Dune Vegetation Research Articles

Response of Terrestrial Arthropod Assemblages to Coastal Dune Restoration

To restore historical dune vegetation, substantial effort has been made to remove the invasive plant species, European beach grass ( Ammophila arenaria ), from coastal dunes of California, USA. However, little effort has been made to examine the response of terrestrial arthropod assemblages to coastal dune restoration. We sampled terrestrial arthropods at 6 dune restoration sites to determine the response of the arthropod communities to vegetation restoration along the central and northern coast of California. Using pitfall traps, we examined restored and adjacent unrestored foredunes and collected reference data from dunes that had not been invaded by European beach grass. Both arthropod abundance and richness were significantly higher on restored and uninvaded dunes than on unrestored dunes. However, we detected no difference in arthropod richness and abundance between restored and uninvaded dunes. The species composition of the arthropod community reflected greater similarity of geographically adjacent sites, rather than similarity within treatments. We conclude that restored dunes provide higher quality habitat for terrestrial arthropods than unrestored dunes dominated by European beach grass, but longer-term studies are needed to determine if restoration efforts will be effective at fully restoring historical arthropod assemblages.

Size distributions and dispersions along a 485-year chronosequence for sand dune vegetation.

Using a sand dune chronosequence that spans 485 years of primary succession, we collected nearest-neighbor vegetation data to test two predictions associated with the traditional “size-advantage” hypothesis for plant competitive ability: (1) the relative representation of larger species should increase in later stages of succession; and (2) resident species that are near neighbors should, over successional time, become more similar in plant body size and/or seed size than expected by random assembly. The first prediction was supported over the time period between mid to later succession, but the second prediction was not; that is, there was no temporal pattern across the chronosequence indicating that either larger resident species, or larger seeded resident species, increasingly exclude smaller ones from local neighborhoods over time. Rather, neighboring species were generally more different from each other in seed sizes than expected by random assembly. As larger species accumulate over time, some relatively small species are lost from later stages of succession, but species size distributions nevertheless remain strongly right-skewed—even in late succession—and species of disparate sizes are just as likely as in early succession to coexist as immediate neighbors. This local-scale coexistence of disparate sized neighbors might be accounted for—as in traditional interpretations—in terms of species differences in “physical-space-niches” (e.g., involving different rooting depths), combined with possible facilitation effects. We propose, however, that this coexistence may also occur because competitive ability involves more than just a size advantage, with traits associated with survival (tolerance of intense competition) and fecundity (offspring production despite intense competition) being at least equally important.

Effects of Trampling Limitation on Coastal Dune Plant Communities

Sandy coastlines are sensitive ecosystems where human activities can have considerable negative impacts. In particular, trampling by beach visitors is a disturbance that affects dune vegetation both at the species and community level. In this study we assess the effects of the limitation of human trampling on dune vegetation in a coastal protected area of Central Italy. We compare plant species diversity in two recently fenced sectors with that of an unfenced area (and therefore subject to human trampling) using rarefaction curves and a diversity/dominance approach during a two year study period. Our results indicate that limiting human trampling seems to be a key factor in driving changes in the plant diversity of dune systems. In 2007 the regression lines of species abundance as a function of rank showed steep slopes and high Y-intercept values in all sectors, indicating a comparable level of stress and dominance across the entire study site. On the contrary, in 2009 the regression lines of the two fenced sectors clearly diverge from that of the open sector, showing less steep slopes. This change in the slopes of the tendency lines, evidenced by the diversity/dominance diagrams and related to an increase in species diversity, suggests the recovery of plant communities in the two fences between 2007 and 2009. In general, plant communities subject to trampling tended to be poorer in species and less structured, since only dominant and tolerant plant species persisted. Furthermore, limiting trampling appears to have produced positive changes in the dune vegetation assemblage after a period of only two years. These results are encouraging for the management of coastal dune systems. They highlight how a simple and cost-effective management strategy, based on passive recovery conservation measures (i.e., fence building), can be a quick (1–2 years) and effective method for improving and safeguarding the diversity of dune plant communities.

