The plant population of the Natural Reserve “Sorgenti del Pescara”
The Natural Reserve “Sorgenti del Pescara” was established in 1986 by Regional Law No. 57: it protects a vast spring area with numerous water springs coming directly from the Campo Imperatore plateau. Situated at the foot of the Capo Pescara hill, the Reserve consists of a crystal-clear stretch of water of rare beauty that, after a few metres, flows into the Fiume Aterno to form the Fiume Pescara. The protection restriction, placed entirely in the municipal territory of Popoli (PE), covers an area of about 50 hectares around which a protection strip of 86 hectares develops. The heart of the Reserve is represented by the humid environment to which the Capo Pescara hill, chalky and barren, acts as a decisive contrast: the charm of the places is born from the clear dichotomy created between the luxuriant vegetation of the flat area and the bare harshness of the hill.
The aquatic ecosystem is the main element of this site: a peculiar characteristic of the river environment is the diversity of habitats that come to life in it, thanks to the variation of important factors, such as flow rate, regime, current speed, temperature, oxygen and carbon dioxide availability, trophic content, lithology and substrate granulometry and water transparency. The heterogeneity linked to the variety of environments that the river ecosystem offers determines the particular distribution of plant coenoses, which are diversified (according to their adaptation to the various factors listed) both longitudinally and transversally.
The bottom, consisting of rather coarse clasts, is not a hospitable environment for the settlement of macrophytes. Where, on the other hand, the velocity of the current allows sandy sediments to be deposited, abundant aquatic vegetation settles, creating luxuriant submerged islands, consisting of long stems and laciniate, ribbon-like leaves forged by the stress of the water: flowering apparatuses, not always very conspicuous, emerge instead at water level. Corridor-type phytocoenoses therefore form in these contexts, side by side, parallel to the course of the river.
All plant communities described below are taken from Pirone et al., 1997. The class Lemnetea minoris characterises the plant communities of weakly flowing or still waters in a peculiar manner: these are free-floating pleustophytes with a greatly reduced root system. In this phytocoenosis, the most frequently occurring genus is Lemna with the species L. trisulca and L.minor.
Fast-flowing waters are colonised by rhizophytes that can be traced back to the class Potametea pectinati and, within it, to the order Potametalia pectinati. The alliance Ranunculion fluitans is also found in this area. Characteristic species of this alliance is Ranunculus trichophyllus subsp. trichophyllus, which frequently grows together with dense stands of Berula erecta (=Sium erectum), giving rise to the association Ranunculus–Sietum erecto-submersi, ecologically similar to Veronicum-Apietum submersi. Stagnant waters or waters with a weak current may be colonised by totally submerged rhizophytes or by rhizophytes with floating leaves.
In the former case, the most frequent alliance in our environment is Potamion pectinati, with the associations Potametum pectinati and Ceratophylletum demersi. Nymphaeion albae is the representative alliance of rhizophytes with floating leaves: here we find the associations Myriophylletum spicati and Callitrichetum stagnalis.
In shallower bays with rather moderate water velocities, communities belonging to the Sparganio–Glycerion fluitans alliance are found: the typical coenoses of such environments are Apietum nodiflori and Nasturtietum officinalis.
Phytocoenoses dominated by cespitose and stoloniferous elophytes, belonging to two alliances: Phragmition australis and Magnocaricion elatae, develop at the edges of water bodies.
Typical associations of Phragmition australis are: Phragmitetum australis, Typhetum angustifoliae, T. latifoliae and Scirpetum lacustris. The latter cenosis has been reported for Capo Pescara and is not known from other stations in Abruzzo. Magnocaricion elatae is instead characterised by the cenoses Caricetum acutiformis and Caricetum ripariae.
The area immediately above the summer water limit is affected by hygrophilous vegetation: these are woody species, with tree and shrub habitats, that mark the transition between the areas close to the riverbed, where the plant elements are influenced by the water environment, and the surrounding areas where the typical zonal stands are established.
The association Salicetum albae (referable to the class Salicetea purpureae) characterises these environments: the typical species of these consortia is Salix alba, which is found both in isolated individuals and in small hygrophilous thickets, in which it is associated with hybrid poplars. In the shrub layer of such consortia, Corpus sanguinea, Ligustrum vulgare, Rubus caesius, R. ulmifolius and Sambucus nigra are also frequent.
The phytosociological category that dominates the hilly area is the class Querco-Fagetea. In this area, along the best exposed slopes, there is an oak wood (Quercus pubescens): the floristic composition allows this association to be included in the Roso sempervirentis-Quercetum pubescentis with Quercus pubescens, Fraxinus ornus, Cytisus sessifolius, Brachypodium sylvaticum, Euonymus europeus, Lonicera etrusca, Clematis flammula, Rosa sempervirens, Paliurus spina-christi and many other species. Along the north-eastern side of the Reserve, in the hilly sector there is also a small patch of woodland dominated by holm oak, which can be ascribed to the Orno-Quercetum ilicis.
On the edge of the woodland there are vegetation cloaks and fruticeti that can be ascribed to the Rhamno-Prunetea class: in this area we find the Cytison sessilifolii characterised by the shrub Cytisus sessilifolius and the shrubs and hedges that develop on nitrified soils characterised by brambles and widely distributed species, included in the Pruno-Rubion ulmifolius alliance.
The hilly, arid area of the Reserve is colonised by steppe-like herbaceous formations with Cistus creticus garrigue, dominated by Bromus erectus: the dominant class in this area is Festuca-Brometea.
Dr. Piera Lisa Di Felice
(Executive director of the Natural Reserve “Sorgenti del Pescara”)
CORBETTA F., ABBATE, FRATTAROLI A.R., PIRONE G. (1998). Vegetazione e specie da conservare S.O.S. verde. Ed. Agricole.
DI FELICE P.L. (2006). La popolazione autoctona dell’Aterno – Pescara appartenente al complesso Salmo Trutta ed attribuibile al Taxon Macrostigma Dumeril: Aspetti ecologici e gestionali. Tesi di Laurea. Università degli studi dell’Aquila. Dipartimento di Scienze Ambientali.
PIRONE G., FRATTAROLI A.R., CORBETTA F. (1997). Vegetazione, cartografia vegetazionale e lineamenti floristici della riserva naturale “Sorgenti del Pescara” (Abruzzo – Italia). Università degli Studi dell’Aquila. Dipartimento di Scienze Ambientali.