The Aire and Candeeiros Ranges Natural Park (in Portuguese, Parque Natural das Serras de Aire e Candeeiros, or PNSAC) is a natural park in the Central-West region of Portugal. It occupies an area of 383.9 km2 (148.2 sq mi) and is the most important limestonedeposit in Portugal, with a variety of geological formations and climate associated with karstgeomorphology and topography, such as underground caves and sinkholes.[3] It was designated a protected area in 1979 with the intent to preserve its natural aspects, and the architectonic and cultural heritage linked to the local human populations.[4]
With a mountainous landscape, PNSAC contains some of the most interesting geomorphological features within Portugal.[7] It mostly includes mountain ranges, locally designated as "Serras", and plateaus.
The Jurassic period rocks of the limestone massif flourish to a great extent,[9] standing out by its relief as a prominent mass that rises about 200 m (660 ft) relative to its surroundings.
The East side of the Aire Range as seen from the castle of Torres Novas
Southeast view of Santo António Range from Alcanena
The adjacent Candeeiros Range (615 m (2,018 ft)) to the west, between Porto de Mós and Rio Maior
Santo António Plateau in the centre
Part of the São Mamede Plateau to the north.[10][11]
The park's white and jointed limestone strata are constantly dissolved by the relatively abundant rainwater, which preferentially flows along and infiltrates through the joints, and further widens the natural fissures that so form in the process, on the surface and deep below the ground. In such ways, water, practically invisible on the surface, is the main erosive agent, forming karst features.
After infiltrating and flowing from higher ground, and on surface depressions where the rainwater outflow cannot match the inflow (such as poljes), water is naturally and ephemerally pooled, and sediment is deposited. After the wet season, these depressions eventually drain, leaving behind newly deposited fertile terra rossa.
These phenomena justify the absence of shallow watercourses, and the presence, instead, of a vast network of underground galleries, being perhaps one of the largest freshwater reservoirs in the country, giving rise to some important water courses, such as the Alviela and Lena river springs.[10]
Karst Features
The park includes a great diversity of karst features, such as underground caves, pit caves, sinkholes, uvalas, poljes, limestone pavements, and ponors, among others.[3] There are over 130 identified caves in the park.[7] Some notable cave complexes include the Mira de Aire Caves, the Alvados Caves, the Almonda spring caves (including the Cave of Aroeira) and the Algar do Pena.[12]
Other notable geological formations include:
Minde-Mira de Aire Polje, a great karst depression and Ramsar wetland[13] located between the towns of Minde and Mira de Aire, which floods with some frequency during the winter.[14]
Arrimal Lagoons, sinkholes with naturally waterproofed bottoms with clays and other sediments[16]
Rio Maiorsalt pans, known at least since 1177, the only inland salt pans in Portugal, created by an underground gallery that passes through a rock saltfield and feeds a well.[7][17]
The Minde-Mira de Aire Polje floods in the winter months
The characteristic morphology of Fórnea
Santo António Caves
Paleontology
The park contains some small and scattered Middle Jurassicdinosaurtracks locations that dot the landscape, but two major dinosaur trackway sites are outstanding. Both sites are the oldest known dinosaur footprint locations in the Iberian Peninsula.:[18]
Despite the great annual precipitation, the park has a large water deficiency in the summer due to its climate and the porous nature of its soil, as seen in the margin of the Serra de Santo António plateau
The park has a Mediterranean climate, with mild, rainy winters and cool to hot, dry summers but variations in temperature, precipitation and insolation occur throughout the region. Areas closer to the Atlantic in the west have warm summers (with average summer highs around 24 °C (75 °F)) whilst areas that border the Ribatejo to the east tend to have hot summers (with average summer highs around 28–29 °C (82–84 °F). Altitude also plays a role. At altitudes above 400 m (1,300 ft), precipitation is plenty, with values above 1,200 mm (47 in) per year, but can go down to 800 mm (31 in) at lower altitudes.[10] Average temperature ranges from 13.5 °C (56.3 °F) atop the Aire Range, to 16.0 °C (60.8 °F) at the lower plains.[11][24][25]