Studies on the prospects and some problems of sand dune vegetation at the fragile coastal zones of West Bengal and Orissa, in Eastern India

Platostoma africanum P. Beauv. is a tropical plant species valued for its efficacy in traditional medicinal system in West Africa. Although studied for its chemical properties, no cytogenetic study has been reported on this plant species. Axillary buds obtained from the growing plants were used to conduct mitotic study. Results obtained in this study showed that P. africanum is a diploid species with chromosome number, 2n = 10. The mean chromosome length was 3.93 µm and chromosomes ranged from 3.08 to 5.39 µm, with a haploid set length of 19.64 µm. The karyotype showed assymetry with a formula, 1m+1sm+2a+1t and indicated good adaptation and advancement in evolution in this species. This is the first report of the chromosome number in this indigenous medicinal plant species. Key words: Cytology, mitosis, medicinal plants, Lamiaceae.

2011年巨大津波が宮城県蒲生潟の地形，植生および底生動物相に及ぼした影響

Gamo Lagoon (Sendai, Miyagi Prefecture, Japan), a shallow brackish lagoon, was struck by a 7.2-m-high tsunami on 11 March 2011. In order to assess the tsunami-induced changes in the ecosystem of Gamo Lagoon, we examined the topography and distribution of plants and macrobenthos between April and August, 2011, and compared them with available pre-tsunami data. The submerged area decreased from 17.3 to 11.8 ha, sand dune vegetation from 8.6 to 0.1 ha, pine forest from 4.2 to 2.0 ha, and macroalgal patches from 7.8 to 1.8 ha. Conversely, the area of bare intertidal flats increased from 4.7 to 5.3 ha, mainly owing to the near disappearance of reed marshes (7.8 to 1.2 ha). Muddy sediment was flushed out and the sediment became sandier. The population of the marsh-associated gastropod Cerithidea rhizophorarum in the lagoon declined sharply from about 40,000 (estimated from mean density and habitat area) to just 26 individuals. Of 79 species of macrobenthos found before the tsunami, 47 species (especially bivalves) were absent or nearly extirpated after the tsunami. The temporary immigration of 12 marine species was noted shortly after the tsunami, but most disappeared within 5 months. The populations of dotillid crabs (i.e., Scopimera globosa and Ilyoplax pusilla), the nereidid polychaete Hediste diadroma, and opportunistic species including polychaetes (e.g., Pseudopolydora cf. kempi, Heteromastus cf. similis, and Capitella sp.) and amphipods (Grandidierella japonica and Corophiidae sp.) recovered rapidly within the same 5-month period.

Coastal Dune Vegetation of the Southern Pampas (Buenos Aires, Argentina) and Its Value for Conservation

MONSERRAT, A.L.; CELSI, C.E., and FONTANA, S.L., 2012. Coastal dune vegetation of the Southern Pampas (Buenos Aires, Argentina) and its value for conservation.Vegetation structure and species composition of southern Pampas coastal dunes were studied to evaluate their significance for conservation. The vegetation was described in 41 plots of 100 m2 along four transects perpendicular to the coast. The floristic dataset was classified by two-way indicator species analysis. Vegetation distribution patterns were analysed in relation to the geomorphology and environmental factors. Fifty-one taxa (19 families) of vascular plants were recorded, with Asteraceae, Poaceae, and Fabaceae being the most abundant. The main vegetation groups obtained from the classification are related to distinctive geomorphology. (1) Upper beach and active dunes are habitats with extreme conditions, characterized by species-poor associations with low vegetation cover; group dominated by few shrubs and gramines like Panicum urvilleanum, Calycera crassifolia, and Senecio bergii. (2) Fixed/semifixed dunes are habitats with more stable substrate, characterized by dense vegetation, high species richness, and woody life forms; group dominated by Poa lanuginosa, Hyalis argentea var. latisquama, Oenothera mollissima, and Glycyrrhiza astragalina. (3) Hygrophilous communities are mostly associated with dune slacks with high herbaceous vegetation cover; group largely dominated by Cortaderia selloana, Typha sp., and Imperata brasiliensis. Detrended correspondence analysis shows that the major floristic variation follows a gradient from the beach inland. Also, there is a clear zonation pattern strongly associated with geomorphologic heterogeneity. The occurrence of threatened species (e.g., Adesmia filipes, Neosparton ephedroides) and endemic taxa (S. bergii and Baccharis divaricata) plus the high habitat diversity and plant species richness confers to the area special value for conservation. The ecological role of dune vegetation is discussed in conservation and management context.La estructura de la vegetación y la composición de especies de las dunas costeras australes de la Región Pampeana fueron estudiadas para evaluar su importancia para la conservación de la biodiversidad. La vegetación fue descrita en 41 cuadrantes de 100m2 cada uno, a lo largo de cuatro transectas lineales perpendiculares a la costa. El set florístico fue clasificado mediante un análisis de dos vías de especies indicadoras (TWINSPAN). Los patrones de la distribución de la vegetación fueron analizados en lo referente a la geomorfología y a los factores ambientales. Dentro de los cuadrantes, se registraron 51 taxa (19 familias) de plantas vasculares, con Asteraceae, Poaceae y Fabaceae siendo los más abundantes. Los grupos principales de vegetación obtenidos de la clasificación se relacionan con distintivas localizaciones geomorfológicas: (1) playa superior y dunas activas son ambientes con condiciones extremas, caracterizados por asociaciones pobres en especies con baja cobertura vegetal; el grupo es dominado por pocos arbustos y gramíneas, como Panicum urvilleanum, Calycera crassifolia y Senecio bergii; (2) dunas fijas/semifijas son ambientes con un substrato más estable, caracterizado por vegetación densa, alta riqueza de la especie y formas de vida leñosas; el grupo fue dominado por Poa lanuginosa, Hyalis argentea var. latisquama, Oenothera mollissima y Glycyrrhiza astragalina.; (3) comunidades higrófilas, asociadas principalmente a bajos interdunales con alta cobertura vegetal; el grupo está ampliamente dominado por Cortaderia selloana, Typha sp. y Imperata brasiliensis. El análisis de correspondencia muestra que la principal variación florística sigue un gradiente desde la playa hacia el interior del continente. También, hay un patrón claro de zonación fuertemente asociado a la heterogeneidad geomorfológica. La ocurrencia de especies amenazadas y de taxa endémicos, sumado a la alta diversida

