Dune Vegetation Research Articles

Gradient analysis of an area of coastal vegetation in the State of Paraíba, northeastern Brazil

A transect of coastal vegetation was surveyed forits plant communities in the state of Paraíba, Northeastern Brazil. Two main plant formations are found in this region. The ‘restinga’ is the coastal sand dune vegetation and the ‘tabuleiro’ is the adjacent savanna-like formation. The ordination of sample units and species of the transect showed that these plant formations cannot be considered as discrete communities but they are actually a vegetational continuum made up of species adapted to sandy soils but with varying distributional patterns according to the exposure to maritime influences.As comunidades vegetais de uma transeção de vegetação costeira foram inventariadas no litoral norte do estado da Paraíba, Brasil. Duas formações vegetais predominam nesta região: a restinga, que é a vegetação das dunas arenosas costeiras, e o tabuleiro, que é a formaçõo savânica (cerrado) adjacente. A ordenação de parcelas e espécies da transeção mostrou que estas duas formações vegetais não podem ser consideradas como comunidades discretas, mas sim como um contínuo vegetacional composto de espécies adaptadas a solos arenosos, mas com variados padrões distribucionais de acordo com a exposição às influências marinhas.

Impact of protection and free grazing on sand dune vegetation in the Rajasthan Desert, India

AbstractIn the Thar (Rajasthan) Desert of India, sand dunes and sandy plains dominate the landscape. Livestock raising and marginal land cultivation are the main occupations. Owing to the high growth rates of human and livestock populations and a decrease in pasture area and its primary productivity, these lands bear acute grazing pressure. Average rainfall is low and vegetation growth is restricted to the short rainy season of two to four months duration. Often there are years of lower than normal rainfall. In these circumstances, fenced areas, established to stabilize formerly active sand dunes, are increasingly opened to grazing to prevent high stock mortality during droughts. This study was conducted in four fenced and one open site, representative of the region's different vegetation types and grazing pressures. The impact of 2 and 5 per cent free grazing pressure on protected sand dune vegetation density and cover was tested in the two fenced sites. The vegetation data for grazed sites are compared with those for the two ungrazed fenced (protected) and one unfenced (open) site subjected to unlimited grazing pressure throughout the year. The vegetation sampling was carried out by the qaudrat and line‐transect method before and after grazing from November 1984 to October 1986. It shows a significant reduction in the density and cover of many palatable species and an increase of unpalatable plants. The effect of vegetation degradation is greater in the unfenced area. The low grazing pressure on the fenced sand dunes sites can still cause drastic changes in the vegetation density and cover. Protection resulted in reduced sand erosion and enhanced growth of palatable plants in the fenced sites under similar climatic and edaphic conditions to the unfenced sites. The grazing pressure in the unfenced areas remains high to extreme during the year, due to low land productivity and high feed demand. The regeneration rate is very slow under the constant (3rd to 5th degree) overgrazing. Low intensity grazing pressure on the fenced sites during droughts can cause heavy utilization and mortality of palatable vegetation.

Quaternary Vegetation Change and Dune Formation on Bermuda: A Discussion

The Bermuda oceanic islands are comprised mainly of lithified dunes (i.e. calcareous eolianites) which formed during Quaternary sea-level regressions. This short communication considers the vegetation history of Bermuda in relation to these dune-building episodes. At 32?N, Bermuda is the northernmost limit of most frost-intolerant stibtropical vascular plant species in the northern hemisphere. The global cooling that caused the Quaternary glacial periods and also the lowering of sea level, may have led to the local extinction of Bermuda's subtropical interglacial floras. Located >900 km from the nearest continental source area, the filling of the vacated niches on Bermuda by long-distance dispersal may have involved low frequency events requiring more than 6000 years. The result would have been a very sparse vegetative cover during the dune-building episodes which would explain why the Bermuda eolianites reach elevations greater than 60 m above the present-day sea level. This hypothesis is supported by: (1) the absence of reliable fossil evidence for vegetation interfering with, or interbedded within, the eolian deposits; and (2) preliminary palynological analyses of.the clay-rich fossil soils intercalated between the eolianite formations which have revealed pollen that does not appear to correspond to the existing native flora of Bermuda.

