Coastal Dune Ecosystem Research Articles

Effects of wind erosion and sand burial on growth and reproduction of a clonal shrub

Sand burial and wind erosion are two of the most severe stresses for plants in arid areas. Performance of herbaceous plants after burial has been extensively studied in inland and coastal dune ecosystems. However, studies of how clonal shrubs withstand these disturbances remain relatively scarce. Here, we tested the hypothesis that sand burial has negative effects and moderate erosion has positive effects on a clonal shrub, and maintaining rhizome connections helps plants tolerate both burial and erosion. One hundred eight 2m×2m plots of Calligonum arborescens were established on an inland dune in the Badain Jaran Desert in northwestern China. Rhizomes at the edges of 54 (half) plots were severed to mimic the loss of rhizome connections. The top 15 or 30cm of sand was removed for 2.5 or 5 months to simulate short- and long-term moderate and severe erosion, respectively. Addition of 5, 10, 20, or 40cm layers of sand simulated sand burial. Untreated plots were used as controls. Both sand burial and wind erosion had significant effects on the growth and regeneration of C. arborescens. The number of ramets and biomass production decreased with increased burial depth and with severe erosion, but increased in moderate erosion treatments. Rhizome connections greatly increased ramet number and biomass production under both sand burial and severe erosion treatments. We concluded that both sand burial and severe erosion had negative effects on the clonal growth of C. arborescens, but that moderate wind erosion had positive effects. Rhizome connections alleviated the negative effects of sand burial and of severe erosion on the growth and performance of C. arborescens.

Starmera pilosocereana sp. nov., a yeast isolated from necrotic tissue of cacti in a sandy coastal dune ecosystem.

Two strains of a novel cactophilic yeast species were isolated from the columnar cactus Pilosocereus arrabidae in a sand dune ecosystem in Rio de Janeiro, Brazil. Phylogenetic analysis of sequences of the large subunit rRNA gene D1/D2 domains showed that the strains represent a sister species to Starmera caribaea, from which it differs by 21 nt substitutions and two indels. The novel species is heterothallic and the asci are deliquescent with the formation of two to four hat-shaped ascospores. The name Starmera pilosocereana sp. nov. is proposed for the species. The type strain is UFMG-CM-Y316T ( = CBS 13266T) and the allotype is UFMG-CM-Y346a ( = CBS 13265). The Mycobank number is MB 810683. In addition, Candida stellimalicola belonging to the Starmera clade, is reassigned to Starmera as a new combination.

Comprehensive sampling of an isolated dune system demonstrates clear patterns in soil fungal communities across a successional gradient

Coastal sand dunes are extremely dynamic ecosystems, characterized by stark ecological succession gradients. Dune stabilization is mainly attributed to plant growth, but the establishment and survival of dune-inhabiting vegetation is closely linked to soil microorganisms and to the ecological functions they fulfill. Fungi are particularly important in this context, as some interact intimately with plant roots, while others are critical to soil structure and nutrient availability. Our study aimed to describe wholly fungal diversity and community composition in a secluded coastal dune ecosystem at eight different stages of succession. We comprehensively sampled a relic foredune plain, which is part of an archipelago in the Gulf of Saint Lawrence (Québec, Canada), by collecting soils from 80 sites and measuring soil characteristics. Soil fungal communities were characterized by pyrosequencing, followed by taxonomic classification and assignment of putative roles. Even though we did not observe clear patterns in diversity, we were able to detect distinct taxonomic and community composition signatures across succession stages, which seemed to translate into variations in fungal life strategies. Our results show that a taxonomically and functionally diverse fungal community exists at each dune succession stage, even in the barren foredunes.

