Journal articles: 'Dune patterns'

1

Gadal, C., C. Narteau, S. Courrech du Pont, O. Rozier, and P. Claudin. "Periodicity in fields of elongating dunes." Geology 48, no. 4 (2020): 343–47. http://dx.doi.org/10.1130/g46987.1.

Full text

Abstract:

Abstract Dune fields are commonly associated with periodic patterns that are among the most recognizable landscapes on Earth and other planetary bodies. However, in zones of limited sediment supply, where periodic dunes elongate and align in the direction of the resultant sand flux, there has been no attempt to explain the emergence of such a regular pattern. Here, we show, by means of numerical simulations, that the elongation growth mechanism does not produce a pattern with a specific wavelength. Periodic elongating dunes appear to be a juxtaposition of individual structures, the arrangement of which is due to regular landforms at the border of the field acting as boundary conditions. This includes, among others, dune patterns resulting from bed instability, or the crestline reorganization induced by dune migration. The wavelength selection in fields of elongating dunes therefore reflects the interdependence of dune patterns over the course of their evolution.

APA, Harvard, Vancouver, ISO, and other styles

2

Els, A., S. Merlo, and J. Knight. "Comparison of two Satellite Imaging Platforms for Evaluating Sand Dune Migration in the Ubari Sand Sea (Libyan Fazzan)." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL-7/W3 (April 30, 2015): 1375–80. http://dx.doi.org/10.5194/isprsarchives-xl-7-w3-1375-2015.

Full text

Abstract:

Sand dunes can change location, form or dimensions depending on wind direction and strength. Sand dune movements can be effectively monitored through the comparison of multi-temporal satellite images. However, not all remote sensing platforms are suitable to study sand dunes. This study compares coarse (Landsat) and fine (Worldview) resolution platforms, specifically focussing on sand dunes within the Ubari Sand Sea (Libya). Sand dune features (crest line, dune ridge basal outlines) were extracted from Landsat and Worldview 2 imagery in order to construct geomorphic maps. These geomorphic maps were then compared using image overlay and differencing, and the Root Mean Squared Error (RMSE) was used to determine if the mapped dune patterns were significantly different. It was found that Landsat is a sufficient data source when studying dune patterns within a regional sand sea, but smaller dunes identified from Worldview data were not capable of being extracted in the data sourced from Landsat. This means that for studies concerned with the dune patterns and movements within sand seas, Landsat is sufficient. But in studies where the specific dynamics of specific dunes are required, a finer resolution is required; platforms such as Worldview are needed in order to gain more detailed insight and to link the past and present day climate and environmental change.

APA, Harvard, Vancouver, ISO, and other styles

3

Bar Kutiel, Pua, and Michael Dorman. "The Importance of Annual Plants and Multi-Scalar Analysis for Understanding Coastal Dune Stabilization Process in the Mediterranean." Applied Sciences 11, no. 6 (2021): 2821. http://dx.doi.org/10.3390/app11062821.

Full text

Abstract:

Since ecological phenomena and patterns vary with scale, scalar analysis is a developing practice in ecology. Scalar analysis is most valuable in heterogeneous environments, since habitat heterogeneity is a key factor in determining biodiversity. One such case can be seen in the changes in annual vegetation in coastal sand dune systems. Most studies in these environments are carried out at the dune scale, comparing dunes at different stabilization states. However, a broader understanding of dune stabilization processes requires analyses at the finer scales of dune slope aspects (directions of exposure to wind) and patches (under and between woody perennial species). Here, we present the results of a study that combines the three scales (dune, slope, and patch) in the Mediterranean coastal dune systems in Israel. Through this multi-scalar analysis, we are able to describe processes at the finer patch and aspect scale and explain how they shape patterns at the dune scale. The results indicate that the dune scale exposes the differences in annual plant characteristics between mobile and fixed dunes, their slopes and patches and the reorganization and spatial distribution of annual plants within mobile and fixed dunes during the stabilization process.

APA, Harvard, Vancouver, ISO, and other styles

4

Lü, Ping, Clément Narteau, Zhibao Dong, et al. "Direct validation of dune instability theory." Proceedings of the National Academy of Sciences 118, no. 17 (2021): e2024105118. http://dx.doi.org/10.1073/pnas.2024105118.

Full text

Abstract:

Modern dune fields are valuable sources of information for the large-scale analysis of terrestrial and planetary environments and atmospheres, but their study relies on understanding the small-scale dynamics that constantly generate new dunes and reshape older ones. Here, we designed a landscape-scale experiment at the edge of the Gobi desert, China, to quantify the development of incipient dunes under the natural action of winds. High-resolution topographic data documenting 42 mo of bedform dynamics are examined to provide a spectral analysis of dune pattern formation. We identified two successive phases in the process of dune growth, from the initial flat sand bed to a meter-high periodic pattern. We focus on the initial phase, when the linear regime of dune instability applies, and measure the growth rate of dunes of different wavelengths. We identify the existence of a maximum growth rate, which readily explains the mechanism by which dunes select their size, leading to the prevalence of a 15-m wavelength pattern. We quantitatively compare our experimental results with the prediction of the dune instability theory using transport and flow parameters independently measured in the field. The remarkable agreement between theory and observations demonstrates that the linear regime of dune growth is permanently expressed on low-amplitude bed topography, before larger regular patterns and slip faces eventually emerge. Our experiment underpins existing theoretical models for the early development of eolian dunes, which can now be used to provide reliable insights into atmospheric and surface processes on Earth and other planetary bodies.

APA, Harvard, Vancouver, ISO, and other styles

5

Poppema, Daan, Kathelijne Wijnberg, Jan Mulder, and Suzanne Hulscher. "THE EFFECT OF BUILDING GEOMETRY ON AEOLIAN DEPOSITION AND EROSION PATTERNS: A FIELD EXPERIMENT." Coastal Engineering Proceedings, no. 36v (December 28, 2020): 21. http://dx.doi.org/10.9753/icce.v36v.sediment.21.

Full text

Abstract:

Buildings at the beach-dune interface, such as restaurants and (holiday) houses, affect wind-driven sand transport in their surroundings. Hereby they shape the development of the beach-dune system. This can have implications for the flood protection offered by dunes. Therefore, this research aims to understand the effect of buildings at the beach-dune interface on beach-dune morphology. In this contribution we present the results of a field experiment which focused on the effect of building size and geometry on the size and location of the deposition patterns directly around buildings.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/hlcMP7Ev1m0

APA, Harvard, Vancouver, ISO, and other styles

6

McArthur, E., and Stewart Sanderson. "Great Sand Dunes National Monument Vegetation Patterns." UW National Parks Service Research Station Annual Reports 15 (January 1, 1991): 185–89. http://dx.doi.org/10.13001/uwnpsrc.1991.3019.

Full text

Abstract:

This project is designed to chacterize and map the vegetation of the Great Sand Dunes National Monument, Colorado (GSDNM) and to determine if the vegetated areas in the dune field are permanent, temporary, or migratory. It is not known if the vegetation around the dunes is encroaching on the dunes, being replaced by the dunes or is stable. There are also concerns about the possible effect a proposed water export project adjacent to GSDNM would have on the dunes and their vegetation.