BARRIER BEACH IMPACT MANAGEMENT PLANNING: FINDINGS FROM THREE LOCATIONS IN MASSACHUSETTS

This paper integrates the findings from social and ecological impact studies at three barrier beaches in Massachusetts to demonstrate the value of an inter-disciplinary approach to resource allocation and visitor management. Fragile barrier beaches have a high demand for human recreation, but a low tolerance for human impact. Because barrier beaches also serve as nesting habitat for rare birds (piping plovers and least terns), balancing preservation and recreation requires management plans based on both social and ecological impact studies. The social data were obtained from on-site surveys using self-administered questionnaires. Information regarding visitor behaviours, beliefs and attitudes was collected from three distinct groups: those who parked their car in a parking lot and walked to the beach, those who drove 4-wheel drive vehicles on the beach, and those who landed boats on the beach. The ecological data consisted of dune vegetation and bird surveys in recreation areas and those protected from human impact. Results were used to develop management techniques to mitigate impact and educate visitors.

Near-future sea level impacts on coastal dune landscapes

Very little attention has been paid to the impact of global warming, especially sea level rise, on coastal dunescapes, despite the fact that these provide natural protection along many of the world's shorelines. This paper reviews likely responses given the IPCC climate change predictions to 2030AD, which include sea level rise in the order of 0.09 to 0.29m. It is envisaged that coastal dunes will react in a variety of ways dependent both on regional and local factors. Rising water levels will increase susceptibility to erosion, but the fate of released sediment, particularly the onshore/offshore partitioning, must depend on morphodynamic antecedence, and the propensity for periodic domain shifts. The release of material at the shoreline may allow construction of coastal dunes, to the point of progradation in some zones. The response of dune vegetation to a warmer, wetter climate is uncertain. Most of the main temperate dune species are C3 plants which given favourable conditions would respond positively to CO2 enhancement. However local factors may offset such potential gains.

Vegetation of a coastal sand dune system in southern New Zealand

The introduction of vigorous exotic species has destroyed much of the native sand dune vegetation along the coasts of South Island, New Zealand. However, some dunes built by the native cyperad Desmoschoenus spiralis still remain in the southwest.The dunes at Cole Creek, on the West coast of South Island, were chosen as a relatively pristine study area. 15 transects were laid through semi‐fixed dunes into dwarf forest. Environmental measurements were taken at regular intervals through the dunes: pH, soil moisture, organic matter, conductivity, nutrient status and elevation. Classification and ordination of these data demonstrated that two major environmental areas were present ‐ open dune and dwarf forest ‐ with an abrupt ecotone between them. Vegetation analyses revealed a loosely‐banded pattern, parallel to the sea. Vegetation types with few but constant species such as Desmoschoenus spiralis and Calystegia soldanella, predominated in the open dune. Forest species were rarely found seaward of the dune/forest boundary, though there was evidence the Spatial Mass Effect was operating.Multiple regression and canonical correlation of the vegetation and environmental factors showed that the main factors affecting vegetation patterns were the environmental complex related to distance from the sea, elevation above mean tide, soil alkalinity and moisture.

Disturbance regimes as determinants of seed banks in coastal dune vegetation of the southeastern Cape