A coastal sand dune in New Zealand reveals high arbuscular mycorrhizal fungal diversity

Arbuscular mycorrhizal fungi (AMF) are components of coastal dune ecosystems around the globe where they provide a range of benefits to plants. The diversity and structure of AMF communities within these ecosystems, however, are poorly known. This study presents the first report of an AMF community in a New Zealand dune. Root samples were collected from the grass Spinifex sericeus R. Br., which dominates dunes of the North Island of New Zealand, along a 90 m transect at Anawhata Beach. Spores were also collected from here. The AMF community within the roots was surveyed using 454 sequencing of the SSU gene region. Spores were identified by their morphology, and sequenced. The 22 operational taxonomic units recognised following the high throughput sequencing formed a phylogenetically diverse community, including at least 7 genera across the Glomerales and Diversisporales, with an additional genus detected by the spore investigation. Some root and spore derived sequences generated close BLAST matches to AMF from distant countries while others represent previously unknown biodiversity. Spore morphology also suggests undescribed AMF are present. High diversity was found within the genera Rhizophagus and Racocetra, and within a clade with no matches to a described genus. Spatial heterogeneity was observed, with taxonomic composition changing over distances of only 30 m.

Early successional microhabitats allow the persistence of endangered plants in coastal sand dunes.

Many species are adapted to disturbance and occur within dynamic, mosaic landscapes that contain early and late successional microhabitats. Human modification of disturbance regimes alters the availability of microhabitats and may affect the viability of species in these ecosystems. Because restoring historical disturbance regimes is typically expensive and requires action at large spatial scales, such restoration projects must be justified by linking the persistence of species with successional microhabitats. Coastal sand dune ecosystems worldwide are characterized by their endemic biodiversity and frequent disturbance. Dune-stabilizing invasive plants alter successional dynamics and may threaten species in these ecosystems. We examined the distribution and population dynamics of two federally endangered plant species, the annual Layia carnosa and the perennial Lupinus tidestromii, within a dune ecosystem in northern California, USA. We parameterized a matrix population model for L. tidestromii and examined the magnitude by which the successional stage of the habitat (early or late) influenced population dynamics. Both species had higher frequencies and L. tidestromii had higher frequency of seedlings in early successional habitats. Lupinus tidestromii plants in early successional microhabitats had higher projected rates of population growth than those associated with stabilized, late successional habitats, due primarily to higher rates of recruitment in early successional microhabitats. These results support the idea that restoration of disturbance is critical in historically dynamic landscapes. Our results suggest that large-scale restorations are necessary to allow persistence of the endemic plant species that characterize these ecosystems.

Effect of an invasive plant and moonlight on rodent foraging behavior in a coastal dune ecosystem.

Understanding how invasive plants may alter predator avoidance behaviors is important for granivorous rodents because their foraging can trigger ripple effects in trophic webs. Previous research has shown that European beach grass Ammophila arenaria, an invasive species in coastal California, affects the predation of other seeds by the rodents Microtus californicus, Peromyscus maniculatus, and Reithrodontomys megalotis. This may be due to lower perceived predation risk by rodents foraging in close proximity to the cover provided by Ammophila, but this mechanism has not yet been tested. We examined the perceived predation risk of rodents by measuring the ‘giving up density’ of food left behind in experimental patches of food in areas with and without abundant cover from Ammophila and under varying amount of moonlight. We found strong evidence that giving up density was lower in the thick uniform vegetation on Ammophila-dominated habitat than it was in the more sparsely and diversely vegetated restored habitat. There was also evidence that moonlight affected giving up density and that it mediated the effects of habitat, although with our design we were unable to distinguish the effects of lunar illumination and moon phase. Our findings illustrate that foraging rodents, well known to be risk-averse during moonlit nights, are also affected by the presence of an invasive plant. This result has implications for granivory and perhaps plant demography in invaded and restored coastal habitats. Future research in this system should work to unravel the complex trophic links formed by a non-native invasive plant (i.e., Ammophila) providing cover favored by native rodents, which likely forage on and potentially limit the recruitment of native and non-native plants, some of which have ecosystem consequences of their own.

Microsatellite marker development for the coastal dune shrub Prunus maritima (Rosaceae).

• Premise of the study: Microsatellite primers were developed in the beach plum, Prunus maritima, to investigate the genetic composition of remaining populations in need of conservation and, in future studies, to determine its relation to P. maritima var. gravesii.• Methods and Results: Fourteen primer pairs were identified and tested in four populations throughout the species’ geographic range. Of these 14 loci, 12 were shown to be polymorphic among a total of 60 P. maritima individuals sampled (15 individuals sampled from four populations). Among the polymorphic loci, the number of alleles ranged from two to 10 and observed heterozygosity of loci ranged from 0.07 to 0.93 among specimens tested.• Conclusions: These microsatellites will be useful in evaluating the population genetic composition of P. maritima and in developing approaches for further conservation and management of this species within the endangered coastal dune ecosystem of the northeastern United States.

