Dune Vegetation Research Articles

Rescuing Cattleya granulosa Lindley in the wild

The Orchid Society of Rio Grande do Norte State, Brazil, through its Group of Experimental Interactive Research (SORN/GEPI), has been study- ing the occurrence of Cattleya granulosa Lindley, 1842, specifically in the coastal sand plain and dune vegetation (“restinga”) and in remaining patches of Atlantic Rainforest in the state.

Mediterranean coastal dune vegetation: Are disturbance and stress the key selective forces that drive the psammophilous succession?

Plant communities of coastal dunes are distributed along a characteristic sea-inland gradient. Generally, there is a shift from annual and short height species with small leaves in the initial successional stages to perennial tall shrubs with tough leaves in later phases. Assessing the community-weighted mean (CWM) trait values is used in plant ecology to describe ecosystem properties especially during succession. In particular, CSR (Competitive, Stress-tolerant, and Ruderal strategy) classification allows us to explore community functional shifts in terms of disturbance, stress and competition selective forces. The functional basis of the psammophilous succession was studied based on the following questions: (1) Can we circumscribe different functional types among plant species of Mediterranean coastal dunes? (2) How do CWM trait values vary along the environmental sea-inland gradient? (3) What is the relative importance of competition, stress and disturbance in the processes of plant community assembling? (4) Can we postulate that along primary successions there is generally a shift from ruderality to stress-tolerance? An explorative analysis of functional groups was performed by Non-Metric Multidimensional Scaling (NMDS) analysing nine morpho-functional traits measured for 45 taxa from 880 dune plots localised in Tuscany (central Italy, Europe). NMDS ordination showed a scattered distribution of psammophytes that could not be delimited in precise plant functional types. The first NMDS axis has been interpreted as a leaf economics axis because it was correlated to leaf area (LA) and leaf dry matter content (LDMC), while the second one was a plant size axis because of its correlation with canopy height. Along the sea-inland gradient, pioneer plant communities of upper beach were dominated by ruderals (with the lowest values of LDMC and specific leaf area - SLA), well-adapted to the harsh environmental conditions of coastal dunes. More distant from the sea, where ecological conditions were less extreme, late-successional communities of backdunes were characterised by the prevalence of stress-tolerance. This study suggested that psammophytes have evolved not a single but multiple adaptive strategies showing a high degree of functional diversity and complexity. Moreover, CSR classification supported the hypothesis of a functional shift from R-strategists in early successional stages to S-strategists in late-successional communities along a primary succession.

Responses of Dune Plant Communities to Continental Uplift from a Major Earthquake: Sudden Releases from Coastal Squeeze

Vegetated dunes are recognized as important natural barriers that shelter inland ecosystems and coastlines suffering daily erosive impacts of the sea and extreme events, such as tsunamis. However, societal responses to erosion and shoreline retreat often result in man-made coastal defence structures that cover part of the intertidal and upper shore zones causing coastal squeeze and habitat loss, especially for upper shore biota, such as dune plants. Coseismic uplift of up to 2.0 m on the Peninsula de Arauco (South central Chile, ca. 37.5º S) caused by the 2010 Maule earthquake drastically modified the coastal landscape, including major increases in the width of uplifted beaches and the immediate conversion of mid to low sandy intertidal habitat to supralittoral sandy habitat above the reach of average tides and waves. To investigate the early stage responses in species richness, cover and across-shore distribution of the hitherto absent dune plants, we surveyed two formerly intertidal armoured sites and a nearby intertidal unarmoured site on a sandy beach located on the uplifted coast of Llico (Peninsula de Arauco) over two years. Almost 2 years after the 2010 earthquake, dune plants began to recruit, then rapidly grew and produced dune hummocks in the new upper beach habitats created by uplift at the three sites. Initial vegetation responses were very similar among sites. However, over the course of the study, the emerging vegetated dunes of the armoured sites suffered a slowdown in the development of the spatial distribution process, and remained impoverished in species richness and cover compared to the unarmoured site. Our results suggest that when released from the effects of coastal squeeze, vegetated dunes can recover without restoration actions. However, subsequent human activities and management of newly created beach and dune habitats can significantly alter the trajectory of vegetated dune development. Management that integrates the effects of natural and human induced disturbances, and promotes the development of dune vegetation as natural barriers can provide societal and conservation benefits in coastal ecosystems.

