Grey Dunes Research Articles

Nitrogen deposition and grass encroachment in calcareous and acidic Grey dunes (H2130) in NW-Europe

We present an overview of high nitrogen deposition effects on coastal dune grasslands in NW-Europe (H2130), especially concerning grass encroachment in calcareous and acidic Grey Dunes. The problem is larger than previously assumed, because critical loads are still too high, and extra N-input from the sea may amount to 10kgha−1yr−1. Grass encroachment clearly leads to loss of characteristic plant species, from approximately 16 in open dune grassland to 2 in tall-grass vegetation. Dune zones differ in grass encroachment, due to the chemical status of the soil. In calcareous and iron-rich dunes (Renodunal district), grass encroachment showed a clear gradient over the dune area. Grass encroachment is low in calcareous foredunes, due to low P-availability, and large grazers were not needed to counteract grass encroachment after 2001. In partly decalcified middle dunes, P-availability and grass encroachment are high due to dissolution of calcium phosphates, and grazing only partially helped to control this. In acidic, iron-rich hinterdunes, grass encroachment gradually increased between 1990 and 2014, possibly because P-availability increased with time due to increased soil organic matter content. In acidic, iron-poor dunes (Wadden district), grass encroachment is a large problem, because chemical P-fixation with Ca or Fe does not occur. Large grazers may however reduce tall-grass cover. High cumulative N-deposition could theoretically lead to increased N-storage and N-mineralization in the soil. Mineralization indeed increased with N-deposition, but in 15N experiments, most ammonium was converted to nitrate, and storage in soil organic matter was low. Soil N-storage is probably reduced by high nitrate leaching, which will favour dune restoration when N-deposition levels decrease.

Assessment of degradation of white and grey dune habitats in the Curonian Spit: a case study of Parnidis Dune (Nida environs, Lithuania)

Assessment of degradation of white and grey dune habitats in the Curonian Spit: a case study of Parnidis Dune (Nida environs, Lithuania)

Environmental factors and ground disturbance affecting the composition of species and functional traits of ground layer lichens on grey dunes and dune heaths of Estonia

A unique, species‐rich and endangered lichen biota can be found on European coastal and inland sand dunes. However, it is increasingly affected by natural succession as well as by anthropogenic disturbances. We studied lichen diversity on the grey dunes and dune heaths of coastal and inland regions of Estonia. A total of 28 study plots were investigated; in each 0.1 ha study plot general environmental variables and anthropogenic disturbances were described and all epigeic lichen species were identified. We found 66 lichenized fungus (lichen) species, including several rare and ten red‐listed lichens. Multivariate analysis (DCA, CCA) was performed to examine gradients in species composition and to relate variation in species data to environmental factors. In addition, we used redundancy analysis (RDA) to relate variation in species’ trait composition to environmental factors. Species composition on grey dunes differed significantly from that on dune heaths. The characteristic species for grey dunes are, besides several Cladonia species, foliose lichens, e.g. Hypogymnia physodes, Parmelia sulcata and Peltigera spp. Also species’ traits composition was different for either habitat, indicating that sorediate lichens, foliose lichens, lichens with cyanobacterium as the main photobiont, and sparsely branched Cladonia species dominate on grey dunes, while esorediate, green‐algal, crustose and richly branched fruticose lichens are common on dune heaths. Soil pH was the most essential environmental variable for determining both species composition and species’ traits composition. The composition of lichen species was also significantly influenced by forest closeness, soil Mg content and cover of bare sand; the effect of ground disturbances was low compared to the effect of these environmental factors. To protect and conserve the species‐rich lichen biota, it is necessary to protect the dune habitats from building activity, to avoid overtrampling in recreation areas and to regularly remove shrubs and trees.

