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Natural Environment


Climate

Clima

Clima

The local climate is of the semi-arid continental (IGME, 1980) type, characterised by marked seasonal differences, with very cold wet winters and hot dry summers.

Strong winds are a fairly common feature in this area. The prevailing wind blows in a south-westerly direction for most of the year, winter being the windiest season.

More detailed information on the climate over a fourteen-year period is given below from data provided by Tapioles Weather Station situated more or less in the centre of the SPA.

Altitude: 691 m.
Annual average temperature: 12 ºC, 53.6 ºF
Annual rainfalls: 431.9 mm.
Annual everage temperature of the coldest month: -1.3 ºC, 29.66 ºF
Absolute minim: -17.5 ºC, 0.5 ºF
Average of the maxims of the hottest month: 33.8 ºC, 92.84 ºF
Absolute Maxim: 45 ºC, 113ºF




Hydrology

The SPA is part of the main secondary basin of the Salado Stream (16,800 hectares), which includes the entire lagoon complex. In the rest of the area, the waters drain directly into the River Esla and River Valderaduey, both tributaries of the Duero.

Although there are very large underground water resources, the water lying below 695 metres in Villarrín de Campos, Villafáfila and Revellinos is extremely brackish and not fit for irrigation or human consumption.

There are two main aquifers in the area, one regional and the other local. The regional aquifer, which lies fairly deep down, has no direct natural outlet into the lagoons. The phreatic level of thelocal aquifer is very close to the surface and is directly connected to the lagoons, which cover about 500 hectares of land in the period of maximum flooding.

As can be seen from the table below, the three main lagoons account for 80% of the flooding area.




Laguna Término Municipal Superficie
Laguna Grande Villafáfila 192 has
Laguna de Barillos Revellinos y Villafáfila 118 has
Laguna de las Salinas Villafáfila y Villarrín de Campos 70 has


Hidrología

Hidrología

The waters from the three main lagoons contain high concentrations of sodium chloride, with smaller proportions of sulphates and carbonates. Although the phytoplankton is very poor due to the water?s high turbidity, the zooplankton and meiobenthos are very diverse and interesting. Villafáfila is one of the few places on the Iberian Peninsula where Brachinecta ferox occurs. The largest Anostraca (an order of crustaceans) in the Palearctic (as much as 4 cm), in the rest of Europe, it has only been recorded on the steppes of eastern Hungary. This rare species represents a pre-glacial relic in Villafáfila. (LIMNOS, 1995).



Geology

Geología

Geología

Most of the action area lies on land with sediments dating from the Middle-Upper Miocene (Vindoboniense), and it is possible to distinguish two lithological facies.

  • "Montamarta" facies has many detrital levels at the edges and contains materials dating from between the lower Vindoboniense and the upper.

  • "Tierra de Campos" facies. The different detrital levels are easier to make out although less abundant than the aforementioned facies. It contains materials from the Middle or Upper Vindoboniense.

There are deposits of lowland earth, originally from the Pliocene, in the lagoons and along their edges. They consist of pebbles of rounded quartzites, with reddish sandy clays and sands. The bed of the Salado Stream contains alluvial sediments from the Quaternary.




Landscape

The area is characterised by gently undulating relief in which slight differences in altitude and broad horizons predominate. The land is mostly given over to dry-farmed cereals (mainly wheat and barley), interspersed with small meadows, vineyards and alfalfa fields, making up a habitat that some authors have dubbed "cereal pseudosteppe".

There are two well-differentiated landscape units in the area.

Paisaje

Paisaje


  • One of them, the cereal steppe, which is characterised by wide horizons and monotonous uniformity, covers most of the SPA. Alternating cultivated and fallow fields produce the famous seasonal differences, with the green hues of spring giving way to the yellows and ochres of summer and autumn. The flocks of sheep that range over the stubble fields all year round are another characteristic feature highlighting the monotony of the surroundings.

  • The second unit, the series of saline lagoons, is markedly seasonal. It provides a spectacular counterpoint to the surrounding arid panorama, manly in the wettest months of the year. Patches of relatively shallow water are scattered over the landscape, and the pasture land associated with them turns green again. These spots give rise to a certain amount of landscape diversity and, thanks to their temporary seasonal nature, the perceptual changes in the landscape they bring about make them a really attractive feature.





Vegetation

Land consolidation efforts in the 1970s entailed the disappearance of virtually all the tree cover in the area and caused a very considerable decrease in the bush cover associated with verges and other border areas that had not been brought under cultivation until then. This factor, together with the large amount of land given over to cereal farming from time immemorial, means that natural vegetation in the form of trees and bushes is currently very scarce in the SPA.