AbstractSoil‐stored seed banks of grassland, fynbos and thicket, all growing on calcareous dunes and each subject to different disturbance regimes, were examined. Seed banks were determined from counts of germinants from 50 soil cores from each type. Aboveground estimates of plant species cover in 10 1‐m2 plots were used in determining vegetation/seed bank similarities. There was no evidence for seed bank densities to be markedly higher in the most frequently disturbed community (grassland ‐4273 seeds/m2) than the least disturbed community (thicket ‐ 3417 seeds/m2). Highest similarity between seed bank and above‐ground vegetation composition in terms of species and growth form/life‐span classes was recorded for grassland (CC = 50%). Lowest similarity (CC = 13%) was found in the less frequently disturbed thicket where no seeds of climax trees were recorded in the seed bank. A fynbos community on a north‐facing (warm, dry) slope had intermediate‐sized seed banks (1683 seeds/m2) with intermediate vegetation/seed bank similarity (CC = 46%). However, on the south‐facing slope, which has a large post‐fire ephemeral herb component, seed banks were larger (4518 seeds/m2) but less similar to above‐ground vegetation (CC = 39%o). Ordination (DCA) of vegetation data from the four communities was different from an ordination of their seed bank data. Fynbos shrub species were absent from seed banks of both grassland and thicket, even though secondary succession proceeds from grassland, through fynbos to thicket. Their seed banks appear less persistent than those of European heath or Californian chaparral shrubs.

The Corrubedo beach-lagoon complex, Galicia, Spain: Dynamics, sediments and recent evolution of a mesotidal coastal embayment

The Corrubedo beach-lagoon complex is situated in an embayment on the northwestern coast of Spain. The 4.1 m tidal range and southwesterly winds are the main agents of sediment transportation. The sediments are hybrid arenites (siliciclastic + bioclastic), with carbonate percentages ranging from 27.36 to 54.10%; silt, clay and organic matter occur in minor amounts. Repeated mapping and sampling of the beach, tidal channels, salt marshes and active and vegetated dunes recorded the vertical facies associations and their temporal evolution. Two peat layers at 0.6 and 1.7 m below the present-day marsh have yielded ages of 2280 ± 60 yrs B.P. and 1045 ± 125 yrs B.P. respectively. The possible causes of the relative sea-level rise are discussed.

Coastal sand dune vegetation of Tabasco and Campeche, Mexico

Abstract. Sand dune vegetation along the coast of the Mexican states of Tabasco and Campeche was sampled by means of 1501 releves and the data were analyzed with classification and ordination programs. 36 community types were distinguished, which were grouped into 10 higher‐order groups. The communities are described in a sequence reflecting the main vegetation zonation. Beach, embryo dune and foredune community groups include 12 community types, the sheltered zone includes 16 types and the fixed dunes 8 types. The ordination results reveal one main vegetation gradient corresponding to the increase in mean distance from the shoreline and elevation, and being covariant with species richness, mean vegetation cover and mean vegetation height.Additional differences are related to the geographical transition between the Gulf and Caribbean coastal vegetation and environmental conditions, mainly type of sand, occurring in the study area. Siliceous sand and a Gulf climate are characteristic for most of Tabasco, and calcareous sand and a Caribbean‐type climate are characteristic for Campeche.Disturbance caused by coconut plantations, cattle grazing and tourism favours the invasion of ruderal species from waste places behind the dunes, which attain local dominance in the dunes described here. Consequently some separate community types had to be distinguished.The distribution of community types is analyzed in the context of the transitions between calcareous and siliceous substrates in the study area.

