Nowadays, the change of many ecological, economic and social parameters is reaching heretofore unknown rates, being the predictions of changes in land uses alarming at global scale. In the context of global change, there is a pressing need to understand processes of species colonization because of the ecosystem-scale consequences they have.
Associated with anthropogenic activity, mainly agrarian practices, species undertook a human-meditated overcoming of the natural biogeographic barriers to dispersal. In the Neolithic Era, the Mediterranean Basin was one of the cradles of agriculture, farming activities and first human civilizations. Its agrosilvopastoral systems and cultural landscapes were ‘exported’ to the New World during the European colonialism that took place since the XV Century.
Mediterranean-type ecosystems offer a great chance to study plants colonization. Chilean Mediterranean region (CMR) contains over 18% of alien plant species. This is particularly noteworthy in the espinales, agrosilvopastoral systems functionally similar to the Spanish dehesas and of great ecological and socioeconomic interest.
We analyzed Chile’s alien flora, considering three scales of analysis: national, regional (CMR) and at community level (espinales within CMR). We compared flora recorded in similar areas in both Chile and the Iberian Peninsula to elucidate the mechanisms operating in the colonization in Chile.
Our results showed that most of Chile’s alien plants were annual species of Eurasian-Mediterranean origin. There was a relationship between species origin and biological cycle associated with the purpose of introduction (annual plants originated in the Mediterranean Basin and woody plants in Africa and America). The alien flora of CMR was a good expression of the country’s as a whole considering the percentages of the most represented families, life cycle and regions of origin. The proportion of alien flora in Chile tended to be greater at more detailed spatial scales (13% in the whole country, 18% in CMR, and 49% in the espinales).
The similarity between the espinales and the Spanish dehesas was greater than between the espinales and the flora present in the whole Chilean country. This seems to suggest that Chilean espinales have been subjected to an intense homogenization process. The fact that the most frequent species in the espinales was an alien first recorded in Chile five decades ago appears to indicate that the colonization process and the subsequent floristic homogenization in Chilean human-made agroecosystems has become accentuated in the last few decades. These findings could change the approach for future studies of colonization in Mediterranean regions.