Habitats with Sea Grape (Ephedra distachya) on the Dunes of Letea (Danube Delta, Romania)

Abstract The Danube Delta is known for its unique, biogeographical-important ecosystem complex that includes a large range of habitats from the permanently water-covered to the extremely dry area. These ecosystems are well represented in the area nearest to the Black Sea in the dune area of Letea, Caraorman and Sărăturile. Sea grape (Ephedra distachya) communities taking part of the habitat type 2130* fixed coastal dunes with herbaceous vegetation (grey dunes), Subtype 16.22 B Pontic fixed dunes and their classification in the European habitat system are discussed and a proposal is made for their appropriate integration in a corresponding category of habitat types in the frame of the Pontic bioregion.

Constructing notches in foredunes: Effect on sediment dynamics in the dune hinterland

Measurements were carried out on the island of Ameland (The Netherlands) to determine whether notches cut into foredunes stimulated the supply of fresh calcareous beach and dune sand into the white and grey dune habitats behind the dunes, increasing these habitats' biological quality. Sediment characteristics and dynamics (deposition flux and grain size properties) as well as aspects of the vegetation (occurrence, composition and cover density) were studied along six transects, three behind an intact foredune and three behind a foredune with a notch cut into it. Compared to an intact foredune, the notched foredune exhibited higher deposition and accumulation behind the dune. The extra supply of sand was small, however, and for the notches studied, limited to the zone within approximately 50–60m of the foredune's crest. Farther away from the dune, the effect of the notches became negligible. The presence of a notch did affect the grain size composition of sediment deposited behind the foredune. For intact foredunes, the grain size composition behind the dune was similar to that on the dune itself. When a notch had been cut, the sediment was finer behind the foredune, gradually coarsening away from the dune. Sand spray (deposition of sand eroded from the dune and transported in modified saltation during heavy winds) explains these granulometric results. The effect of the notches on the vegetation in the grey dune habitat behind the foredune was small and, for the notches studied, limited to the first approximately 35m of the grey dune area, between 30 and 65m from the foredune's crest. The notches had a greater effect on the white dune habitat but – in the opinion of the authors – this remained disproportionately small relative to the effort required for notch excavation and maintenance.

Moss invasion in a dune ecosystem influences ground-dwelling arthropod community structure and reduces soil biological activity

One of the most invasive moss species worldwide is Campylopus introflexus, which can change vegetation and habitat conditions of native ecosystems (dunes, heathland). However, the impact of the moss on the community structure of multiple arthropod taxa and ecosystem functions is still poorly understood. For a better understanding of impacts of invasive species, scientific studies are needed which explicitly define the investigated impact. We defined impact based on the most recently recommended categories: ‘directionality’, ‘classification and measurement’, ‘ecological or socio-economic changes’, and ‘scale’. We investigated the impact of C. introflexus on a wide range of ground-dwelling arthropods (pitfall traps) and on soil biological activity (bait-lamina test) by comparing invaded and uninvaded grey dunes in a field observational study on the island of Hiddensee, Germany. We found that the moss and the associated habitat modifications influenced the arthropod community structure. The effects on arthropod densities were taxon-specific and were positive (Coleoptera, Formicidae, Opiliones) or neutral (Araneae, Orthoptera). For Collembola and Isopoda we assumed an indirectly negative effect of the moss due to associated lower field layer cover and soil moisture. C. introflexus drastically reduced the soil biological activity, which was about six times lower in invaded grey dunes. The reduced soil moisture associated with the moss invasion was identified as the main driver of the shifts in community structure and soil biological activity. By explicitly defining ‘impact’ in our study, we add to recent discussions within invasion ecology about invasive species impacts. Our study demonstrates the importance of cross-taxon approaches which include key ecosystem processes such as soil biological activity and therefore contributes to the progress towards the general understanding of plant invasion impacts.