APA, Harvard, Vancouver, ISO, and other styles

7

Honrado, J., J. Vicente, A. Lomba, et al. "Fine-scale patterns of vegetation assembly in the monitoring of changes in coastal sand-dune landscapes." Web Ecology 10, no. 1 (2010): 1–14. http://dx.doi.org/10.5194/we-10-1-2010.

Full text

Abstract:

Abstract. Understanding dune ecosystem responses to multi-scale environmental changes can provide the framework for reliable forecasts and cost-efficient protocols for detecting shifts in prevailing coastal dynamics. Based on the hypothesis that stress and disturbance interact as primary community controls in coastal dunes, we studied the fine-scale floristic assembly of foredune vegetation, in its relation to topography, along regional and local environmental gradients in the 200 km long coastline of northern Portugal, encompassing a major biogeographic transition in western Europe. Thirty topographic profiles perpendicular to the shoreline were recorded at ten sites along the regional climate gradient, and vegetation was sampled by recording the frequency of plant species along those profiles. Quantitative topographic attributes of vegetated dune profiles (e.g. length or height) exhibited wide variations relatable to differences in prevailing coastal dynamics. Metrics of taxonomic diversity (e.g. total species richness and its additive beta component) and of the functional composition of vegetation were highly correlated to attributes of dune topography. Under transgressive dynamics, vegetation profiles have fewer species, increased dominance, lower turnover rates, and lower total vegetation cover. These changes may drive a decrease in structural and functional diversity, with important consequences for resistance, resilience and other ecosystem properties. Moreover, differences in both vegetation assembly (in meta-stable dunes) and response to increased disturbance (in eroding dunes) between distinct biogeographic contexts highlight a possible decline in facilitation efficiency under extreme physical stress (i.e. under Mediterranean climate) and support the significance of functional approaches in the study of local ecosystem responses to disturbance along regional gradients. Our results strongly suggest that assessing fine-scale community assembly can provide insights on the relation between dune vegetation, environmental filters and ecosystem processes. A combination of cost-efficient indicators from dune topography and vegetation is thus suggested as a promising approach to survey, forecast and monitor changes in coastal dune ecosystems.

APA, Harvard, Vancouver, ISO, and other styles

8

Bishop, Steven R., Hiroshi Momiji, Ricardo Carretero-González, and Andrew Warren. "Modelling desert dune fields based on discrete dynamics." Discrete Dynamics in Nature and Society 7, no. 1 (2002): 7–17. http://dx.doi.org/10.1080/10260220290013462.

Full text

Abstract:

A mathematical formulation is developed to model the dynamics of sand dunes. The physical processes display strong non-linearity that has been taken into account in the model. When assessing the success of such a model in capturing physical features we monitor morphology, dune growth, dune migration and spatial patterns within a dune field. Following recent advances, the proposed model is based on a discrete lattice dynamics approach with new features taken into account which reflect physically observed mechanisms.

APA, Harvard, Vancouver, ISO, and other styles

9

Carson, M. A., and P. A. MacLean. "Development of hybrid aeolian dunes: the William River dune field, northwest Saskatchewan, Canada." Canadian Journal of Earth Sciences 23, no. 12 (1986): 1974–90. http://dx.doi.org/10.1139/e86-183.

Full text

Abstract:

Observations have been made on the structure, morphology, and pattern of sand movement on large-scale, roughly elongate, northwest–southeast-aligned aeolian sand dunes in a desert area of northern Saskatchewan, Canada. Transverse profiles show steeper northeast flanks, the lower parts of which are covered with psammophilous grasses. Dune structure is dominated by northeast-dipping accretion laminae, and 14C dates of organic material trapped between such exposed laminae on the southwest flank indicate migration to the northeast at about 0.5 m/year in the last few centuries. On the other hand, there is a progressive increase in height, bulk, symmetry, and peakedness of the dunes from northwest to southeast, suggestive of substantial along-dune sand movement. The present-day wind regime shows a potential resultant sand-transport vector to the southeast, virtually parallel to the dune axis; winds from the north-northeast and northeast dominate the first 6 months of the year, followed by winds from the west-southwest in the latter half. Field evidence of airflow and sand-movement patterns upon the surfaces of two dunes also indicates a strong along-dune component. The dunes are interpreted as hybrid landforms reflecting both transverse and longitudinal processes acting at the present time. Of particular sedimentological significance is the discordance between dune stratigraphy and the wind regime. Dune structure is controlled by a southwest–northeast imbalance in sand movement assumed to result from an asymmetric distribution of sand-trapping vegetation and from a seasonal contrast in sand mobility that partly correlates with seasonality in the wind regime. Both factors promote northeast migration normal to the potential resultant of effective winds.

APA, Harvard, Vancouver, ISO, and other styles

10

Zorndt, Anna Christina, Andreas Wurpts, Torsten Schlurmann, Nino Ohle, and Thomas Strotmann. "DUNE MIGRATION AND SAND TRANSPORT RATES IN TIDAL ESTUARIES: THE EXAMPLE OF THE RIVER ELBE." Coastal Engineering Proceedings 1, no. 32 (2011): 38. http://dx.doi.org/10.9753/icce.v32.sediment.38.

Full text

Abstract:

Large parts of the tidal estuary of river Elbe (Germany) are characterized by regular patterns of sand dunes. They are presumed to evolve due to complex sand transport mechanisms and show multi-faceted migration patterns. Direction and magnitude of their migration are influenced by hydrodynamic boundary conditions such as river runoff and tides. Dune Migration can lead to residual sand transport rates, depending on its direction and magnitude and the dune’s characteristics. The understanding of dune migration patterns and associated sand transport is the basis of an effective sediment management as well as an important requirement for planning offshore structures. This study focuses on methods for computing migration and sand transport rates in automated ways. In a comparison and validation of different approaches, a cross-correlation technique was found to produce best results. From a unique data set of up to six annual bathymetrical multi-beam soundings between 1995 and 2010, dune characteristics and migration rates were processed and analysed autonomously. The findings show that in a long perspective, average dune migration and sand transport rates in the present study reach are directed upstream.

APA, Harvard, Vancouver, ISO, and other styles

11

Yang, Hui, Jiansheng Cao, and Xianglong Hou. "Characteristics of Aeolian Dune, Wind Regime and Sand Transport in Hobq Desert, China." Applied Sciences 9, no. 24 (2019): 5543. http://dx.doi.org/10.3390/app9245543.

