Showing papers in "Journal of Coastal Conservation in 1997"
TL;DR: The Ebre (Ebro) Delta is one of the most important wetland areas in the western Mediterranean as mentioned in this paper, and its mean rates of secular subsidence in the Ebre Delta and eustatic sea level rise are ca. 1 -2 mm/yr.
Abstract: The Ebre (Ebro) Delta is one of the most important wetland areas in the western Mediterranean. Ca. 40 % of the delta plain is less than 0.5 m above mean sea level and part of the southern margin of the delta is at mean sea level in an area protected by dikes. Both mean rates of secular subsidence in the Ebre Delta and eustatic sea level rise are ca. 1 – 2 mm/yr. Thus, the present annual relative sea level rise (RSLR) rate in the Ebre Delta may be at least 3 mm/yr. Measured accretion rates in the delta range from 4 mm/yr in the wetlands surrounding the river mouth to 99 % of the riverine sediments are retained in the reservoirs and rice fields are losing ca. 0.2 mm/yr.
80 citations
TL;DR: In this article, aeolian sediment dynamics on a coastal foredune on the Dutch Wadden island of Schiermonnikoog were studied from November 1990 to May 1991.
Abstract: Sediment dynamics on a coastal foredune on the Dutch Wadden island of Schiermonnikoog were studied from November 1990 to May 1991 to get an insight into rates and frequencies of aeolian processes. Digital Terrain Models were constructed to describe volume changes and zonation of deposition. Recording of heights were related to important events. Three periods are distinguished: (1) a period with storm surges resulting in dune erosion, (2) a winter period with mainly offshore winds; (3) a period with several days with strong onshore winds, resulting in dune building. In these periods detailed meteorological measurements and observations of aeolian sediment transport rates were performed. This paper presents comparisons between volumetric changes as derived from DTM calculations and calculated aeolian transport based on meteorological observations and current transport equations. The main conclusion is that only during a part of the year the observed changes in volume correspond reasonably well to the predicted transport, using standard transport equations and meteorological measurements.
65 citations
TL;DR: In this paper, an inner dune area in the Dutch coastal dunes several artificially stabilized blowouts were reactivated and the purpose was to investigate whether these reactivated blowouts could remain active despite the increased atmospheric deposition of nutrients, how much area would be affected by sand from the blowouts, whether the vegetation would respond to the deposition of sand, and whether the reactivation of blowout could be a measure against acidification and eutrophication.
Abstract: In an inner dune area in the Dutch coastal dunes several artificially stabilized blowouts were reactivated. The purpose was to investigate whether these reactivated blowouts could remain active despite the increased atmospheric deposition of nutrients, how much area would be affected by sand from the blowouts, whether the vegetation would respond to the deposition of sand, and whether the reactivation of blowouts could be a measure against the effects of acidification and eutrophication.
61 citations
TL;DR: In this paper, the authors compared salt marsh development on the coastal barrier island of Schiermonnikoog (the Netherlands) with two other salt marsh systems in the Wadden Sea.
Abstract: Salt marsh development on the coastal barrier island of Schiermonnikoog (The Netherlands) was compared with two other salt marsh systems in the Wadden Sea. Accretion rate, nitrogen accumulation and changes in plant species composition were investigated using chronosequences. The age of the marsh was estimated from aerial photographs and old maps. In 7230 plots, the elevation of the marsh surface, the thickness of the sediment layer (clay) and the presence of plant species was recorded. In addition, the nitrogen pool was measured at each successional stage. Accretion rates were similar in the three salt marshes. Higher accretion rates were found at younger marshes. A strong linear relationship between nitrogen pool size and thickness of the clay layer was found for the three marshes. The accumulation rate of nitrogen is therefore strongly related to the accretion rate. Thus, more nitrogen is present in the sediment of later successional stages where more clay has accumulated. On the high salt marsh (55 cm+MHT),Ameria maritima disappeared andArtemisia maritima, Juncus gerardi andElymus athericus established at sites with a thicker clay layer. On the low salt marsh (25 cm+MHT),Plantago maritima, Puccinellia maritima andLimonium vulgare disappeared andAtriplex (Halimione) portulacoides established. Apparently, with the accumulation of clay and therefore of nitrogen, tall growing species take over in salt marshes not grazed by livestock.