Proposal for new EU habitats associated with coastal dune fields of the Macaronesian region. A case study in the Canary Islands (Spain)

The aim of this work is to identify habitats of European interest for the existing dunes in the Canaries, in order to provide data for their proper management. Dune systems considered were the following: aeolian sedimentary systems that cover both most of the island of La Graciosa and also the dune fields of Maspalomas (Gran Canaria) and Corralejo (Fuerteventura). The methodology consisted of overlapping layers of habitats and vegetation by using geographic information systems, so the correspondence between habitat and plant community are analyzed. The results indicate that dune habitats in the Canary Islands have not been well defined. The habitat “2110 embryonic shifting dunes” is associated with several situations incompatible with their biotic and abiotic characteristics. Meanwhile, habitat “2130 fixed dunes with herbaceous vegetation (grey dunes)” is linked, among others, to the phytosociological association Traganetum moquinii. However, embryonic dune formation in the Canaries is mainly done by this community, which is inconsistent with its inclusion in the grey dunes habitat. The proposed habitats of European interest associated with dunes in the Canaries are the following: Coastal shifting dunes with Traganum moquinii, dunes with Tamarix canariensis, Macaronesian aeolian sand sheets and humid dune slacks. It is also suggested the need for a comprehensive study of dune habitats existing in the Canaries and Macaronesia, covering the whole of aeolian sedimentary systems, performing a proper identification, characterization and detailed mapping of these habitats, based on both the existing vegetation and also on the associated landforms and geomorphic processes.

Annoying neighbors: Multi-scale distribution determinants of two sympatric sibling species of birds

Abstract We tested the role of interspecific competition in driving species distribution at multiple spatial scales using two sibling species of Galerida larks (G. cristata and G. theklae) in Morocco (sympatry), Balearic islands (G. theklae only) and Israel (G. cristata only). We first investigated regional-scale determinants by contrasting allopatric versus sympatric patterns in five distinct habitat types. We next focused on a single habitat used by both species, the coastal sand dunes. Dune quadrats were established along the Moroccan coast and completed by a quadrat in the nearest distinct landscape habitat. Poisson regressions were used to model Galerida counts together with ecological predictors as concerns the climate, topography, vegetation structure and soil gra-nulometry. At the local scale, both species preferred grey dunes over white sand dunes, and both were negatively affected by the abundance of the congeneric species in the dune. However, we found that G. theklae tended to replace G. cristata in more arid sand dunes, even if the transition was not strictly clinal. Instead, the transition occurred when the surrounding landscape changed from coastal wetlands to bathas (grasslands with shrubs), highlighting the importance of habitat composition at the landscape scale. The fact that G. cristata used bathas in allopatry, but not in sympatry, suggested that the competitive environment contributed to determine sand dune occupancy. We suggest that landscape-level effects may be pivotal in explaining species distribution not only at the local scale, by affecting the pool of potential immigrants, but also at the regional scale, by contributing to species’ range limit.

Year-round grazing to counteract effects of atmospheric nitrogen deposition may aggravate these effects

Excessive nitrogen input in natural ecosystems is a major threat to biodiversity. A coastal dune area near Amsterdam in the Netherlands suffers from high atmospheric nitrogen deposition affecting sensitive habitats such as fixed coastal dunes with herbaceous vegetation (‘grey dunes’). To mitigate its effect year round grazing was applied from 2007 until 2012. In winter, when natural food supply is low, the cattle received supplementary hay that caused additional inputs of nitrogen. Estimates based on nitrogen contents of hay, as well as of manure, showed the input through winter feeding (c. 3–14 kg N ha−1.y−1) is in the same order of magnitude as both the actual deposition (c. 17 kg N ha−1.y−1) and the critical load for a number of herbaceous habitat types (10–15 kg N ha−1.y−1). Locally, the effect of winter feeding adds to the effect of nitrogen redistribution within the area caused by the cattle's terrain usage. We conclude that winter feeding may aggravate effects of atmospheric nitrogen deposition.