Full text

Abstract:

A systematic study of the wind regime characteristics in a region can not only accurately grasp the dynamic factors of the development of aeolian geomorphology, but also provide a scientific basis for the prevention and treatment of regional sand disasters. Taking the Hobq Desert as the study area, the basic characteristics of dune are analyzed by using remote sensing images. Based on the annual meteorological data of six meteorological stations from 2009 to 2018, the spatial and temporal distribution characteristics of wind speed were obtained. With the daily wind data of three stations from 2009 to 2018, we have figured out the wind regime and sand transport characteristics of the Hobq Desert. The results show that the sand dune height of the Hobq Desert ranges large, the highest height is 5010 m and the lowest is 10 m. It decreases gradually from the west to the east. The height of dune mainly distributed below 1500 m, followed by 1500–2000 m. Migratory sand dunes in Hobq Desert accounts for 51.8% and is mainly distributed in the west of the desert. The distribution area of fixation sand dunes in Hobq Desert is the least, accounting for 8.3%. The migratory dune pattern is trellis dune, semimigrated dune and semifixed dune patterns include honeycomb dune, parabolic duneand brush dune, and fixation dune pattern is grass dune. Annual wind speed was greatest in the southeast and decreased moving to the northwest. The dominant wind direction was W and SW from 2009 to 2018 in the Hobq Desert, the average wind speed of the prevailing winds mainly distributed at 4–8 m/s. The frequency of wind speed exceeding 10 m/s is very low, with a maximum value of 10% or below. There is a low energy wind environment in the Hobq Desert, with intermediate annual directional variability and obtuse or acute bimodal wind regime. The resultant drift direction (RDD)at Dongsheng station was relatively constant from 2009 to 2018, it was about 350°. RDD differed significantly at Baotou and Linhestations were 181 ± 169° and 231 ± 121°, respectively.The relationship between drift potential (DP) and the average and maximum wind speed was expressed as a power function. DP was strongly correlated with them. There is no significant correlated between the temporal changes in DPandprecipitation and temperature from 2009 to 2018 in the Hobq Desert.

APA, Harvard, Vancouver, ISO, and other styles

12

Brodie, Katherine, Ian Conery, Nicholas Cohn, Nicholas Spore, and Margaret Palmsten. "Spatial Variability of Coastal Foredune Evolution, Part A: Timescales of Months to Years." Journal of Marine Science and Engineering 7, no. 5 (2019): 124. http://dx.doi.org/10.3390/jmse7050124.

Full text

Abstract:

Coastal foredunes are topographically high features that can reduce vulnerability to storm-related flooding hazards. While the dominant aeolian, hydrodynamic, and ecological processes leading to dune growth and erosion are fairly well-understood, predictive capabilities of spatial variations in dune evolution on management and engineering timescales (days to years) remain relatively poor. In this work, monthly high-resolution terrestrial lidar scans were used to quantify topographic and vegetation changes over a 2.5 year period along a micro-tidal intermediate beach and dune. Three-dimensional topographic changes to the coastal landscape were used to investigate the relative importance of environmental, ecological, and morphological factors in controlling spatial and temporal variability in foredune growth patterns at two 50 m alongshore stretches of coast. Despite being separated by only 700 m in the alongshore, the two sites evolved differently over the study period. The northern dune retreated landward and lost volume, whereas the southern dune prograded and vertically accreted. At the start of and throughout the study, the erosive site had steeper foredune faces with less overall vegetation coverage, and dune growth varied spatially and temporally within the site. Deposition occurred mainly at or behind the vegetated dune crest and primarily during periods with strong, oblique winds (>∼45 ∘ from shore normal). Minimal deposition was observed on the mostly bare-sand dune face, except where patchy vegetation was present. In contrast, the response of the accretive site was more spatially uniform, with growth focused on the heavily vegetated foredune face. The largest differences in dune response between the two sections of dunes occurred during the fall storm season, when each of the systems’ geomorphic and ecological properties modulated dune growth patterns. These findings highlight the complex eco-morphodynamic feedback controlling dune dynamics across a range of spatial scales.

APA, Harvard, Vancouver, ISO, and other styles

13

Ramsey, DSL, and RM Engeman. "Patterns of grazing on coastal dune systems by insular populations of two species of macropod." Wildlife Research 21, no. 1 (1994): 107. http://dx.doi.org/10.1071/wr9940107.

Full text

Abstract:

A study of grazing patterns on a coastal dune system on South Stradbroke Island, Queensland, by two species of wallaby was undertaken. Utilisation of sand spinifex (Spinifex sericeus) by agile wallabies (Macropus agilis) and swamp wallabies (Wallabia bicolor) was highly variable between different sites on the dune system. Although wallaby activity on secondary dune strata was significantly higher than on the primary dune, this was not reflected statistically in spinifex grazing levels. However, spinifex stolons on the toe of the primary dune were heavily grazed. Grazing levels on dune systems on the island were negatively associated with the width of the frontal dune and the relative area of open forest vegetation adjacent to the dune system.

APA, Harvard, Vancouver, ISO, and other styles

14

de Francesco, Maria Carla, Maria Laura Carranza, Marco Varricchione, Francesco Pio Tozzi, and Angela Stanisci. "Natural Protected Areas as Special Sentinels of Littering on Coastal Dune Vegetation." Sustainability 11, no. 19 (2019): 5446. http://dx.doi.org/10.3390/su11195446.

Full text

Abstract:

Beach litter threatens coastal dunes integrity across the world. European countries are committed to improving the environmental status of the marine and coastal environment by 2020, and to do this, they need to reduce the gap of knowledge about litter accumulation patterns in coastal environments. We analyzed the distribution pattern of waste, differentiated by material and origin, in the coastal dune vegetation mosaic along protected natural areas in the Adriatic seashore (central Italy). Litter data were collected following a random stratified procedure. We registered litter occurrence on 180 (2 × 2 m) sampling plots randomly distributed in the different habitats of European conservation concern mapped for the analyzed protected areas. Litter was classified by origin and material, and their abundance on different habitats was explored by multivariate ordination techniques and tested by nonparametric ANOVA followed by Mann-Whitney pairwise post-hoc tests. Most of the plots included at least one waste element being plastic. Plastic was the most abundant material, and fishing and touristic the most polluting activities. Waste distribution varies across coastal dune vegetation types and involves the back dune zone too. Our results stress the need for (a) specific cleaning tasks able to preserve the ecological value of coastal dune habitats and (b) actions aimed at preventing litter production and accumulation.

APA, Harvard, Vancouver, ISO, and other styles

15

Walker, Ian J., and William G. Nickling. "Dynamics of secondary airflow and sediment transport over and in the lee of transverse dunes." Progress in Physical Geography: Earth and Environment 26, no. 1 (2002): 47–75. http://dx.doi.org/10.1191/0309133302pp325ra.

Full text

Abstract:

Recent research literature on secondary airflow and sediment transport patterns over flow-transverse dunes is reviewed. Various issues surrounding the behaviour, modelling and sedimentological implications of near-surface airflow dynamics over dunes are discussed, including: the Law of the Wall; the Jackson and Hunt airflow model; the effects of streamline compression, acceleration and curvature on stoss slope shear stress; and, in particular, recent efforts to characterize secondary lee-side airflow patterns. A revised conceptual model of lee-side airflow is presented and areas for further research are identified regarding the implications of such patterns for dune sedimentary dynamics, morphology, and migration.

APA, Harvard, Vancouver, ISO, and other styles

16

VITAL, HELENICE, ARNO MASCHMANN DE OLIVEIRA, and WERNER FARKATT TABOSA. "Caracterização de Padrões de Formas de Fundo da Foz do Rio São Francisco." Pesquisas em Geociências 28, no. 2 (2001): 125. http://dx.doi.org/10.22456/1807-9806.20277.