The effects of shifting vegetation mosaics on habitat suitability for coastal dune fauna—a case study on sand lizards (Lacerta agilis)

Encroachment of tall grasses and shrubs in coastal dunes has resulted in loss of vegetation heterogeneity. This is expected to have negative effects on animal diversity. To counteract encroachment and develop structural heterogeneity grazing is a widely used management practice. Here, we aim to functionally interpret changes in vegetation composition and configuration following grazing management on habitat suitability for sand lizards. Aerial photographs taken over a period of 16 years were used to quantify changes in vegetation composition. A GIS-based method was developed to calculate habitat suitability for sand lizards in a spatially explicit manner, encompassing differences in vegetation structure and patch size. From 1987 to 2003 dune vegetation shifted from small patches of moss and sand to larger patches covered by shrubs and grasses. Grazing management did not have any significant effect on the overall level of heterogeneity, measured as habitat suitability for sand lizards. However, on a more local scale highly suitable patches in 1987 were deteriorating whereas unsuitable patches became more suitable in 2003. This inversion results from a broad shift with shrubs being a limiting habitat element in 1987 to sandy patches being the limiting element in 2003. Future changes are believed to negatively impact sand lizards. The habitat suitability model has proven to be a useful tool to functionally interpret changes in coastal dune vegetation heterogeneity from an animal’s perspective. Further research should aim to include multiple species operating on different scale levels to fully capture the natural landscape dynamics.

Effects of sand fences on coastal dune vegetation distribution

Sand fences are important human adjustments modifying the morphology of developed shores. The effects of sand fences on sediment transport and deposition in their initial stages have been well studied, but little is known about the effect of deteriorated sand fences that have become partially buried low scale barriers within the dune, potentially benefiting vegetation growth by protecting it from onshore stress. Data on vegetation, topography and fence characteristics were gathered at three dune sites in Ocean City, New Jersey on September 2007 and March 2008 to evaluate the effect of fences within the dune on vegetation distribution. Variables include: distance landward of dune toe, degree of sheltering from onshore stressors, net change in surface elevation (deposition or erosion), vegetation diversity and density, presence of remnant fence, and distance landward of fence. Results for the studied environment reveal that 1) vegetation diversity or density does not increase near remnant fences because most remnants are lower than average vegetation height and can not provide shelter; but 2) vegetation distribution is related to topographic variables, such as degree of sheltering, that are most likely the result of sand accretion caused by fence deployment. Fence deployment that prioritizes the creation of topographically diverse dunes within a restricted space may increase the diversity and density of the vegetation, and the resilience and value of developed dunes. Managers should consider the benefits of using sand fences on appropriately wide beaches to create a protective dune that is also diverse, functional and better able to adapt to change.