Ecology of Sandy Shores

1. Introduction. 2. The Physical Environment. Sand. Porosity and permeability. Penetrability. Waves. Types of waves. Wave energy. Refraction. Shoaling and breaking. Wave-driven longshore currents and rip currents. Bound and infragravity waves - surf beat. Edge waves. Tides. Internal waves. Wind. Sand movement. Interaction between beach slope, waves and particle size. Beach types. Circulation cells and mixing. Water filtration by the sand. Exposure rating. Conclusion. 3. Beach and Surf-zone Flora. Benthic microflora. Surf-zone phytoplankton. Conclusions. 4. Sandy-beach Invertebrates, with special reference to the Macrofaunal Genera. Phylum:Porifera. Phylum:Cnidaria. Phylum:Platyhelminths. Phylum:Nemertea. Phylum:Nematoda. Phylum:Rotifera. Phylum:Gastrotricha. Phylum:Kinorhyncha. Phylum:Loricifera. Phylum:Annelida. Phylum:Echiurida. Phylum:Sipunculoidea. Phylum:Brachiopoda. Phylum:Mollusca. Phylum:Tardigrada. Phylum:Arthropoda. Phylum:Ectoprocta. Phylum:Echinodermata. Phylum:Hemichordata. 5. Adaptations to Sandy-beach Life. Locomotion:burrowing. Locomotion:surfing. Rhythms of activity. Sensory responses and orientation. Choice of habitat. Nutrition. Respiration. Environmental tolerances. Reproduction. Aggregations and gregariousness. Responses to and avoidance of predators. Conclusions. 6. The Macrobenthic Communities. Sampling methods. Diversity and abundance. Distribution and zonation. Migrations and spatial and temporal changes. Competition, disturbance and predation. Trophic relationships. Conclusions. 7. Interstitial Ecology. The interstitial climate. The biota. Distribution of the interstitial fauna. Temporal changes. Meiofaunal communities. Trophic relationships. Biological interactions. Conclusions. 8. Surf-zone Fauna. Zooplankton:composition. Adaptations of surf-zone zooplankton. Zooplankton:migrations. Zooplankton:distribution. Zooplankton:biomass and abundance. Food and feeding relationships. Surf-zone fishes. Juveniles and nursery areas. Surf-zone fish communities. Fishes:temporal variability. Ichthyofaunal trophic relationships. Other groups. Conclusions. 9. Birds and other Terrestrial Vertebrates. 10. Sandy Beach Ecosystems. Food sources. Macroscopic food chains. Examples of macroscopic food chains. The interstitial food chain. The microbial loop. Energy flow in beach and surf-zone ecosystems. The sandy beaches of the Eastern Cape. Nutrient cycling. Conclusions. 11. Sandy Beaches and Pollution. Crude oil pollution. Oil dispersants. Sewage and organic enrichment. Factory effluents. Thermal pollution. Indicators of pollution. Toxicity studies. Conclusions. 12. The Dune Ecosystem and Dune/Beach Exchanges. The physical environment - wind and sand transport. Coastal dune formation by vegetation. Dune types. Edaphic features. Water. The gradient across coastal dunefields. Dune vegetation. The fauna. Food chains of the dune ecosystem. Dune/beach exchanges. A case study of dune/beach exchanges. Conclusions. 13. Conservation and Management.

Florística e estrutura da comunidade herbácea e arbustiva da Praia do Ferrugem, Garopaba-SC

A Praia do Ferrugem, constituída por sedimentos do Quartenário e afloramentos do Complexo Cristalino, localiza-se no litoral sul de Santa Catarina, Município de Garopaba. Nesta praia, foi realizada uma análise da vegetação de dunas em outubro de 1989. Um total de 50 unidades amostrais, na forma de quadrados com área de 1m² cada, foram distribuídas sistemático-aleatoriamente na vegetação herbácea. Foi registrada a cobertura das espécies (escala de Daubenmire por Bailey & Poulton). Devido a ocorrência de formações arbustivas, foram feitos registros de presença de espécies e estrutura desta comunidade distinta. São apresentadas descrições dos diversos habitats e suas espécies dominantes com base nos parâmetros fitossociológicos, listagem das espécies e respectivas formações vegetais, bem como diagrama de perfil de uma formação arbustiva típica.

The role of vegetation in Pleistocene eolianite sedimentation: an example from Eastern Tunisia

In Tyrrhenian eolianites of E Tunisia root traces of different types indicate semi-permanent vegetation during the coastal eolian deposition. In order to discuss their paleoclimatic significance, the diverse types of vegetated dunes are reviewed and the terminology of root fossilisation is criticized. Differences between the significance of coastal and desert eolian dunes and their vegetation with respect to the reconstruction of paleo-aridity are emphasized.