56 citations
TL;DR: In this paper, the results from monitoring over decades are discussed in view of the knowledge on succession over centuries as derived from a chronosequence, and the results of the monitoring are discussed.
Abstract: After a formerly grazed salt marsh was released from cattle grazing, changes in plant species composition were monitored for 20 yr, using vegetation maps and permanent plots. Three areas, differing in age and nutrient status were compared. The number of plant species and plant communities decreased.Elymus athericus (Elytrigia pungens) became dominant in most plant communities after 5–20 yr on the oldest and most productive salt marsh. In younger areas it took more time forE. athericus to become dominant. At least 7 cm of clay seemed to be a prerequisite for this plant species to increase in dominance. The results from monitoring over decades are discussed in view of the knowledge on succession over centuries as derived from a chronosequence.
53 citations
TL;DR: A review of results of fertilization experiments in wet dune slacks is presented in this article, where the above-ground biomass appeared to be limited by nitrogen availability, while the characteristic basiphilous pioneer species (including mosses) decreased or even disap- peared.
Abstract: A review of results of fertilization experiments in wet dune slacks is presented. In most cases the above-ground biomass appeared to be limited by nitrogen availability. Pri- mary phosphorus limitation was assessed only once in a dune slack where sod cutting had been applied very recently. In most other case studies phosphorus limits biomass production after nitrogen deficiency was lifted. Potassium availability is of minor importance for biomass production in this type of ecosystem. Singular nitrogen additions led to increased domi- nance of Carex and Juncus species as well as perennial grasses, such as Agrostis stolonifera and Calamagrostis epigejos. A combined addition of nitrogen and phosphorus led to total dominance of grasses, while the characteristic basiphilous pioneer species (including mosses) decreased or even disap- peared. Certain mechanisms are considered which may main- tain nutrient availability in slacks with basiphilous pioneer vegetation at a low level, despite of the accumulation of nutrients in the developing organic soil layer. Some implica- tions for management and further research are discussed.
40 citations
TL;DR: In this article, the authors investigated differences in vegetation and soil properties between grass-dominated and still existing open dune grassland plots at four locations along the coast, and concluded that grass encroachment is probably triggered by atmospheric deposition and is enhanced by positive feedbacks in the N-cycle.
Abstract: The encroachment of some tall grass species in open dune vegetation, as observed in a Dutch dry dune area, is considered unfavourable from a conservation viewpoint. This paper investigates differences in vegetation and soil properties between grass-dominated and still existing open dune grassland plots at four locations along the coast. Soil properties studied include nitrogen and phosphorus pools and nitrogen availability by mineralization. Vegetation properties included are above and below-ground biomass and nitrogen and phosphorus concentrations in above-ground biomass. Systematic differences in N-pools between grass-dominated and open dune grassland plots were not observed. However, N-availability by mineralization and its turnover rates are higher in grass-dominated plots than in open dune grassland plots, as well as above and below-ground biomass. In open dune grassland plots, atmospheric N-input is an important source of N, whereas in grass-dominated plots mineralization largely exceeds atmospheric N-input. However, these observations do not explain the mosaic-like vegetation pattern. Grazing intensity is most likely the determinant factor in the dry dune system. It is concluded, that grass encroachment is probably triggered by atmospheric deposition and is enhanced by positive feedbacks in the N-cycle. The relevance of these results for restoration management is briefly discussed.
38 citations
TL;DR: The idea that microbial mats may assist in extending the life span of early pioneer stages during dune slack succession by inhibiting the growth of species of later successional stages is supported.