Field Spectroscopy in the VNIR-SWIR Region to Discriminate between Mediterranean Native Plants and Exotic-Invasive Shrubs Based on Leaf Tannin Content

The invasive shrub, Acacia longifolia, native to southeastern Australia, has a negative impact on vegetation and ecosystem functioning in Portuguese dune ecosystems. In order to spectrally discriminate A. longifolia from other non-native and native species, we developed a classification model based on leaf reflectance spectra (350–2500 nm) and condensed leaf tannin content. High variation of leaf tannin content is common for Mediterranean shrub and tree species, in particular between N-fixing and non-N-fixing species, as well as within the genus, Acacia. However, variation in leaf tannin content has not been studied in coastal dune ecosystems in southwest Portugal. We hypothesized that condensed tannin concentration varies significantly across species, further allowing for distinguishing invasive, nitrogen-fixing A. longifolia from other vegetation based on leaf spectral reflectance data. Spectral field measurements were carried out using an ASD FieldSpec FR spectroradiometer attached to an ASD leaf clip in order to collect 750 in situ leaf reflectance spectra of seven frequent plant species at three study sites in southwest Portugal. We applied partial least squares (PLS) regression to predict the obtained leaf reflectance spectra of A. longifolia individuals to their corresponding tannin concentration. A. longifolia had the lowest tannin concentration of all investigated species. Four wavelength regions (675–710 nm, 1060–1170 nm, 1360–1450 nm and 1630–1740 nm) were identified as being highly correlated with tannin concentration. A spectra-based classification model of the different plant species was calculated using a principal component analysis-linear discriminant analysis (PCA-LDA). The best prediction of A. longifolia was achieved by using wavelength regions between 1360–1450 nm and 1630–1740 nm, resulting in a user’s accuracy of 98.9%. In comparison, selecting the entire wavelength range, the best user accuracy only reached 86.5% for A. longifolia individuals.

Habitat Preference and Effects of Coastal Fragmentation in the Sand-Dwelling Spider <i>Allocosa brasiliensis</i> (Lycosidae, Allocosinae)

Allocosa brasiliensis is a sand-dwelling wolf spider considered a good bioindicator to evaluate the quality of coastal dune ecosystems from Uruguay. Habitat fragmentation and human activities have impacted and reduced the Southern Uruguayan coast during the last decades. The aim of the present study was to evaluate the density, surface activity and habitat preference of A. brasiliensis in beaches with different human impact. For that purpose, we sampled during the night with head lamps and applied the capture-mark-recapture method. Females were more abundant than males and were the most recaptured sex. The most fragmented beaches showed lower number of burrows and individuals, especially in immatures stages. We found that the most suitable sandy habitat for A. brasiliensis should present a vegetation cover optimum of 25% - 50% of the surface. This study could provide tools for the implementation of future management conservation plans of the Southern Uruguayan coastline.

Ant community structure and response to disturbances on coastal dunes of Gulf of Mexico

Coastal dunes are complex and fragile ecosystems. The decrease in environmental stressors from sea to inland creates zonation patterns of habitats, which support high biodiversity. Although coastal dunes have been examined in primary succession studies for more than 100 years, invertebrates have received much less attention than other taxa. In this study, we examined ant community composition and its relationship with vegetation structure on dunes, and used ants as indicators to reveal the influence of anthropogenic disturbances on these habitats. Quadrat sampling, hand collecting, and beating plants were used to sample ants on coastal dunes fringing the northern Gulf of Mexico. Ants representing 44 species were found, with diversity and number of functional groups increasing from foredunes to backdunes. Bush areas of the backdunes supported a unique ant community. Ant diversity was correlated with plant richness, stem number, and plant cover, but the correlation was not consistent among habitats. Ant diversity was lower in degraded, young-planted, and re-built but not in old-planted sites. In addition, different types of disturbance changed the ant community and functional groups in different ways. Our study emphasizes the importance of protecting the whole dune system, especially the backdunes, which support high diversity but are often completely destroyed by urban development. Data from this research provides a benchmark to examine trajectories of coastal dune ecosystem degradation or recovery when exposed to natural or anthropogenic disturbances.