Full text

Abstract:

On the basis of a regional side-scan sonar survey covering a distance of 12 km on the São Francisco River Mouth between Piaçabuçu and Cabeço-Pontal da Barra (NE Brazil) a variety of bedforms have been distinguished. The river bed morphology of this area can be characterized by three main patterns: dunes, ripples and planar beds. Sand dunes occur as extensive 2D and 3D dune fields. Between Piaçabuçu and Fitinha Island the dunes are asymmetric indicating a sand movement toward the river mouth. These dunes range in height from 1 to 2 m, and in wavelength from 30 to 90 m. Between Fitinha Island and Negra Island large asymmetric dunes with smaller symmetric ones superimposed can be seen, showing tidal influence. At the river mouth, the dunes give place to symmetrical ripples with height smaller than 0,3 m and wavelength shorter than 1 m. The dune and ripples fields can be intercalated by planar beds.

APA, Harvard, Vancouver, ISO, and other styles

17

Catling, Paul M., and G. Mitrow. "The dune race of Vitis riparia in Ontario: Taxonomy, conservation and biogeography." Canadian Journal of Plant Science 85, no. 2 (2005): 407–15. http://dx.doi.org/10.4141/p03-084.

Full text

Abstract:

Although poorly known, the native dune grape, Vitis riparia Michaux var. syrticola (Fernald & Wiegand) Fernald, is a potentially important source of valuable traits for the improvement of cultivated grapes. In order to clarify its taxonomic and conservation status in Ontario and to evaluate ecological and geographic patterns, data were collected from 623 specimens from 10 herbaria. In addition, five plants referable to var. syrticola with densely hairy petioles and five referable to var. riparia with glabrous petioles were cultivated in a greenhouse under uniform mesic conditions. Although the sample was considered reliable, there was no bimodal pattern in the putatively distinctive dense pubescence to support taxonomic recognition of var. syrticola; it may be referred to simply as “the dune race.” Cultivated plants retained their initial pubescence characteristics for 3 consecutive years, suggesting that the character is relatively stable. Plants referable to the dune race with dense pubescence occurred in extremely dry and open natural habitats and occurred significantly more often than expected on shoreline sand dunes of the Great Lakes. In contrast, plants without hair or less pubescent were significantly under-represented in dry habitats and shoreline dunes. While Vitis riparia is widespread in southern Ontario, the pubescent race is restricted and has a predominantly Great-Lakes-shoreline distribution pattern. It has been reported from only 43 locations and is considered vulnerable to decline. Key words: Grape, Vitis, Ontario, germplasm protection, crop relative

APA, Harvard, Vancouver, ISO, and other styles

18

Kadmon, Ronen. "ECOLOGY OF LINEAR DUNES: II. DIFFERENTIAL DEMOGRAPHIC RESPONSES OF ANNUAL PLANTS TO LOCAL SCALE VARIATION IN SAND STABILITY." Israel Journal of Plant Sciences 42, no. 4 (1994): 275–84. http://dx.doi.org/10.1080/07929978.1994.10676580.

Full text

Abstract:

An experimental study was designed to investigate the demographic mechanisms by which annual plants inhabiting desert sand dunes respond to local gradients in the stability of the sand. The results indicated that individual plants emerging at different topographic positions along the dune experience different probabilities of survival and reproduction. The general trend observed was a decrease in seedling survival, plant biomass, fecundity, reproductive allocation, and fruit weight from the relatively stable, interdune corridor towards the unstable crest of the dune. However, all of these demographic responses were highly species-specific, indicating that coexisting annual species respond differentially to underlying patterns of spatial heterogeneity in the stability of the sand. These results suggest that local-scale spatial heterogeneity in sand stability may be important in promoting coexistence of desert sand dune annuals.

APA, Harvard, Vancouver, ISO, and other styles

19

Valentini, Emiliana, Andrea Taramelli, Sergio Cappucci, Federico Filipponi, and Alessandra Nguyen Xuan. "Exploring the Dunes: The Correlations between Vegetation Cover Pattern and Morphology for Sediment Retention Assessment Using Airborne Multisensor Acquisition." Remote Sensing 12, no. 8 (2020): 1229. http://dx.doi.org/10.3390/rs12081229.

Full text

Abstract:

Coastal sand dunes are highly dynamic aeolian landforms where different spatial patterns can be observed due to the complex interactions and relationships between landforms and land cover. Sediment distribution related to vegetation types is explored here on a single ridge dune system by using an airborne hyperspectral and light detection and ranging (LiDAR) remote sensing dataset. A correlation model is applied to describe the continuum of dune cover typologies, determine the class metrics from landscape ecology and the morphology parameters, and extract the relationship intensity among them. As a main result, the mixture of different vegetation types such as herbaceous, shrubs, and trees classes shows to be a key element for the sediment distribution pattern and a proxy for dune sediment retention capacity, and the anthropic fingerprints can play an even major role influencing both ecological and morphological features. The novelty of the approach is mostly based on the synergistic use of LiDAR with hyperspectral that allowed (i) the benefit from already existing processing methods to simplify the way to obtain thematic maps and coastal metrics and (ii) an improved detection of natural and anthropic landscape.

APA, Harvard, Vancouver, ISO, and other styles

20

Kostaschuk, R. A., J. L. Luternauer, J. V. Barrie, P. H. Leblond, and L. Werth Von Deichmann. "Sediment transport by tidal currents and implications for slope stability: Fraser River delta, British Columbia." Canadian Journal of Earth Sciences 32, no. 7 (1995): 852–59. http://dx.doi.org/10.1139/e95-071.

Full text

Abstract:

Tidal currents on the sandy, southern slope of Fraser River delta have generated dunes with heights of 0.5–3.5 m and lengths of 11–108 m. Dune geometry and migration measurements indicate net sediment transport to the northwest in the direction of flood tidal currents. Two current meters moored in the dune field showed greater frequencies of occurrence and higher mean current speeds in the flood direction compared with the ebb. Predictions from two bed-material load models indicate sediment transport is overwhelmingly dominated by flood currents. There is no obvious source of sand to replace sediment transported in the dune field, suggesting net erosion of the surface. A previous analysis of bathymetric data also shows recent erosion of the lower slope and overall slope steepening. These patterns of erosion could lead to slope failure and damage to coastal structures.

APA, Harvard, Vancouver, ISO, and other styles

21

Jackson, Derek, Natalia Cruz-Avero, Thomas Smyth, and Luis Hernández-Calvento. "3D airflow modelling and dune migration patterns in an arid coastal dune field." Journal of Coastal Research 165 (January 3, 2013): 1301–6. http://dx.doi.org/10.2112/si65-220.1.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Laporte-Fauret, Quentin, Bertrand Lubac, Bruno Castelle, et al. "Classification of Atlantic Coastal Sand Dune Vegetation Using In Situ, UAV, and Airborne Hyperspectral Data." Remote Sensing 12, no. 14 (2020): 2222. http://dx.doi.org/10.3390/rs12142222.

