Exotic flora from the forest parks in the Madrid Community. The 'Casa de Campo' case.

Abstract

An alien flora study has been carried out in the forest parks of Madrid Community. Considering the 'Casa de Campo' Park as a model, a high number of xenophytes (54) pertaining to 20 botanical families has been found, which represents the 24% of the alien flora recently described in Madrid Community. The alien species more frequently found belong to the following families: Compositae (19%), Solanaceae (14%) and Gramineae (10%). The investigation revealed the existence of dominant invasive species in the ecosystems where they have been established. These species, (Ailanthus altissima, Gleditsia triacanthos, Crepis bursifolia, Datura stramonium, Paspalum dilatatum, Sporolobus indicus y Arundo donax), are capable of a profound alteration of the environments, which limits its possibility of restoration. The greatest presence of xenophytes has been observed in the area of major anthropic pressure (zoological garden, funfair and artificial lake). A positive correlation between xenophyte levels and anthropic pressure has been found (r=0.96). The frequency of alien plants could be established as a valuable ratio of anthropic major pressure.