Experimental study of dune vegetation impact and control on leatherback sea turtle Dermochelys coriacea nests

The leatherback sea turtle Dermochelys coriacea is a Critically Endangered species that nests on oceanic beaches. Natural disturbance cycles of erosion and accretion maintain nest- ing habitat on these beaches by controlling dune vegetation and sand quality. The nesting beach at Sandy Point National Wildlife Refuge in St. Croix, US Virgin Islands, is designated 'critical habi- tat' for leatherback turtles by the US Fish and Wildlife Service. It harbors the largest nesting pop- ulation (>800 females) in the USA. It is an important rookery for Atlantic leatherback recovery efforts. For the past 30 yr, the beach has been continuously monitored and managed in order to increase hatchling recruitment and conservation. Our study highlights how a multiyear change in the natural disturbance cycle has affected dune plant growth and leatherback production at this beach. Reduced summer erosion relaxed natural control of Ipomoea pes-caprae, a native dune plant, allowing its seaward spread to cover >75% of the nesting beach. This spread of vegetation led to both direct and indirect interactions between nesting leatherbacks and I. pes-caprae. Because the beach is managed in order to protect leatherback nests, a dune vegetation control plan was needed. We measured the effects of 3 vegetation management options on nest success: herbicide treatment, aboveground mechanical removal, and undisturbed vegetation. These treat- ments were compared to nest success at a non-vegetated control site. We found that the spread of I. pes-caprae reduced nesting habitat and nest productivity. Aboveground vegetation treatment did not control root growth into nests. We discuss possible vegetation management strategies to improve leatherback nesting habitat quality and maximize nest productivity while minimizing anthropogenic disturbance to the natural beach dynamics.

Conservation management of coastal dunes for Orthoptera has to consider oviposition and nymphal preferences

Dune and heathland ecosystems can harbour a multitude of specialized insect species. To assess the habitat quality of these ecosystems, the presence of specialized insect species may act as a useful indicator. The Orthoptera species Myrmeleotettix maculatus, Decticus verrucivorus, and Platycleis albopunctata present such umbrella species. Because knowledge of oviposition and nymphal habitats of these species is insufficient, we conducted a combined study consisting of an outdoor oviposition experiment and a field survey analyzing nymphal habitat preferences during summer 2009 on the Baltic island of Hiddensee, Germany. The oviposition experiment showed, that all three species mostly avoid oviposition under lichens (= mature grey dunes). M. maculatus preferred bare ground for oviposition, D. verrucivorus favoured both bare ground and mosses, and P. albopunctata laid most eggs into mosses. Young nymphs of both M. maculatus and P. albopunctata preferred initial grey dunes with a high proportion of bare ground and moss-rich grey dunes. Old nymphs were related to moss-rich and lichen-rich grey dunes with more dense vegetation. Based on our results, early seral stages of dune succession with bare ground and mosses as keystone structures are crucial for the conservation of the three studied umbrella species. Because old nymphs and adults additionally require more dense grey dune vegetation or adjacent heath stands, practical dune and heathland management measures should aim to maintain a mosaic-like pattern of different grey dune and dwarf-shrub vegetation stands.

Phaseolinae (Leguminosae, Papilionoideae, Phaseoleae) no estado do Paraná, Brasil

Resumo No Paraná, a subtribo Phaseolinae Benth. está representada por 20 espécies, alocadas em quatro gêneros. Vigna Savi apresentou o maior número de espécies (12), seguido de Macroptilium (Benth.) Urb. (5), Phaseolus L. (2) e Lablab Adans. (1), sendo os dois últimos gêneros representados apenas por espécies cultivadas. Segundo os critérios da IUCN, cinco espécies foram classificadas como ameaçadas. As espécies ocorrem nos mais diversos ambientes, desde restinga, estepe e cerrado até habitats úmidos, como margens de rios. O Paraná representa o limite sul de ocorrência no Brasil para três espécies. São fornecidos chaves de identificação, ilustrações, descrições e comentários taxonômicos, biogeográficos, sobre floração e frutificação.

Epistasis, phenotypic disequilibrium and contrasting associations with climate in the land snail Theba pisana.