Full text

Abstract:

Mapping coastal dune vegetation is critical to understand dune mobility and resilience in the context of climate change, sea level rise, and increased anthropogenic pressure. However, the identification of plant species from remotely sensed data is tedious and limited to broad vegetation communities, while such environments are dominated by fragmented and small-scale landscape patterns. In June 2019, a comprehensive multi-scale survey including unmanned aerial vehicle (UAV), hyperspectral ground, and airborne data was conducted along approximately 20 km of a coastal dune system in southwest France. The objective was to generate an accurate mapping of the main sediment and plant species ground cover types in order to characterize the spatial distribution of coastal dune stability patterns. Field and UAV data were used to assess the quality of airborne data and generate a robust end-member spectral library. Next, a two-step classification approach, based on the normalized difference vegetation index and Random Forest classifier, was developed. Results show high performances with an overall accuracy of 100% and 92.5% for sand and vegetation ground cover types, respectively. Finally, a coastal dune stability index was computed across the entire study site. Different stability patterns were clearly identified along the coast, highlighting for the first time the high potential of this methodology to support coastal dune management.

APA, Harvard, Vancouver, ISO, and other styles

23

Cowling, Richard M., Caryl Logie, Joan Brady, Margie Middleton, and B. Adriaan Grobler. "Taxonomic, biological and geographical traits of species in a coastal dune flora in the southeastern Cape Floristic Region: regional and global comparisons." PeerJ 7 (July 31, 2019): e7336. http://dx.doi.org/10.7717/peerj.7336.

Full text

Abstract:

In Mediterranean-Climate Ecosystems (MCEs), Holocene coastal dunes comprise small, fragmented and dynamic features which have nutritionally imbalanced and excessively drained, droughty, sandy soils. These characteristics, along with summer drought and salt-laden winds, pose many challenges for plant colonization and persistence. Consequently, MCE dune floras are likely to be distinctive with a high proportion of habitat specialists and strong convergence in growth form mixes. Very little research has compared the species traits of dune floras within and across MCEs. This paper contributes to filling that gap. Here, we analyze the taxonomic, biological and geographical traits for all 402 species in a flora from a dune landscape (Cape St Francis) in the southeastern Cape Floristic Region (CFR) and compare patterns with the trait profiles of other dune floras at a regional (CFR) and global (MCE) scale. Within the CFR, the southeastern (all-year-rainfall) flora at Cape St Francis had a similar trait profile to western (winter-rainfall) dune floras, except for having a lower representation of species belonging to CFR-endemic clades, and higher number of species associated with tropical lineages. The St Francis flora, in common with other CFR and MCE floras, was dominated by members of the Asteraceae, Fabaceae and Poaceae. Some 40% of the St Francis flora was endemic to the CFR, typical of the high rate of MCE-level endemism elsewhere in the CFR, and in other MCEs. About 30% of the flora was confined to calcareous sand, a value typical for many other MCE sites. The St Francis flora, as well as other CFR dune floras, differs from those of other MCEs by having many species associated with shrubby lineages, and by the relatively high incidence of species associated with tropical lineages. The growth form profile of the St Francis and other CFR floras shows strongest similarity with that of Australian MCE dunes in that in both regions, evergreen hemicryptophytes and shrubs share dominance, and annuals are floristically and ecologically subordinate. The least similar of MCEs to the St Francis trait profile is the Mediterranean Basin where annuals are the most frequent growth form while shrubs are subordinate. California and Chile dune floras appear to occupy an intermediate position, in terms of growth form mix, between the Cape and Australia on the one hand, where dune floras have retained features typical of nutrient-poor soils, and the Mediterranean Basin, where dwarf, deciduous shrubs and annuals dominate the life form spectrum. All MCE dunes are threatened by alien plants, infrastructure development, tourism demands and rising sea levels. The high incidence of species of conservation concern in CFR dune floras underestimates the exponentially increasing threats to their habitats, which are already historically at a much-reduced extent. All remaining coastal dune habitat in the CFR, and probably in other MCEs, should be conserved in their entirety.

APA, Harvard, Vancouver, ISO, and other styles

24

Guillaumet, Alban, and Guillaume Leotard. "Annoying neighbors: Multi-scale distribution determinants of two sympatric sibling species of birds." Current Zoology 61, no. 1 (2015): 10–22. http://dx.doi.org/10.1093/czoolo/61.1.10.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

25

Ewing, Ryan C., George D. McDonald, and Alex G. Hayes. "Multi-spatial analysis of aeolian dune-field patterns." Geomorphology 240 (July 2015): 44–53. http://dx.doi.org/10.1016/j.geomorph.2014.11.023.

Full text

APA, Harvard, Vancouver, ISO, and other styles

26

Pluis, J. L. A., and B. de Winder. "Spatial patterns in algae colonization of dune blowouts." CATENA 16, no. 4-5 (1989): 499–506. http://dx.doi.org/10.1016/0341-8162(89)90031-3.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

BEVERIDGE, CARRIE, GARY KOCUREK, RYAN C. EWING, et al. "Development of spatially diverse and complex dune-field patterns: Gran Desierto Dune Field, Sonora, Mexico." Sedimentology 53, no. 6 (2006): 1391–409. http://dx.doi.org/10.1111/j.1365-3091.2006.00814.x.

Full text

APA, Harvard, Vancouver, ISO, and other styles

28

Zuo, X. A., J. M. H. Knops, X. Y. Zhao, H. L. Zhao, Y. Q. Li, and Y. R. Guo. "A positive correlation between plant diversity and productivity is indirectly caused by environmental factors driving spatial pattern of vegetation composition in semiarid sandy grassland." Biogeosciences Discussions 8, no. 6 (2011): 11795–825. http://dx.doi.org/10.5194/bgd-8-11795-2011.

Full text

Abstract:

Abstract. Although patterns between plant diversity and ecosystem productivity have been much studied, a consistent relationship has not yet emerged. Several different patterns have been observed both naturally and experimentally, likely caused by spatial variability of environmental factors and vegetation composition. In this study, we measured the vegetation cover, plant diversity, productivity, soil properties and site characteristics along an environment gradient of natural sandy grasslands (mobile dune, semi-fixed dune, fixed dune, dry meadow, wet meadow and flood plain grassland) in a semiarid area of Northern China. We used multivariate analysis to examine the relationships between environment factors, vegetation composition, plant diversity and productivity. We found a positive correlation between plant diversity and productivity. Vegetation composition had also a significantly positive correlation with plant diversity and productivity. Environment gradients in relation to soil properties and topography features affected the distribution patterns of species diversity, vegetation composition and productivity. However, environment gradients are a better determiner for vegetation composition and productivity than for species diversity. The analysis from optimization model of structural equation suggests that environmental factors determine vegetation composition, which in turn drives independently both plant diversity and productivity. Thus the positive correlation between plant diversity and productivity is not direct, but indirectly driven by the spatial pattern of vegetation composition determined by environment gradients in soil and topography.

APA, Harvard, Vancouver, ISO, and other styles

29

Costa, César S. B., Ulrich Seeliger, and César V. Cordazzo. "Leaf demography and decline of Panicum racemosum populations in coastal foredunes of southern Brazil." Canadian Journal of Botany 69, no. 7 (1991): 1593–99. http://dx.doi.org/10.1139/b91-203.