Patrones de diversidad liquénica en las dunas arenosas de la costa del norte de Portugal

Coastal sand-dunes of northern Portugal are dynamic ecosystems under natural and human disturbances. Still, they constitute an interesting subject for ecological research, since they spread over a main biogeographic transition between the Eurosiberian and the Mediterranean regions. Despite the awareness of lichen contribution to grey dune stability and protection, there are no recent published studies focusing on their lichen flora. Therefore, the overarching goal of this research was to evaluate the patterns of lichen diversity along biogeographic - and coastal dynamics - related gradients in northern Portugal. A catalogue with 17 species is presented, and includes a new species for Portugal, Cladonia rei Schaer. Patterns of lichen diversity were analysed through Mann-Whitney tests and Analysis of Similarity (ANOSIM), which showed distinct signals when considering different diversity components and scales of analysis. These results have strong implications for conservation and monitoring strategies of this type of ecosystem.

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.

Trend monitoring of the areal extent of habitats in a subsiding coastal area by spatial probability sampling

The European Habitats Directive requires a regular reporting of areal changes of the Habitat types defined under this Directive. To monitor changes in Habitat types in a dune and salt meadow area in the eastern part of the back-barrier island of Ameland (The Netherlands) a sampling scheme was designed suitable for both unbiased estimation of such changes and for mapping the Habitat types. As a space–time design a supplemented panel was chosen, with a proportion of permanent plots of 0.5. Sampling plots were selected by probability sampling, with sampling designs that spread the plots evenly over the study area. These design decisions are motivated in the paper. Eight vegetation types were distinguished, corresponding to six Habitat types. The areal extent of the ‘grey dunes’ type significantly decreased over the observation period, whereas the extents of two ‘salt meadow’ types significantly increased. This has to be considered as a loss of habitat quality. It is doubtful whether for the Natura 2000 area in its entirety, wherein we expect smaller rates of change compared to our study area, it will be possible to detect areal changes in Habitat types at acceptable costs and within the requested six-year periods. The supplemented panel design performed nearly equal to a pure panel design (all plots permanent) in terms of precision of estimated linear trends, but was by far superior to an independent synchronous design with all plots changing.

Biological Flora of the British Isles: Eryngium maritimum

Summary This account presents information on all aspects of the biology of Eryngium maritimum L. (Sea Holly) that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, history and conservation. Eryngium maritimum is a native perennial hemicryptophyte, with a large taproot, spiny and leathery leaves and a pale bluish inflorescence. It has a more or less continuous distribution in suitable habitats along the coasts of Great Britain and Ireland up to about 55° N, but it is more scattered further north. On the west coast, it is found south of the Hebrides, and on the east coast, with some exceptions, south of Yorkshire. In Europe, it has a wide, but mainly southern temperate, European distribution along the coasts of the Atlantic Ocean, the Baltic, the Mediterranean, and the Black and Azov Seas. Its northern distribution limit is at c. 60° N. Eryngium maritimum grows typically on sand and shingle beaches, foredunes and yellow dunes, as well as in semi‐fixed grey dunes. Its habitats have full sunlight and are more or less dry. It occurs in many coastal plant communities from the beach inland, and because of its wide European distribution, it occurs with members of several different biogeographical species groups. Protected from grazing by its spininess and sclerophylly, E. maritimum is nevertheless vulnerable to direct damage by trampling. It supports few insect herbivores, probably because of chemical defences. Historically, it has had a great number of medicinal uses. Eryngium maritimum is unable to withstand competition from faster and more densely growing plant species. In many coastal regions, in both temperate and mediterranean parts of Europe, it is one of the rarest and most threatened plant species, mainly because of habitat loss and land‐use changes.

Development of new dunes in the Dutch Delta: nature compensation and ‘building with nature’

A new dune area was constructed by beach and foreshore nourishments along the Delfland Coast in the southwestern Netherlands. The new area is intended to be a compensation for losses of existing high quality dunes in nearby areas, due to the use/construction of Maasvlakte 2, the new harbour extension of Rotterdam opening in 2013. The target habitats for compensation include dry grey dunes and moist dune valley grassland. Due to the habitat type, the nourished material had to have a special character. The nourishment was carried out according to a special design and initial development of the new area had to follow certain pathways. In order to meet the compensation requirements in time. Careful monitoring is done to assess whether development of the new habitat is taking place in the direction of the desired target habitats. This paper reports on the construction of the new area and on the first years of development and monitoring. The monitoring mainly concerns development of the abiotic landscape elements, geomorphology, groundwater and soils. The lessons learned from this area are discussed in the light of the development of other recent young nature areas in the sandy Dutch delta coast. This gives new insights for coastal management in general in the context of building with nature.