Unexpected ecotone dynamics of a sand dune vegetation complex following water table decline

Unexpected ecotone dynamics of a sand dune vegetation complex following water table decline

Patterns of Trophic-level Diversity Associated with Herbaceous Dune Vegetation Across a Primary Successional Gradient

Abstract While ecologists have studied succession for well over 100 y, there has been little characterization of diversity patterns in nonplant organisms or their interactions across successional gradients. In this study we examined herbaceous vertical vegetation structure and diversity in plants, arthropods, and arbuscular mycorrhizal fungi (AMF) in three Great Lakes sand dune chronosequences. Plant species richness increased linearly across the primary successional gradients at the three sampling sites, while plant vertical structure remained constant. Total arthropod abundance and species richness were positively associated with plant vertical cover, while AMF spore abundance and morpho-type richness were positively associated with plant species richness. Carnivore and herbivore functional groups of arthropods responded differently to plant vertical cover and species richness. Diversity across early primary successional gradients does not consistently increase among different trophic levels, and the ve...

Mycorrhizal fungal communities in coastal sand dunes and heaths investigated by pyrosequencing analyses.

Maritime sand dunes and coastal ericaceous heaths are unstable and dynamic habitats for mycorrhizal fungi. Creeping willow (Salix repens) is an important host plant in these habitats in parts of Europe. In this study, we wanted to assess which mycorrhizal fungi are associated with S. repens in four different coastal vegetation types in Southern Norway, three types from sand dunes and one from heaths. Moreover, we investigated which ecological factors are important for the fungal community structure in these vegetation types. Mycorrhizal fungi on S. repens root samples were identified by 454 pyrosequencing of tag-encoded internal transcribed spacer 1 (ITS1) amplicons. Significantly higher fungal richness was observed in hummock dunes and dune slacks compared to eroded dune vegetation. The compositional variation was mainly accounted for by location (plot) and vegetation type and was significantly correlated to content of carbon, nitrogen and phosphorus in soil. The investigated maritime sand dunes and coastal ericaceous heaths hosted mycorrhizal taxa mainly associated with Helotiales, Sebacinales, Thelephorales and Agaricales.

Vegetation Dynamics of Coastal Dunes with Juniperus spp. in Crete, Gavdos and Chrysi Islands (Greece)

We aimed to determine the composition, structure and ecological processes of the vegetation of the coastal dunes with Juniperus spp. in Crete, Gavdos and Chrysi in the South Aegean, Greece, in order to apply sound habitat management and restoration. Vegetation composition, structure and zonation were investigated with plots and transects. Data from seven study sites were classified using TWINSPAN. The major patterns of the vegetation data and their relation to environmental variables were explored by DCA and CCA ordination techniques. Ellenberg indicators for moisture, nutrients, and salt were used to characterise the community types identified. The habitat’s floristic composition includes 142 plant species. Five principal community types were identified. Vegetation distribution was related to geomorphology and disturbance gradients. The analysis of transect data identified 20 vegetation units on incipient dune, foredune, interdune and hind dune. Vegetation and geomorphological data were used to construct sand dune profiles for each site, while a set of 36 keystone and 76 indicator species were identified. The sites examined have varied levels of dune development and face different threats. Habitat management should address grazing and trampling at the local level but also land use changes at the catchment level.

Changes in plant species composition of coastal dune habitats over a 20-year period.

