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Humanised spaces
Forest environmentsRiparian environmentsAquatic environments | Scrub and thicketsMeadowsRocky environments | Humanised spaces
The abandonment of cultivated land in the 20th century greatly shaped the landscape we see today, in which farmed areas account for just 6.44 % of the Park’s total territory. Such activity is concentrated in two sectors: the Llobregat side and the Vallès side of the Serra.
Collserola is also an important reserve of land for the introduction of a varied and complex series of urbanising elements. On this point, we can identify two highly differentiated areas: the exterior of the massif, comprising the urban fronts that surround the Park; and the interior, in the shape of dispersed centres of population.




This is, today, the site of the largest agricultural zone inside the Park itself, with small allotments distributed amongst the many valleys here, alternating with herb, shrub and even forest formations. There are also a few herds of sheep and goats here, which pasture in areas that are now delimited and controlled by Park technical services.

This is one of very few areas of the park where fruit trees grow, including wild cherry (Prunus avium), peach (Prunus persica), almond (Prunus dulcis), olive (Olea europaea var. europaea), fig (Ficus carica) and carob (Ceratonia siliqua). This is also where we can easily observe herbaceous plants, the first to colonise abandoned fields. Such plants include milk thistle (Galactites tomentosa), coolatai grass (Hyparrhenia hirta), red poppy (Papaver rhoeas), field bindweed (Convolvulus arvensis), alyssum (Alyssum maritimum), viper’s grass (Echium vulgare), cucumber grass (Borago officinalis) and shepherd’s purse (Capsella bursa-pastoris).
The variety of landscape that goes to form this mosaic or patchwork is of the greatest interest in terms of fauna.

Environmental diversity provides a habitat for species with many different requirements.

A frequent sight in the aerial space in this sector is the kestrel (Falco tinnunculus). Moreover, this bird has recently been joined by an important guest, the short-toed snake eagle (Circaetus gallicus), which is present every summer in these valleys, hunting for the snakes on which it feeds.

Another frequently-spotted bird of prey is the little owl (Athene noctua), which can even be seen during the day. Turtle dove (Streptopelia turtur), cuckoo (Cuculus canorus), hoopoe (Upupa epops), Sardinian warbler (Sylvia melanocephala), nightingale (Luscinia megarhynchos), common stonechat (Saxicola torquata) and melodious warbler (Hippolais polyglotta) are other species frequently found in this sector of the Park. Outstanding, however, is the highly localised presence of the orphean warbler (Sylvia hortensis), a bird closely associated with Mediterranean environments: several pairs still nest here, amongst the pines, mixed with olive and carob trees.

On the slopes between the patches of cultivated land can also be seen the holes of hoopoe nests (Upupa epops). Though small in number, these hoopoe colonies are of great importance within the context of the Park.
The ocellated lizard (Lacerta lepida), formerly a familiar sight in this environment, has now become a highly rare species in the Serra. In the low walls that separate fields and in the old stone huts, however, the common gecko (Tarentola mauritanica) is a frequent sight, as this reptile hides amongst the cracks and holes of these constructions during the day.

The irrigation cisterns in the market garden area are the main points where such amphibians as the common toad (Bufo bufo) reproduce, whilst in more irregular water sources we find the natterjack toad (Bufo calamita), a species highly adaptable to extreme conditions.
European or common rabbit (Oryctolagus cuniculus), abundant here, and even the occasional red-legged partridge (Alectoris rufa), introduced as part of repopulation processes, form the main source of food for several animals of prey, such as the fox (Vulpes vulpes).
It is in the Sant Just valley that we find the highest density of the badger (Meles meles) population, one of the most studied species in the Serra. 





The influence of human activity has left a strong mark on this side of the hills. Even today, there are cultivated fields here, mostly pertaining to dry farming operations, both in the clearings around the farmhouses in the forested interior of the Serra and in the peripheral zone formed by the Vallès plain.

This entire sector is characterised by alternating woods, streams and fields of cultivated land. This patchwork of environments provides a rich habitat for much fauna. The seasonal nature of work on the cultivated land is reflected in the substantial variations noted amongst this fauna, in terms of both the composition of species and their densities.