Hotter conditions favour effectively unbanded (EUB) shells in the snail Theba pisana. T. pisana is also polymorphic for colour of the shell's apex, determined by a pair of alleles at a locus linked to the banding locus. Apex colour is epistatic to shell banding, such that banded snails with a dark apex have darker bands. Annual censuses over 22 years across an ecotone between a sheltered Acacia thicket and open dune vegetation showed a persistent association of both EUB shells and pale apex with the Open habitat. The parallel variation was due partly to strong phenotypic disequilibrium, as the combination of EUB with dark apex was rare. Nevertheless, in fully banded shells the frequency of pale apex was also higher in the Open habitat, confirming independent, parallel associations of the two contributors to paleness. Within the Acacia habitat, temporal variation of the frequencies of banding morphs was much greater than for apex colour, and EUB shells were associated with hotter summers. Consistent with its primary effect only on the very small snails, apex colour did not vary with summer conditions, but instead, higher frequencies of pale apices were associated with sunnier winters. The intensity of selection was lower on apex colour than shell banding, due partly to the constraint of phenotypic disequilibrium. The shell traits in T. pisana are an example of complex responses to climatic variation, in which phenotypic disequilibrium constrains evolution of apex colour, but separate mechanisms of selection are evident.

Patterns in Species Diversity during Succession of Coastal Dunes

The humped-back relationship in species diversity during succession was tested using vegetation in a coastal sand dune system of the German Wadden Sea island of Spiekeroog. Permanent plots were studied over 15 years along a spatial chronosequence from young grey dunes to old brown dunes. Species diversity, succession rate, and environmental indicator value were used to evaluate multitemporal dynamics of the ecosystem. Long-term development of the dune vegetation was reflected along the chronosequence, whereas fluctuations of plant communities were analyzed by short-term changes of each permanent plot. The study confirmed the intermediate stress theory, whereas highest species diversity was reached at the transition zone of the environmental gradients. Total species richness showed humped-back relations along the xerosere. Hotspots in species diversity varied with the life form group. Highest richness of herbaceous plants was reached in semidynamic young grey dunes, whereas highest richness of bryophytes and lichens shifted due to competition effects to the driest parts of the dune gradient in older successional stages. Moreover, the study confirmed the biodiversity-stability theory, with highest ecosystem stability at highest diversity. More stable environments showed lower succession rates than dynamic, disturbed environments. Thus, during secondary succession with probably repeated disturbance, the succession rate was higher and no clear direction of vegetation development was found in comparison to primary succession. The succession rate in a primary series represented a unimodal relation with total species richness. Thus, species-poor vegetation often dominated by one species, such as heathlands, as well as species-rich vegetation, showed lowest succession rates. These communities probably are more stable due to a balanced species combination represented by higher evenness.

Groundwater sources in a permeable coastal barrier: Evidence from stable isotopes

This paper presents isotopic composition (δ18O, δ2H) of groundwater, lagoon water, and seawater collected in a coastal lagoon system in Southern Brazil as a tool to define groundwater sources within a permeable barrier that separates the lagoon from the ocean. The isotopic signature of the barrier groundwater differs both from the isotopic composition of lagoon water and seawater. The groundwater is significantly lighter, indicating that the major recharge source to the barrier is precipitation, rather than lagoon water. In the southern and central part of the barrier no interaction of groundwater with lagoon water was observed. In the northern part, however, lagoon water intrusion into the barrier was identified. This effect is apparently caused by different vegetation types on the barrier influencing subsurface hydrological processes. The central and the southern areas are characterised by natural dune vegetation (high infiltration, low evapotranspiration rates) whereas the northern part is covered by extensive pine tree plantations (low infiltration, high evapotranspiration rates). The presence of pine trees may enhance lagoon and seawater intrusion into the shallow aquifer and decrease fresh submarine groundwater discharge.

A phytosociological and phytogeographical survey of the coastal vegetation of western North America: beach and dune vegetation from Baja California to Alaska

