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Ecological restoration of coastal sand dunes: Guincho beach study case (Portugal)

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The Guincho beach dunes account for a small portion of the Guincho-Oitavos dune complex located in Sintra-Cascais Natural Park (Portugal). It is a system exposed to intense anthropogenic pressure that has led to its degradation. To recover its natural value requires measures of restoration and protection. Habitat management actions have been aimed essentially to ease and manage the impacts on the sand dunes, through the installation of biophysical structures (which reduce the wind speed and promote sand deposition), planting of characteristic species (e.g. Ammophila arenaria) plus the removal of nonnative species (e.g. Acacia sp. pl.). The material for constructing biophysical structures was based on bibliography and installed on the primary frontal dune, perpendicular to the prevailing wind direction. The levels of sand accumulated by the biophysical structures were monitored. Four years after intervention, the planted native species are now well-established and natural vegetation occurs spontaneously, although it has been necessary to replace some plants and sections of biophysical structures. Modelling sand accumulation and monitoring the establishment of vegetation continues.
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ISSN: 2013-2939
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With the support of:
101
Ecological restoration of coastal sand
dunes: Guincho beach study case
(Portugal)
Vasco Silva1, Irene Correia2, Alexandre Neto3, José Romana2 and Sara Saraiva2
1 Centro de Ecologia Aplicada Prof. Baeta Neves, Instituto Superior de Agronomia, Universidade de Lisboa, Lisboa, Portugal.
2 Department of Natural Areas, Cascais Ambiente – Empresa Municipal de Ambiente de Cascais, Alcabideche, Portugal
3 Direcção-Geral de Recursos Naturais, Segurança e Serviços Marítimos, Algés, Portugal
102
1. Abstract
The Guincho beach dunes account for a small portion of the Guincho-Oitavos dune complex located in
 
has led to its degradation. To recover its natural value requires measures of restoration and protection.

       
Ammophila arenaria
Acacia
bibliography and installed on the primary frontal dune, perpendicular to the prevailing wind direction. The
levels of sand accumulated by the biophysical structures were monitored. Four years after intervention,
the planted native species are now well-established and natural vegetation occurs spontaneously,

sand accumulation and monitoring the establishment of vegetation continues.
2. Introduction
The Guincho-Cresmina sand dunes account for a small part of the Guincho-Oitavos dune complex,

This dune system, known as the Cresmina-
      
as the sand coming from the Guincho and
Cresmina beaches returns to the sea further
south, between Oitavos and Guia, after
  
et al
The Guincho-Cresmina dune system is
active on account of the constant drifting of
sand particles blown by the prevailing winds


    
    
     
corridor and thus accelerated its dynamic.
    
sediments began to appear in an area further
away from the coastline, with a consequent
        

103

et al

In the long term, these circumstances may have dramatic impact and cause a loss of arable soil,
     
et al
On account of their dynamic nature, the natural habitats exhibit a delicate ecological balance, with a

et al
is a system subject to strong anthropogenic pressure, which has led to its degradation, and in order to
safeguard its natural value requires restoration and protection measures as recommended in the Coastal

The main purpose of this study is to characterize the Guincho-Cresmina dunes and analyze the
response to the installation of biophysical structures on embryonic and primary dunes with a view to
et al
essentially to restore and manage impacts on the beach-dune system through the implementation of

et al

104
2.1. Previous experience of dune restoration in Portugal and
characterization of the method used
On the west coast of Portugal and of the Algarve, where there is both severe coastal erosion and

  et alet al
or through the implementation of what are known as “ripado móvel
recently, garden shadow net attached to treated wood trunks was used to trap sand in the Peniche-
    et al           
             
 et al      
simple to acquire and easily assembled, and pose no environmental hazard. This system counteracts
wind erosion and yields a more extensive homogeneous accumulation of sand, thus achieving much
et al
pioneer vegetation naturally plays in dune formation. Its function is to reduce wind speed and therefore
            

et
al       
restoring dunes than earlier techniques implemented in Portugal.
2.2. Biophysical characterization
The Guincho-Cresmina coastal dune system is quite unique
as the sand from these beaches returns to the sea further
south, between Oitavos and Guia, after migrating through the
 
active, semi-open and extremely unstable on account of the
coastal morphology, orientation and constant mobilization of

The dune system overlaps the Cretaceous limestone layers
 et al
The area of intervention corresponds to the aeolian corridor
entrance, where for morphological reasons wind velocity is

amount of sand depends on the coastal drift of sediment
         
availability and transportation of sand can be observed
during the summer. Prior to intervention, the formation of
ripples, sand sheets and hummocky dunes was observed

      
parabolic dunes. Adapted from Roxo et al
105



et al
     
       
         
et al              
previously halonitrophile vegetation Salsolo kali-Cakiletum maritimae
missing on account of high anthropogenic pressure, although occasional specimens of Cakile maritima
         Elytrigia juncea subsp.
boreoatlantica (Elytrigietum junceo-boreoatlantici
Ammophila
arenaria subsp. arundinacea, Lotus creticus, Otanthus maritimus, Eryngium maritimum and Pancratium
maritimumLoto cretici-Ammophiletum australis

of Juniperus turbinataOsyrio quadripartitae-Juniperetum turbinataeet al
et al   Armeria welwitschii
Tuberarietea guttatae in the clearings. On
stretches of waterline, which are subject to long periods of drought, there are Tamarix africana or Tamarix
gallicaPolygono equisetiformis-Tamaricetum africanae)

were observed in the community of Armeria welwitschiiet al

106
     

          

2.3. Habitat management actions
The ecological restoration of the sand dunes of Guincho beach and the reestablishment of vegetation

material, as well as the distance between the rows of the biophysical structures, were established with
et al


Order Action Procedure
   
   Carpobrotus edulis
  Acacia pycnantha, A. retinodes
   
   
embryonic and primary perpendicular to the direction of the prevailing wind, placed
dune vertically where vegetation was absent and distributed
  
  Elytrigia juncea ssp. boreoatlantica on the embryonic
herbaceous dune species dune and Ammophila arenaria ssp. arundinacea, Lotus creticus,
Eryngium maritimum on primary dune, during the dormancy
  

In addition, fences were placed in the study area along with raised wooden walkways to avoid trampling
and vehicular access, and wooden benches, litter bins and interpretive panels on the Guincho-Cresmina
et al
2.4. Data collection and analyses
             

protective wood oil to enhance their durability. These were then placed in the study area in rows parallel
         
poles were distributed uniformly in alternate rows, not only to cover the area fully, but also to minimise
         
107

their planimetric and altimetric coordinates.

period the poles were monitored each month on site and the levels of sand accumulation were registered.
All the stolen, broken or vandalized poles were replaced in the shortest time possible. Two surveys were


planimetric coordinates. Because of the constant disappearance and vandalism of the poles during the
monitoring period, it was not possible to keep a continuous record of the total sand accumulation on each
pole. Although this method was suitable for measuring dune evolution, it did not provide reliable estimates
 

basis for each pole with respect to the previous measurement, without consideration for unavailability of


of the total study area corresponding to each measurement date, and totalling them for prolonged periods

et al


of biophysical structures on the primary frontal dune, control of invasive alien species, as well as planting
   Ammophila arenaria. Summary data of the development and establishment of
spontaneous vegetation and the planted species was also registered.
2.5. Actions and monitoring results




108
of establishment of other species such as Pancratium maritimum, Otanthus maritimus and Artemisia
crithmifolia.






Following the initial installation of the biophysical structures, a one year measurement period was




      
109


development and of dune movement that buried the plants. The Ammophila arenaria plants were not
able to adapt to the sudden deposition of sand. The loss of sand from the root area was also observed
in the intradune depression plantation.

         



110



Quantities Actions
  
 Elytrigia juncea subsp. boreoatlantica
 Ammophila arenaria subsp. arundinacea
 Lotus creticus
 Eryngium maritimum
  

               
    
which are not discussed here.
2.6. Discussion
The levels of sand accumulated by the biophysical structures were monitored using poles distributed
       

111


errors were noticed after the instalment of raised wooden walkways as they became buried when
installed. The high susceptibility of the poles to vandalism, despite the installation of fences and gates,
    
results. Another measurement method should therefore be sought. The plantation area on the primary
frontal dune was excessive and premature. It should have been implemented gradually, after a prior
study of sand deposition in order to determine how the system would react to intervention. The planted
vegetation is, meanwhile, well established although it has been necessary to replace some plants after

of E. juncea subsp. boreoatlantica and Cakile maritima. In the back rows of the system some stabilization
was observed. The reduction of disturbance, combined with plantation, led to widespread establishment
of Lotus creticus
of Medicago marina
           
et al




and mixed techniques have been used, back up the positive results obtained at Guincho.

            


Acknowledgments




         
   
              
         
              


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References




      
      

          
             




                


             



   

     
            





      


               


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



            

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
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            


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               
             


Taveira Pinto F. The practice of coastal zone management in Portugal. Journal of Coastal Conservation.
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             

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Resumo – O pisoteio é um dos principais fatores de perturbação da duna frontal, originando uma rede de caminhos e clareiras no meio da vegetação densa, por eliminação de plantas vulneráveis como Ammophila arenaria. em comunidades vegetais não perturba‑ das, à medida que A. arenaria se torna dominante, a coexistência de outras espécies é inibida, tanto pela sua estratégia de crescimento em falange, como pela diminuição da mo‑ bilidade da areia junto à superfície. Porém, a dominância desta perene, responsável pelo crescimento em altura da duna, pode ser localmente invertida após o cessar do pisoteio. Dados recolhidos em três áreas de estudo no litoral de Vila nova de Gaia em 2006, três anos após a primeira grande intervenção da Câmara Municipal no ordenamento dos acessos à praia através das dunas, sugerem que a súbita abundância de Medicago marina se relacio‑ nará com a maior disponibilidade de locais adequados ao seu recrutamento, na sequência da morte de indivíduos de A. arenaria. ao estabilizar eficazmente a areia de caminhos e cla‑ reiras de perturbação, M. marina cria condições para a colonização de variadas espécies anuais e modifica de forma significativa o gradiente de mobilidade e deposição da areia na duna frontal. Palavras ‑chave: Biogeomorfologia, duna frontal, perturbação, pisoteio, dinâmica de comunidades, filtros ambientais. abstract – loCal replaCeMent of AmmophilA ArenAriA by medicAgo mArinA after foredune traMpling disturbanCe. Human trampling is amongst the major cau‑ ses of foredune disturbance. it creates a diffuse path network and the opening of bare‑ ‑ground clearings within dense vegetation patches as a result of plant removal, namely of Ammophila arenaria. in undisturbed plant communities A. arenaria becomes dominant, and strongly inhibits the co ‑existence of other species, due to its phalanx growth strategy recebido: abril 2012. aceite: fevereiro 2013.
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O pisoteio é um dos principais fatores de perturbação da duna frontal, originando uma rede de caminhos e clareiras no meio da vegetação densa, por eliminação de plantas vulneráveis como ammophila arenaria. Em comunidades vegetais não perturbadas, à medida que A. arenaria se torna dominante, a coexistência de outras espécies é inibida, tanto pela sua estratégia de crescimento em falange, como pela diminuição da mobilidade da areia junto à superfície. Porém, a dominância desta perene, responsável pelo crescimento em altura da duna, pode ser localmente invertida após o cessar do pisoteio. Dados recolhidos em três áreas de estudo no litoral de Vila nova de Gaia em 2006, três anos após a primeira grande intervenção da Câmara Municipal no ordenamento dos acessos à praia através das dunas, sugerem que a súbita abundância de medicago marina se relacionará com a maior disponibilidade de locais adequados ao seu recrutamento, na sequência da morte de indivíduos de A. arenaria. Ao estabilizar eficazmente a areia de caminhos e clareiras de perturbação, M. marina cria condições para a colonização de variadas espécies anuais e modifica de forma significativa o gradiente de mobilidade e deposição da areia na duna frontal.
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Due to their position of interface between the sea and land, the flora and vegetation of coastal beaches and dunes, occupy ecologically extreme, sensitive, unique and valuable habitats. The occurrence of a large number of endemic taxa and specific plant associations endowed with key ecological services and adapted to a stressful and harsh environmental gradient, gives them a high interest for nature conservation and an important role in sustainable territorial planning. However, such ecosystems are vulnerable to the disruption caused by several anthropogenic sources. Among other global threat factors, the inevitable sea rise caused by climate change and, at a local scale, the non-negligible implications of trampling caused by disorderly coastal touristic exploitation, growing construction pressure in the littoral, and a seasonal population boom in late spring and in summer, plus all derivate forms of pollution, are threat factors to their integrity. Therefore, a correct planning of the touristic economic activities requires the understanding of the vegetation composition and spatial distribution patterns, intrinsically determined by their biogeographic context in the Euro-Siberian or Mediterranean Regions. This comprehensive work, based on a broad phytogeographic study, brings together disperse information on plant communities of the Portuguese sandy coasts (beaches and dunes), by analysing floristic compositions, chorology and ecological characteristics, and matching them with the “Nature 2000” network habitats. Resilience and vulnerability are also studied. In a nature conservation perspective, a positive balance (and a sustainable co-existence) between the preservation of natural values and human development in the Portuguese coast, will benefit with the integration of this knowledge in coastal planning and management activities.
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The practice of coastal zone management in Portugal is very recent. Key issues and considerations about natural shoreline dynamics, main policy instruments, and lessons learned from the EU Demonstration Programmes on Integrated Coastal Zone Management in Portugal will be outlined in this paper in an attempt to understand how the practice of ICZM and its prospects are. Coastal zone management problems and their associated side effects, as well as national and international evolution patterns will be drawn. Some means of achieving better coastal zone management practices and ways of addressing some of its forefront issues are also identified. Special attention will go to erosion problems. The pressure induced by urban development and economic activities on coastal areas is increasing. Poor sediment availability combined with years of neglected management and over-exploitation of resources have had a negative impact, and there are many areas showing evidence of coastal erosion. There is a need to improve policies and instruments of coastal planning and management. Coastal zone management plans are being developed for the nine sectors of the continental Portuguese coast, providing a full analysis of coastal systems and a delimitation of uses in relation to the carrying capacity of the shoreline. KeywordsCoastal policies-Coastal zone management plans-EU Demonstration Programmes-Erosion-ICZM
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