Full text

Abstract:

We studied the effect of nutrient status and sand movement on the population biology of Panicum racemosum Spreng. over a 5-year period (1982–1986) on mobile, semifixed and fixed coastal foredune habitats in southern Brazil. The soils were deficient in nitrate, phosphate, and potassium (<0.5, 0.2–1.2, and 3–5 mg/kg, respectively) in all habitats, and a gradient of decreasing availability existed from the mobile to the fixed dunes. Half-lives of leaves were shorter in the fixed dune as compared with the mobile dune. Similarly, half-lives of leaves were shorter in summer than in winter. Experiments using cuttings of P. racemosum tillers showed that as P. racemosum plants grew, so did the deposition of sand on mobile foredunes. The mechanical deposition of sand itself did not stimulate P. racemosum growth. The deposition of saline sand provided a substrate that supported vertical growth of P. racemosum rhizomes and tillers and was a source of adsorbed nutrients. Also, active sand deposition limited the invasion of frontal dunes by other species. Panicum racemosum populations changed from "invader" to "mature" to "regressive" age states over a 5-year period, apparently in response to the spatial patterns of sand deposition and salt spray input. Key words: Panicum, leaf demography, growth vigour, sand dunes, temporal changes.

APA, Harvard, Vancouver, ISO, and other styles

30

Stallins, J. Anthony. "SOIL AND VEGETATION PATTERNS IN BARRIER-ISLAND DUNE ENVIRONMENTS." Physical Geography 22, no. 1 (2001): 79–98. http://dx.doi.org/10.1080/02723646.2001.10642731.

Full text

APA, Harvard, Vancouver, ISO, and other styles

31

Filion, Louise, and Pierre Marin. "Modifications morphologiques de l'Épinette blanche soumise à la sédimentation éolienne en milieu dunaire, Québec subarctique." Canadian Journal of Botany 66, no. 9 (1988): 1862–69. http://dx.doi.org/10.1139/b88-254.

Full text

Abstract:

The characteristic growth forms of white spruce (Picea glauca (Moench) Voss) were studied within a dune located north of Whapmagoostui (Subarctic Québec). Thirty-two trees (14 living and 18 dead) were excavated and their morphology and ring patterns are described. Adventitious root development at the base of buried stems and spindle-like trunks (diameter smaller at collar than at higher levels) were the most important morphological modifications in response to slow sedimentation rates (close to 5 – 6 cm/year), as long as total sedimentation did not exceed a depth of approximately 1.25 m. The decrease in radial growth with depth was most likely due to low temperatures caused by long-lasting snow lenses within the niveoeolian sediment during the growing season. Tree dieback occurred when the sedimentation rate rose to 8 cm/year. The combined weight of sand and buried snow caused severe mechanical damage to the trees (e.g. branch and stem breakage). Life expectancy of tall trees was about 50 years under such high stress conditions. The dune moves towards the north at a rate of 0.74 m/year. The mean sedimentation rate is 7.65 cm/year. These values are similar to those found in coastal dunes in Finland. The ultimate fate of these trees is death through dune displacement.

APA, Harvard, Vancouver, ISO, and other styles

32

Kocurek, Gary, and Ryan C. Ewing. "Aeolian dune field self-organization – implications for the formation of simple versus complex dune-field patterns." Geomorphology 72, no. 1-4 (2005): 94–105. http://dx.doi.org/10.1016/j.geomorph.2005.05.005.

Full text

APA, Harvard, Vancouver, ISO, and other styles

33

Stefansdottir, G., A. L. Aradottir, and B. D. Sigurdsson. "Accumulation of nitrogen and organic matter during primary succession of <i>Leymus arenarius</i> dunes on the volcanic island Surtsey, Iceland." Biogeosciences 11, no. 20 (2014): 5763–71. http://dx.doi.org/10.5194/bg-11-5763-2014.

Full text

Abstract:

Abstract. Initial soil development and enhanced nutrient retention are often important underlying environmental factors during primary succession. We quantified the accumulation rates of nitrogen (N) and soil organic matter (SOM) in a 37-year-long chronosequence of Leymus arenarius dunes on the pristine volcanic island Surtsey in order to illuminate the spatiotemporal patterns in their build-up. The Leymus dune area, volume and height grew exponentially over time. Aboveground plant biomass, cover or number of shoots per unit area did not change significantly with time, but root biomass accumulated with time, giving a root / shoot ratio of 19. The dunes accumulated on average 6.6 kg N ha−1 year−1, which was 3.5 times more than is received annually by atmospheric deposition. The extensive root system of Leymus seems to effectively retain and accumulate a large part of the annual N deposition, not only deposition directly on the dunes but also from the adjacent unvegetated areas. SOM per unit area increased exponentially with dune age, but the accumulation of roots, aboveground biomass and SOM was more strongly linked to soil N than time: a 1 g m−2 increase in soil N led on average to a 6 kg C m−2 increase in biomass and SOM. The Leymus dunes, where most of the N has been accumulated, will therefore probably act as hot spots for further primary succession of flora and fauna on the tephra sands of Surtsey.

APA, Harvard, Vancouver, ISO, and other styles

34

Wilson, BA, NM White, A. Hanley, and DL Tidey. "Population fluctuations of the New Holland mouse Pseudomys novaehollandiae at Wilson?s Promontory National Park, Victoria." Australian Mammalogy 27, no. 1 (2005): 49. http://dx.doi.org/10.1071/am05049.

Full text

Abstract:

The New Holland mouse (Pseudomys novaehollandiae) was first recorded at Wilson?s Promontory in 1972 in heathland vegetation, but has not been located in this habitat subsequently. The species was not trapped again until 1993 when it was found in calcarenite dune woodland on the Yanakie Isthmus. The aims of this study were to assess the population dynamics and habitat use of the species in this dune habitat. Mark-recapture trapping was conducted at three sites from 1999 to 2002. One site was located on low (0 - 5 m), flat sand dunes and open swales, another on medium (5 ? 10 m) vegetated dunes, and the third on high (20 m) steep vegetated dunes. The three sites had not been burnt for 30 to 50 years. The abundance of P. novaehollandiae was related to understorey vegetation density and differences in population densities on the sites are likely to be related to the primary succession stages on the sand dunes, rather than fire history. The maximum density (24 ha-1) recorded at one site was very high compared to other Victorian populations, however this was followed by a substantial decline in numbers within the year. At another site a small population declined to extinction. Populations on the isthmus are thus capable of achieving high densities but may decline quickly. Rainfall patterns may have affected the population fluctuations, but further research is required to elucidate fully the factors involved in the long-term dynamics of this species.

APA, Harvard, Vancouver, ISO, and other styles

35

Marin, Pierre, and Louise Filion. "Recent Dynamics of Subarctic Dunes as Determined by Tree-Ring Analysis of White Spruce, Hudson Bay, Québec." Quaternary Research 38, no. 3 (1992): 316–30. http://dx.doi.org/10.1016/0033-5894(92)90041-g.