AbstractQuestions: What is the floristic composition of the plant communities that inhabit the beaches and dunes of the Pacific coast of North America? What are their ecological relationships in the zonal and successional gradients typical of coastal dune systems? Does climate affect the latitudinal distribution of the azonal vegetation? What other environmental factors influence their distribution on the regional or local scale?Location: Pacific coast of North America, from Baja California (23°02′ N) to Cook Inlet, Alaska (61°30′ N).Methods: A total of 1730 phytosociological relevés were obtained by sampling 279 coastal localities. In all localities, zonation was interpreted by considering transects from the shoreline inland. Through traditional phytosociological tabular classification and average linkage clustering, relevés were syntaxonomically classified. Syntaxa, supported by fidelity calculations, are described and interpreted according to their phytogeographical distribution, their relationships with macrobioclimate (MB) and bioclimates (BIO), and to the topographic and ecological gradients typical of coastal sandy areas.Results: Our bioclimate analysis served to define four MB and 11 BIO, each characterized by a particular type of potential natural vegetation. By floristically analysing the 522 vascular taxa detected, these were related to 16 phytogeographical elements. Syntaxonomically, the communities observed comprise 74 vegetation types, 70 of which are considered associations characterized by their diagnostic combination of species. These associations were classified into 24 alliances, 16 orders and 12 phytosociological classes. Two new classes, five new orders, 10 new alliances and 34 new associations are presented. Some syntaxa have been revised or validated.Conclusions: The coastal vegetation of the northern Pacific shows a distribution that is mainly linked to the four MB of the latitudinal gradient examined. Higher syntaxa are preferentially linked to a macrobioclimate, although some edaphic factors determine that some occupy two different but geographically close bioclimate zones. Regional factors, such as alkaline sands, induce the appearance of specialized vegetation types rich in endemic plants.

Nematodes surfing the waves: long‐distance dispersal of soil‐borne microfauna via sea swept rhizomes

Dispersal mechanisms of soil‐borne microfauna have hitherto received little attention. Understanding dispersal mechanisms of these species is important to unravel their basic life history traits, biogeography, exchange of individuals between populations, and local adaptation. Soil‐borne nematodes and root‐feeding nematodes in particular occupy a key position in soil‐food webs and can be determinants for plant growth and vegetation structure and succession. However, their dispersal abilities have been scarcely addressed, predominantly focusing on species of agricultural importance. Still, root‐feeding nematodes are usually considered as being extremely limited and bound to the rhizosphere of plants. We investigated a mechanism for long distance dispersal of root‐feeding nematodes associated to two widespread coastal dune grasses. The nematodes are known to be crucial for the functioning of these grasses. We experimentally tested the hypothesis that root‐feeding nematodes are able to move across long distances inside rhizome fragments that are dispersed by seawater. We also tested the survival capacities of the host plants in seawater. Our study demonstrates that root‐feeding nematodes and plants are able to survive immersion in seawater, providing a mechanism for long distance dispersal of root feeding nematodes together with their host plant. Drifting rhizome fragments enable the exchange of plant material and animals between dune systems. These results provide new insights to understand the ecology of dune vegetation, the interaction with soil‐borne organisms and more importantly, re‐set the scale of spatial dynamics of a group of organisms considered extremely constrained in its dispersal capacities.

Temporal and spatial changes in plant dune diversity in urban resorts

We investigated the temporal and spatial changes in the floristic composition and abundance in sand dunes along a coastal strip in the province of Buenos Aires (Argentina). Firstly, we analysed changes over a span of 70 years, comparing 41 of our own inventories carried out in 14 beach resorts in 2005–2006 with 18 inventories made in the first half of the XXth century (1930–1940) in the same study area. We grouped sampled plots into four categories for comparison, taking into account the time period (1930–1940 or 2005–2006) and location at each end of the surveyed coastal strip in the northern or southern ‘tourist’ sectors. Secondly, we analysed the effect of afforestation with exotic trees on extant sand dune vegetation for the period 2005–2006. A total of 74 plant inventories were carried out in afforested and natural dunes at the same resorts. In both comparisons we contrasted plant richness, percentage plant cover, similarity and diversity. A cluster analysis was used to classify categories taking into account plant abundance and composition. Significant differences in total diversity were observed between sampling years, suggesting an increase in diversity at the present time due to urbanization and recreation related activities. Nevertheless, no single exotic plant species was clearly dominant across the sampled sites, suggesting that these coastal areas are, up to now, resistant to alien invasion. Diversity indexes discriminated by plant groups indicating different habitat conditions and exotics were shown to be more sensitive to existing changes than to total richness and cover.