The effect of salinity on the growth of some New Zealand sand dune species

Soil salinity affects many coastal communities, but it is not clear to what extent salinity is involved in the distribution of sand dune vegetation. Twenty-nine species (including nine exotic species) found on New Zealand sand dunes were used in a study of root-salinity tolerance. Six concentrations of salt were added to plants grown in water culture; growth rates and the percentage of live material were measured. About half the species were more intolerant of root-salinity than the glycophytic control (wheat). These were mainly native New Zealand herbs and grasses and the introduced species Silene gallica and Lupinus arboreus. Tolerant species included the native species Desmoschoenus spiralis and Scirpoides nodosa. Most tolerant exotic species were grasses; Elymus farctus was the most salt tolerant species tested, and possibly in Barbour's ‘facultative halophyte’ category. Species scores from the first vegetation gradient of an ordination of field data from four dune systems were plotted against results from this study. For some species, root-salinity tolerance correlated with their field position. However, there was little correlation with distributions on West Coast dunes, with some glycophytes growing in the semi-fixed dunes. This was attributable to the high rainfall. On the dry east coast, however, species were more tolerant and their distribution more closely linked to their salinity tolerance. New Zealand dunes contain a mixture of root-salinity tolerant species and root-salinity intolerant species. It is suggested that root-salinity is only one of a complex of environmental factors important on dunes.

Plant communities of the British sand dunes

SynopsisThe National Vegetation Classification has details of some 2000 samples of sand dune vegetation collected nationally. Analysis of these data has resulted in the recognition of about thirteen plant communities of the sand dune system. Details of these communities are presented, elaborating on their species composition, variability, ecological relationships and distribution. As might be expected, the major direction of variation is from strandline, through the vegetation of active dunes, to the fixed dune grasslands, heath and scrub. The precise pattern is affected by the calcium status of the dune and by its geographic location. The vegetation of dune slacks is also dependent on the calcium status of the sand, as well as the amount and persistence of standing water. Superimposed on this natural pattern of variation is the use of dune systems by the grazing of domestic animals as seen on the machair of the Hebrides in particular.

Coastal sand dunes as geomorphological systems

SynopsisThe importance of aeolian deposition is clearly shown by the size and bulk of coastal dunes. Sand dunes occur where there is a large supply of sand, a wind to move it, and a place in which it can accumulate. A dune classification is presented which takes into account the origin, internal geometry and surface geomorphology of coastal dunes. Since the main element that distinguishes coastal dunes from desert dunes is vegetation, the relative amount of vegetation may be used as a typology. Four dune types are distinguished: vegetated dunes, parabolic dunes, medanos (i.e. large sand hills devoid of vegetation), and artificially-inseminated dunes. Vegetated and medano dunes are the end members, with parabolic dunes in between. Parabolic dunes are “anchored” by vegetation, but the centre of the dunes has migrated in the down-wind direction. The artificially-inseminated dunes are formed by vegetation plantings, fencing, or other artificial means, but with natural sand accumulation around these obstacles. These now account for a very substantial portion of the world's coastal dunes.The role of wind and its relation to the internal geometry (i.e. cross-bed dip and direction) are discussed in some detail, with examples from Brazil, U.S. east and south coasts, Israel and China. Differences in these characteristics are detailed, and related to the different modes of formation of the four dune types.The role of the wind in transporting and depositing sand in coastal areas is being quantified through both wind tunnel and field transport measurements. An example from a field study along the coast of Israel illustrates the differences between desert and coastal dune transport, where the role of vegetation and beach topography must be taken into account. From the Israeli study, and others, it appears that transport in coastal dunes is reduced by one-third to one-half of that in deserts, due to these factors.Coastal dunes provide a useful, and often necessary, buffer against storm waves and the presently rising sea level. They form primarily through vertical sand accretion trapped by the sensitive dune vegetation. Provided that sufficient space exists between the high tide line and developed areas, planned dunes can be easily formed with the aid of plantings and fencing.