Full text

Abstract:

AbstractThe radial-growth patterns of white spruce were studied on a number of trees growing in subarctic dunes along the eastern coast of Hudson Bay to calculate the rates of accumulation, erosion, and migration of cold-climate sand dunes. The average rate of sand accumulation in sheltered dunes (forest sites) was 2.5 to 3.3 cm/yr, which is two to three times lower than in highly exposed dunes with a rate of sedimentation of 7.65 cm/yr. The average erosion rate was 1.4–1.7 cm/yr, about two times lower than the accumulation rate. The migration rate of sheltered dunes was 18 to 30 cm/yr, three to five times lower than for an exposed dune which advanced at a speed of 74 cm/yr. This migration rate established for highly exposed dunes in the Subarctic with tree-ring methods is about 10 times lower than that established for a barchan in the Sahara with other methods.

APA, Harvard, Vancouver, ISO, and other styles

36

OURIEMI, MALIKA, PASCALE AUSSILLOUS, and ÉLISABETH GUAZZELLI. "Sediment dynamics. Part 2. Dune formation in pipe flow." Journal of Fluid Mechanics 636 (September 25, 2009): 321–36. http://dx.doi.org/10.1017/s0022112009007927.

Full text

Abstract:

We present a phase diagram of the different dune patterns observed when a bed composed of spherical particles is subjected to a pipe flow. While the threshold for incipient motion is determined by the Shields number, that for dune formation seems to be controlled by the Reynolds number. A simple linear stability analysis based on a particle flux derived by Ouriemi, Aussillous & Guazzelli (J. Fluid Mech., 2009) accounts reasonably well for the experimental observations.

APA, Harvard, Vancouver, ISO, and other styles

37

Barrows, Cameron W., and Michael F. Allen. "Patterns of occurrence of reptiles across a sand dune landscape." Journal of Arid Environments 74, no. 2 (2010): 186–92. http://dx.doi.org/10.1016/j.jaridenv.2009.09.005.

Full text

APA, Harvard, Vancouver, ISO, and other styles

38

Baddock, M. C., I. Livingstone, and G. F. S. Wiggs. "The geomorphological significance of airflow patterns in transverse dune interdunes." Geomorphology 87, no. 4 (2007): 322–36. http://dx.doi.org/10.1016/j.geomorph.2006.10.006.

Full text

APA, Harvard, Vancouver, ISO, and other styles

39

Wen, Qing, and Zhibao Dong. "Geomorphologic patterns of dune networks in the Tengger Desert, China." Journal of Arid Land 8, no. 5 (2016): 660–69. http://dx.doi.org/10.1007/s40333-016-0092-x.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Stefansdottir, G., A. L. Aradottir, and B. D. Sigurdsson. "Accumulation of nitrogen and organic matter during primary succession of <i>Leymus arenarius</i> dunes on the volcanic island Surtsey, Iceland." Biogeosciences Discussions 11, no. 5 (2014): 6591–613. http://dx.doi.org/10.5194/bgd-11-6591-2014.

Full text

Abstract:

Abstract. The volcanic island of Surtsey has been a natural laboratory where the primary succession of flora and fauna has been monitored, since it emerged from the N-Atlantic Ocean in 1963. We quantified the accumulation rates of nitrogen (N) and soil organic matter (SOM) in a 37 year long chronosequence of Leymus arenarius dunes in order to illuminate the spatiotemporal patterns in their build-up in primary succession. The Leymus dune area, volume and height grew exponentially over time. Aboveground plant biomass, cover or number of shoots per unit area did not change significantly with time, but root biomass accumulated with time, giving a root-shoot ratio of 19. The dunes accumulated on average 6.6 kg N ha−1 year−1, which was 3.5 times more than is received annually by atmospheric deposition. The extensive root system of Leymus seems to effectively retain and accumulate large part of the annual N deposition, not only deposition directly on the dunes but also from the adjacent unvegetated areas. SOM per unit area increased exponentially with dune age, but the accumulation of roots, aboveground biomass and SOM was more strongly linked to soil N than time: 1 g m−2 increase in soil N led on the average to 6 kg C m−2 increase in biomass and SOM. The Leymus dunes, where most of the N has been accumulated, will therefore probably act as hot-spots for further primary succession of flora and fauna on the tephra sands of Surtsey.

APA, Harvard, Vancouver, ISO, and other styles

41

Zuo, X. A., J. M. H. Knops, X. Y. Zhao, et al. "Indirect drivers of plant diversity-productivity relationship in semiarid sandy grasslands." Biogeosciences 9, no. 4 (2012): 1277–89. http://dx.doi.org/10.5194/bg-9-1277-2012.

Full text

Abstract:

Abstract. Although patterns between plant diversity and ecosystem productivity have been much studied, a consistent relationship has not yet emerged. Differing patterns between plant diversity and productivity have been observed in response to spatial variability of environmental factors and vegetation composition. In this study, we measured vegetation cover, plant diversity, productivity, soil properties and site characteristics along an environmental gradient (mobile dune, semi-fixed dune, fixed dune, dry meadow, wet meadow and flood plain grasslands) of natural sandy grasslands in semiarid areas of northern China. We used multivariate analysis to examine the relationships between environmental factors, vegetation composition, plant diversity and productivity. We found a positive correlation between plant diversity and productivity. Vegetation composition aggregated by the ordination technique of non-metric multidimensional scaling had also a significantly positive correlation with plant diversity and productivity. Environmental gradients in relation to soil and topography affected the distribution patterns of vegetation composition, species diversity and productivity. However, environmental gradients were a better determinant of vegetation composition and productivity than of plant diversity. Structural equation modeling suggested that environmental factors determine vegetation composition, which in turn independently drives both plant diversity and productivity. Thus, the positive correlation between plant diversity and productivity is indirectly driven by vegetation composition, which is determined by environmental gradients in soil and topography.

APA, Harvard, Vancouver, ISO, and other styles

42

Jiang, De Ming, Xue Hua Li, Chun Ping Miao, Quan Lai Zhou, and Toshio Oshida. "Patterns of Species Diversity across Scales and along the Slope on the Ecotone between the Active Sand Dune and the Inter-Dune Lowland in Horqin Sandy Land, China." Advanced Materials Research 726-731 (August 2013): 4390–96. http://dx.doi.org/10.4028/www.scientific.net/amr.726-731.4390.

Full text

Abstract:

To better understand the succession process of vegetation restoration from the active sand dune to the inter-dune lowland, species diversity which refers to species richness and abundance across scales and along the slope were studies in Horqin Sandy Land, China. A 0.25 ha square sampling plot, which sampled on the ecotone, was divided into five grain sizes and equal distance intervals along the slope from the top to the bottom. The results showed that both species abundance and richness increased as the grain sizes increased and along the slope, but the decreasing CV values indicated that species diversity gradually vary from heterogeneity to relatively homogeneity. In conclusion, species abundance and richness showed asynchronous changes and their relationship are more closely across scales than along the slope. Except that, more studies on the biotic and abiotic factors interaction concerning the vegetation patterns of sand dune ecosystems should be conducted. These could not only improve our understanding the mechanisms of vegetation invasion and succession, but also be beneficial for vegetation management and biodiversity conservation in semi-arid sand dune ecosystems.

APA, Harvard, Vancouver, ISO, and other styles

43

Hilton, Michael, Richard Walter, Karen Greig, and Teresa Konlechner. "Burial, erosion, and transformation of archaeological landscapes." Progress in Physical Geography: Earth and Environment 42, no. 5 (2018): 607–27. http://dx.doi.org/10.1177/0309133318795844.

