Evidence for community assembly constraints during succession in dune slack plant communities

Community assembly during succession can be constrained by both local and regional factors. Despite an increasing regional species pool size during succession, we found a limit on the number of species in 1 × 1 m plots in dune slacks. Three alternative hypotheses (habitat heterogeneity, dispersal limitation and niche limitation) explaining this community saturation were tested. A null model analysis showed that species richness in the plots had an unusually low variance suggesting that beta habitat diversity was not likely to explain the limitation on species richness. Because we did not find a correlation between the distribution of species over the slack and their dispersal capacity, we also excluded the dispersal limitation hypothesis. Finally, a guild proportionality analysis revealed that the abundances of forb, graminoid and ruderal species showed low an unusually low variance over all age classes involved. This provides evidence for nonrandom community assembly during succession, likely to be determined by competitive exclusion among species of the same guild.     

The relationship between vegetation dynamics and water table in tropical dune slacks

Abstract. Inundation of tropical dune slacks is an irregular phenomenon produced by consecutive years with high precipitation and also by intense tropical storms. Our hypothesis was that the distribution, structure and composition of vegetation in tropical dune slacks have changed over time as a result of various factors, principally their topographical position with respect to the water table, frequency and duration of inundation, and historical fluctuations in climate. We tested this hypothesis in two different slacks that represent the slack community at the study site. Inundation caused changes in species composition and distribution, as well as in vegetation structure. In one slack, inundation was considered as disturbance because its intensity increased when areas remained inundated for longer periods of time, causing death of vegetation cover and favouring invasion of more aggressive, secondary species (Pluchea odorata, Ambrosia artemisiifolia, Panicum maximum). When inundation lasted less than three months, rhizomatous herbs remained (Cyperus articulatus, Lippia nodiflora, Hydrocotyle bonariensis) inhibiting the succession process. The results suggest that the different degrees of inundation and the irregular frequency and intensity of inundation in the slacks under study, have favoured different successional tendencies.     

Restoration of coastal dune slacks in the Netherlands

In order to stop the continuous decline of typical dune slack communities along the Dutch coast, restoration projects have been carried out since 1952. Restoration measures consisted of re-introducing traditional management techniques in dune slacks, such as mowing, grazing and sod removal, or constructing artificial dune slacks to compensate for lost biodiversity elsewhere. An analysis of successful and unsuccessful projects showed that constructing new dune slacks was not very successful for maintaining new populations of endangered dune slack species, since such projects were often carried out in areas where seed banks were depleted, while hydrological conditions and seed dispersal mechanisms were sub-optimal. The construction of sand dikes to prevent sea intrusion in large beach plains was, unintentionally, a temporary success for the establishment of many Red List species, although such measures often disrupted natural dune slack formation. Successful sites were all characterised by a regular discharge of calcareous groundwater provided by local or regional hydrological systems, where not very long ago populations of typical dune slack plants were present. Under such conditions, sod removal was a successful measure to create pioneer stages which were relatively stable, due to a very slow accumulation of organic matter in the topsoil. It is argued that new and more flexible coastal defence strategies can provide new opportunities for natural and relatively stable pioneer stages of dune slack formation, suitable for the long term preservation of endangered dune slack species.     

Dune Slack Vegetation in Southern New Zealand

A range of slack vegetation in southern New Zealand was described by detailed sampling of four dune slacks, contrasting in topographic situation and in vegetation. Comparison is made with a slack previously sampled on Stewart Island. The five slacks differed markedly in the plant communities present. One slack, where there was considerable peat accumulation, was dominated by the megaherb Phormium tenax and the restiad Leptocarpus similis. In another, the peat was deep and had apparently accumulated over a long period; the vegetation contained the trunked sedge Carex secta and was similar in species composition to carr vegetation described from the region. These two slacks were predominantly native in species composition, though the European Erica lusitanica was a component at the second. The other two slack sites were on substrate largely comprising sand; the vegetation was shorter, and included a mixture of native and exotic species. Many of the exotic species found in these sites have been recorded in European slacks. Communities were defined by Cluster analysis. With rare exceptions, each plant community was specific to one or another of the five sites. Even the few community/site overlaps were in the vegetation of the surrounding dune areas, not of the slack itself. The communities within a site generally formed discrete zones, related to small differences in elevation. The environment was characterised in terms of elevation, water table level, and soil salinity (chloridity), organic content, pH, physical texture and fertility (assessed by bioassay). There were varying amounts of organic matter accumulation, but the mineral part of the substrate was almost pure sand throughout, except that at one site a stream had brought in silt. In three of the sites, the mineral base was below high tide level. The water table fluctuated through the year, with the same pattern as described for Northern Hemisphere slacks. Chloridity was low, but varied through the year. Some features of the yearly variation could be related to weather events. It is concluded that slacks in the area show considerable variation in vegetation, much of which can be correlated with peat accumulation.     

