The aim of this study is to clarify the role of gardening and agriculture in the introduction of alien vascular plants to the western Mediterranean Basin during the last century. The main country in which this study is based is Spain. However, other countries in the Western Mediterranean Basin also form part of it. These are Portugal, France, Italy and Morocco. Three percentages were calculated. Firstly, the percentage of alien flora was calculated. Then, we calculated the percentages of species introduced as either a consequence of gardening or of agriculture. The figures were based on thirty-four floristic studies carried out in the western Mediterranean Basin between 1904 and 2006. A regression model, in which the explanatory variable is time and the dependent variables are the three percentages mentioned above, was drawn up with the data obtained. The results show the existence of positive correlation between time and the percentages of total exotic flora and the species introduced through gardening (R = 0.64 and 0.56, respectively) and the negative correlation between time and the percentage of alien species introduced through agriculture (R = -0.43). During the last century, the roles of agriculture and gardening as sources of the introduction of exotic flora to the western Mediterranean Basin were reversed. However, in the areas where the socioeconomic scene is more predominantly agrarian, the role of gardening is still limited.

Sanz Elorza, M., González Bernardo, F., Serreta Oliván, A. & Gavilán Iglesias, L.P. Invasiveness of alien vascular plants in six arid zones of Europe, Africa and America. Lazaroa 31: 109-126 (2010).Biological invasions are one of the most important components of global change, and have increasing effects on the loss of biodiversity and on human societies as a whole. The difficulties of accurately predicting the fate of a given introduction has led to increased interest in identifying situations where the risk posed by invaders is particularly high. We analyse patterns of plant invasions in arid zones to develop explicit invasion risk protocols. The study zones are five arid regions in three continents: the Mojave and Sonoran Deserts in North America, the Atacama Desert in South America, the Sahara in northern Africa and the Tabernas and Monegros in southwest Europe, (Spain). We test which life-history traits are related to invasiveness in these areas. We use Generalized Linear Mixed Models (GLMM) to model variation between species in invasion success as a function of eight predictors, potentially related to invasiveness: clonality, pollination model, dispersal syndrome, linking to moist soils, seed size, linking to disturbed habitats, salinity tolerance and longevity. We also analyse the differences that exist between the total alien flora in these six areas of the world with respect to the attributes that were considered. From the species perspective, when taxonomic effects were accounted for, only dispersal syndrome and linking to disturbed habitats appeared to be related to the invasive nature of plants. However, if taxonomic effects are not taken into account the variable salinity tolerance is also significantly related. In spite of the fact that the regions have important climatic analogies, there does not appear to be a clear general pattern in the attributes of alien flora, as these are largely dependent on local conditions. Key words: plant invasions, alien flora, arid zones.Resumen: Sanz Elorza, M., González Bernardo, F., Serreta Oliván, A. & Gavilán Iglesias, L.P. Capacidad invasora de las plantas vasculares alóctonas en seis zonas áridas de Europa, África y América. Lazaroa 31: 109-126 (2009).Las invasions biológicas constituyen en la actualidad uno de los factores más influyentes del cambio global, con evidente influencia tanto en la pérdida de biodiversidad como en las actividades del ser humano. Ante la dificultad de predecir la ocurrencia de estas invasiones, cada vez va cobrando mayor interés la identificación de áreas especialmente susceptibles de ser invadidas. En este trabajo, analizamos los atributos de las plantas alóctonas invasoras de zonas áridas en aras a establecer las bases científicas que permitan identificar y valorar las situaciones de riesgo. Se han elegido para este estudio seis zonas áridas situadas en tres continentes: los desiertos de Mojave y Sonora en América del Norte, el desierto de Atacama en América del Sur, el desierto del Sahara en el norte de África y los sub...