Photographic Essay

Piano Grande di Castelluccio: an incredible source of biodiversity and colours

by Laura Tenconi

[Photos by S.Reynolds except where indicated otherwise; the assistance of Prof. Franco Pedrotti with species identification is appreciated]


INTRODUCTION

Umbria has always been described as the "Green Heart of Italy", and with 260,000 hectares of woodland (some 30.8% of the total surface area) and its central position, with an abundance of natural environments, it is a very appropriate description. Although Umbria possesses neither coastline nor towering mountains or vast forest, it is an extremely beautiful and refined rural landscape.
In the area extending from the Val Nerina to the stretch of the Appennines running through Umbria and Marche, nature offers one of the most spectacular sights of this mountainous area of Umbria: the road climbs up from the picturesque town of Norcia to the village of Castelluccio (1,452 metres above sea level) and the traveller is met by the sight of the Piano Grande, a vast karst basin that encloses an incredible source of plant biodiversity, and which, particularly in Spring and Summer, is a mass of colour. The basin is dominated by the sheer bluish walls of Monte Vettore (2,478 metres above sea level and the fourth highest in the Appennines) which with the entire Sibillini range, is now part of a large national park. 

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Figure 1: View of the Piano Grande, and in the background the village of Castelluccio can be seen.
www.umbriaviva.it/castelluccio.htm
[N.B. Click on thumbnails to view full pictures]

GEOLOGY AND MORPHOLOGY

The "Piano Grande" is a wide basin, resulting from karstic and orogenic processes, surrounded by mountains that generally reach an altitude of 1,600-1,700 m. Some 6.5 km long and 3 km wide, the basin extends over an area of approximately 1,300 ha. In the lowest part of the basin (1,252 m) is the "Fosso Mergani" which gathers surface runoff (from precipitation) and ends in a blind valley with a large swallet. Around this area are wide dolines, bowl shaped and with a flat bottom and full of water for most of the year.
Throughout the "Piano Grande" are paths and mule tracks but with no rural constructions except for two farmhouses.

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Figure 2: General view of the karst basin of the Piano Grande.

From the morphological point of view, it is possible to distinguish an area of limestone and chert fragments, well drained and characterized by the presence of croplands and pastures, and an area of lacustrine and swampy clays, deposited in the lake which once covered the basin floor and which were left behind after the lake dried up. This kind of soil is not well drained, probably due to the impermeability of the sediment itself.

VEGETATION AND SOILS

From the environmental point of view, the "Piano Grande" can be divided into four areas, each having a different floristic composition and ecology.

  • Cultivated area
  • Pasture and grassland area
  • The slopes
  • Lacustrine area

CULTIVATED AREA

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Figure 3: General view of the cultivated area

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Figure 4: Cultivated fields

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Figure 5: Forage peas (Pisum sativum)

This large area is located in the basin immediately under the village of Castelluccio, and forms a wide belt between the central flat part and the initial slopes of the "Piano". Probably in the past the cultivated area was more extensive. The main crops are lentils, barley, forage peas (see figure 5) and hay, and also many weeds which in the Spring result in a profusion of colour and transform the whole area. The plants include:

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Figure 6: Flowering of Sinapis arvensis and buttercup (Ranunculus bulbosus)

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Sinapis arvensis

Figure 7: Sinapis arvensis is a common weed species and a relative of Brassica napus. It usually grows on heavy calcareous soils, to a height of up to 75 cm with an erect, little branched stem. Dark green leaves are irregularly hairy and irregularly toothed. Flowers 15 - 20mm across of four petals with yellow-green sepals and corollas yolk-yellow maturing to seed pods, either somewhat hairy or not at all. Flowers from April to October.

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Ranunculus bulbosus

Figure 8: Ranunculus bulbosus, is a tender perennial and annual plant, commonly known as Buttercup. It grows 20 cm to 60 cm tall and forms clumps of deeply cut and lobed, medium to dark green leaves. In late spring and early summer, a profusion of double, pompon-like flowers are borne atop thin, rigid, branching stems. They are golden yellow with a greenish centre.

Figure 9: Anchusa barrerieli, Common bugloss is a perennial herb with a deep taproot. The plant ranges from 30-60 cm tall, with several flowering stems. The stems and leaves are fleshy, and the overall plant is coarsely hairy. The basal leaves are petiolate, and are narrowly oblong. The leaves along the plant stem are narrow and slightly pointed, with a short petiole. The leaves are progressively smaller up the stem. The blue to purple flowers have white throats. The petals are five equal lobes, forming an uncurved tube. The flowers are found in cymes, or helicoid clusters, at the end of the stems. As the flowers open, these coils unfold and straighten out.