Does the seed bank contribute to the restoration of species‐rich vegetation in wet dune slacks?

Questions: What is the contribution of the seed bank to restoration of species‐rich vegetation in oligotrophic wet dune slacks? Does the restoration management affect the seed bank? Location: Calcareous coastal dune slacks at the west coast of The Netherlands. Methods: Species composition of the seed bank and the above‐ground vegetation was sampled in dune slacks that had a variable extent of groundwater level rise in combination with either topsoil removal or mowing. Results: The seed bank had a high potential for restoration of species‐rich vegetation: 60 species were found in the seed bank of which 14 were characteristic of oligotrophic, wet dune vegetation. While topsoil removal almost completely removed the seed bank, groundwater level rise did not permanently submerge the seed bank of species of oligotrophic, wet conditions. Changes in abundance in the established vegetation were unrelated to species abundance in the seed bank. Of all new species establishments in the vegetation relevés, 76% occurred where the species was not found in the seed bank. The chance that presence of a species in the seed bank led to establishment the following year was only 11%. Conclusion: The seed bank was not the dominant source for newly establishing species following the large disturbance that was induced by restoration management. Changes in species abundance after the restoration impact were not related to species abundance in the seed bank, but to ongoing succession and current year dispersal. To attain a high number of new establishments, restoration projects should preferably be planned in the proximity of refuge populations, rather than relying on the seed bank alone.     

Changes in soil and vegetation during dune slack succession

Many rare plant species occur in Dutch wet dune slacks, particularly in the Junco baltici‐Schoenetum nigricantis. For nature management it is important to understand the processes controlling the presence of these basiphilous early successional communities, which is why we investigated vegetation and soil development during succession in coastal dune slacks. We compared 12 chronosequential stages of 0, 2, 4, 9, 10, 13, 25, 30, 43, 60, 70 and 85 yr in five different dune slack systems. In four of these locations turf had earlier been removed in order to restore the basiphilous pioneer stage. The main variation in the vegetation is related to the acidification/soil enrichment gradient and the salinity/maritime gradient. During succession, organic matter accumulates and acidification takes place. Maritime influence can buffer the soil and postpone the succession of basiphilous pioneer communities for many years. A significant correlation with age was found for 18 variables. Multiple regressions predicted changes in the vegetation (dependent variables: biomass, cover of Salix repens, Calamagrostis epigejos and Schoenus nigricans) as a function of acidification, organic matter accumulation, increase in available P and presence of Na in the soil. We conclude that natural ageing of the vegetation and the associated process of accumulation of biomass drive succession in this hydrosere. The underlying soil processes are acidification and organic matter accumulation. During succession dominance shifts from S. nigricans to S. repens or C. epigejos. Maintenance of the pioneer character of the habitat is only possible by local intervention or by natural or man‐induced dune forming. The effect of sod‐stripping depends on the environmental conditions and, in case of acidification, success is limited. Succession can be postponed by mowing.     

Aspects of the population biology of Liparis loeselii (L.) Rich. var. ovata Ridd. ex Godfery (Orchidaceae) in the dune slacks of South Wales, UK

Demographic techniques have been employed to study populations of the rare orchid Liparis loeselii var. ovata across a range of dune slack habitats at a South Wales site. The study has shown that very large numbers of shoots (>300) may occur within a single 1 times 1 m quadrat and that the vegetative production of side shoots is common. Regular population surveys over time have shown that individuals represented by a single shoot can live for 8 years. Subsequent analyses of the floristic composition of the study quadrats has revealed the presence of subtle variations in species composition and vegetation structure in relation to age and hydrology, although all of the plots still fall within the SD14 Salix repens-Campylium stellatum dune slack community defined by the British National Vegetation Classification. When attributes of population flux are analysed in relation to floristic composition, one significant trend to emerge is that the appearance of new genets is most prevalent in successionally young slacks. As the natural formation of new slacks by sand blow is now a rare event in the South Wales dune field, the management of Liparis loeselii var. ovata is currentiy aimed at attempting to ensure the persistence of suitable communities through biomass reduction techniques.     