Coastal sandy ecosystems are increasingly being threatened by human pressure, causing loss of biodiversity, habitat degradation and landscape modifications. However, there are still very few detailed studies focussing on compositional changes in coastal dune plant communities over time. In this work, we investigated how coastal dune European Union (EU) habitats (from pioneer annual beach communities to Mediterranean scrubs on the landward fixed dunes) have changed during the last 20 years. Using phytosociological relevés conducted in 1989-90 and in 2010-12, we investigated changes in floristic composition over time. We then compared plant cover and the proportion of ruderal, alien and habitat diagnostic species ('focal species') in the two periods. Finally, we used Ellenberg indicator values to define the 'preferences' of the plant species for temperature and moisture. We found that only fore dune habitats showed significant differences in species cover between the two time periods, with higher plant cover in the more recent relevés and a significant increase in thermophilic species. Although previous studies have demonstrated consistent habitat loss in this area, we observed that all coastal dune plant communities remain well represented, after a 20-year period. However, fore dunes have been experiencing significant compositional changes. Although we cannot confirm whether the observed changes are strictly related to climatic changes, to human pressure or to both, we hypothesize that a moderate increment in average yearly temperature may have promoted the increase in plant cover and the spread of thermophilic species. Thus, even though human activities are major driving forces of change in coastal dune vegetation, at the community scale climatic factors may also play important roles. Our study draws on re-visitation studies which appear to constitute a powerful tool for the assessment of the conservation status of EU habitats.

Vegetation, distance to the coast, and aeolian geomorphic processes and landforms in a transgressive arid coastal dune system

The main objective of this study was to determine the nature and relative importance of environmental factors that shape the distribution of dune vegetation in the Maspalomas dune field in the Canary Islands, an arid transgressive dune system. Environmental factors were defined according to their expression related to the linear distance from the coast and to the local aeolian geomorphic process-landform context. Plant communities were characterized through an integration of field mapping, digital orthophoto interpretation and GIS analysis. The vegetation of the study area consists of 19 plant communities. In areas with active sedimentary processes, vegetation tends to be localized in slacks. In areas with more stabilized landforms, vegetation appears at both dunes and slacks. In conclusion, the main factor controlling the distribution of vegetation in the transgressive dune system of Maspalomas is the local aeolian sedimentary process-landform context. Distance to the coast is not as significant as an influence. The gradient structuring of environmental factors associated with retentive coastal dune systems and expressed as distance to the coast does not fully capture the biogeomorphic dynamism of transgressive dune fields.

Dune Vegetation and Insect Communities Vary with Barrier Beach Geomorphic Setting on Sapelo Island, United States

Mallinger, R., 2014. Dune vegetation and insect communities vary with barrier beach geomorphic setting on Sapelo Island, USA. Journal of Coastal Research, 30(6), 1210–1217. Coconut Creek (Florida), ISSN 0749-0208. Coastal geomorphic processes, including shore disturbance events, shape coastal landforms and sand dune ecosystems. The magnitude and frequency of shore disturbance can affect dune vegetation diversity, community composition, and succession. Furthermore, these processes might impact higher trophic levels, such as insects, either directly or indirectly through changes in dune vegetation. The objective of this study was to characterize differences in vegetation and insect communities along sand dunes varying in geomorphic setting and exposure to shore disturbance. Vegetation and insects were sampled along Nannygoat Beach, Sapelo Island, Georgia, United States, in areas historically documented to differ in erosion rates and in exposure to storm surges and overwash. Dune height and beach berm width were measured to describe geomorphic setting. The north end of Nannygoat Beach had taller sand dunes and a shorter beach berm width, indicating less overwash but greater rates of erosion compared to the south end. Plant diversity was significantly greater on the north end of Nannygoat, while insect richness was significantly greater on the south end of Nannygoat beach. Both plant and insect community composition were significantly different between the north and south ends of the beach. Furthermore, the plant community composition was significantly related to the abiotic variables, while the insect community composition was significantly related to the plant community. These results suggest that vegetation communities of barrier islands are strongly influenced by geomorphic processes, while insect communities are, in turn, shaped by the vegetation communities.