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Anchusa barrerieli

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Papaver rhoeas

Figure 10: Papaver rhoeas is an annual, herbaceous plant, growing to a height of about 60 cm beset with diverging hairs, and having deeply 5-cleft leaves, the segments being cut-toothed and lance-shaped. The flowers are red and showy. The capsules are truncate at the top, smooth, short, obovate in shape and contain many, very small, blackish seeds. Usually associated with heavily disturbed land and has a very persistent seed bank. Among the most competitive broad-leaved weeds with winter cereal crops.
Figure 11: Echium vulgare, is a non-native herbaceous plant which can reach 80 cm in height. The entire plant is hairy.The leaves are alternate. Leaves can reach 25 cm in length. Most leaves are much smaller, progressively reduced. Each leaf is entire. The flowers are irregular in shape and are up to 2 cm wide. They are blue. Blooms first appear in early summer and continue into mid autumn.

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Echium vulgare

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Cardus nutans

Figure 12: Cardus nutans is a prickly-beautiful, common foreign invader of grasses, roadsides, and disturbed mountain fields. It reproduces by seed which it produces prodigiously, resulting sometimes in a spiny, impenetrable thicket of thistle. During its first year, Cardus grows a basal rosette (sometimes 0.5 in diameter) and in its second year produces a stout, tall flower stalk armed with sharply pointed leaves.
Figure 13: Coronilla varia, is a non-native herbaceous plant; it is a perennial which can reach 100 cm in height. The leaves are alternate. Each leaf is divided. The flowers are irregular in shape. They are pink and white. Blooms first appear in early summer and continue into late summer. Flowers in umbels to 15 cm wide (usually smaller) with from 5 to 20 flowers. It grows in fields, fencerows and waste places.

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Coronilla varia

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Figure 14: A magnificent display of flowers in late spring in a lentil field.

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Figure 15. A close up of the field

PASTURE AND GRASSLAND AREA

This is a large area that occupies the central part of the “Piano”. Grazing of local cattle and sheep is practised throughout the year except for the period when the soil is covered by snow. The vegetation dynamic follows two different evolutionary processes: the first one can be observed on clays with different conditions of soil drainage and is represented by Nardetum. The second one, on limestone and chert fragments, is related to the antrophic action of deforestation, elimination of the natural beech woodland (Fagus sylvatica) followed by the introduction of a secondary vegetal association of pastures (Bromion) and meadows (Cynosurion). Both are maintained as a result of the human activity of mowing and grazing, and for this reason it is probable that if the human activity ceased, the vegetation would evolve again to beech wood.

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Figure 16: Sheep are grazed on the large pasture areas

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Figure 17: Hay bales for winter feed

Nowadays it is possible to identify the following different vegetation associations:
Nardetum appeninicum
This kind of pasture is developed in the part of Piano Grande characterized by an acid humid soil or subject to waterlogging for part of the year, such as the areas surrounding dolines and the “Fosso Mergani” -Nardus stricta, Agrostis canina, Trifolium badium, Genista saggitalis and Meum athamanticum, Viola canina, Poa violacea, Polygala and many others…

Figure 18: Viola eugeniae, is an endemic species of the central Apennines. It is one of the biggest and most elegant among the spontaneous violets growing on grasslands. It is characterized by a short stem and oval and roundish leaves. The velvet flowers present a corolla with five yellow or blue-violet petals.

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Viola eugeniae

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Lotus corniculatus

Figure 19 : Lotus corniculatus belongs to the Pea family and flowers in May-September. This species differs from all members of the pea family by its 5 leaflets and head-like umbels of bright yellow flower. The stems are erect or sprawling on the ground, branched, smooth or sparsely hairy. The leaves are alternate, pinnately compound with 5 leaflets, the leaflets elliptic, rounded or pointed at the tip, tapering to the base, without teeth, somewhat hairy, up to 6-20 mm long, without leaflet stalks. The flowers are several in head-like umbels, bright yellow, up to 9-15 mm long. Also see figure 32.

Festuca brometea -Arid pasture Pastures belonging to the Festuca brometea class are very common in the whole of the Appennine area and with their numerous associations; they represent the most common herbaceous vegetation. The floristic composition is mainly of sub-Mediterranean origin. The central part of “Piano Grande” is occupied by a vast area of an arid pasture characterized by a new sub-association named Festuca-Koelerietum gracilis developed on a less fertile, stony soil, well drained and hence drier. This area is under intensive pasture activity/grazing throughout the year. Festuca ovina and Koeleria gracilis can be cited as examples of characteristic species belonging to this association.