Nutrient limitation and vegetation changes in a coastal dune slack

Abstract. Basiphilous pioneer species are among the most endangered plant species in The Netherlands. They find most of their refuges in young coastal dune slacks, especially on the Wadden Sea islands. For the purpose of nature management it is important to know which processes control the presence of basiphilous pioneer communities, and to learn about the nature of slacks harbouring the concerning successional sequences. In a large dune slack on the Island of Terschelling, we assessed soil nutrient status and tested for nutrient limitation in four chronosequential stages: 2, 6, 37 and ca. 80 yr of age. Stage 2 harboured a basiphilous pioneer vegetation; in the stages 3 and 4 a dense vegetation of dwarf shrubs and grasses occurred. Soil organic matter and nutrient concentrations in each stage were measured in 1991. In 1992 and 1993 fertilizers were applied to all stages to detect nutrient limitation. Rates of accumulation of organic matter, nutrients and above-ground biomass were estimated. When interpreted as successional stages, the different stages represent a sequence as expected on the basis of general successional theory. There was a peak in yearly nutrient accumulation between the 6- and 37-yr old stage and a steady state after ca. 80 yr. Between the first two and the latter two stages a shift occurred from allogenic to autogenic succession which correlated with a shift in emphasis from available nutrients to light availability as limiting resources. Basiphilous pioneer species suffered only deficiency of nitrogen, probably because of their low phosphorus requirements. It is concluded that in dune slack habitats, in addition to a low nutrient availability in general, a very low phosphorus availability favours basiphilous pioneer species to species showing co-limitation of nitrogen and phosphorus as found in some grasses and dwarf shrubs. A comparison between the effects of lime addition and the effects of nitrogen and phosphorus additions suggests that, in the early stages, soil buffering increases the availability of nitrogen and inhibits the availability of phosphorus. Sod cutting is an effective technique for restoring basiphilous pioneer vegetation, when slacks are acidified only superficially and buffering-mechanisms can be reactivated. Yearly mowing and removing of standing crop may prolong the life-span of basiphilous pioneer vegetation, when soil acidification has not yet dropped below pH 6.     

Seed bank assembly follows vegetation succession in dune slacks

Question: Is the seed bank in dune slacks during the whole successional range mainly composed of early successional species or does it vary according to the changing vegetation? Location: Belgium, western part of the coast. Methods: We investigated the soil seed bank composition using a seedling germination method in a chronosequence of 20 dune slacks, ranging in age from five to 55 yr. Results: Both seed density and species richness in the seed bank were very low in the first successional stages and increased with age, mainly as a result of increasing seed production. The similarity between seed bank and vegetation was higher in older slacks. A comparison of characteristics between seed bank and vegetation showed that the seed bank was, to a large extent, composed of later successional species. Occurrence patterns of individual species also showed that seeds become incorporated in the soil after the species has established in the vegetation. Conclusion: The seed bank is not likely to be the driving force for successional changes in the vegetation, and successional changes rely on dispersal. Some early successional species persist in the seed bank, but generally only in low numbers. The results also confirm that most typical dune slack species do not form persistent seeds, so that re‐establishment from the seed bank is not to be expected when the species has disappeared from the vegetation.     

Enhanced nitrogen loss may explain alternative stable states in dune slack succession

Ecological theory emphasizes competitive interactions between plant species when explaining primary succession in plants. Ecosystem processes, such as nutrient accumulation, are often regarded as independent, steering successional changes without being affected by the interacting plant species. We present experimental evidence that plant species in wet dune slack systems are able to affect ecosystem processes in their favor by reducing the rate of nitrogen accumulation by coupled nitrification–denitrification, promoting their competitive position. We compared denitrification rates of two early successional species having radial oxygen loss (ROL) with two non-ROL late successional species in a mesocosm experiment. The denitrification rates were significantly higher in mesocosms planted with early successional species Littorella uniflora (P<0.001) and Schoenus nigricans (P<0.05), relative to the rates found in the presence of non-ROL species, Carex nigra and Calamagrostis epigejos . We analyzed the consequences of enhanced nitrogen loss on the competition between an early and a late successional species by means of a simple theoretical model. Our analysis revealed that early successional species capable of ROL might retard successional changes and lock the ecosystem in an unproductive state for an extended period of time. We emphasize that understanding of ecosystem processes is crucial in successful conservation of high biodiversity vegetation in wet dune slacks.     

