**2.3.2 Class** *Polygono-Poetea*

338 Ecosystems Biodiversity

distribution that were accidentally introduced by man are often strongly represented, and these are distinguished by their high invasive capacity; in some cases, these same species

*Stellarietea* has a ruderal, nitrophilous or semi-nitrophilous character, and it is diffuse throughout the World, except in the tropical zones. Relative to the temperate zones and to part of the Mediterranean bioclimate distribution area, five different orders can be

 *Centaureetalia cyani*: This syntaxon includes the infesting coenoses of the autumn to winter crops (cereals) without irrigation. This is well represented on marly-arenaceous or calcareous soils more or less rich in nutrients and alkaline or subalkaline, in the hilly

*\*Biforo testiculatae-Adonidetum cupanianae* (Fig. 2): This is the reference association for the commensals of the autumn to winter seeded crops of the marly-arenaceous hilly sectors of central Italy. It can be found in the Mesomediterranean and temperate hilly bioclimate belts, and it belongs to the alliance *Caucalidion lappulae*. The species belonging to this association have relatively early flowering, and the characteristic species are *Legousia hybrida*, *Adonis annua* ssp. *cupaniana*, *Papaver hybridum*, *Bifora* 

 *Aperetalia spicae-venti*: This order groups the coenoses that are mainly found on the alluvial plains of the temperate zones, as commensals of autumn-winter annual-seeded crops. It is well represented on subacid, sandy or sandy-silty soils that are well supplied

 *Solano nigri-Polygonetalia convolvoli*: The associations coming from this syntaxonomic unit are composed of infesting species that can colonise the sown spring-summer crops (both irrigated and not) or the rows between grapevines that have not been seeded. This syntaxon is distributed mainly in the temperate zones and in part in the zones with a

*\*Linario spuriae-Stachyetum annuae*: This belongs to the alliance *Polygono-Chenopodion polyspermi* and it represents the infesting vegetation of spring-summer crops in the hilly clayey and marly zones that are not irrigated. It is diffuse in many sectors of the Italian peninsula south of the River Po, and it is mainly present in situations of strong edaphic aridity, interrupted only by the contribution of the limited summer rain. The characteristic species are *Linaria spuria*, *Stachys annua* and *Picris echioides* (Baldoni, 1995). *Chenopodietalia muralis*: This order represents the nitrophilous-ruderal vegetation of the Mediterranean area that is relatively mesophilous. It includes herbaceous pioneering coenoses, often dominated by exotic species, which grow on soils heavily enriched in

 *Sisymbrietalia officinalis*: This syntaxon includes the pioneer and ruderal plant communities of temperate Europe and the Mediterranean that grow along the edges of farm tracks and paths, which is also a habitat that is often subjected to compaction (and therefore on substrata that are particularly compact) and near to human habitation. *\*Sinapidetum albae*: This coenosis belongs to the alliance *Sisymbrion officinalis* (of the temperate zones) and overall it is dominated by the early flowering Crucifera *Sinapis alba*, which characterises the edges of the tracks and fields in March and April with its garish flowers. It has been described for the hilly Marche territories (Allegrezza Ballelli and Biondi, 1987) and prefers soils rich in organic deposits that are frequently disturbed

have a dominant physiognomy and end up by taking over from the other species.

identified, as described below.

with water.

Mediterranean bioclimate.

nitrogen nutrients.

or removed.

and montane zones of the temperate bioclimate.

*testiculata*, *Gladiolus italicus* and *Valerianella eriocarpa*.

The class *Polygono-Poetea* is diffuse throughout the World and includes the vegetation typologies that are characteristic of habitats that are compacted. It is linked to humanised and strongly compacted environments, as it has the ability to grow in environments such as the edges or centres of dirt tracks; some communities can colonise the spaces between the bricks of paved tracks or paths (Rivas-Martinez et al., 2002). The phytocoenoses in this class are ephemeral and are made up of annual plants, and in some cases, small perennials, which are anyway always characterised by the ability to grow in edaphic contexts with relatively high nitrate contents. In the agroecosystem, the communities that are included in this syntaxon can frequently be found where the tyres of farm vehicles have compacted the ground.