Abstract: Laminated microbial mats from a sandy beach plain were grown in water-saturated pots in a glass house for six months and then used to assess their effect on the establishment of juveniles of three plant species representing different successional stages in dune slack development. The selected species wereSamolus valerandi, characteristic of pioneer stages,Calamagrostis epigejos, characteristic of more productive, late successional stages, andJuncus alpinoarticulatus, which occurs in a wide range of successional stages. Juveniles of all three species that were placed on top of intact living microbial mats established themselves in the mat.C. epigejos andJ. alpinoarticulatus survived for several weeks but later on their numbers decreased and the total biomass production of the species after six months was poor.S. valerandi, in contrast, grew profusely in intact microbial and algal mats. Heating of the microbial mat by heat sterilization, prior to the experiment, did not improve the performance of the species. When the juveniles were planted in the microbial mats after breaking the surface of the mat, the survival of juveniles ofC. epigejos andJ. alpinoarticulatus was much higher and so was the biomass of surviving plants after six months. Planting ofSamolus in the mats had some positive effect on the survival percentage of the juveniles, but not on the total biomass at the end of the experiment. Slightly lower water tables had a negative effect on the performance of all species. Measurements of the pH in the pots revealed that there were no significant differences in the top layer. Sulphide concentrations were very low in all the pots where juveniles had been planted and also in the pots withS. valerandi. Relatively high concentrations (30–50 μmol/l) were found in pots with poor growth ofJuncus andCalamagrostis plants. These values may exceed toxic levels for these species. Although oxygen concentrations in the pots were generally low, no relation existed between plant biomass and oxygen content, indicating that plant growth was not primarily limited by oxygen stress. These experiments support the idea that microbial mats may assist in extending the life span of early pioneer stages during dune slack succession by inhibiting the growth of species of later successional stages.
28 citations
TL;DR: It was concluded that in wind-blown sand the pathogen inoculum is reduced, and serious consideration should be given to allowing controlled reactivation of blow-outs to rejuvenate decliningmmophila in stabilized foredunes.
Abstract: In stabilized dunesAmmophila arenaria (marram grass) degenerates due to a process involving soil-borne pathogens and parasites. This leads to exposure of the sand surface so that wind erosion may create blowouts.Ammophila rejuvenates on the edges of the blowouts, where the sand has accumulated. We tested the hypothesis that such rejuvenation of plants may be related to a reduction of the plant-parasitic nematodes and fungal propagules during the process of wind-driven transport.
26 citations
TL;DR: In 1990, the Dutch government decided to stop any further long-term landward retreat of the coastline as discussed by the authors, which was mainly aimed at safety against flooding and at sustainable preservation of the values and interests concerning the dunes and beaches.
Abstract: In 1990 the Dutch government decided to stop any further long-term landward retreat of the coastline. This policy choice for a ‘dynamic preservation’ is primarily aimed at safety against flooding and at sustainable preservation of the values and interests concerning the dunes and beaches. Five years later, a first overview of the benefits and bottlenecks of the new coastal defence policy could be presented, which was published in the second governmental coastal report ‘Kustbalans 1995’ (coastal balance 1995). This consists of three elements: (1) evaluation of the implementation of ‘dynamic preservation’, (2) the consequences of several natural and anthropogenic developments in the coastal zone and (3) integrated coastal zone management. The present report describes experiences of Dutch coastline management and summarizes the main conclusions of the second governmental report.
25 citations
TL;DR: In this article, the above and below ground biomass and nitrogen and carbon composition of Spartina maritima, Halimione portulacoides and Arthrocnemum perenne, dominating species in plant communities of the lower, middle and higher salt marsh, respectively, were compared in an estuarine salt marsh in Portugal.
Abstract: Above and below-ground biomass and nitrogen and carbon composition ofSpartina maritima, Halimione portulacoides andArthrocnemum perenne, dominating species in plant communities of the lower, middle and higher salt marsh, respectively, were compared in an estuarine salt marsh in Portugal. Plant and soil nitrogen and carbon pools were estimated. For all three species root biomass was significantly higher (70–92% of total biomass) than above-ground biomass. The percentage of root biomass was related to the location of the plants in the marsh: higher values were found in plants growing in the lower salt marsh where the sediment was more unstable and subject to tidal action, which stresses the role of the roots as an anchor. For all three species nitrogen concentrations were highest in leaves, reflecting the photosynthetic role of the tissue. For carbon higher concentrations were found in the stems, with the exception ofS. maritima. In general, lower nitrogen concentrations were found in summer, which can be explained by dilution processes due to plant growth. For both nitrogen and carbon, higher concentrations were found in the soil surface layers. Higher soil nitrogen and carbon levels were associated with higher organic matter contents. Most of the nitrogen in the salt marsh occurred in the sediments (0–40 cm) and only ca. 5.7–13.3% of the total was found in the plants. The greater portion (76.5%–86%) of carbon was found in the sediment.