Can soil seed banks contribute to the restoration of dune slacks under conservation management?

Questions: Does the soil seed bank resemble the former early successional stages of a dune slack system more than the established later successional vegetation? Does it have the potential to contribute to the conservation of a highly endangered habitat? Location: Dune slacks at Newborough Warren, UK. Methods: The composition of the soil seed bank in two depth layers was determined using the seedling emergence method between March 2004 and April 2005. Long-term monitoring data on the floristic composition of the established vegetation were obtained from the national conservation agency, and additional monitoring was undertaken in 2003. Floristic composition, seed weights, seed longevity of component species and Ellenberg indicator values were used to compare the seed bank and established vegetation. Results: The soil seed bank was diverse and contained typical dune slack species, species of early successional stages and species of conservation interest. A comparison between the composition of the seed bank and historical data on the composition of the established vegetation showed that the seed bank reflects earlier successional stages more closely than the current aboveground vegetation. This study increases the scarce information currently available on the seed bank ecology of several species, including two orchid species. Conclusions: The soil seed bank can be expected to contribute to vegetation change after disturbance. Stimulation of germination from the seed bank through management may contribute to the conservation of both characteristic and threatened species typical of dune slacks.     

Vegetation development in dune slacks: the role of persistent seed banks

Abstract. The soil seed bank composition was determined at four sites in the dune slack ‘Koegelwieck’ on the Dutch Wadden Sea island of Terschelling. At three different sites in the slack, where sod-cutting experiments down to the mineral sand had been carried out, the established vegetation and seed bank were assessed after 5, 9 and 39 yr of undisturbed development, respectively. In addition, a fourth site in the slack was investigated, where vegetation development had proceeded for 80 yr since plant colonization of bare soil and where nowadays a vegetation dominated by Calamagrostis epigejos and Salix repens occurs. Together these four sites can be regarded as a chronosequence of dune slack formation. Clear time sequences were detected in the seed bank data. Many late successional species showed a significant increase in the number of seeds during the succession. Some of the early successional basiphilous pioneer species such as Anagallis minima, Centaurium littorale, Littorella uniflora, Radiola linoides and Samolus valerandi, showed either a decrease during the time of succession or an optimum in the vegetation while remaining present in the seed bank in low but detectable numbers. They could, therefore, play a role in re-establishment of the vegetation after sod-cutting. One of the target species, Schoenus nigricans, established within a few years after removal of the sod. However, no seeds of this species have been detected in the soil below either of the successional stages. Based on the species disappearance from the established vegetation and based on the independent data of Thompson et al. (1997) an estimation of seed longevity could be made for several Red List species of wet dune slacks.     

Restoration of Wet Dune Slacks on the Dutch Wadden Sea Islands: Recolonization After Large-Scale Sod Cutting

The effects of sod cutting were studied in a dune area on the Dutch Wadden Sea Island of Texel. Sod cutting was carried out in a range of different dune slacks in order to restore dune slack vegetation with many endangered Red List species. Sod cutting removed approximately 96% of the soil seed bank. Species abundant in the seed bank, notably Juncacea, also had a high frequency in the vegetation that established during the first year after the restoration measures. Many other species not registered in the seed bank or in the former vegetation also appeared. Species richness in the monitored plots exceeded that of uncut reference plots after a few years. Colonization rates were higher than extinction rates in most plots, indicating that a stable state has not been reached after 5 years. Differences in species richness between slacks appeared to be related to the occurrence of source areas nearby and availability of dispersal agents, such as flooding and animals.     

Is succession in wet calcareous dune slacks affected by free sulfide?