Along the banks of the water courses and on the outskirts of the towns there are small poplar groves, with vegetation consisting mainly of white poplars (Populus alba) and black poplars (Populus nigra). Smooth-leaved elm (Ulmus minor), which was common until recently, has virtually disappeared due to the same disease that brought it to the verge of extinction on the rest of the Iberian Peninsula.

Vegetación

Vegetación

In phytosociological terms, the reserve lies in the domain of the holm oak (Quercus ilex), within territory corresponding to the Genisto hystrici-Querceto rotundifoliae sigmetum and Junipero thuriferae-Querceto rotundifoliae sigmetum series (RIVAS-MARTÍNEZ, 1985). The holm oak, which is very scarce at present in the interior of the SPA, is still found in large numbers in some neighbouring areas.

Bushes are limited to the sporadic presence of some broadly distributed species, including dog rose (Rosa canina), blackberry (Robus sp.), Spanish broom (Spartium junceum), white broom (Retama sphaerocarpa) and vine (Vitix vinifera).

The lagoon vegetation is specially adapted to flooding-desiccation cycles and to high soil salinity. The representative species in the lagoons are sea club-rush (Scirpus maritimus) and bulrush (S. littoralis) in the flooded areas, and the salt-tolerant grass Aeluropus littoralis on the edges of the stands of water.




WildLife

The wildlife that frequents the SPA is very rich and varied, particularly the extraordinary numbers of ecologically valuable aquatic invertebrates. Hydrobiological communities typical of steppe live in the lagoons, including species that are unique on the Iberian Peninsula. This SPA represents the western limit of their distribution area in the Palearctic.

These communities are highly productive and concentrate their main growth period in the short periods of time that flooding lasts, which explains why they are of considerable interest as a food resource for many migratory aquatic birds.

As far as vertebrates are concerned, birds merit a special mention as there are species here with local populations worthy of international recognition. Even so, very interesting species belonging to other wildlife groups may also be seen in the area.

One of the most representative local fish is the carp (Cyprinus carpio), which makes its way up the River Salado to spawn in years when there is enough rain, and is an important food item for several species of predators. In 1986, some fish belonging to three North American species- catfish (Ictalurus melas), pumpkinseed (Lepomis gibbosus) and black-bass (Micropterus salmoides)- were illegally introduced into some permanent lagoons. Fortunately, they have not spread into the interior of the SPA although they have proliferated considerably in nearby areas.

The local reptile, amphibian and mammal populations are not particularly interesting, except for the hare (Lepus granatensis), much appreciated by local people as a game species. This is a direct result of the considerable manmade alterations to the environment (lack of cover in the extensive cereal monocultures, intensive use of pesticides, etc.). Also worth mentioning are the sharp-ribbed salamander (Pleurodeles waltl), natterjack (Bufo calamita), frog (Rana perezi), Montpellier snake (Malpolon monspessulanus), three-toed skink (Chalcides chalcides), ocellated lizard (Lacerta lepida), fox (Vulpes vulpes), common hedgehog (Erinaceus europaeus) and shrew (Crocidura russula).

As far as birds are concerned, it is advisable to differentiate between the SPA?s two main environments.

Fauna

Fauna

Cereal steppe shelters the highest world concentration of great bustar (Otis tarda), that shares its habitat with a predatory bird, the lesser kestrel (Falco naumanni), which most numerous nesting colony is sited in this area of Castilla y León. But steppe habitat also shelters another long list of species including birds that are as significant in this environment as little bustard (Tetrax tetrax), ortega (Pterocles orientalis), ashen eaglet (Circus pygargus), pale eaglet (Cyrcus Cyaneus) and stone-curlew (Burhinus oedicnemus).

Almost 50% of all the aquatic birds recorded in Castilla y León occur in this lagoon system, it being the only regional wetland that currently meets the requisite criteria, both quantitatively and qualitatively, to be considered a ?wetland of international importance?. Significant nesting species associated to a greater or lesser degree with aquatic environments include the black-winged stilt (Himantopus himantopus), avocet (Recurvirostra avosetta), marsh harrier (Circus aeruginosus), gull-billed tern (Gelochelidon nilotica), lapwing (Vanellus vanellus), mallard (Anas platyrhynchos), little grebe (Tachybaptus ruficollis), white stork (Ciconia ciconia), shoveler (Anas clypeata), gadwall (Anas strepera), little ringed plover (Charadrius dubius), etc. Wintering birds or birds on passage include the greylag goose (Anser anser), with 35,000 birds recorded in January 1998, crane (Grus grus), gadwall (Anas strepera), mallard (Anas platyrhynchos), teal (Anas crecca) and spoonbill (Platalea leucorodia).