TL;DR: In this article, the possible impact of a sea-level rise of this magnitude on coastal habitat types is discussed for three case studies, based on previous investigations of vegetation, topography and soil of localities at the Baltic coast of Denmark.
Abstract: According to estimates from the Danish Meteorological Institute global warming until 2080 may cause a relative sea-level rise in Danish waters of 33–46 cm. In the present paper the possible impact of a sea-level rise of this magnitude on coastal habitat types is discussed for three case studies, based on previous investigations of vegetation, topography and soil of localities at the Baltic coast of Denmark.
TL;DR: In this article, the authors report on a primary succession on a beach plain on the Dutch Wadden island of Schiermonnikoog and conclude that the different stages of succession and associated diversity of plant species only can persist through the maintenance of the natural dynamics of the area.
Abstract: This study reports on a primary succession on a beach plain on the Dutch Wadden island of Schiermonnikoog. Vegetation succession started in 1959 when a sand dike was constructed to prevent structural erosion of the area by storm floods. Since then the sandy beach behind the dike has been protected from the direct influence of the North Sea. Heavy storms in 1972, however, created a large gap in the dike which has remained open since. Occasional storm floods during winter penetrate deeply into the area and salt water can cover parts of the beach plain for several months. This had a pronounced impact on the vegetation. Vegetation maps for six different years and data from a permanent plot have been used to reconstruct vegetation succession over a 42-yr period. Certain parts of the area seem to have changed little, while others have developed a grassland or scrub cover. The heavy storms and associated processes such as sand blowing, intensive flooding and increased salinity have created a disturbance/stress gradient of progressive and regressive succession across the beach plain. In certain places the vegetation cover has repeatedly been destroyed and succession re-initiated. It is concluded that the different stages of succession and associated diversity of plant species only can persist through the maintenance of the natural dynamics of the area.
TL;DR: In this paper, the authors dealt with spatial and temporal variation in the chemical composition of the groundwater in the upper metres of the soil of a degraded dune slack complex on the Dutch barrier island of Schiermonnikoog, with emphasis on groundwater composition, water level and decalcification patterns.
Abstract: Basiphilous, open, species-rich vegetation types of young dune slacks have declined throughout Europe in recent years, and have largely been replaced by often acidophilous, tall marsh and scrub vegetation. This succession appears to be accelerated by a decrease in the discharge of calcareous groundwater from sandy ridges or small dune hummocks. The present study deals with spatial and temporal variation in the chemical composition of the groundwater in the upper metres of the soil of a degraded dune slack complex on the Dutch barrier island of Schiermonnikoog, with emphasis on (1) groundwater composition, (2) water level and (3) decalcification patterns. The main aim was to assess perspectives for restoring basiphilous vegetation types which had been abundant in this slack from 1954 to 1977. The depth of decalcification was related to former hydrological conditions along a transect of 200 m. Acidifying effects of rainfall were reflected in the chemical composition of the groundwater below small dune hummocks within the slack. Distinct precipitation water lenses, poor in dissolved ions, were formed under the dune hummocks during a wet period. This microtopography did not contribute to the discharge of calcareous groundwater to lowlying parts of the slack. Here, groundwater showed decreasing concentrations of the dissolved ions after a rain shower. Except for the peripheral sections of the slack—where upward seepage of groundwater (exfiltration)still occurs—infiltration conditions are now dominant in the slack. The consequences of the present hydrological conditions for restoration are briefly discussed.
TL;DR: Beach conservation and management on the high-value French Riviera in southeastern France have had mixed fortunes in shoreline economic development strategies over the past half century as mentioned in this paper, leading in particular to beach erosion and degradation of beach environmental quality.