Abstract. Consequences of sulfide toxicity on succession in wet calcareous dune slacks were investigated. Sulfide may exert an inhibitory effect on dune slack plants, but several pioneer species exhibit ROL (Radial Oxygen Loss) and thereby protect themselves against free sulfide. Under oxic conditions free sulfide will be oxiginated to harmless sulfate. However, successive species when not capable of ROL may be sensitive to free sulfide and cannot invade the area. Therefore, the occurrence of free sulfide may have a stabilizing effect on the pioneer vegetation. Data on the vertical distribution of oxygen, redox and sulfide were collected in mesocosms with Littorella uniflora or Carex nigra, with and without microbial mats and compared to control mesocosms. Also, in situ data were collected in a dune slack on the Frisian Island of Texel. In the mesocosms, free sulfide was detected only at nighttime in C. nigra populated mesocosms and in unvegetated units, but not in L. uniflora vegetated mesocosms. In the field, sulfide and redox profiles showed distinct differences between the groundwater exfiltration and infiltration site of the dune slack. At the exfiltration site, sulfide was only occasionally found; in contrast, measurable amounts of free sulfide were regularly found at the infiltration site of the slack. Since Phragmites australis dominates in the infiltration site of the slack, the results suggest that free sulfide accelerate the succession, rather than slowing it down by the exclusion of some plant species.     

The vegetation of a New Zealand dune slack

The vegetation of a dune slack at Mason Bay, Stewart Island, New Zealand was found to comprise a mosaic of communities. Although the broad vegetational patterns could be correlated with the depth of the water table, the patterns were far from simple. Species diversity over the whole slack was lower than values reported from European dune slacks; even the most diverse communities did not reach European mean values.For nomenclature see Wilson in press. Vascular plants of Stewart Island. D.S.I.R., Wellington, New Zealand; Sainsbury (1955). A handbook of the New Zealand mosses. N.Z. R. Soc. 5: 1–490 & Hamlin (1972). Hepaticae of New Zealand, Dominion Museum, Wellington.     

Habitat preferences of an endangered insect species,Cepero’s ground-hopper (<Emphasis Type="Italic">Tetrix ceperoi</Emphasis>)

Preventing the global decline in biodiversity is a major task for conservation biologists. Although habitat loss has been identified as a key factor driving extinction processes, our knowledge on the habitat requirements of many endangered species, particularly invertebrates, is still sparse. We present a feasible method to study the microhabitat preferences of insect species. In Central Europe, the endangered Cepero’s ground-hopper, Tetrix ceperoi, is believed to have its only remaining natural habitats in dune slacks of the Wadden Sea Islands. Our results suggest that this species performs an active habitat choice of damp, bare patches with high temperatures. While ponds and fens in dune slacks provide large areas of damp bare ground and algal mats, grasslands, degraded dune slacks and the transitional zone between salt marsh and dunes are less suited as habitats. The major threat for T. ceperoi is found in the succession of its pioneer habitats due to the reduced natural dynamics. In industrialized countries, pioneer habitats and species are threatened substantially by coastal protection and floodplain regulation. This is only compensated in part by anthropogenic creation of secondary habitats, such as different kinds of pits or coal heaps. Nevertheless, there is a strong need for restoration of dynamic habitats by floodplain revitalization and dune slack restoration.     

Relative abundance distributions in plant communities: effects of species richness and of spatial scale

Abstract. Relative abundance distributions (RADs) are an important feature of community structure, but little is known of the factors affecting which type of RAD is observed in a particular community. We examined the influences of species richness and of spatial scale on the RAD of plant communities. The effect of species richness was examined by analysing simulated communities generated under the Broken stick model, the Sequential breakage model, and a randomized version of Niche pre-emption model. In all cases, when there were few species in the community the data only occasionally gave the best fit to the model that was used to generate it. With 40–65 species, a best fit was obtained for the correct model in about 75 % of cases, almost irrespective of the model. Effects of spatial scale were examined in data from four dune slacks and from two semi-arid grasslands, by analysing biomass values at a range of sample sizes. The model that best fitted the whole sample differed between the four slacks and between the slacks and the semi-arid grasslands. The change in which model of RAD fitted best, as sample size was reduced, varied between sites and between habitat types. At the smallest sample sizes, the Zipf-Mandelbrot model often fitted, and in the slack sites the Broken stick also, though neither fitted (in the vegetation examined) at larger spatial scales. It is concluded the RAD is affected by species richness and by spatial scale, in ways that currently do not enable simple prediction. RADs can theoretically give information on the processes such as resource partitioning, immigration and competition that have structured the community, but they are a blunt tool for this purpose.     