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Festuca ovina

Figure 20: Festuca ovina is a perennial plant, small size, hairless, cespitous. Stems are erect, 20 - 50 cm high. Needle blade, narrow (about 1 mm), and greyish green to bluish green, rough. The ligule is very short and the auricles are very reduced, sometimes distinct. Panicle-like inflorescence is short (3 to 10 mm), with erect or more or less spreading branches. The spikelets with 3 - 8 aristate flowers. Widespread in climates of the temperate and the Mediterranean area. Thrives in warm microclimates. High resistance to cold. Does not tolerate shade.
Figure 21: Koeleria gracilis, is a loosely-tufted, shallow-rooted, native grass of small stature. This cool-season perennial bunchgrass has long, mostly basal leaves. The panicle is narrow and spikelike, except during spring flowering, when open. Quantitative botanical characteristics are extremely variable depending upon sample location. The spikelike panicle can range from 2.5 to 17.8 cm in length and is usually two flowered and compressed. During flowering the spikelike branches are open. The long, narrow, flat leaves range from 3.8 to 12.7 cm long from their basal point of attachment . The leaves are drought resistant and persist under dry conditions .
www.naturenorth.com/summer/mgp/pltstxt2.html

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Koeleria gracilis

Cynosuro- Trifolietum repentis

This is an association of meadows developed on the limestone and cherty fragments at the boundary of the Piano Grande and in its central part, on acid soils, well drained medium saturated, cherty in texture, with a low water holding capacity. The characteristic species are: Cynosurus cristatus, Trifolium repens, Lolium perenne and many other common species such as: Trifolium pratense, Festuca rubra, Salvia pratensis.

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Figure 22: A typical meadow containing Polygonum bistorta,
Plantago media
and other common species

Polygonum bistorta -Perennial herbaceous plant of the dock family - poligonaceae - up to 1 m. Stems are erect, single and glabrous. Lower leaves are ovate, ending abruptly in a long winded stalk; upper ones unstalked, decurrent and lanceolate. Flowers are pink, seldom white (as in this figure), in a dense final spike with the stamens standing out from the corollas;

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Crocus vernus

Figure 23: Crocus vernus, is a very common bulb bloom in very early spring or even late winter. They have narrow, grasslike leaves (usually with the edges turned back and a white or silver streak along the middle) growing directly from the round, slightly flattened corm. The low, funnel shaped flowers also grow directly from the corm and are white, pink, lavender, purple, yellow or orange, sometimes streaked or mottled.

Observing these meadows it is possible to differentiate those that are of private ownership and are open pastures after mowing, from the previous pastures that are the property of the Agricultural Community of Castelluccio and have not been sub-divided.

Spirae filipendulae
This kind of pasture is developed along the slopes of the “Fosso Mergani”, and is characteristic of a well drained soil, mainly due to its morphology that allows a fast flow of water. From the chemical point of view, the soils have a high saturation and a pH of around 6.0, even in the top soil.
More than 62 species are present, among which are: Bromus erectus, Spiraea filipendula, Campanula glomerata, Salvia pratensis, Brachypodium pinnatum.
Along the slopes some bare soil can be observed which has been exposed to erosion as a result of landslips.

Figure 24: Filipendula hexapetala is a clump-forming, upright perennial that features double creamy white flowers arranged in terminal panicles atop mostly leafless stems which rise typically to a height of 15-80 cm, above a basal clump of compound, dark green, pinnate, fern-like leaves. Each flower resembles a small white rose. Blooms late spring to early summer. Easily grown in average, dry to medium wet, well-drained soil in full sun. Prefers constantly moist, fertile, sandy loams; but, unlike most other species of Filipendula, is tolerant of dry soils and drought.

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Filipendula hexapetala

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Campanula glomerata

Figure 25: Campanula glomerata is a clustered bellflower plant. It is an upright perennial which typically grows 2.5-5 cm tall on erect, branching stems and spreads by rhizomes. Has ovate to lance-shaped, toothed, somewhat hairy, medium green basal leaves (to 2 cm long) with shorter stem leaves. Upward facing, bell-shaped, shell pink to lavender flowers appear primarily in terminal spherical clusters atop the stems, with smaller flower clusters blooming in the upper leaf axils. Main bloom is in late spring to early summer. Clusters can have up to 15 flowers each, hence the common name; easily grown in average, medium wet, well-drained soil in full sun to part shade. Prefers part shade in hot summer climates. Plants naturalize by rhizomes, and can be somewhat invasive, particularly in moist soils.
www.flogaus-faust.de/e/campglom.htm

THE SLOPES

Brachypodium pinnatum

The Brachypodium pinnatum is the association that occupies the slopes that come down to the "Piano". It is developed on shallow lime-rich soils generally overlying limestone rocks. This calcareous grassland is typically managed as a component of pastoral or mixed farming systems, supporting sheep, cattle or sometimes horses; sometimes cut for hay.

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Figure 26: Horses are grazed on the slopes surrounding the "Piano Grande".