Abstract: Beach conservation and management on the high-value French Riviera in southeastern France have had mixed fortunes in shoreline economic development strategies over the past half century. Prior to 1965, socio-economic growth related to immigration and tourism resulted in considerable pressure on the coastal zone, leading in particular to beach erosion and degradation of beach environmental quality. Between 1965 and 1980, over 20% of the 132 km-long French Riviera was permanently altered through the implantation of yachting harbours and reclamation fill structures, while beach-based recreation had a rather low ranking as a development choice, except in the two major resorts of Cannes and Nice which exhibit a densely urbanized seafront. On this preponderantly bold rocky coast, the mediocre recreational value inherited by many of the beaches from the regional geologic setting, and from development pressures and earlier errors in coastal management, left them vulnerable to appropriation and so-called ‘valorization’ by yachting harbour and estate developers. Over the last decade, artificial shoreline development has virtually ceased, in response to several more or less interrelated factors. These include relative stagnation of socio-economic growth, increasing development and maintenance costs of yachting harbours, saturation of the yachting harbour market as a result of the burgeoning of new, often cheaper, resorts and of reconversion of commercial and shipbuilding ports to leisure ports in the Mediterranean, more stringent legislation, since 1986, on the implantation of residential and major engineering structures on the coastline, pressure for conservation of the cultural and environmental heritage, and greater demand for beach recreational space. This situation has forced a diversification of shore-based activities, as it has been realised that better managed beaches may balance economic aspirations while contributing to enhanced environmental quality and sensible shoreline conservation. This change in strategy has entailed considerable efforts and money on the improvement of coastal water quality, the provision of amenities for beach-goers, and especially the nourishment of eroding beaches and the creation of several artificial beaches. The extent to which beaches will continue to play a role in the sustainable development of French Riviera resorts will depend largely on the capacity of local authorities to maintain environmental quality in the face of inherited and persistent handicaps such as beach erosion.
TL;DR: In this paper, the initial vegetation development of traditionally planted stands with stands established from seeds and from rhizomes was compared on an artificial foredune originating from dredged sea sand.
Abstract: In coastal foredunes marram grass (Ammophila arenaria) is used to stabilize windblown sand. The development of traditionally plantedAmmophila into a more natural foredune vegetation may take 5–10 yr. For economic reasons, traditional planting may be replaced by alternative techniques such as planting seeds or disk-harrowing rhizome fragments. In this paper, we compare the initial vegetation development of traditionally planted stands with stands established from seeds and from rhizomes. The experiments were conducted on an artificial foredune originating from dredged sea sand. The total experimental area covered more than 100 ha and the vegetation development was studied for 6 yr. The data were analysed bya priori grouping of plant species according to their ecology, as well as by Principal Components Analysis (PCA) and Redundancy Analysis (RA) of the percentage ground cover per plant species. Comparing ecological groups of plants showed that all planting methods delivered equal numbers of plant species that are indicative for coastal dunes. PCA and RA showed that methods based on the use of rhizome material resulted in a higher percentage cover of clonal perennials (Calammophila baltica, Festuca rubra ssp.arenaria, Carex arenaria andCirsium arvense) than the traditionally planted stands and the stands obtained from seeds. The latter two were characterized by the dominance of annuals, bi-annuals and (mostly nonrhizomatous) perennials. Initially, the rates of succession were highest in the stands obtained from rhizomes. However, after 3–6 yr there were no differences between the various stands. During the first four years, the percentage cover by rhizomatous foredune plants developed faster than that of annuals, bi-annuals and perennials. After 6 yr, the latter contributed almost as much to the percentage cover as the clonal species.
TL;DR: In this article, the effects of nitrogen addition on the growth of the salt marsh grass Elymus athericus were studied under greenhouse conditions, and the addition of inorganic nitrogen (in the form of nitrate or ammonium and ranging from 0-24 g N/m2) stimulated the growth.
Abstract: Effects of nitrogen addition on the growth of the salt marsh grassElymus athericus were studied under greenhouse conditions. The addition of inorganic nitrogen (in the form of nitrate or ammonium and ranging from 0–24 g N/m2) stimulated the growth ofElymus athericus at the highest addition. Addition of nitrogen led to an increase of the soil nitrate concentrations both in the nitrate and ammonium treated soil in the first period of the experiment, whereas no differences were present at the end of the experiment. Ammonium in the ammonium treatments was transformed to nitrate within 15 days.
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TL;DR: In this article, a 1.2 km × 1.1 km area, which includes zones with different degrees of conservation and perturbation, consisting of five different habitats, was selected: well preservedJuniperus woodland, Pinus pinea plantations with dense scrub, dense scrub and pioneer scrub in recent pine afforestation.
