Figure 3
Regression trees for intraregional invasion success (percentage of territorial units within each Mediterranean-climate region where a species native to the Iberian Peninsula is naturalised) and different descriptors of the species. We applied this analysis to the species native to the Iberian Peninsula that are naturalised in each of the three Mediterranean-climate regions (Western Cape was not considered because of the lack of data available to accurately calculate intraregional invasion success). The squares at the bottom indicate invasion success (average proportion of territorial units occupied by the species in relation to the total number of territorial units in each region) and the number of species in the group appears in brackets. For each split the cut value of the variable selected is shown. Time refers to minimum residence time. The variables for latitude (in km), altitude (m) and cover (%) were calculated according to the data on the Iberian relevés in which the species is present. Occurrence is the number of relevés in which the species appears. Risk estimated value: Central Chile 0.035, California 0.053, Australia = 0.049.