This kind of grassland includes species such as: Linum alpinum, Anthyllis vulneraria, Polygala micaensis, Globularia cordifolia, Rosa canina, Bromus erectus, Brachypodium pinnatum, Koeleria pyramidata, Festuca guestfalica, Festuca lemanii, Avenula pubescens, Sesleria albicans, Briza media, Carex caryophyllea, Carex flacca, Gentianella germanica, Gentianella ciliata, Gentiana cruciata, Trifolium montanum, Lotus corniculatus, Ononis repens, Medicago lupulina, Galium verum, Salvia pratensis, Carlina vulgaris, Viola hirta, Plantago media, Dactylorhiza fuchsii etc...

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Linum alpinum

Linum alpinum or Alpine Flax, is a native of Europe. It is a pretty dwarf variety, growing 10 to 30 cm high. It has many thin, wiry stems that are covered with sheath like leaves. They produce many large, pale blue flowers in June.
Figure 28: Rosa canina is a perennial bush of the Rose family - Rosaceae - up to 2 m tall. Vine shoot like stems, green, pendulous, with strong hooked prickles. Composite leaves; 3-4 pairs of toothed, oval leaflets. Solitary flowers or in 1-4 corymbs. White or pink, up to 4 cm wide with numerous stamens and sepals which fall before the fruit is ripe. Fruit 2 cm wide, dark red (Hips). Sometimes there are some protuberances over the branches, which are produced by the plant itself to locate the larvae of the insects Rhodite rosae.

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Rosa canina

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Salvia pratensis

Figure 29: Salvia pratensis is a perennial herb of the Mint family - Labiatae - up to 1 m tall. Erect, hairy stems , glandular. Leaves are generally basal, toothed or lobed, wrinkled. The upper leaves scarce and unstalked. It has blue-purple flowers in loose spikes, seldom white. It displays a corolla of 3 cm with curved upper lip, a glandular calyx and a very long style.
www.pnr-vercors.fr/nature/milieux.php?milieu_id=9
Figure 30: Globularia is a perennial bushy plant of the Globularia family - globulariaceae - up to 60 cm. The stems are erect and ligneous. The leaves are short-stalked, lanceolate ending in a spine. The bluish flowers are in heads up to 2.5 cm in diameter.
causses-cevennes.com/flore/causse.htm

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Globularia cordifoglia

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Figure 31: Dactylorhiza sambucina

Figure 32: Lotus corniculatus (also see figure 19)

 

Figure 33. And many other species as shown in the following photographs.

Chrysanthemum leucanthemum
and Trifolium pratense

Polygala major

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Tulipa australis

Polygala major

Polygala major

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Dactylorhiza sambucina

Anthyllis vulneraria

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Ornithogalum umbellatum. Anthericum ramosum Primula veris
Trifolium pratense Trifolium montanum Chamaespartium sagittale
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LACUSTRINE AREA

As mentioned earlier the lowest part of the "Piano Grande" is drained by the "Fosso Mergani" that originates from a spring at 1,270 m. The water supplies of the "Fosso Mergani" are exclusively of meteorological origin. In the surrounding mountains some sources gush out and the water either gets lost in the detritus or is channeled in order to supply fountains and aqueducts.

In this area various types of vegetation associated with boggy or marshy conditions are found with a prevalence of Cyperaceae.

Caricion gracilis is a waterloving plant, developed on the impermeable clay deposit in the dolines and in the bed of the Mergani stream. These kind of soils are highly hydromorphic, under water for a relatively long period (around seven months in a year), and with a variable content of carbonates. Here can be seen the following vegetation associations: Caricetum vesicariae and Caricetum vulpinae (narrowly diffused), Caricetum gracilis (widely diffused).

Caricetum vesicariae and Caricetum vulpinae
These two associations are present in a fragmentary way. The Caricetum vesicariae association occupies the centre part of the bigger dolines, where the water is 60-70 cm deep and is surrounded by Caricetum gracilis. Whereas Caricetum vulpinae occupies the bottom of some smaller dolines that have a roundish shape with a diameter of 6-8 cm. Both are monospecific associations.

Caricetum gracilis

Caricetum gracilis is widely developed in the flat-bottomed dolines along the "Fosso Mergani" and in other depressions.
This association can be easily identified for its absolute dominance of Carex gracilis.

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Figure 34: Carex gracilis belongs to the Cyperaceae family and has a height of 30 to 100 cm. The foliage is clustered, the basal grass-like leaves usually form tufts, flat, thick, some species are evergreen or variegated gold or white; stems are triangular compared to rounded grass stems, flower stems are solid without nodes compared to grasses usually hollow with nodes; where blade and sheath join (ligule) is generally absent in sedges but conspicuous in grasses.

Carex gracilis