Abstract: In the asperillo dune system, Southwest Spain, lichen vegetation covering the dune sand, has a low species diversity but is an important component of the perennial vegetation, providing stability, nutrients, and moisture to the soil layer. The Asperillo dunes harbour (1) natural ecosystems, (2) disturbed systems affected by forestry activities where the natural vegetation is eliminated, and (3) pine forest resulting from afforestation withPinus pinea since the end of the 1940s where the composition and abundance of the lichen flora has been drastically changed. Our hypothesis was that the lichen species composition and distribution are influenced by the type and period of human intervention. To test this hypothesis a 1.2 km × 1.1 km area, which includes zones with different degrees of conservation and perturbation, consisting of five different habitats, was selected: well preservedJuniperus woodland,Pinus pinea plantations with dense scrub, dense scrub,P. pinea plantations cleared from scrub, and pioneer scrub in recent pine afforestation. In each area, randomly located 5m × 5 m homogeneous plots were sampled. In each plot the cover of shrub and lichen species was recorded. The first results show that lichen cover is higher in the most preserved areas,Cladonia mediterranea being the dominant species under theJuniperus phoenicea canopy. The lichen community changes in composition and abundance depending on the time elapsed since the last perturbation.
TL;DR: In this paper, changes in surface elevation in a former blowout in the coastal dunes of Meijendel, The Netherlands, have been monitored almost weekly during one year at 48 erosion pin sites, distributed over 12 units.
Abstract: Changes in surface elevation in a former blowout in the coastal dunes of Meijendel, The Netherlands, have been monitored almost weekly during one year at 48 erosion pin sites, distributed over 12 units. The units are characterized by specific geomorphological processes. The changes in elevation are caused by wind, slope wash and mass movements. At almost each pin, periods of erosion alternate with periods of accumulation in a random way. Erosion and accumulation sequences are relatively long in areas dominated by aeolian activity, but even here they are randomly distributed. It is the balance between the effects of periods of erosion and periods of accumulation which determines the formation of blowouts or dunes.
TL;DR: In this article, the results of 12 years of hydrological monitoring at the St. Fergus dune system in northeastern Scotland were reported, where the dunes include a substantial freshwater wetland which is seasonally flooded and provides an important habitat for waterfowl.
Abstract: This paper reports the results of 12 years of hydrological monitoring at the St. Fergus dune system in northeastern Scotland. The site is adjacent to the UK’s largest gas terminal and the dunes are crossed in five places by North Sea gas pipelines which were constructed between 1976 and 1990. These are buried beneath the dune system which was restored after pipeline installation. The dunes include a substantial freshwater wetland which is seasonally flooded and provides an important habitat for waterfowl. The hydrogeology of the site is characterized and the hydrogeological processes that sustain this wetland feature are considered including recent climatic fluctuations.
TL;DR: In Europe, Britain was relatively early in being aware of the necessity of conserving natural coastal sites, though not as early as The Netherlands as discussed by the authors, and the promptness of the British reaction was a result of a sensitive public opinion and of powerful private trusts (National Trust with Enterprise Neptune) rather than of a commitment by the Government.
Abstract: In Europe, Britain was relatively early in being aware of the necessity of conserving natural coastal sites, though not as early as The Netherlands. In the 1960s and 1970s, increasing economic and tourist pressures in Europe prompted measures geared to the protection of other coasts in Europe. The promptness of the British reaction was a result of a sensitive public opinion and of powerful private trusts (National Trust with Enterprise Neptune) rather than of a commitment by the Government. In France a specific organization, in part inspired by the British principle, was set up. However, the French system is based much more on a public authority, theConservatoire de l’Espace Littoral et des Rivages Lacustres and on legislation (Coastal Law of 1986). Although very different in the beginning, French and British conservation politics today show many similarities, along with the similarities in the concerns of both countries.
Abstract: In 1994, the sinking of the ‘Apollo Sea’ off the West coast of South Africa led to the deposition of ca. 2 500 tons of heavy fuel oil over 150 km of coastline. The impact of the spill on rocky shore invertebrates, rock-pool fish fauna and rock lobsters was assessed by conducting surveys shortly after the spill, and again two months later. Where possible, results of these surveys were compared with existing data from before the sinking of the Apollo Sea. Among the fish fauna of rock-pools, changes in total density of fishes were largely due to changes in the abundance ofClinus superciliosus and were within the range of natural variation for the species and the community as a whole. Community structure of the rock-pool fish fauna also remained unaffected.
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