Do you know what are the differencies between the autochthonous spices from the exotic ones? Do you know which the problems associated with abandonment of the latter?
They are considered autochthonous species those that are coming from a place or territory, or because they reproduce, winter or are of step, that is, that are natives of the region. However, a an exotic species is that one that has been introduced, in a voluntary or involuntary way, and that it finds out of their area of natural distribution. The transport and introduction of these exotic species has been produced from immemorial times. Only it is necessary to remember that organizations so much familiars for us how the fig tree or the rat are really exotic species introduced many centuries, even millennia, ago. The problem turns up when some of these species are capable of expanding notably for the new territories in a relatively short period of time. These are the called invading species that, in many cases, are capable of producing considerable impacts of diverse nature.
The factors so that an exotic species can become invader depend of the characteristics of the species themselves as well as of those of the territory where it works in.
Among the ecological impacts that can cause the invading species it is necessary to highlight the displacement of native species (for competition, predation, transmission of illnesses, hybridization, etc) and the changes in the structure and the functioning|operation of the ecosystems (because they can modify the regimes of disturbances, the cycle of the water, the biogeochemical cycles, etc). Moreover, the invading spices can also cause socioeconomic impacts, with strong repercussions in the economy, the society and the human health. For example, they can reduce the production of the crops, to obstruct infrastructures of canalization, to reduce the availability of water, to cause allergies or dermatitis, o to increase the transmission of some illnesses you infecciones. The economical costs brought about by these species can manage to be huge, either for direct losses in different economic sectors, like the agriculture, the fishing or the navigation, or for the indirect costs derived from the necessary management to reduce the impacts that they provoke.
Nowadays you can find in the city of Barcelona different exotic species, the majority sometimes introduced by the human action. In the web site of the "Department of Agriculture, Stockbreeding, Fishing, Feeding and Natural Environment orders of information about the allochthonous and exotic species of Catalonia and to the web site of the Generalitat de Catalunya, can also unload you a PDF with more information about invading exotic species in Catalonia that it can be from yours interest.
In the websitel Centre for Ecological Research and Forestry Applications find new knowledge and skills in the field of terrestrial ecology and specific studies on exotic species and the site of the Catalan Water Agency can find exotic species affecting aquatic media.