Fatty Acid Composition of Seed Oils in Some Sand Dune Vegetation Species from Turkey

Six species from sand dunes of northwest Turkey were investigated for their total seed oil lipid and fatty acid (FA) profiles. The total oil content ranged from 4.26 to 33.64% (Plantago scabra and Glaucium flavum, respectively). The major FAs were linoleic, oleic, palmitic, and stearic acids (20.78–60.69%, 14.73–56.64, 5.42–15.13, and 1.65–3.67%, respectively). Considerable amounts of γ-linolenic acid were found in Plantago scabra and Cionura erecta (13.13 and 1.37%, respectively). The unsaturated FA content ranged from 83.09% in Cardaria draba to 87.80% in Eryngium maritimum. Significant correlations between FA concentrations in these species were evaluated. These species, as alternative sources of unsaturated FAs, should be evaluated as novel salt-tolerant crops and used for improving salt tolerance of existing oilseed crops.

Changes in foredune vegetation caused by coastal forests

The need for coastal forests has been emphasized by the increased risk of natural disasters in coastal areas in recent years. To identify the effect of coastal forests on the foredune plant ecosystem, plant species numbers, cation distribution, wind speed, temperature and humidity were compared at the grass-covered dune (D1) and the planting site of Pinus thunbergii (D2) in Sohwang dune field, South Korea. The number of plant species at D2 turned out to be 2.1 times larger than at D1, with a total of 44 taxa, including 29 families, 40 genera, 35 species, 7 varieties, and 2 forms. Terrestrial plants such as Artemisia princeps and Lonicera japonica were commonly found at D2, whereas D1 was covered by typical dune plant species such as Elymus mollis and Carex kobomugi. Decreased wind velocity and changes in nutrients due to the forest of P. thunbergii have resulted in these differences. This study demonstrates that developing coastal forests on foredune environments reduces wind velocity, salt spray and blown sand, and thus, disturbs dune vegetation due to the accelerated introduction of terrestrial and alien plants.

The classification of coastal dune vegetation in Central Black Sea Region of Turkey by numerical methods and EU habitat types

Coastal sand dune vegetation in Central Black Sea Region of Turkey was investigated by numerical methods. Eight plant associations were determined according to two-way indicator species analysis (TWINSPAN) and detrended correspondence analysis (DCA). Plant associations were also classified according to NATURA 2000 and European Nature Information System. Coastal dune ecosystems in the Central Black Sea Region include eight habitat types. Eight plant associations belonging to four classes, order and alliances are described and five of them are new associations. TWINSPAN revealed the existence of a gradient from drift line to the inner parts. These have been separated into shifting dunes and fixed dunes. DCA allowed determining the plant associations in shifting dunes along the shoreline as well as the annual vegetation of drift line and embryonic shifting dunes and of fixed coastal dunes with herbaceous vegetation. The syntaxonomical classification is given in the following:

The potential future influence of sea level rise on leatherback turtle nests

Climate change models predict sea level rise and increased intensity of storms and hurricanes in tropical sea turtle nesting areas. These factors could significantly increase beach inundation and erosion, thus affecting water content of sea turtle nesting beaches. Here, we conducted a field and laboratory study of how sand water content is related to embryonic development and hatching success of leatherback turtle nests. Moreover, we have experimentally incubated eggs of this species in beach sand under standardized conditions, but at different realistic levels of sand water content, varying from 1% to 12%. On the beaches, females nested from the intertidal zone to the lower part of the sand vegetation dunes, where nests were exposed to a wide range of sand water contents that ranged from 0.8% to 22%. However, both field and experimental studies revealed a strong negative correlation between sand water content and emergence success (field study: r=−0.73, P<0.0001; experiment: r=−0.84, P<0.0001). In the field, mean emergence success varied from 0% for the wettest nests to 64% for the driest ones. Nests in wet sand suffered higher mortality, primarily in the earlier developmental stages. Eggs incubated in the driest sand lost mass, but there were no significant effects on hatchling mass or run speed compared to eggs that gained water during incubation. However, hatchling straight carapace length (SCL) was greater in eggs from the driest treatment. The results of the present study inform management of change under future climate change sea level rise scenarios, suggesting that leatherback turtle nesting success should be expected to decrease.