Biological Control of Sheath Blight of Rice using Marine Associated Fluorescent pseudomonads

Rice, the crop that gives staple food for India, is being severely affected by several diseases and insect pests. Of these “Sheath Blight” (ShB) disease is one of the economically significant disease that gains serious concern. It is one of the most destructive fungal diseases of rice caused by Rhioctonia solani. It recorded a very high yield loss. Biological control is an efficient disease management strategy. Several microorganisms belong to the genera Bacillus, Pseudomonas, Streptomyces etc are used as “Biological Control Agents” (BCAs) for the management of sheath blight disease in rice. In this scenario, the present work has been aimed to isolate antagonistic rhizobacteria from the least explored coastal sand dune ecosystem, characterize their biological control potential for the suppression of ShB pathogen R. solani and evaluate them in vivo. A total of 46 rhizobacterial strains were isolated from the root hairs of sand dune plant samples using Kings B Agar (KBA) medium. The isolated strains were screened for their antagonist activity against R. solani by using dual culture assay on Potato Dextrose Agar (PDA) medium. About 10 strains were found to have higher in vitro antifungal activity against R. solani i.e., they exhibited zone of inhibition around them. These 10 strains were evaluated for their biocontrol potential in suppressing sheath blight disease in rice using detached leaf bits assay. Five marine associated fluorescent pseudomonad strains such as AMET1102, AMET1104, AMET1133, AMET1133 and AMET1140 have noticeably reduced the ShD incidence in rice leaves.

Competitive effect of a native-invasive species on a threatened shrub in a Mediterranean dune system.

The canopy shade of the Retama species has been widely reported to ameliorate the environmental conditions in the understory, thus facilitating other species' establishment. The shading effect of the native-invasive leguminous shrub Retama monosperma (L.) Boiss on the endangered Thymus carnosus Boiss was analysed to determine a positive or negative net effect. Data was taken in all four seasons, representing contrasting light and water availability in a Mediterranean coastal dune ecosystem (SW Spain). The morphological and physiological status of sun-exposed T. carnosus plants growing in open areas versus shaded plants growing under R. monosperma were measured seasonally. Leaf mass area, leaf area index and pigment content showed typical sun-shade responses. In contrast, sun-exposed T. carnosus displayed higher stem water potential, transpiration rate and water use efficiency, both intrinsic and integrated, denoting low tolerance to the presence of R. monosperma. Five years after the measurements, canopy cover had decreased and mortality was higher in shaded plants, thus confirming the competitive effect of R. monosperma on T. carnosus. R. monosperma arises as a competitor for endangered T. carnosus communities, consequently reinforcing its invasive behaviour. This species-specific shrub study demonstrates that eventual beneficial effects of Retama canopy may be overridden by competition in the understory, particularly in the case of species well-adapted to high light and low water levels.

Transplanting native woody legumes: a suitable option for the revegetation of coastal dunes

Acacia longifolia is an invasive woody legume in many coastal sand dunes ecosystems around the world. A useful option to aid in the restoration of invaded areas after acacia removal is the revegetation of the newly open areas using appropriate native dune plants. A field experiment was performed to determine whether two shrubby legumes native to European Atlantic coastal dunes, Cytisus grandiflorus (Brot.) DC. and Ulex europaeus europaeus subsp. latebracteatus (Mariz) Rothm., are suitable to revegetate areas formerly invaded by A. longifolia. Plants of both species were grown for 5 months in a greenhouse and subsequently transplanted to three sites in a coastal dune ecosystem. We monitored survival and growth during 21 months. The effect of soil fertility at the nursery and of root nodulation on the performance of these species in the field was also analyzed. Soil fertility and nodulation had a significant effect on plant growth at the nursery, but only the symbiosis with root nodulating bacteria had a significant positive effect on the survival of both native legumes in the field and on final plant height of U. europaeus plants. We conclude that (1) both native legumes can successfully establish on sites where A. longifolia has been previously removed, thus providing a suitable tool to help in the restoration of invaded areas, and (2) the symbiosis with root nodulating bacteria is crucial for plant performance in the field.

