develop appropriate strategies of conservation and management for these ecosystems? Cluster analysis and non-metric multidimensional scaling separated the peninsular from the insular sites, both of which were characterised by low to moderate values of vulnerability (0.32 < MDVI < 0.49). The most critical factors for the coastal systems examined in this study were marine negative influence, low stabilising ability of vegetation, and human disturbance. Hence, coastal managers are encouraged to plan specific management actions such as protection of foredunes from marine factors (particularly erosion), to promote dune formation with the reintroduction of native dune builder species and to minimise human pressure where vulnerability depends on these variables.

Roig-Munar, F. X. y Quintana Pou, F. J. (Coords.) (2016). Restauración y Gestión de Sistemas Dunares. Estudio de casos. Colección Recerca i Territori, 8. Cataluña: Càtedra d’Ecosistemes Litorals Mediterranis, Parc Natural de Montgrí, Illes Bledes i el Baix Ter. 220 pp.

Los sistemas dunares costeros han sido uno de los ecosistemas más alterados a causa de la creciente presión humana sobre los espacios litorales, que en las últimas décadas se han convertido en un producto turístico. Los sistemas dunares son hábitats sensibles a la frecuentación, a las gestiones no planificadas y el pisoteo excesivos que se produce durante la temporada de baño, y que desencadena procesos erosivos a lo largo del período estival. Por sus características dinámicas de sustrato arenoso en movimiento, se encuentran además, muy afectados por las actividades relacionadas con el mantenimiento de las playas, tales como la prestación de servicios, la limpieza mecánica o la retirada de materia orgánica. Esto facilita la reactivación de procesos dinámicos que distorsionan y afectan al balance sedimentario, muchos de ellos de tipo erosivo.

Vegetation roles on changes of soil properties and microbial activities in a coastal sand dune. A case study

The vegetation effects on changes of soil physicochemical properties and microbial activities in the costal sand dune were investigated to understand the roles of vegetation on sand dune ecosystem. Eight sites from six vegetation zones and two bare zones in the dune front, dune crest, and dune back regions were selected. Soil microbial enzyme activities of β-glucosidase, acid phosphatase, arylsulfatase, and dehydrogenase, and soil physicochemical properties of each site were evaluated. The results showed that all the enzyme activities were higher in the mixed vegetation sites with native sand dune plants and naturalized plants and in Pinus thunbergii community site both located in the dune back regions where the accumulation of organic matter and nitrogen were more prominent. The results demonstrated that soil organic matter and nutrients are the primary determinants of the microbial activity in sand dune where are exposed to a gradient of physicochemical stress such as high salinity, moisture and salt spray. Therefore, the conservation of vegetation that generates more soil organic matter and nutrients is important factor in controlling the soil microbial activities and biogeochemical cycles in the coastal sand dune systems.