Coastal heathland succession influences butterfly community composition and threatens endangered butterfly species

Succession has a strong influence on species diversity and composition of semi-natural open terrestrial ecosystems. While several studies examined the effects of succession on butterflies in grassland and forest ecosystems, the response of heathland butterflies to succession had not been investigated so far. To address this issue we sampled butterfly abundance and environmental parameters on the Baltic island of Hiddensee (NE Germany) along a gradient of coastal heathland succession from grey dunes to birch forest. Our results provide evidence that succession of coastal heathland has a strong influence on butterfly diversity, abundance, and species composition. Thereby grass and tree encroachment present the main threats for heathland butterflies. Diversity and abundance of butterflies were highest in shrub-encroached heath directly followed by early stages of coastal heathland succession (dwarf-shrub heath, grey dune). Both observed threatened species (Hipparchia semele, Plebeius argus) were negatively affected by succession: abundance decreased with increasing vegetation density (both species) and grass cover (P. argus); consequently, the two later successional stages (shrub, birch forest) were not occupied. Our findings highlight the importance of the preservation of early stages of coastal heathland succession for endangered butterfly species. For coastal heathland management we therefore suggest to maintain early successional stages by sheep grazing, mowing or, in case of high nutrient contents, intensive techniques such as sod-cutting or choppering. To a lower extend shrub-encroached sites should also be present, which might be beneficial for overall species richness.

Grey dune ground layer vegetation in the Curonian Spit Nature Reserve, Lithuania

Grey dune ground layer vegetation in the Curonian Spit Nature Reserve, Lithuania

Caracterização geo-ecológica dos sistemas de cordões dunares da Estremadura

GEO-ECOLOGYCAL STUDY OF SOME DUNE SYSTEMS IN THE PORTUGUESEESTREMADURA. The Portuguese Estremadura coastal area between Nazaré and Peniche displays great variety of landforms. Most are cliff systems cut in sedimentary rocks with incisions controlled by tectonic activity. In the river mouths sand bars and beaches are present. Beach systems make up about 40% of the referred coastline and have ridges of diverse form and size, and rates of vegetation cover. These dunes appear on the inland side of the beach or even backshore as a result of erosion. They may have piled up into sand backs that cut off the lagoon estuaries to the West in the historic period. The geomorphologic and sedimentary characteristics that appear permit the identification of double ridges separated by interdunal corridors or depressions in West Nazaré, S. Martinho do Porto and Peniche (Consolação) and in a simple and continuous form in Baleal. This difference could be related with local topography, wind/wave climatology and/or vegetation cover. With regard to flora and vegetation, psammphitic and halonitrophilous pioneer plants that colonise foreshore ecosystems and transitions to backshore are Salsolo kali-Cakiletum aegyptiacae in the studied area. Springtime terophitic is sparse and grows where organic remains have accumulated. Flat backshore areas which are overrun by sea during spring-tides and storms are colonised by open vegetation, predominantly Elymus boreli-atlanticus (Euphorbio-Agropyretum junceiformis). Alongside the clumps of marran grass, on the backshore and on the crests of white dunes, Loto-Ammophiletum grows abundantly together with Otanthus maritimus and Lotus creticus. Grey dunes, which are further away from the effects of the ocean (winds and salinity), are characterised by relative sand stability and a succession of dune peaks and interdune corridors with thermophilic associated Armerio welwitschii-Cruciannelletum. The openings display terophitic associated Violo-Silenetum litoreae with Atlantic features. The mature stage of the system consist in the more interior stabilised dune of dense shrubs, consisting mostly of Juniperus turbinata (Osyrio-Juniperetum turbinatae).