Impact of alien species on dune systems: a multifaceted approach

We applied a multifaceted approach, in terms of taxonomic, phylogenetic and functional diversity, to study at fine scale how three plant communities occurring in a Mediterranean dune have been affected by the encroachment of alien species. We sampled 81 sites in a Site of Community Importance in Central Italy. Past and present land use/cover data have been derived using GIS and remote sensing tools. Information on plants phylogenesis and functional traits has been gathered from several databases. Ecological variables have been collected. GLMs in conjunction with an Information Based approach were used to model species composition, richness and phylogenetic diversity. Multivariate analysis has been used to study functional diversity. The results outlined how total species richness is related to recent land transformations and to a set of environmental factors. The analyses of functional and phylogenetic diversity support the idea that alien species significantly affect the functional and phylogenetic characteristics of the native plant communities. Habitat filtering seems to be predominant in not-invaded plots, whereas limiting similarity/niche differentiation is predominant in driving community assembly of invaded communities. The attained scenario depicts the spread of a reduced group of alien species phylogenetically and functionally well-differentiated, able to reduce the abundance of native species, not to exclude them though. Ultimately, the multifaceted approach assisted in understanding the community assembly of dune vegetation, and to discern the relative impact of alien species on native plant communities. Such approach represents a crucial step to achieve an efficient management of dune habitats, as useful tool to monitor and to effectively protect their biodiversity and functioning.

Plant communities of a coastal lagoon foredune: definition of the reference and restoration after compaction

Throughout the world, dunes are being altered by human activities. Dunes can be restored to naturally functioning systems to protect human settlements and coastal strips and preserve biotopes. This study took place on the Jaï dunes, on the shore of a coastal lagoon in southeastern France, which were mainly degraded by vehicles. The objectives of this work were (1) to define the reference ecosystem by gathering historical information and exploring other regional sand dunes; (2) to find out about the restoration potential of the site by studying the degraded seed bank; (3) to test the efficacy of a few basic restoration actions. Historical information was of little help in defining the reference ecosystem. The description of EU Habitat Directive habitat types and the selection of regionally less degraded sites allowed us to compile the following list of plant species that we could expect to find in the restored area: Anthemis maritima, Elytrigia juncea, Glaucium flavum and Sporobolus pungens. The seed bank of the road was mainly composed of Juncus acutus, which is not a typical dune species and therefore did not have much potential for restoration. Ploughing can therefore be used to decompact the sand road without hampering colonization from the seed bank. Ploughing was only efficient when the following other conditions were met: environmental conditions adequate for the establishment of dune vegetation, and a sufficient connection between the beach, the foredune and the restored area.

Effects of Monsoon on Topography, Soil Variables, and Coastal Plants

Coastal dunes are highly vulnerable to disturbances. We characterized changes in the plant distribution, soil properties, and topology of a coastal dune field during the monsoon period. We selected a 600 × 300 m rectangular area of Dadaepo in the Nakdong River estuary and measured variables at 40 sampling points. A field survey was performed over two periods (pre- and post-monsoon) in 2009. Soil, topological features, and vegetation were surveyed at each point, and canonical correspondence analysis was used to identify relationships among the variables during the monsoon. The volumetric net change in the study site was 33,104 m3 during the monsoon. When topographic and edaphic variables were compared, topological variables were found to be the dominant factors in dune vegetation zonation; however, their influence on vegetation change during the monsoon was less prominent than that of edaphic variables. Inland exotic species (Oenothera odorata and Conyza canadensis) and Cynodon dactylon replaced most of the Carex pumila distribution (54 % decrease) after the monsoon. Phragmites australis expanded its distribution and replaced the adjacent community after the monsoon. The area of Suaeda japonica decreased by more than 85 %, and this area was also replaced by P. australis. This knowledge of the dynamics of dune vegetation and environmental variables will be important for predicting the impacts of climate change, such as sea level rise and increased rainfall frequency.

The contribution of DNA metabarcoding to fungal conservation: diversity assessment, habitat partitioning and mapping red-listed fungi in protected coastal Salix repens communities in the Netherlands.