Although this is a vegetation class that has a strong human footprint, *Polygono-Poetea* does not tolerate excessive disturbance and reacts negatively to practices such as weeding or soil tillage, which, as already indicated, more favours species from the class *Stellarietea*. From an evolutive point of view, *Polygono-Poetea* is positioned a step higher than *Stellarietea*.

The only order recognised for this class is *Polygono arenastri-Poetalia annuae*.

 *Polygono arenastri-Poetalia annuae*: This order includes communities of grass, whether or not creeping, that can be found in temperate and Mediterranean climates, in sandy, silty and clayey edaphic contexts, and in some cases, rich in limestone. This order has a large ecological valence: some of the coenoses included in the order favour more wet and shady locations, others instead grow in more arid contexts.

Environmental Evaluation and Monitoring of Agro-Ecosystems Biodiversity 341

than the other two classes presented above. In the areas of temperate Europe and the

 *Agropyretalia repentis*: This syntaxon includes the post-cultivation, ruderal grassland formations that are medium nitrophilous and are found in the Eurosiberian temperate and Submediterranean areas, on substrata that are mainly of the clayey type. The coenoses here are particularly diffuse in agricultural areas that have been abandoned, as they mainly characterise plots that have not been used for 3 or 4 years or the calanchi areas, with low or higher salt concentrations in the soil, that have been subjected to

*\*Senecio erucifolii-Inuletum viscosae* (Fig. 4): This phytocoenosis is found in the abandoned fields of the central Adriatic hilly sectors with temperate or Submediterranean bioclimate (Biondi & Allegrezza, 1996). The diagnostic species are *Senecio erucifolium*, *Bellevalia romana* and *Cirsium italicum*. This community is included in the alliance *Inulo-Agropyrion* and it is usually physiognomically dominated by the Composita with a Euromediterranean distribution area, *Inula viscosa*. It prefers marly and clayey terrain and in situations that are more mesophilous it is enriched in species of the class *Molinio-Arrhenatheretea*, such as *Holcus lanatus* and *Agrostis stolonifera*. *Artemisietalia vulgaris*: This represents the central order of the class, and it includes ruderal and moderately mesophilous communities of the temperate areas. These coenoses often grow on soils that are sufficiently deep and wet, as well as being well supplied with nitrogenous nutrients, and they can also be found along the edges of

 *Onopordetalia acantii*: This order is represented by the ruderal and pioneering phytocoenoses of the meso-orotemperate or thermo-oromediterranean areas. These communities are usually dominated by species of thistles, and in particular of the genus *Onopordum*, and on average, they are more thermophilous than the formations included in the other two orders, They grow on soils of various natures: sandy, clayey and more

*Molinio-Arrhenatheretea* is the vegetation class to which the regularly cut grasslands are referred, or in some cases pastured, that develop on deep, wet, neutral to subacid soils that

Mesomediterranean, three orders are found.

water courses.

or less calcicole.

Fig. 4. *Senecio erucifolii-Inuletum viscosae*

**2.4.2 Class** *Molinio-Arrhenatheretea*

strong erosive morphological modifications.

*\*Poetum annuae*: These communities are dominated by the small Graminacea *Poa annua*, and they are part of the alliance *Matricario-Polygonion avicularis* and are found in contexts subjected to strong compaction and with soils that are not subjected to water retention. The dominant species is accompanied by many other entities of the same class that are particularly resistant to soil compaction. This coenosis is spread diffusely through the agroecosystems analysed, although it had not been previously noted for the territories investigated. Instead, it had been found in various locations on the Balcan peninsula Carni et al., 2002; Carni, 2005; Silc & Kosir, 2006).

*\*Coronopodo procumbentis-Sclerochloetum durae* (Fig. 3): This coenosis grows in situations under more intense impaction and it usually has a very low coverage index (50%-60%) and is dominated by the Graminacea *Sclerochloa dura*. It belongs to the alliance *Sclerochloo durae-Coronopodion squamati*, reaching its full development between the end of April and the beginning of May, and it is found along farm tracks. It has been described for the subcoastal territory of Marche (Biondi et al., 2002).

Fig. 3. *Coronopodo procumbentis-Sclerochloetum durae*.