The classification and assessment of vegetation for monitoring coastal sand dune succession: the case of Tuzla in Adana, Turkey

This study aimed to provide an assessment of coastal sand dune vegetation through a number of analyses meant to provide a better understanding of the structure of plant communities and the successional stages of coastal sand dunes in a human-induced coastal landscape, the Seyhan Delta in southern Turkey. Therefore, as a baseline data inventory for monitoring, succession and the community-based classification of sand dune vegetation and human impacts were the major concerns of this study. The zonation of coastal sand dune vegetation was also determined within this scope, providing a contemporary assessment of different successional stages. A total of 96 taxa were recorded in 103 sampling relevés, which were randomly placed along 2 replicated transects perpendicular to the coastline. Multivariate classification techniques (TWINSPAN and DECORANA) were employed to classify sand dune vegetation into groups corresponding to different successional stages and to determine the response of plant community structures to human influence. Multivariate analysis resulted in a clear demonstration of 7 floristically distinct community groups associated with 4 main geomorphologic units. These plant communities were matched to the European Nature Information System (EUNIS) habitat classification. The results of this study provided a baseline data inventory covering plant communities and successional stages that demonstrated the current state of the coastal dunes in the study area.

Determinants of beta diversity of spiders in coastal dunes along a gradient of mediterraneity

AbstractAim The Mediterranean Basin is recognized for its high levels of species richness, rarity and endemicity. Our main aim was to evaluate the relative effects of environmental and spatial variables and their scale‐specific importance on beta diversity patterns along a gradient of mediterraneity, using spiders as a model group.Location This study was carried out in 18 coastal dune sites along the Portuguese Atlantic coast. This area encompasses 445 km and comprises two distinct biogeographic regions, Eurosiberian (northern coast) and Mediterranean (centre and south).Methods A forward selection procedure was carried out to select environmental and spatial variables responsible for determining beta diversity patterns. Variation partitioning and principal coordinates of neighbour matrices (PCNM) were used to estimate the contribution of pure environmental and pure spatial effects and their shared influence on beta diversity patterns and to estimate the relative importance of environmental structured variation and pure spatial variation at multiple spatial scales.Results Climate, ground vegetation dune cover and area were selected by a forward selection procedure. The same procedure identified three PCNM variables, all corresponding to large and medium spatial scales. Variation partitioning revealed that 46.1% of the variation of beta diversity patterns was explained by a combination of environmental and PCNM variables. Most of this variation (42.5%) corresponded to spatial variation (environmental spatially structured and pure spatial). Climate and vegetation structure influences were predominant at the PCNM1 and PCNM3 scales, while area was more important at the intermediate PCNM2 scale.Main conclusions Our study revealed that beta diversity of spiders was primarily controlled by a broad‐scale gradient of mediterraneity. The relative importance of environmental variables on the spider assemblage composition varied with spatial scale. This study highlights the need of considering the scale‐specific influence of niche and neutral processes on beta diversity patterns.

Geographic and Temporal Variations in Population Dynamics ofIxodes ricinusand AssociatedBorreliaInfections in The Netherlands

In a countrywide investigation of the ecological factors that contribute to Lyme borreliosis risk, a longitudinal study on population dynamics of the sheep tick Ixodes ricinus and their infections with Borrelia burgdorferi sensu lato (s.l.) was undertaken at 24 sites in The Netherlands from July 2006 to December 2007. Study sites were mature forests, dune vegetations, or new forests on land reclaimed from the sea. Ticks were sampled monthly and nymphal ticks were investigated for the presence of Borrelia spp. I. ricinus was the only tick species found. Ticks were found in all sites, but with significant spatial and temporal variations in density between sites. Peak densities were found in July and August, with lowest tick numbers collected in December and January. In some sites, questing activities of I. ricinus nymphs and adults were observed in the winter months. Mean monthly Borrelia infections in nymphs varied from 0% to 29.0% (range: 0%-60%), and several sites had significantly higher mean nymphal Borrelia infections than others. Four genospecies of Borrelia burgdorferi s.l. were found, with B. afzelii being dominant at most sites. Borrelia infection rates in nymphal ticks collected in July, September, and November 2006 were significantly higher (23.7%, p<0.01) than those in the corresponding months of 2007 (9.9%). The diversity in Borrelia genospecies between sites was significantly different (p<0.001). Habitat structure (tree cover) was an effective discriminant parameter in the determination of Borrelia infection risk, as measured by the proportion of nymphal ticks infected with B. burgdorferi s.l. Thickness of the litter layer and moss cover were positively related to nymphal and adult tick densities. The study shows that Borrelia-infected ticks are present in many forest and dune areas in The Netherlands and suggests that in such biotopes, which are used for a wide variety of recreational activities, the infection risk is high.