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:

Mediterranean coastal dune systems: Which abiotic factors have the most influence on plant communities?

Mediterranean coastal dunes are dynamic and heterogeneous ecosystems characterised by a strong interaction between abiotic and biotic factors. The present study aimed to adopt a multidisciplinary approach - integrating data on dune morphology, sediment texture and soil parameters as well as shoreline trend - in order to define which are the abiotic factors that most affect the distribution and composition of Mediterranean plant dune communities. The study was carried out in two protected areas, located in central Italy, subjected to different shoreline trends in recent years. 75 plots were identified along eleven randomly positioned cross-shore transects, starting from the beach continuing up to the plant communities of the backdunes. In each plot floristic and environmental data - such as distance to the coastline, plot altitude, inclination, shoreline trend, mean grain-size, sorting, pH, conductivity and organic matter concentration - were collected. The analyses revealed significant changes of vegetational cover, dune morphology and geopedological features along the coast-to-inland gradient. Relationships between vegetation composition and environmental factors were investigated through Canonical Correspondence Analysis (CCA). Four factors - distance to the coastline, mean grain-size, shoreline trend and organic matter – were found to be closely correlated with the floristic composition of plant communities. Finally, soil properties were highlighted as the most determinant factors of community zonation in these Mediterranean coastal dune ecosystems. These results could be taken into account by local managers in conservation actions such as protecting the eroding foredunes as well as in artificial dune reconstructions.

Survival and Growth of Planted Uniola paniculata and Dune Building Using Surrogate Wrack on Perdido Key Florida, U.S.A.

AbstractThe increasing number of stresses on coastal dune ecosystems requires the use of more effective restoration strategies to enhance dune‐building and increase vegetation reestablishment. In this study, the use of a wheat straw as a surrogate wrack was an effective method to improve growth of spring planted Uniola paniculata (sea oats). Approximately 1,000 U. paniculata plugs were planted within 21 × 4 m plots at six replicate sites. Two weeks later, plantings were divided into 11 × 4 m subplots with half of the subplots receiving five bales of wheat straw and the remaining subplots receiving no wheat straw. This surrogate wrack layer measured approximately 10 cm in depth. Mean aboveground biomass of U. paniculata 6 months after planting with surrogate wrack was 9.25 ± 1.00 g compared with 2.18 ± 0.24 g without surrogate wrack. Number of tillers, tiller height, and basal width were also greater at the end of the first growing season for plants treated with surrogate wrack (p < 0.05). Two years after planting, significantly more inflorescences occurred and aboveground biomass (g/m2) was greater with than without surrogate wrack. Sand accumulation was notably greater with surrogate wrack (11.16 cm) than without wrack (7.78 cm) 8 months after planting (p = 0.1093). However, relative sand accumulation was significantly greater with than without surrogate wrack 2 years after planting. Increased sand accumulation suggests surrogate wrack either directly or indirectly traps more sand by creating an additional obstacle or promoting the growth of dune grasses.

Remotely Sensed Mapping of Ammophila spp. Distribution and Density at Cape Cod National Seashore

Timm, B.C.; Smith, S.M., and Greenspan, S.E., 2014. Remotely sensed mapping of Ammophila spp. distribution and density at Cape Cod National Seashore. Ammophila breviligulata and Ammophila arenaria are pioneer grass species that have been planted within and outside their natural ranges in efforts to stabilize mobile dune fields. While the presence of Ammophila spp. may be considered beneficial in some situations (e.g., for dune stabilization and storm surge protection), there are other cases where Ammophila spp. introductions have had negative ecological consequences (e.g., reduction in native plant and animal diversity, altered dune dynamics). Thus, it is important to be able to effectively map and monitor the distribution and density of these species. In this study, we constructed and assessed the accuracy of a fine-resolution (i.e. 1.0-m-pixel resolution) remote-sensing-based distribution and density map of Ammophila spp. throughout an extensive coastal dune ecosystem at Cape Cod National Seashore, United States. We achieved high classification accuracies for both the presence/absence and percent cover throughout our study area, indicating that this approach is an effective method to map and monitor Ammophila spp. in dune ecosystems.

