Plant invasions in agricultural systems. Retrospective of the last 40 years in Catalonia.
Agricultural systems are one of the preferred ways of introduction of exotic weed species and the disturbance associated with these habitats has favored many cases of invasion. However, the study of this process has received less interest than in natural or semi-natural systems. This fact seems to be the result of an unequal view about the impact caused on the ecological equilibrium of the system. In this article, a review of the intrinsic causes that favor the weed invasion processes and the features that define the invasibility of agricultural systems is carried out. As an example, the different cases registered in the last 40 years in Catalonia, and for which a lot of information is available, are used. The different crop typologies preferably sensitive to host exotic weeds and the environmental characteristics and management strategies to which these species have shown better adaptation are exposed. The main agricultural scenarios that are defined are: rice fields, corn fields and other annual irrigated crops, alfalfa fields and irrigated orchards. It also includes the different existing legislative rules in this regard at the level of Catalonia, exposing critically, the differences in criteria used among the alert lists published at European, national and regional level, with respect to the species that constitute a problem or threat in the farmlands.