Accumulation rates of soil organic matter in wet dune slacks on the Dutch Wadden Sea islands

Background and aims

A long-term monitoring program (ranging from 16 to 77 years) on the Dutch Wadden Sea Islands provided well-documented examples of vegetation succession in wet dune slacks. We used this opportunity to study soil organic matter (SOM) accumulation in relation to vegetation succession. The aim of this paper is to identify the factors which regulate accumulation rates of SOM in wet dune slacks.

Methods

We used several soil chronosequences using data from the monitoring program together with data from a long-term research activity and more recent measurements. We used several soil chronosequences using data from the monitoring program together with data from a long-term research (up to 150 years) and more recent measurements. Field measurements included pH, soil organic matter, above ground standing crop and water levels. Water level regimes (inundation duration and mean minimum water level), were simulated using a hydrological model. Capable of simulating inundation duration and water-level fluctuations, this model used field measurements collected over more than 5 years, as well as precipitation and evapotranspiration data collected over a period of 25 years.

Results

Sampling two synchronic chronosequences showed that SOM accumulations increased linearly during the first 50–60 years and then levelled off. Sampling various diachronic chronosequences over time showed a wide variation in accumulation rates. Slacks with low productive species, such as Littorella uniflora, showed low accumulation rates (0.02–0.08 kg/m²/year), and persisted even over a period of more than 90 years. In contrast, slacks dominated by high productive species, such as Phragmites australis, showed ten times higher accumulation rates (0.17–0.26 kg/m²/year) over a similar time period and comparable annual inundation periods (176–240 days). A multiple linear regression showed that variation in SOM accumulation rates was best explained by above-ground biomass of the vegetation.

Conclusions

We conclude that the rate of SOM accumulation in wet dune slacks is primarily controlled by plant above-ground biomass. Both above-ground biomass and SOM accumulation can remain very low over a long period of time when dune slacks are flooded during most of the year and plants with adaptive traits are able to maintain vegetation succession at a pioneer stage.     

Genetic diversity and ecological differentiation in the endangered fen orchid (<Emphasis Type="Italic">Liparis loeselii</Emphasis>)

Liparis loeselii is a rare and endangered orchid occurring in Europe and north-east America. Genetic diversity and structure of this species in north-west France and the United Kingdom were investigated using amplified fragment length polymorphisms (AFLPs). Although clonality and autogamy are common in L. loeselii, we found moderate to important variability within populations. We observed a significant genetic differentiation between populations occurring in dune slacks and fens. This may be correlated with leaf shape as dune slack individuals are sometimes treated as the distinct variety L. loeselii var. ovata. Genetic differentiation between populations was generally low suggesting that gene flow can occur over long distances and possibly across the English Channel. These results show that populations from dune slacks and fens should be managed separately and that geographically distant populations may be equivalent.     

Changes in nutrient heterogeneity along sand dune and slack chronosequences at Tentsmuir Point,Eastern Scotland

Summary

Recent models have attempted to explain species coexistence and community structure by resource heterogeneity at a spatial scale below that of the individual plant. In this paper, we examine how heterogeneity changes through time. A comparative study of the heterogeneity of pH, phosphate, nitrate and nitrite levels was made within and along a transect inland from the shore at Tentsmuir Point, Fife, Scotland, an example of primary sand dune succession. This locality provided marked topographic relief created by dunes and slacks, and a well-characterised chronosequence. Soil samples were taken at the intersections of grids in quadrats. To examine macroscale heterogeneity in soil constituents, these intersections were 1 m apart in each direction in a large quadrat (5 m × 2m); for microscale heterogeneity they were 0.1m apart in a smaller quadrat (50 cm × 20 cm).

Mean concentration levels, and spatial heterogeneity of the values of nutrients and pH changed with time through the stages of the succession. pH and nitrate showed a simple decrease with time, whereas the other nutrients showed a more complex pattern of change.

Microscale heterogeneity was found to be greater than macroscale heterogeneity. Furthermore, principal components analysis of the two data sets showed differences in the main axes of variation, such that in the macroscale data set the main axis showed a trend from dune sites, through fresh water slacks to those influenced by salt water, while in the microscale data set the main axis related to levels of nitrogen.

‘The natural world is a patchy place … from the arrangement of continents and oceans to the alternation of the solid grains of beach sand and the spaces between them.’ (Dale, 1999)