The role of sediment grain-size, mineralogy, and beach morphology on plant communities of two Mediterranean coastal dune systems

Coastal dune ecosystems are characterized by a strong relationship between abiotic and biotic factors. The aim of the study is to identify the abiotic factors that mostly affect distribution and composition of plant dune communities along the coast-to-inland gradient, focusing the attention on sediment grain-size parameters, mineralogy, and dune morphology. The research was carried out on two coastal dune systems belonging to protected areas in the Mediterranean Basin, specifically in Northern and Southern Tuscany (Italy). Grain-size analysis, X-ray powder diffraction, topographic surveys, and floristic data recording were carried out along 11 transects perpendicular to the shoreline; the portion of the beach investigated is comprised within the foreshore and the backdune area. The analyses revealed some differences between the two coastal dune systems in terms of sediment parameters, mineralogy, and dune topography. The differences are mainly ascribed to the physical characteristics of the sites where the surveys were carried out. These data were matched with those provided by the vegetation sampling and then statistically processed by means of methods such as the Canonical Correlation Analysis (CCA), which showed that the mean grain-size is the most important abiotic factor that influences the composition of these coastal plant communities. These results might be considered to improve and optimize management and conservation programs for these ecosystems, since nowadays artificial dune reconstruction is a practice frequently used as a form of coastal protection.

The role of invasive pine on changes of plant composition and functional traits in a coastal dune ecosystem

ABSTRACT In this article we investigate how invasion by Pinus taeda L. alters plant community composition and functional traits in sand dunes. In invaded psammophilous vegetation in southern Brazil, we randomly selected 15 P . taeda individuals and measured their age based on the number of growth rings. For each tree, we sampled 1 m 2 quadrats beneath and 2 m away of its crown. In each quadrat, we assessed non-graminoid plant composition and performed a multivariate analysis of variance. Data on species’ functional traits were scaled up to community level, and their variations were compared to tree age by linear regression. Species’ composition and functional traits under P . taeda crown were different from control plots. Tree age affected the presence of thorns, potential height, and functional diversity. P. taeda individuals likely change the micro-habitat beneath their crowns, thereby benefiting species with some traits and increasing functional diversity of plants that are not characteristic of open dune communities. © 2014 Associacao Brasileira de Ciencia Ecologica e Conservacao. Published by Elsevier Editora Ltda.

Upland Movement Patterns and Habitat Selection of Adult Eastern Spadefoots (Scaphiopus holbrookii) at Cape Cod National Seashore

There is a paucity of empirical results regarding many aspects of the movement ecology and upland habitat use and preferences of the Eastern Spadefoot Toad (Scaphiopus holbrookii), an ephemeral, wetland-breeding anuran that is rare throughout a number of states in the northern portion of its range. We radio-tracked 45 adult Eastern Spadefoots in a coastal dune ecosystem at Cape Cod National Seashore, Massachusetts, United States and assessed a number of attributes related to the upland movement ecology and habitat preferences of this species. The mean maximum distance that we found for each of the 19 successfully tracked individuals, immediately post-breeding from the breeding wetlands, was 130.4 ± 28.0 m with a range of 3 – 449 m. Paired logistic regression results indicated that individuals selected areas closer to deciduous shrub edges and areas with greater percent cover of 1) ground-running pitch pine (Pinus rigida) branches at a 1-m scale, 2) deciduous shrubs at a 1-m scale, and 3) reindeer lichen (Cladonia sp.) at a 5-m scale compared to randomly selected locations. We recorded surface activity during 22/24 (∼91.7%) nocturnal survey nights and during 77/127 (∼60.6%) toad-nights; the presence of rainfall was the only significant predictor (positive) of surface activity. Our results provide an assessment of upland movement patterns and habitat preferences that will help guide the development and implementation of effective conservation and management strategies for this regionally rare species.