The grazing of British sand dune vegetation

SynopsisThe herbaceous vegetation of sand dunes is quite strongly influenced by a number of different grazing animals, principally vertebrates. Between 1985 and 1987 forty-eight dune sites were visited and studied, information being recorded on the vegetation and grazing status of 777 quadrats.The results of the survey confirm that the dominant grazing animal in British sand dunes is the rabbit. Over 70% of the quadrats are regarded as being rabbit-grazed directly and over 98% of the dune sites sampled appeared to be affected by rabbit grazing to some extent. Just over a third of the sites were grazed by cattle and a similar proportion by sheep; generally it was either cattle or sheep although five sites were grazed by both. There was only one site significantly grazed by ponies although a number of other sites were grazed occasionally by passing ponies.The intensity of grazing was very variable. Out of the forty-eight sites, three were regarded as being ungrazed and a further ten only lightly grazed, while nine sites were considered to be heavily grazed. However the remaining twenty-six sites were recognised as being intermediate only to the extent of not being obviously overgrazed or undergrazed. It was further recognised that the present state of the vegetation tended to reflect the grazing management in the recent past rather than current practice. A change in the grazing management often took many years to effect a permanent change in the vegetation.The grazing requirements to promote species diversity are very different for the different habitat types. In the yellow dunes the plant community is open with bare ground for colonisation and plant competition is not intense. There is thus little need for the control of plant growth by grazing.Dune grassland, in the narrow sense, needs to be grazed to maintain plant species diversity. The purpose of grazing is to remove prolific growth from the most vigorously growing plants to reduce competition. Lower grazing intensities are needed for all the year round grazing than when grazing is first applied to an area or is a permanent measure for limited periods of the year only.Dune slacks are generally best grazed by cattle and, with the higher soil moisture, grazing intensities can be higher than those applied to dune grassland. Excessive grazing is likely to cause serious damage to both the soil and the vegetation, especially in the wetter areas.Dune heath vegetation has a low productivity and its own special management problems. It needs to be grazed (or cut or burnt) to maintain the internal mosaic by the successful regeneration of the main species, but too much grazing will lead to conversion to a species-poor acid grassland.

A transect study of the sand dune vegetation at Bakers Beach, Tasmania

Vegetation zonation on coastal sand dunes at Bakers Beach consists of Spinifex hirsutus grassland, Helichrysum paralium-Acacia sophorae heath and a complex of Acacia sophorae heath with Lomandra longifolia herbland, the latter community being concentrated in the swales. Melaleuca ericifolia swamp forest occupies the drainage line to the rear of the sand dunes. Although the two seaward zones and the swamp forest may be in equilibrium with the environmental complex, the vegetation on the main body of the dunes has been degraded from its original state by clearing and stock grazing and shows evidence of shifting from its present condition towards communities dominated by Leucopogon parviflorus and Banksia marginata. Eucalyptus viminalis open-forest may have occupied much of this dune system in the past. Floristic variation along a transect through the dunes is closely related to edaphic and topographic conditions, supporting models of soil-vegetation relationships on sand dune systems that have been developed elsewhere in southeastern Australia

The host range and selectivity of a parasitic plant: Rhinanthus minor L.

Rhinanthus minor (Yellow-rattle) is a widespread hemiparasitic plant of grassland habitats throughout Britain. Association analysis of the dune vegetation at Holme-next-the-Sea in eastern England revealed only two potential host plants through positive association. In contrast direct examination of the root systems revealed haustorial connections with 20 host species. The number of species parasitized by one plant ranged from one to seven. Data from another four sites in Britain and one in central Europe indicate that the natural host range of R. minor encompasses at least 50 species from 18 families with 22% in the Leguminosae and 30% in the Gramineae. Comparison of the number of haustorial connections made to each species with the abundance of roots in the soil shows that R. minor is a highly selective parasite, but that the selectivity is not consistent between populations or between plants from different parts of the same population. The reasons for host selectivity are discussed.

The dynamics of the dune vegetation on the Polish Baltic coast

The dynamics of the dune vegetation on the Polish Baltic coast

Phenological and biogeographical aspects of coastal dune plant communities in southern Brazil

The coastline of southern Brazil is characterized by vast sand dunes. From March 1982 to April 1984 the dune vegetation was sampled along a transect between the Atlantic shore and an inland freshwater marsh, and phenological cycles of plant species were observed at monthly intervals.