Figure 2
Classification tree for interregional invasion success (number of Mediterranean-climate regions in which species native to the Iberian Peninsula are naturalised) and different descriptors of the species. We applied the analysis to 2,664 species native to the Iberian Peninsula, classifying their success into five categories (graphs at the bottom): species exclusive to the Iberian Peninsula (value 0) or appearing as naturalised species in 1, 2, 3 or 4 of the other Mediterranean regions. Bar charts represent the observed frequency of interregional invasion success for the species assigned to each terminal node. The number of species assigned to each terminal node is indicated below each bar chart. For each split the cut value of the variable selected is shown. Latitude range (km) and mean altitude (m) correspond to geographic variables calculated according to the data on the Iberian relevés in which the species are present. Risk estimated value: 0.254. Occurrence is the number of relevés in which the species appears. Distribution represents the extent of the distribution area, categorised from value 1 (endemic to Iberia) to value 6 (cosmopolitan).