Western European coastal sand dunes are highly important for nature conservation. Communities of the creeping willow (Salix repens) represent one of the most characteristic and diverse vegetation types in the dunes. We report here the results of the first kingdom-wide fungal diversity assessment in S. repens coastal dune vegetation. We carried out massively parallel pyrosequencing of ITS rDNA from soil samples taken at ten sites in an extended area of joined nature reserves located along the North Sea coast of the Netherlands, representing habitats with varying soil pH and moisture levels. Fungal communities in Salix repens beds are highly diverse and we detected 1211 non-singleton fungal 97% sequence similarity OTUs after analyzing 688,434 ITS2 rDNA sequences. Our comparison along a north-south transect indicated strong correlation between soil pH and fungal community composition. The total fungal richness and the number OTUs of most fungal taxonomic groups negatively correlated with higher soil pH, with some exceptions. With regard to ecological groups, dark-septate endophytic fungi were more diverse in acidic soils, ectomycorrhizal fungi were represented by more OTUs in calcareous sites, while detected arbuscular mycorrhizal genera fungi showed opposing trends regarding pH. Furthermore, we detected numerous red listed species in our samples often from previously unknown locations, indicating that some of the fungal species currently considered rare may be more abundant in Dutch S. repens communities than previously thought.

Nitrogen limitation in the coastal heath at Anholt, Denmark

The purpose of the study was to investigate, wheth- er the coastal grey dune vegetation at Anholt, Denmark, is limited by nitrogen or phosphorus. The island Anholt (22,37 km 2 ) is situated in the centre of Kattegat A two factor fertilization experiment with nitrogen as NH4NO3 (N- addition) and phosphorus asKH2PO4(P-addition) was carried out in the coastal grey dune vegetation of Anholt. The N- addition corresponded to 40 kg N ha �1 year �1 and the P- addition to 7 kg P ha �1 year �1 The experiment included N-, P-, N + P-addition and control. Lichens (genera: mainly Cladonia, Stereocaulon, Cetraria, Hypogymnia) and bryo- phytes (genera: Polytrichum, Racomitrium) cover most of the surface. Only two plant species, Corynephorus canescens and Empetrum nigrum, constitute nearly all vascular plant cover and biomass of this calcium poor coastal heath commu- nity. Corynephorus and Empetrum increased their cover sig- nificantly following N and N + P addition. No effect was observed by P addition alone. N limitation of this coastal heath vegetation remote from agricultural and industrial ac- tivities was evident. The effect on the plant species of the single application was short-lived. After two-three years of enhanced cover, the Corynephorus and Empetrum cover had returned to their level before the experiment. The lichen vegetation, however, changed more permanently, and after 12 years the subplots with N + P addition was dominated by rich growth of Cladina and Cetraria species. The results are discussed in relation to anthropogenic nitrogendeposition and conservation of this high priority ecosystem.

Mediterranean coastal sand dune vegetation: influence of natural and anthropogenic factors.

The aim of the present work was to assess the conservation status of coastal dune systems in Tuscany (Italy). Emphasis was given to the presence and abundance of plant communities identified as habitat in accordance with the Directive 92/43/EEC. Twenty transects perpendicular to the shoreline were randomly positioned on the whole coastal area (30km in length) in order to sample the full spectrum of plant communities. Vegetation zonation and relationships with the most frequent disturbance factors in the study area-beach cleaning, coastline erosion, presence of paths and roads, bathing settlements and trampling-were investigated through principal coordinate analysis and canonical correspondence analysis. Natural factors, such as distance from the sea and total length, were also considered. Differences in the conservation status of the sites were found, ranging from the total disappearance of the foredune habitats to the presence of the complete psammophilous (sand-loving) plant communities. Erosion, trampling, and paths were found to be closely correlated with degradation and habitat loss. Furthermore, the overall plant species diversity of dunes was measured with NHDune, a modified version of the Shannon index; while the incidence of invasive taxa was calculated using N, a naturalness index. However, these diversity indices proved to be a weaker bioindicator of ecosystem integrity than habitat composition along transects. A possible strategy for the conservation and management of these coastal areas could be to protect the foredunes from erosion and limit trampling through the installation of footbridges or the use of appropriate fences.