putes upgma6 trees using Pearson’s correlation index as the distance between variables. With 0.75 being selected as the maximum correlation threshold, from each group of highly correlated variables, one was retained. The remaining variables (elevation, slope, topographical-wetness index, mean solar radiation, accessibility index, distance to water resources, and the distances to roads of first, second, third, and fourth order) were used to compose three data sets corresponding to the years 1987, 2001 and 2010, which had in common topographic variables but differed in the values of the distance variables (Figure 1).
Figure 1: Flowchart I. Making of the environmental datasets and presence samples
Greenhouse coverages and presence records For the calibration and evaluation of MaxEnt suitability maps and Geomod simulations, presence records and greenhouse coverages are needed. For calculating greenhouse coverages for 1987 and 2001, digital land use maps from the years 1991 and 1999 (stored as polygon layers) were 6 Unweighted Pair Group Method with Arithmetic mean
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Parece un baile de fechas confuso, pero se explica por asincronía en las distintas fuentes de datos. Los años a tener en cuenta son 1987, 2001 y 2010, y para cada intervalo trabajo con los datos más próximos temporalmente.