In spring, the dominant species in this cultivated land are European serin (Serinus serinus), goldfinch(Carduelis carduelis) and nightingale (Luscinia megarhynchos), these last in hedgerows and near streams. In winter, though, the cultivated land attracts many bird species from northern latitudes, and this is when, for example, we can observe vast flocks of chaffinches (Fringilla coelebs).

The outstanding reptiles here include Montpellier snake(Malpolon monspessulanus), ladder snake(Elaphe scalaris), Iberian wall lizard (Podarcis hispanica) andocellated lizard (Lacerta lepida). One of the most characteristic mammals of this cultivated land, moreover, is theMediterranean pine vole(Microtus duodecimcostatus). Other denizens include field mice(Mus spretus), hedgehog(Erinaceus europaeus) and European or common rabbit (Oryctolagus cuniculus).

On the outskirts of the Park, where there continue to exist large swathes of cultivated land, we can observe species characteristic of open spaces that are not present in the interior of the Serra. These include birds from the lark family, such as the crested lark (Galerida cristata).

Here, too, are nocturnal birds of prey, such as the little owl (Athene noctua), the scops owl(Otus scops) and the occasional barn owl(Tyto alba), though, regrettably, this last is now practically extinct in Collserola.

Other birds of prey also hunt here, including the northern goshawk (Accipiter gentilis), the sparrowhawk(Accipiter nisus) and, even more frequently, the kestrel(Falco tinnunculus), which is easy to spot throughout the year.

The gradual disappearance of cultivated land has led to reductions in the populations of several species, such as the barn owl, once found in this sector and now fast becoming rare sighting anywhere in the Park.



The city outside Collserola quickly grew to occupy the highest reaches of the Vallvidrera sector, which already had 208 residents in 1848.

Later, population pressure and the lack of adequate planning provisions allowed the front of the external city to occupy ever-higher reaches in all the townships around the Park, whilst dispersed urban centres were also established in the principal valleys in each of these municipalities.



In the early-20th century, a process began in which forestry land was occupied by summer residential areas whose development has varied over the years, in terms both of architecture and planning, and even in its orthodox or marginal nature.

The result is a territory that is dotted with urbanised roads and dispersed built-up areas, some of which, due to their size and degree of consolidation, have finally been recognised under current planning provisions. There is no doubt that the central axis of the Park is the zone most affected by road infrastructure and urban development.

The establishment of these residential zones has facilitated the introduction of species of allochthonous plants. Many such species were introduced as gardening plants that, little by little, became naturalised. Black locust (Robinia pseudoacacia) is amongst the trees that have been naturalised longest, and its population today appears to have stabilised. Another, more worrying case is that of the tree of heaven (Ailanthus altissima), a species that was introduced more recently and has a high capacity for reproduction. Other allochthonous tree species that we can observe in Collserola include paper mulberry (Broussonetia papyrifera), plane(Platanus hispanica), sycamore(Acer pseudoplatanus), insignis pine(Pinus radiata), deodara cedar(Cedrus deodara) and Monterey cypress(Cupressus macrocarpa).


 The allochthonous shrubs that can be most easily observed include mimosa (Acacia dealbata) and cherry laurel(Prunus laurocerasus). Other species also present areclarinet reed(Arundo donax), moth catcher(Araujia sericifera), century plant(Agave americana), Indian fig opuntia(Opuntia ficus-indica), jimsonweed(Datura stramonium), spiny cocklebur(Xanthium spinosum), Jerusalem artichoke(Helianthus tuberosus) and pokeweed(Phytolacca americana).


A problem associated with the growth of humanised environments has also been detected with regard to fauna: an increase in foreign species. These include the monk parakeet (Myopsitta monachus) and the Eurasian collared dove (Streptopelia decaocto), though, for the time being at least, their presence is restricted to gardened environments and urbanised areas. On the other hand, the red-billed leiothrix (Leiothrix lutea) is the only exotic species that has successfully colonised forest environments, achieving a high degree of naturality.

Another problem linked to humanised environments is the increase in human commensal species: sparrow (Passer domesticus), magpie(Pica pica) and wild rat(Rattus sp.).


Consorci del Parc Natural de la Serra de Collserola
Ctra. de l'Església, 92. 08017 Barcelona. T: 932 803 552


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