MP-17.09

Montjuïc Hill (Barcelona): A Hotspot for Plant Invasions in a Mediterranean City

“…Meanwhile, quarry activities peaked during the late 19th-early 20th century (with over 100 ha; [57]). In addition, according to old documents (including old maps), large parts of the hill were cultivated extensively until the early 20th century, when the Universal Exposition of 1929 drove the modification of the lower part of the hill, which was urbanized to build the exposition facilities or transformed into urban gardens [21]. Some old records of alien plants in Montjuïc could be testimony to these human activities, with two taxa being worth mentioning that have been cited in Montjuïc before the date of introduction into Catalonia indicated by Aymerich and Sáez [25]: Aloe maculata All., which was cited as very abundant on the hill by Sennen in 1917 (as Aloe umbellata DC.)…”

“…(Figure 9C), Malus domestica (Suckow) Borkh., or Prunus persica (L.) Batsch (Figure 9D)) we have observed on the hill could be remnants of the old orchards observed by Solé and Calvo [63], or alternatively, of those that accompanied the shanty towns, which occupied large parts of the hill in the 1950s (with up to 52,000 people in 1957 [57]) because of the massive immigration wave, mainly from southern Spain (it is estimated that about 1.4 million people migrated to Catalonia during the period 1950-1957 [64]). Although additional areas of Montjuïc hill were transformed into urban gardens during the 1960s and 1970s [21], the largest changes in the hill's landscape were those of the 1980s and 1990s. Most venues for the 1992 Olympic Games were placed on the hill (the Anella Olímpica), and in recent years, additional urban parks and the city's new botanical garden (Barcelona Botanical Garden, of ca.…”

“…Although the SW part of Montjuïc ends in an impressive cliff of ca. 170 m facing the sea (Morrot) that was produced by a fault, there are many cliffs (including quarry "scars") scattered across the hill; indeed, Montjuïc soon became the main quarry of the region (since the Iberian and Roman periods and up to the middle 20th century; [21]). Montjuïc hill is composed of sedimentary rocks (conglomerates, sandstones, mudstones, and marlstones) deposited in a delta during the Middle Miocene [28].…”

“…The study area is delimited by the city masterplan for Montjuïc hill, which covers 3.38 km 2 (Figure 1; see also [21]). The UTM (Universal Transverse Mercator) coordinate system has been used for geolocating the plants included in the study.…”

“…About 33.4% are managed green spaces (urban parks, botanical gardens and nurseries), while the remaining 23.6% are natural or semi-natural areas, including abandoned fields, forest patches (mainly of Pinus spp. ), dry meadows, cliffs and slopes (with some remnants of Quercus coccifera L. formations), and ancient quarries that have been colonized by spontaneous vegetation [21]. We believe, thus, that Montjuïc is an ideal case study of the role of urban areas as a sink/source of alien species for a series of reasons that can be summarized as follows: (1) deep landscape modification; (2) occurrence of multiple gateways for alien species; and…”