The prevailing N-NW winds carry air masses loaded with moisture that cause intense fog and strong winter rainfall.[26] As summer approaches, the Azores High moves further north. Clear skies become more frequent and rain is scarce between July and August. Fog is very common in winter, and in the summer, fog created by the marine layer can move from the Atlantic to the interior, but usually evaporates by midday. Average relative humidity is very high in the winter and values in the summer can have extreme variations, often below 40% during the day and above 80% at night. Temperatures at night are generally cool year-round but the high humidity along an absence of wind can make it more pleasant. Insolation varies between 2300 hours in the northwest mountains (south of Porto de Mós) and 2650 hours in the east.[24][25] In general, Candeeiros Range receives a larger influence from the Atlantic, whereas the Aire Range has a more Mediterranean influenced climate.[11]
Climate data for Serra de Santo António, altitude: 353 m (1,158 ft), 1984-2002
The natural park is part of the Southwest Iberian Mediterranean sclerophyllous and mixed forests and hosts more than 600 different plant species.[29] The vegetation that characterizes the PNSAC is the result of the bioclimatic influences on the territory. There is a great wealth of species with a diversity of sizes and origin (from Atlantic Europe, the Mediterranean, the Iberian Peninsula and North Africa), rare and unique Portuguese species, paleoclimatic species, some even used for medicinal, culinary, aromatic or ornamental purposes.[11] Though floristically rich, the park has suffered dramatic changes over the years. The Alvados Depression is a clear example of this dynamism; at present its landscape is agrarian; however, centuries ago, at the time of its occupation by its first settlers, the area was a marsh that was surrounded by oak groves, pine groves and strawberry trees. Later, with the romanization, it became an olive grove with grafts of wild-olive.[11]
The park has five main associated landscapes:[11][30]
The distribution and biodiversity of mammals is in part due to bioclimatic and geoecological characteristics. The fauna was drastically affected by the human occupation of this territory, which devastated habitats and destroyed resources.[7] According to Alho (1997), a total of 204 species of vertebrates, of which 136 are birds, have been identified.[11] Mammals located in the park can be divided according to size into micromammals, mesomammals and large mammals.[11][31]Bats represent almost half of the mammal species in the park, with 21 known different species.[10][32]
The terrain is characteristically dry due to its porosity and so human settlements lie on and around the fertile terra rossa plains, where maize, potatoes, vines, other varied crops, and even gardens, are grown, allowing for a mosaic of colors and textures to form, with great seasonal dynamics.[3]
There are also Roman remains, notably a road in Alqueidão da Serra, Porto de Mós, which dates between the centuries I BC and I AD.[35]
Christianized dolmen of Alcobertas
Roman road of Alqueidão da Serra
Recent Human Activity
In more recent times, with the population less dependent on agricultural and pastoral activities, there has been a dispersion of buildings in the landscape, both for housing and for support of other economic activities. This diversification of the economy is partly responsible for the abandonment of the most traditional activities.[3]
Ecological Threats
Wind turbines and quarries are the main threat to PNSAC's ecosystem
Even though a protected nature area was created to safeguard the existing natural aspects, several factors still continuously threaten the natural landscape and habitats:
Open-pit mining: the exploit of the limestone beds through numerous open-pit quarries, and the associated trucking traffic, profoundly alters the topography and affects the neighboring habitat via noise pollution and dust and aerosol emission. They are also a nuisance and public health degradation factor for the local human populations.
Urban sprawl: as previously described, the dispersal of urbanization also slowly but steadily deletes and visually pollutes the natural landscape. It also increases the noise pollution that affects the wildlife, introduces alien garden plants and pet animals that are often let loose about, such as cats and dogs, which intrude into and unbalance the trophic equilibriums in the local fauna.
Road traffic: severe numbers of reptile and amphibian species are roadkilled by the automobile traffic.[10]
Wind turbines installations have increased in number over time, affecting the local fauna and flora. Every year, many birds and bats are killed by the blades of wind turbines.
Agriculture: the historical reduction of the natural landscape through the conversion into crop areas, the introduction of alien and potentially invasive species, such as the Australianeucalyptus and acacias, as well as the usage of pesticides and the noise resulting from the mechanization of agriculture also affects the local fauna and flora.
Some measures taken to prevent these problems include the investment in nature tourism, scientific investigation and agriculture, particularly organic farming.[36]
.jpg)
.jpg)
.jpg)