Full text

Abstract:

A high proportion of archaeological sites are located on the world’s shorelines and recent research has documented the vulnerability of these sites to coastal processes and climate change. However, archaeological landscapes on many temperate coasts have already been degraded as a result of changes in dune dynamics related to changes in dune vegetation. These changes have produced marked spatial and temporal variations in patterns of burial and erosion in transgressive dune systems. This paper examines the modification and conservation of archaeological landscapes from a biogeomorphic perspective, using the example of marram grass ( Ammophila arenaria) invasion of dune systems in southern New Zealand. The impact of marram grass on dune system dynamics and the underlying archaeological landscape are complex. Full invasion may result in the general burial and protection of these landscapes, but the risk of degradation of sites is high during the invasion process. In southern New Zealand, marram invasion has resulted in the formation of stable foredunes, often associated with coastal progradation. Archaeological sites located close to the shoreline can be subject to either burial or erosion, or both, as marram grass establishes in the foredune zone. The spatial relationship between cultural sites and the shoreline may be lost as the coast progrades. The impact of marram invasion can extend throughout the hinterland dune system as a result of (i) dune mobility triggered by marram grass invasion and (ii) the development of a negative sand budget, which prevents or reduces beach-foredune-dune system sand exchange. The risk of degradation of the archaeological landscape can be significantly heighted by marram invasion, which can have profound implications for the preservation and interpretation of archaeological sites and materials. Paradoxically, dune system restoration may lead to the re-exposure of these sites, but the principal outcome of dune system restoration is expected to be a decline erosion (manifest as in deflation surfaces) and reburial of the archaeological landscape.

APA, Harvard, Vancouver, ISO, and other styles

44

Bellais, Kaylyn C., Samuel T. Barber, Donald A. Beebe, and Murlene W. Clark. "Lake or Estuary? Sedimentary and Benthic Foraminiferal Characterization of a Gulf of Mexico Coastal Dune Lake." Gulf and Caribbean Research 31 (2020): SC46—SC52. http://dx.doi.org/10.18785/gcr.3101.18.

Full text

Abstract:

Coastal dune lakes are shallow estuaries located within dune environments that share a permanent or intermittent connection with the sea. Because coastal dune lakes are found in few locations worldwide (e.g. Australia, New Zealand, Florida, etc.) they represent unique environments worthy of protection. However; there is a distinct lack of scientific data related to the function and ecology of coastal dune lakes, especially in the Gulf of Mexico. Therefore, the purpose of this study was to characterize the sedimentology and foraminifera of a representative coastal dune lake in Walton County, FL (i.e. Eastern Lake) and determine whether it shares geologic similarities with nearby estuaries. Ten Ekman sediment grab samples were collected along a transect spanning the length of Eastern Lake. The samples were processed to determine sedimentary properties and foraminiferal assemblages. Results from the sedimentary and foraminiferal analyses reveal 3 distinct depositional environments including: (1) a coarse grained, moderately well sorted, organic poor, sandy beach facies with both agglutinated and calcareous foraminifera, (2) a fine grained, very poorly sorted, organic rich central mud basin facies with mostly calcareous foraminifera, and (3) a coarse grained, poorly sorted, organic rich sandy marsh delta facies dominated by agglutinated foraminifera. These environments and foraminiferal patterns are also found in much larger nearby estuaries including Choctawhatchee Bay, Pensacola Bay, and Mobile Bay. Our results therefore suggest that coastal dune lakes may serve as down-scaled micro-estuaries and are functionally related to larger estuaries of the Gulf Coast despite their size.

APA, Harvard, Vancouver, ISO, and other styles

45

Ritsema, Coen J., and Louis W. Dekker. "Soil moisture and dry bulk density patterns in bare dune sands." Journal of Hydrology 154, no. 1-4 (1994): 107–31. http://dx.doi.org/10.1016/0022-1694(94)90214-3.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

Berndtsson, Ronny, Kanichi Nodomi, Hiroshi Yasuda, Thomas Persson, Heshen Chen, and Kenji Jinno. "Soil water and temperature patterns in an arid desert dune sand." Journal of Hydrology 185, no. 1-4 (1996): 221–40. http://dx.doi.org/10.1016/0022-1694(95)02987-7.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

Ewing, Ryan C., Alex G. Hayes, and Antoine Lucas. "Sand dune patterns on Titan controlled by long-term climate cycles." Nature Geoscience 8, no. 1 (2014): 15–19. http://dx.doi.org/10.1038/ngeo2323.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

Jiang, Hong, Hongchao Dun, Ding Tong, and Ning Huang. "Sand transportation and reverse patterns over leeward face of sand dune." Geomorphology 283 (April 2017): 41–47. http://dx.doi.org/10.1016/j.geomorph.2016.12.030.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

Gonzlez-Villanueva, R., S. Costas, M. Prez-Arlucea, S. Jerez, and R. M. Trigo. "Impact of atmospheric circulation patterns on coastal dune dynamics, NW Spain." Geomorphology 185 (March 2013): 96–109. http://dx.doi.org/10.1016/j.geomorph.2012.12.019.

Full text

APA, Harvard, Vancouver, ISO, and other styles

50

Houle, Gilles. "Environmental filters and seedling recruitment on a coastal dune in subarctic Quebec (Canada)." Canadian Journal of Botany 74, no. 9 (1996): 1507–13. http://dx.doi.org/10.1139/b96-181.

Full text

Abstract:

One important factor that often determines the presence of a plant species on a site is propagule availability. Afterwards, abiotic and biotic factors act as a series of filters operating sequentially from the seed to the adult stage, determining the pattern of recruitment. By comparing the spatial pattern of emerging seedlings to those of seed availability and of surviving seedlings, one can determine the relative importance of the environmental filters acting on the seed germination and the seedling establishment phases. On a coastal dune system in subarctic Quebec (Canada), sand accumulation, salt spray, and substrate physicochemistry, all affecting microsite quality for seeds and seedlings, vary along a short topographical gradient. My goal was to determine whether or not conditions changing along this gradient differentially affect the initial stages of population recruitment of two perennial herbaceous species for which adults are segregated along the gradient: Honckenya peploides and Elymus mollis. The spatial pattern of seeds in the seed bank and that of emerging seedlings were not related to one another for either Honckenya or Elymus. However, patterns of surviving seedlings were spatially correlated with those of emerging seedlings. Seed and seedling mortality were not density dependent; they were both spatially variable, although not clinal. These results suggest that the environmental filters acting on the germination stage are those that determine the spatial patterns of recruitment. Spatial segregation along the flank of the foredune between adults of the two species studied thus seems to be maintained in part (and maybe reinforced) by low seed mobility, or low seed retention, and the availability of suitable microsites for seed germination. Population progression towards the upper beach seems to depend mostly on seedling establishment for Honckenya but on clonal growth for Elymus. Keywords: Elymus mollis, Honckenya peploides, Hudson Bay, partial Mantel test, spatial segregation, Whapmagoostui-Kuujjuaraapik.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Dune patterns'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles