The coast of the Veneto faces the Adriatic sea for a length of about 100 km between the estuary of the Tagliamento to the north and the Po Delta to the south. The entire littoral (seafront) is characterized by sandy beaches, widely occupied by tourist resorts and built-up areas. The last few natural beaches with sand dunes remaining, owe their existence to the dynamic equilibrium between the amount of sand brought by the rivers and erosion; the re-deposition of this material, and the modeling brought about by sea and wind. A determining factor, in this sense, is the consolidating and building role carried out by the natural vegetation, without which the dunes would not be able to form. The dynamic equilibrium that results out of this, has as effect the construction of the littoral as we know it, besides being at the root of its great naturalistic importance.
The original aspect of the Venetian coastland, dominated by dune ribbons and variably colonized by vegetation, actually survives in limited, but very important, fragments, which have become the object of protection at local level and by the European Union. In Veneto can be found – among by the sites of Community Importance (acronym S.I.C. in Italian) and the Zones of Special Protection (Z.P.S. in Italian) involved in this project – some of the most interesting stretches of sandy littoral within the entire length of northern Adriatic shoreline.
The heritage of bio-diversity hosted by these sites needs an active and careful management, capable of responding in a concrete way to the numerous threats which it needs to withstand. The spread of exotic species, the erosion and the pressure from tourism – especially when sites are not properly managed –, the excessive density and monotony of the artificial pine-woods encroach with these fragile natural environments; these are some of the main problems.
Thanks to the institution of "Nature 2000" Network, and the financial institute connected to the "LIFE" projects, it has been possible to launch a scheme called "Concerted Actions for the Safeguard of the Venetian Coastland", which sees the collaboration and involvement of the regional agency "Veneto Agricoltura" and the Regional Forestry Commission service. The environmental diversification of the pine-woods, the containment of invasive species, and providing information to the public are the main lines of action envisaged by the project, foreseeing the necessity to hand over this great environmental and cultural heritage to future generations in the best conditions possible.
The Botanical Garden at Porto Caleri
1. At the Discovery of the Garden
The Botanical Garden at Porto Caleri ('Giardino Botanico Litoraneo di Porto Caleri') protects and conserves a unique environment of great scientific interest. It lies within the perimeter of the Po Delta Regional Park, and at the southern extremity of the Caleri peninsula, which separates the sea from the lagoon. It is extended on a surface of 44 ha, and is characterized by the presence of a noteworthy variety of habitats, from lagoon to dunes, to pinewoods. There is also a 300-meters long equipped trail for all abilities (including disabled), through the pinewood to the limit of the maquis. Along the trail, ten boards provide information, through text and models in relief, also in Braille. In order to facilitate the exploration of the site, some wooden posts have also been installed, with directions; their text is reported on this page in bold, like this paragraph. These trails are for everybody, and it is of course advised to observe maximum respect for the environment and the structures. Enjoy the exploration!
The Botanical Garden at Porto Caleri is situated at the southern extremity of the littoral in Rosolina, at the northern edge of the Po Delta. The choice to create a Botanical Garden here has allowed the safeguard of a very important area, both for the richness of its many species and the unique set of habitats between sea and lagoon.
At the Botanical Garden, one can visit – with a unique system of trails and walkways – all the different habitats, displaying the typical succession of the northern Adriatic coastline. Without doubt, the most captivating environments are those of the lagoon, and the shrub habitats with Juniper; these are described in greater detail below. All seasons offer interesting cues to the visitor, but certainly spring is the most atmospheric time for a visit, with its scents and colours.
The presence of Sea Buckthorn – which has here its only station for the Venetian coastland – is the most peculiar floral element for this area, but it is the richness of the totality of this site, due to the variability and diversity of the different habitats, which strikes whoever wishes to deepen the knowledge of the botany and ecology of this area.
Two birds – Cirl Bunting (Emberiza cirlus) and Sardinian Warbler (Sylvia melanocephala) – are the most outstanding presences among the vertebrated fauna. They nest in the shrubby band, in the least disturbed areas. Only a careful observer – but, most of all, whoever is able to listen – will be able to recognize, among the many sounds of spring, the unique song of these birds.
Problems of Conservation and Foreseen Interventions
The "LIFE" project has seen the realization of numerous interventions in the Botanical Garden at Porto Caleri. Amongst these, stand out the safeguarding of some habitats by the invasion of exotic species, and the placing of signs and boards for the different routes and trails within the site, in order to inform the visitors on the characteristics of this littoral.
The Botanical Garden at Porto Caleri is situated in the northernmost section of the Po Delta, in a territory in constant evolution, whose morphology was modified through time by the accumulation of sediments, the modeling action of the great tidal floods and human interventions.
The area where the garden is situated represents a unique site for the protection and the conservation of the habitats of the littoral. Situated at the southernmost extremity of the Caleri peninsula, which separates the sea from the lagoon, the garden is characterized by the presence of a noteworthy variety of habitats, from the lagoon, to the sand dunes, to the beach.
The Caleri peninsula was in origin a sandy isthmus formed by the deposition of sediments transported by an ancient branch of the Po, now extinct. While the northern part of the peninsula was profoundly modified from the 1960s onwards, because of the tourist development of Rosolina Mare, the southern section was very little modified over the last few centuries.
Eco-compatible Tourism on the Venetian Littoral
The presence of tourists and the activities connected with the use of the beach have significantly altered the natural habitats found originally along the coast. It is a transformation that had its maximum expansion – in Veneto as in the rest of Italy – after WW2. Today, maintenance of the residual habitats is not incompatible with tourism; in fact, it constitutes a resource, and an added value which can further characterize the offer of the Venetian coastland.
Tourism and Protection of the Littoral
The Impact of Uncontrolled Tourism
Uncontrolled and non-regulated tourist activities are a factor of strong alteration for the environments of the littoral, and a potential risk of destruction – suffice it to think of the devastating power of fires. The opening of paths, erosion, the spread of invasive plant species, the disturbances to the fauna, the flattening of the dunes are only some of the effetcs that an unsuitable fruition of this coastland can provoke.
The Structures for Eco-compatible Tourism
Tourism and protection of the different environments are two faces of the same coin; the valorization of the first takes advantage and co-exists with the safeguard of nature. The exigences of tourists who arrive on the Venetian coastland for a stay have changed through the years; today, the 'demand' for nature has increased, and whoever comes to the seaside asks more and more to be able to combine their holiday with nature. The structures for tourism can in fact be compatible with the needs of the environment; the solutions are there.
The Management and Protection of the Coastland Habitats
Managing the littoral – according to a modern and careful forest management techniques – means finding formulas for the co-exhistence and synergic co-creation and development between the tourist activities and the safeguard of nature. It is a challenge that the tourist trade and the local governments of today must rise up to, if they want to be able to offer a reality able to compete with other, more competitive destinations, while guaranteeing the protection of bio-diversity for future generations.
2. History of the Woodland
Here we are at the boundary between flatlands and the sea; the typical vegetation of the woodland should be a mixed formation with oak and hornbeam, but the exploitation of the territory by man has led to its disappearance. In front of us, there extends a pinewood, grown on consolidated dunes and far from the sea. The pinewood here is formed by Maritime Pine and Stone Pine, and it is the result of artificial plantations, carried out originaly with the intent to protect the ‘valli’ and shelter the agricultural activities from the cold winds coming from the sea, charged with salt. Overtime, among the pines the understory has grown spontaneously, and Holm Oak has made its reappearance – a typical species of the woodlands along the coast. Overtime, the broadleaved will substitute the pinewoods in a natural way. As we move further towards the sea, the pines give way to maquis, mostly formed by shrubs. Along the trail, some wooden arrows indicate the main plant species.
The Plants and Habitats of the Garden
Holm oak (Quercus ilex) is an evergreen tree with a variable habit of growth, from shrubby to rather tall, depending on the environmental conditions. The flowers are disposed separately in masculine and feminine inflorescences, which appear in spring. From the ripening of the female flowers, an acorn develops. Holm oak is a typical plant of the Mediterranean habitats, especially in the most developed environmental situations, and those less affected by cuts and fires. The area where this species is most widespread includes all the regions facing the Mediterranean: it is very common in Central and Southern Italy; its presence gradually decreases as one proceeds northwards, and it tends to become a termophile relic along the Northern Adriatic coast, and in some inland stations of Northern Italy. Along the Venetian littoral, Holm Oak is present with certain numbers at Bibione, Bosco Nordio and to the south of the Adige estuary – including at Porto Caleri, where thrives one of the most beautiful Holm Oak woodlands of the Northern Adriatic coast.
Hop Hornbeam (Ostrya carpinifolia) is a small tree with an often polycormic (multi-branched) habit of growth, able to tolerate typically Mediterranean climatic conditions (strong sun radiation and high summer aridity). Together with Holm Oak, this is one of the most common components of the coastal woodlands of the Northern Adriatic. It is a formation that originally occupied the relic sand dunes and other sandy terrains with a good degree of maturity – habitats which today have almost all but disappeared, destroyed by the new shoreline settlements (built especially during the 1960s and 1970s), the encroachment of agricultural activities and artificial Black Pine (Pinus nigra) plantations. The importance of the few woodlands composed of Holm Oak and Hop Hornbeam to have remained in the Veneto resides also in the fact that they represent a witness of past, warmer periods (termophile relics); they are thus important markers of climatic history.
Stone Pine (Pinus pinea) is a tree that can reach heights of up to 20-25 meters, and which at maturity takes on a flat top umbrella-shaped size, with a superficial root system. The needles are grouped by two, 7-12 cm long. The cones are quite large and heavy, and they contain the edible seeds (pine-nuts). It typically occupies the coastal areas, where it often has left its trace in place names; it is also used as an ornamental species in the hinterland. Its presence in the Veneto, however, is always artificial, used for plantations realized from the early 1900s onwards.
Maritime Pine (Pinus pinaster) is a tree up to 30 m high, with a pyramidal canopy when young, which becomes umbrella-shaped with maturity. Often (forcibly) associated with other pines in artificial plantations along the sandy littoral, it is easily distinguishable for its very long needles and the elongated pine-cones, which have very pronounced scales and that tend to remain on the plant when ripe. The Maritime Pine features the longest and most robust needles of all European pine species. In the Venetian coastland it is not native, while it forms pure forests in the Western Mediterranean, from Spain to Tyrrhenian Italy and North Africa.
The Management of Pinewoods on Sandy Coasts
Along the Venetian coastline, the artificial plantations of pine – Stone Pine, Maritime Pine, Aleppo Pine (Pinus halepensis), Turkish Pine (Pinus brutia) Scots Pine (Pinus sylvestris) – have, on the one hand, helped to protect the agriculture, but on the other, they have occupied the habitats originally or potentially present. The pinewoods, pure and with specimens of the same age, are subject to attacks by parasites, and prone to fires. In order to safeguard and raise biodiversity, are therefore necessary interventions geared at favouring the gradual penetration of the species typical of these coastlands – such as Holm Oak – or the reinstating of the shrubby and herbaceous vegetation originally present.
Sea Buckthorn (Hippophae rhamnoides) is a spiny shrub with edible fruits belonging to the Eleagnaceae family, with a contorted aspect. The leaves are hairy on the underside, as a likely adaptation to life in conditions of high aridity, while from the small flowers develop small round orange fruits, very rich in vitamin C. The only significant population of this plant along the Venetian coastline is precisely at Porto Caleri, where it probably arrived transported by the rivers (its typical habitat is dry river beds). Here the species is associated with Juniper and other shrubs typical of the Mediterranean maquis; it is also found inland in river beds, dry slopes, low-lying rubble and other similar habitats. Its area of diffusion includes most temperate climatic bands of Europe and Asia, all the way to China. In Eastern Europe, this plant species is cultivated for its fruits, out of which are obtained juices and syrups. In Italy it reaches as far south as Tuscany and the Marches, with an isolated station in Campania.
The Succession of Habitats from Sea to Pinewoods
3. The Flora of the Beach and of the First Dunes.
On the coastal dunes the terrain is unstable; the wind shifts the sand around, and it creates new dunes. Water is scarce; when it rains, it gets readily absorbed, and the salt in seawater is toxic for most plants. A few species manage to thrive in this sort of extreme habitat, and they are known as ‘psammophile’ (“sand-lovers”). Where the sea arrives only during the winter storms, only the first pioneer species manage to thrive, amongst which is European sea rocket (Cakile maritima) — an annual plant that forms gracious mounds on the beach. As we get further away from the beach, the perennial species appear; we encounter, for instance, Common Sand Couch-grass (Elymus farctus), which contributes — with its rhizomes — to consolidate the first dunes; then there is Sea Holly or Seaside Eryngo (Eryngium maritimum) — a thorny plant with a bluish color; and lastly Marram grass (Ammophila arenaria), which — with its thick tufts and long rhizomes — slows down the transportation of sand by wind, and favors the construction of the dunes. These plants will all be sensitive to being trampled upon, and in order to protect them, one is best to avoid straying off the marked paths.
The succession of habitats that follow each other as one proceeds from the sea inland, according to bands that run roughly parallel to the coastline, is known as environmental chain succession. These bands can be discontinuous, and of variable width, but for the littoral of the Northern Adriatic coast, they can be found with a certain consistency, from the Po Delta northbound, all the way to the Tagliamento estuary. The modifications in the environment provoked by the activity of man, and the micro-climatic and geographic differences imply variations in the width of these bands, which the study of the vegetation present (phyto-geography) and of the way in which the species are being grouped (phyto-sociology) help to highlight and interpret.
Herbaceous Flora of the Sand Dunes
Wind, instability and an incoherent substrate; lack of freshwater; strong solar radiation are the main climatic factors that impose a stark selection on the plant species which can colonize the sandy coastal vegetation habitats. The adaptations of the pioneer species to the severe life conditions are fascinating, and they surprise whoever gets close to examine them.
Protecting Against the Wind
Wind is one of the main limiting factors in terms of the participation and development of plants to the ecosystems. This becomes even more evident in the coastal habitats, where the wind takes with it sand granules that hit and scratch the surface of the leaves; or salt coming from the sea, which dessiccates the leaves. The species that manage to win the struggle against the wind often develop crawling habits close to the ground (such is the case, for instance, of Calystegia soldanella); otherwise, they form thick shrubs where the plant manages to slow down the wind-speed, and thus makes its growth possible (this is the case, for example, of Ammophila littoralis).
Defending Against Transpiration
One of the defenses of the plants against excessive heat, associated with the scarcity of water (due to the inability of the substrate to retain water from the precipitations, especially in summer), is that of reducing the amount of water lost via transpiration. The main solutions that have been imposed by the evolution of the species, are: – the reduction of the transpiring surfaces; this is evident in plants with leaves that are not very developed (such as Eryngium maritimum); – the almost complete disappearance of leaves, and of the photo-synthetic activity carried out by the stem (as in Echinophora spinosa); – the reduction of transpiring activity during the warmest and driest periods. The vegetation cycle can be rather quick in some plants: it starts in winter, and already ends in spring (as in Lagurus ovatus); – the leaves can also reduce the number of stomata (the 'pores' on the 'skin' of plants), and develop hairs in order to protect from water loss (as in Medicago maritima).
Protecting Against Excessive Heat and Drought
It is not so much the heat, in fact, as the lack of water associated with it, which can be one of the main causes for natural selection on the vegetation of the coastal regions. The pioneer plant species colonizing these habitats have developed peculiar morphological and physiological solutions: they possess aerial portions which are not very developed, while on the contrary the root systems are very extended and deep, and therefore apt for searching water (as in Ammophila littoralis); they also accumulate water in their tissues, so that they become fleshy and succulent (for instance, Calystegia soldanella).
The Sea Habitats
The water edge is the habitat of transition between land and sea: it is 'land' during low tide; it is 'sea' during high tide. It is a habitat rich in animal and plant species, either pushed here by the tidal waves, or that find in this band of the littoral an apt environment for their life.
Mollusks and Crustaceans of the Water Edge
The water edge is inhabited by animals that have adapted their life cycle to the alterations of the tides, developing survival techniques apt for an environment in constant transformation, where everything is in movement. Among the crustaceans, we can find the water flea and crab, while among the mollusks there are many bivalves, such as Mantis Shrimp (Squilla mantis), nereids such as Mud-shrimps (Callianassa sp.), cockles such as Cerastoderma edule and Tellina sp., which have often been overcollected for culinary purposes.
Birds of the Water Edge
The water edge, precisely as an environment rich in life and organic matter, attracts many animals; some passing (amongst which will be fox); some others, on the contrary, are typically connected to this type of habitat (such as many birds), so much so to have developed behaviours and adapted morphologies in order to search for food (dimension of the legs; shape and length of the beak). This is the case, for instance, of Bar-tailed Godwit (Limosa lapponica), Redshank (Tringa totanus), Eurasian Oystercatcher (Haematopus ostralegus) and Eurasian Curlew (Numenius arquata), each of which colonizes slightly different habitats for water depth and composition of the substrate, always in function – in any case – of the predominating type of food consumed by the individual species.
Amphibian and Reptile Populations in the Garden
4. The Spadefoot Toad
In the small depressions among the consolidated dunes the freshwater aquifer surfaces, and small ponds are thus formed. These little, temporary bodies of water host numerous hygrophile species (plants that love water), such as Common Bulrush (Typha latifolia) and Common Reed (Phragmites australis). Water attracts animals, and often it offers shelter as well as a suitable environment for reproduction. Many species of amphibians live in the garden, amongst which are European Green Toad (Bufo viridis), Common Spadefoot Toad (Pelobates fuscus insubricus), Italian Tree Frog (Hyla intermedia) Agile Frog (Rana dalmatina) and Common Water Frog (Pelophylax esculentus). Additionaly, recently has been discovered a population of the rare Spadefoot Toad (Pelobates fuscus) – generally considered to be the amphibian species to be more at risk of extinction in Italy. A board illutrates the entire biological cycle of this rare animal, from deposition of the eggs in the water – where tadpoles will develop – to the final metamorphosis of the adults. These habitats – and, as a consequence, the animals that inhabit them – are getting rarer and rarer outside of the protected areas, threatened as they are by the lowering of the water plate and land reclamation.
Contrary to what one would expect, the littoral is rich in freshwater wetlands too. Along the Northern Adriatic coast, one can find both brackish and freshwater bodies of water occupied by a peculiar, and sometimes unique, vegetation (with plants such as Salicornia veneta), alternated with internal zones where freshwater gets more readily accumulated, or the aquifer surfaces. In these latter habitats, especially among the artificial pinewoods and the stabilized dunes, live very interesting populations of amphibian and reptile species. They survive sometimes in isolated stations with reduced numbers; often, they are also under threat and at risk of disappearing. Among the amphibian species, are to be counted: European Pond Turtle (Emys orbicularis), European Green Toad (Bufo viridis), Common Spadefoot Toad (Pelobate fuscus insubricus), Italian Tree Frog (Hyla intermedia) and Agile Frog (Rana dalmatina).
Numerous are also the reptile species, which inhabit the Northern Adriatic sandy coastline. Apart from a few exceptions, their presence is, in most cases, a choice that was imposed by the progressive reducing (or the tendency to disappear altogether) of the natural areas where these creatures would thrive inland; places such as the magredi (dry river beds) and other similar habitats. Among the reptile species, one can include: Italian Wall Lizard (Podarcis sicula), European Green Lizard (Lacerta viridis) and Green Whip Snake (Coluber viridiflavus aka Hierophis viridiflavus).
5. Freshwater and Land Tortoises
In the garden, together with snakes and lizards, there are also other reptiles; amongst these, the turtles – which we should here more aplty call tortoises, in fact, as the ‘proper’ turtles are only the marine species. In the vicinity of ponds and other bodies of water, can easily be spotted European Pond Turtle (Emys orbicularis), a carnivore species that finds its preys in the water. One must be very careful not to confuse it with the Red-legged turtle (Chelonoidis carbonarius), of American origin; bought as a pet, it is then abandoned as it becomes too big and difficult to look after. Unfortunately, as that happens, the American turtle enters competition with the local tortoise, which is already on the brink of extinction for the indiscriminate collection made in the past, and the destruction of its natural habitat. Along the littoral, it is also possible to spot Hermann’s Tortoise (Testudo hermanni), which differs from the preceding species as it is mostly vegetarian, and tends to frequent more arid environments.
The Formation and Movement of Dunes
In order for dunes to form, two fundamental components are needed: sand and wind. But the big difference between the dunes of the sandy deserts and those of the littoral is the presence of vegetation. The plant species that colonize the coastline habitats in the band of the so-called "embryonic dunes" and "white dunes" have developed morphologic and physiologic adaptations that allow them to settle, thus resisting the severe climatic conditions.
The Materials: the Sands of the Littoral
The sand that constitutes the Northern Adriatic coast, which, with its characteristics of softness and colour, has made the fortune of beach tourism here, has made a very long journey – a journey that started many kilometres afar, inland. The rivers transport to the sea the sediment which is the fruit of erosion of the rocks, and the washing away of the soil; the sea then accumulates along the coast all this material, thus forming the beaches. The sea, as well as being a factor for deposition, is also cause for erosion of the littoral; all of this stays in a rather precarious and ever-shifing balance between the interplay of massive forces, of which man is part without having as yet fully understood the dynamics at play. The wind (as well as the moon) is also the very cause of the tidal movements, determining therefore – together with the marine currents – the accumulation or erosion of the sediments along the littoral for the emerged part, with consequences for the natural environment, but also for the economic activities settled there.
White Dunes and Grey Dunes
What most strikes the visitor of the Venetian coastline is the presence of extensive sandy dunes, occupied by dense and extensive bushes of a tall plant belonging to the Graminaceae family: Ammophila littoralis. This plant species is the main building and fixating agent of the dunes, with a very extended and deep root system. As the sand transported by the wind accumulates at the base of the plant, the emission of new shoots allows the plant to re-emerge from the sand, which tends to cover it, thus causing also the rising of the dune. With the passing time, and the evolution of the vegetal component for density and number of species, the characteristics of the substrate also change: the organic component rises, and the structure gets better. The most evident modification is the presence of a more or less extended carpet formed by a moss called Tortula: this is in a dormant state during the summer, with the high temperatures and the lack of water, while it grows in winter with the presence of humidity.
The Plants of the Dunes
6. The Flora of the Beach and of the First Dunes.
On the coastal dunes the terrain is unstable, the wind shifts the sand around, and creates new dunes. Water is scarce, and when it rains, it gets readily absorbed; additionally, the salt in seawater is toxic for most plants. Only a few species manage to thrive in this sort of extreme habitat, and they are known as ‘psammophile’ (“sand-lovers”). Where the sea arrives during the winter storms, only the first pioneer species manage to thrive — amongst which is European Sea Rocket (Cakile maritima), an annual plant that forms gracious mounds on the beach. As we get further away from the beach, the perennial species appear. We encounter, for instance, common Sand Couch-grass (Elymus farctus), which — with its rhizomes — contributes to consolidate the first dunes; then there is Sea Holly or Seaside Eryngo (Eryngium maritimum) — a thorny plant with a bluish color; and lastly, Marram grass (Ammophila arenaria), which — with its thick tufts and long rhizomes — slows down the transportation of sand by wind, and favors the construction of the dunes. These plants are all sensitive to being trampled upon, and in order to protect them, one will have to avoid straying off the marked paths.
The Biotic Agents: Pioneer Vegetation
The plants that grow on sand ('psammophile' species; literally, "sand-lovers")
play a significant role in modifying the balance between the physical
forces generated by the wind coming from the sea and the sediments
transported. A biological force is, as such, alive and dynamic; it is
therefore fascinating and quite surprising to understand its mechanisms
of evolution and adaptation. Getting to know deeply the environments
of the littoral allows one to comprehend what is actually happening,
and – above all – to make the right choices and the most appropriate
interventions for their management.
Coming from the sea towards the interior, among the first plants that occupy the dunes, one can find Ammophila littoralis. It is a plant species (a type of Marram Grass) that belongs to the Graminaceae family; to the genus Ammophila (synonymous with Psamma sp.) belong plants that colonize the sandy coasts of almost all continents, and they have an ecology which is very similar amongst them. In Italy, A. littoralis is common along all sandy coastlines, where it is affected by excessive foot traffic and the activities of dune-flattening connected to the creation of beach resorts. Additionally, it is also sensitive to high salt content; therefore, it is always found at a certain distance from the sea, and – above all – in a more elevated position than the salty aquifer.
Marram grass has a rolled leaf that creates a localized environment of water vapour potential within the leaf, and helps to prevent water loss. The stomata (pores) sit in small pits within the curls of the structure, which make them less likely to open and lose water. The folded leaves have hairs on the inside to slow down or stop air movement, much like many other xerophytes (though these are typically found on the outside of the plant, but in Marram grass they are also within the leaf, as this has now become a structure with more volume). This slowing of air movement once again reduces the amount of water vapour being lost. A waxy cuticle on the leaf surface also prevents evaporation.
The Vegetational Behaviour of Ammophila littoralis
Ammophila littoralis possesses a strong rhyzome, from which depart the basal leaves that form a thick bush. It is a gregarious species which creates colonies a few square meters wide. The leaves reduce the speed of the wind, and favour the accummulation of sand. By the following year, the new leaves of Ammophila littoralis have adapted to the changed layout of the terrain, thus developing at a major height than the previous year. In the following years, this phenomenon will repeat itself over and over again, and the dune will get progressively bigger, until finding a point of balance between deposition and erosion.
Despite the name, Trachomitum venetum (aka Apocynum venetum) is a plant that originates in Asia (Balkan and Caucausus; steppes of southern Siberia, Mongolia), whose presence in Italy is limited to the coasts of Veneto and Friuli, with isolated stations in Emilia-Romagna, always along the coast. This species presents a strong, extended subterranean rhyzome, which constitutes its only means of propagation in the Northern Adriatic stations: the pollen of this plant, in fact, is sterile, and this makes its sexual reproduction impossible. On the other hand, vegetative reproduction is considered normal even in optimal conditions. In the Po Delta, Trachomitum venetum preferably occupies the most recently formed dunes, behaving as a pioneer species, vicariously present instead of Spartina juncea or of Ammophila littoralis, where the latter encounters difficulties because of the superficial saltwater aquifer. However, Trachomitum venetum is not considered a species that consolidates the dunes, or – at least – not significantly.
Curry Plant (Helichrysum italicum) is a herbaceous species that belongs to the Asteraceae family. The scent of this plant can be clearly detected during the spring and summer months in the Botanical Garden at Porto Caleri: the unique station in which it is present with a certain consistency in the whole of the Venetian littoral. It is a typically Mediterranean species, even though not exclusively specific to the coastline, characterized by adaptations geared at reducing water loss, and therefore defending from the heat associated to lack of water. Its area of distribution is limited to Southern Europe; in Italy, it is present mainly along the coasts and in the Appenines, with a few stations to the north.
It is a large evergreen shrub up to 3 m high; a typical component of Western Mediterranean maquis, although quite widespread and not limited to the coastline. The leaves are harsh and leathery, glossy above, with a narrow lamina and serrated margins. The abundant flowers are scented, and they produce small, bluish round fruits (drupes), containing one seed only. Rather frequent along the Thyrrhenian coasts from Liguria to Sicily, Sardinia and Corsica, it can rise up to 600 meters above sea level. Present – but quite rare – along the Northern Adriatic coast from Ravenna to Grado, just along the Po Delta (either side) and at the Tagliamento estuary it can be seen with a certain consistency, where it takes on the added value of thermophile relic, while it is totally absent in the area of the Venetian lagoon.
The Birds of the Mediterranean Maquis
7. European Nightjar and Other Birds of the Maquis
If we move in the direction of the sea, we encounter the maquis, which is formed by shrubs and numerous other herbaceous plants, amongst which can be observed many small surfaces covered by mosses and lichens, and inhabited by other herbs. The rare European Nightjar (Caprimulgus europaeus) — a bird with a mimetic plumage — with the plumage similar to a bark and nightly habits, is a migratory bird, which comes from Africa each spring in order to nest. The Red-backed Shrike (Lanius collurio), with its hooked beak and its predatory activity, seems like a bird of prey in miniature. It captures insects and other small vertebrates, which it then threads together on the thorns of certain plants, in order to create its own personal ‘larder’. It has the habit of perching high on the top of posts and shrubs in order to identify a prey. The Sardinian warbler (Sylvia melanocephala) is now a rather rare species along the littoral, where it nests in the maquis. The Po Delta is the northernmost limit of its aerial (area of diffusion). The male is readily recognizable for the black head, and the eyes are surrounded by a red-coloured ring. On the board we find the relief of these three types of birds; beside the models, are recorded the profiles of their songs.
The maquis along the coastline, composed mostly of Juniper and other shrubs, very localized and quite sparse along the Venetian littoral because of the important intermissions caused by man in the past, confirms itself as one of the most meaningful habitats for the nesting of some bird species which, also in the Veneto, are now quite low in numbers and fragmented. This is particularly true in Porto Caleri, where this rather rare plant association is still in a good state of conservation. The most notable bird species include Cirl Bunting (Emberiza cirlus) and Sardinian Warbler (Sylvia melanocephala).
The most rearward portion of the stabilized dunes presents a lightly undulated surface. In the depressions, the soil is darker, richer in humus, more humid; besides, water tends to stagnate there. In these habitats, it is relatively easy to find Common rush (Juncus effusus), accompanied by bushes of Common reed (Phragmites australis), whose flowering stems can reach heights of 3 meters. Less common is the presence of Orchids, such as Marsh Helleborine (Epipactis palustris), and of the Willow Salix rosmarinifolia (these species are not present in the Botanical Garden). The presence of dampness and water during all or part of the year is used by numerous animals, but in particular by amphibian species. Characteristic is, in fact, the presence of Emerald Toad (or European Green Toad, Bufo viridis) – active during the night, when the heat is less strong, and humidity more pronounced – and Agile Frog (Rana dalmatina).
The Endemic Species of the Venetian Littoral
The Venetian coastland is constituted by several areas which, if taken together, constitute a system which has dynamics, relations and problems that differ significantly from those that the plants meet inland. The flora hosted here today is the result of a particular and original geological history, which has also generated some species that can be found only in these areas ('endemics').
This is a small but very gracious plant that belongs to the Orobanchaceae family; it is up to 25 cm high, and it used to be very renowned for curing the eyesight (its common name is Eyebright). It is a typical species of the Venetian coastland, strictly connected to marshy environmens. Because of the land reclamation, drainage and pollution, its population is very reduced, and threatened of extinction. At the Botanical Garden, for ecological reasons – and other aspects connected to the local history –, we do not find Euphrasia marchesettii, which is present instead at the Cavallino littoral.
It is a plant belonging to the Graminaceae family, and to genus Stipa, which is widespread in all tropical and temperate areas of the world, with about 400 species. In Italy are present a few of these species, but Stipa veneta (a type of Feather grass), specifically, thrives only is some locations along the Adriatic coastline (at the Tagliamento estuary, and in few other places). This uniqueness imposes the protection of the habitats where the species grows. Once these environments have disappeared, this beautiful and delicate plant would also be lost forever.
It is an endemic species (a type of Centaury) of the Northern/Central Adriatic coastline, found especially between Ancona and Jesolo, with stations that are ever more rare and isolated. It does display some interesting adaptations to aridity, such as an extended and sturdy root system, and losing part of its leaves at the arrival of the summer season.
Orchids of the Garden
The Orchids of the Littoral
The coastal areas of the Veneto represent refuge stations for some threatened species, or plants with rather limited populations. Many orchid species find precisely in the coastal habitats the last stations for their presence in the Veneto. These are plants with an interesting morphology, and each type of flower conceals stories and meanings that deserve to be better known.
The inflorescence of this orchid (Latin name Orchis morio, aka Anacamptis morio) – not a typically Mediterranean one – is composed of flowers of a colour variable from white to pink to dark purple. The stem is generally about 20 cm high, but it can reach up to 40 cm. It is present in almost all of Italy, from sea level to about 1,300 metres; in the Venetian plains it is localized mostly in the dry river beds (magredi) and along the coast, both in open meadows and in pinewoods.
This is a bulbous orchid (Latin name Ophrys sphegodes), with beautiful flowers devoid of nectar, and the labellum that imitates the hairy belly of a Diptera or Hymenoptera insect species that emits the scent of the respective female (this is a rather sophisticated mechanism of pollination). It is present in many environments up to 1,200 meters, but always with only a few specimens. In the Venetian plains it is found in a few arid stations, such as at Porto Caleri.
This orchid (Latin name, Cephalanthera longifolia) displays stems that can reach up to 45 cm in height, with inflorescences of 10-20 candid flowers. It is frequent in Alpine, Pre-Alpine and hilly Alpine habitats, up to 1,400 meters; rare in the remaining territory. In the Venetian plains, it can be found with a certain frequency in the pinewoods along the littoral, also in shady environments, and growing on pine needles too – provided the substrate is damp enough.
This orchid species (Latin name Epipactis palustris) can reach 50 cm in height. The flowers are whitish, and clustered in a drooping spikelet. Despite not being present in the Botanical Garden, it is rather widespread in the Venetian plains, even though seldom with abundant populations, especially in the areas of springs known as 'risorgive', while along the littoral it is found in several locations, where it tends to vegetate in the areas behind the dunes and in small depressions, often together with Common rush (Juncus effusus).
The Shrub Associations of the Coastland
The shrub associations of the coastland are a fundamental component of the succession of habitats of the littoral. The activities and the intervention of man have compromised their presence almost everywhere along the Adriatic coast of the Veneto. Some residual stations still survive, but only at the Botanical Garden do can we understand its beauty and ecological importance. The basic component of this associations is Juniper (Juniperus communis), to which one must add Phyllirea angustifolia, Etruscan Honeysuckle (Lonicera etrusca) and – sole station for the whole Venetian coastland – Sea Buckthorn (Hippophae rhamnoides). Where the scrub is less thick we can find a few interesting floral presences, such as some orchid species, including Green-winged Orchid, Early Spider-orchid (described above) and Bee Orchid (Ophrys apifera).
The shrub associations are environments full of life, both in relation to the woodlands of the interior and the habitats towards the sea. Maybe the most active group of animal species here are the reptiles, which, thanks to the presence of a good variety and quantity of insects, of refuge areas and other areas used for reproduction, can in fact count on an ideal environment. The species more easy to spot are Italian Wall Lizard (Podarcis sicula), European Green Lizard (Lacerta viridis) and Green Whip Snake (Coluber viridiflavus aka Hierophis viridiflavus), a non-poisonous snake.
Coming from the seaside towards the interior, after the scrub along the littoral, one encounters the proper forest formations. The woodlands originally present have been substituted by artificial pinewood, planted by man in order to defend the cultures from the wind. They are mainly composed of Maritime Pine (Pinus pinaster) and Stone Pine (Pinus pinea). Today these formations show all their fragility: risk of fires, infestation by insects, scarce compatibility from an environmental point of view. The original forest formations are rather those dominated by Holm Oak (Quercus ilex), followed by another termophile oak, Pubescent Oak (Quercus pubescens), accompanied also by Manna Ash (Fraxinus ornus) and numerous other shrubs that enrich the environment.
Pinewood and Woodland with Manna Ash and Holm Oak
The Juniper Scrub and the Coastland Maquis
This band of vegetation has a very important role as a transitional habitat between the open areas towards the sea, populated only by grasses and herbacuos species, and the proper woodlands of the interior. Besides the floral aspects, it is an interesting environment as a nesting site for bird species that are threatened along the Venetian littoral, such as Cirl Bunting (Emberiza cirlus) and Sardinian Warbler (Sylvia melanocephala).
Common Juniper (Juniperus communis) is among the Italian plants of major adaptability, which can be found from sea level to about 2,000 meters of altitude. Along the littorals of the Adriatic coast, it occupies the area of the so-called shrub associations of the coastland, together with Sea Buckthorn (Hippophae rhamnoides), Phyllirea angustifolia and Etruscan Honeysuckle (Lonicera etrusca), even though some isolated specimens (or small groups) can participate to the woodland formations. Porto Caleri is the only location along the Venetian littoral in which it is possible to observe a Juniper band which is so consistent and well-preserved.
Etruscan Honeysuckle (Lonicera etrusca) is a typically Mediterranean species that lives along the Venetian littoral, where it is at the nothernmost edge of its area of diffusion. Along the coast, it normally substitutes Common Honeysuckle, which – on the contrary – tends to vegetate more inland. It can easily be told from the other species of the scrubland by the peculiar scent of its spring blossoms.
The leaves of Prickly Asparagus (Asparagus acutifolius) are reduced to small needles in order to minimize the transpiring surface, and also as an adaptation to the scarcity of water. It is a species that loves the warmest locations, which can be found all along the Venetian littoral, in the open areas or in the scrubland. It is also a threatened species, especially as it has been the object of intense overcollection in spring (the buds are notoriously edible).
The Habitats of the 'barene' and the 'velme'
8. The Flora of Marshlands and Brackish Lagoons
We have arrived at the end of our trip. We are just a few meters away from the sea. After the board, a descent takes us to the gate, past which the paths meander through the dunes, all the way to the sea. To the right, a trail takes one to the area of the brackish lagoons. The plants that thrive in this area must withstand the high percentage of salt in the air, and they are therefore known as ‘alophyte’ (salt-lovers). We then encounter the ‘barene’ (shoals) — tabular islets, periodically submerged by water during high tide, and covered by a lush vegetation. The ‘barene’ are furrowed by the ‘ghebi’ — small channels on whose bottom develops a rich submerged flora. At the end of summer, the ‘barene’ are characterized by the intense lilac-coloured blossoms of Sea-Lavander (Limonium), while the margins are almost entirely occupied by succulent plants — such as Marsh Samphire, amongst which can be identified the small, annual Venice Salicorne (Salicornia veneta). This is yet another proof of the great biodiversity contained within the Botanical Garden at Porto Caleri — a truly unique place.
The 'barene' (shoals) are lands of the lagoon, which are rarely submerged by brackish water, while the 'velme' (a local term which it is impossible to translate) are generally speaking terrains submerged during high tide and emerged during low tide. According to the period of emersion and the depht of water in comparison to the sea level, a vegetation can settle here composed by different species, and displaying different characteristics.
The leaves of this plant are succulent. Sea Purslane (Atriplex portulacoides aka Halimione portulacoides) is an alophite; that is, a plant obliged to live on terrains rich in salt. This plant thrives on soils exposed to the tidal cycles, often together with Salicornia veneta; it can in fact be found along all Italian coasts and a good part of the Boreal hemisphere. The edible leaves can be eaten raw or cooked as a potherb. They are thick and succulent, with a crunchy texture and a natural saltiness.
Small Cordgrass (Spartina maritima) is a herbaceous plant, about 20-40 cm high, provided with a creeping rhyzome. It blossoms from June to August by brackish low water, at the margins of the 'barene' – habitats that are periodically submerged by the tidal waters. It is frequent in the brackish marshes of the Northern Adriatic coast, from the Isonzo estuary to the Po Delta.
Golden Samphire (Inula crithmoides aka Limbarda crithmoides) is a perennial succulent plant, adapted to the lack of freshwater, up to 60 cm high. The flowers are clustered, and of a deep yellow colour. It is an alophite species that colonizes the brackish habitats along the sandy and rocky beaches, always – in any case – in a localized way.
Venice Salicorne (Salicornia veneta) is an annual plant that only thrives on the 'barene' of the Northern Adriatic coast. It is a pioneer species of the 'barene', with very small opposed leaves, fused between them and enveloping the stem to the point of being almost undistinguishable from it.
Evening Sea-lavender (Limonium serotinum) is a species able to live on salty terrain (alophite), also frequently submerged, where it forms characteristic associations together with Aster tripolium. It absorbs the water rich in chloride by expelling salt in excess through secreting cells distributed along the stem and the leaves. The beautiful purple blossoms which appear at the end of the summer have attracted the interest of man, who has intensely overcollected the plant, thus causing its local disappearance from some locations.
This species of Absinth, growing on the littoral, is part of a group of plants with a strong aromatic scent. Generally speaking, it has a development of a few decimeters, with a late flowering season (Sept-Oct), not very conspicuous. This species colonizes the salty environments of the coastland; it thus demonstrates to have adapted to such harsh living conditions.
Dwarf Eelgrass (Zostera noltii) is one of the few flowering plants (fanerogamous) to have adapted to submerged life in saltwater. The leaves are long and strap-shaped, and they develop out of the nodes of a creeping rhyzome in low water depths; each node bears a tuft of up to four short roots that anchor the plant to the sediment. The leaves are up to 22 cm long and contain air spaces, which make them buoyant; a clump of rhizomes may live for many years. Eel grass beds provide a refuge for many invertebrates and a safe haven for developing juvenile fish; it can be told apart from Z. marina, which lives in deeper muddy-sandy waters, also for the longer leaves.