Invasive moss alters patterns in life-history traits and functional diversity of spiders and carabids

Invasive plants can modify terrestrial habitats and affect the natural faunal composition. In acidic coastal dunes the invasive moss Campylopus introflexus can form dense carpets that largely replace native vegetation. As shown in a previous study, moss invasion affects habitat structure and ground-dwelling arthropod diversity. We suggested that including the functional diversity concept in the analysis of moss invasion impacts may offer further insights. We used pitfall trap data to compare trait composition and functional diversity of spiders and carabids in (a) invaded, moss-rich (C. introflexus) and (b) native, lichen-rich (Cladonia spp.) acidic coastal dunes. Moss invasion induced shifts in the trait values body size and feeding preference (carabids) and hunting mode (spiders): Species were smaller in native sites, and the percentages of web-building spiders and phytophagous beetles were reduced in invaded sites. Furthermore, moss invasion led to a more heterogeneous trait composition for spiders, and changed functional diversity of both arthropod groups, although with the opposite effects: While spiders were functionally more diverse in invaded sites, moss invasion reduced carabid beetles’ functional diversity. We also observed changes in the relationship between species richness and functional diversity that indicate a high functional similarity for spiders but a lower one for carabid beetles in native grey dunes. C. introflexus invasion not only alters the arthropod diversity and assemblage structure of endangered acidic coastal dunes but also interferes at a functional level. These results provide further insight into the way plant invasions might alter the structure and function of ecosystems.

Plant species diversity in dry coastal dunes of the southern Baltic coast

This study describes plant species diversity in well preserved dry coastal dune systems along the southern Baltic coast. Variations in diversity and in distributional character of plant species and plant communities throughout the study areas result mainly because of the interplay between plant succession, exposure, disturbance and resource availability. Environmental indicator values, used to describe dynamics in dune habitats, show a decline of light and temperature with increased distance to the sea, accompanied by higher soil moisture due to accumulation of organic matter. Species richness and species diversity showed a humped-shaped curve along a coast-to-inland gradient. The highest species richness of vascular plants and cryptogamic species were found in plant communities of grey dunes at intermediate levels of environmental and disturbance gradients, which confirms the intermediate disturbance theory.

Influence of soil and microclimate on species composition and grass encroachment in heath succession

Mostly due to land use changes, European heathlands have become increasingly rare. In addition, the increasing amount of atmospheric nitrogen deposition has resulted in an encroachment of grasses and a loss in species diversity. Despite many investigations, information about the precise environmental parameters that determine the development and maintenance of heathland vegetation is still insufficient. In order to determine the environmental factors that control heath succession and grass encroachment, and to develop appropriate management schemes, we studied the influence of several soil and microclimate parameters on species composition and vegetation characteristics in five successional stages in a coastal heathland on the island of Hiddensee, north-east Germany, where the encroachment of Carex arenaria has become a major problem. We recorded the highest plant species richness in grey dune and birch forest plots, while the encroachment of C. arenaria let to a significant decline in plant species richness. The most important environmental factors influencing species richness and distribution of single species were microclimate, soil moisture, soil pH and the C/N ratio. While many studies reported the importance of differences in nutrient availability, we found no significant correlations between soil nutrient availability and vegetation pattern. Environmental conditions in dense C. arenaria stands, especially soil properties (e.g. soil pH), showed great differences in comparison to the other successional stages. However, no correlations between the encroachment of C. arenaria and single environmental factors were found. Our results show that not only soil nutrients are important abiotic factors in heaths but that also microclimate and soil moisture play an important role and that many factors are involved in heath succession and in the promotion of grass encroachment. Management plans for the conservation and restoration of heathlands should therefore focus on the specific site conditions and should take several abiotic and biotic factors into account.