Figure 3.

The three sampling design approaches accounting for landscape characteristics. The three maps illustrate how the eight sampling sites are chosen under three different sampling designs. Under a geographical strategy (a), sample location is selected using only geographical coordinates in order to maximize distance between sites. The environmental design (b) is computed using environmental variables (after filtering out highly correlated variables), in order to maximize the climatic distance between the chosen sites. The hybrid strategy (c) is a combination of the first two designs: first the landscape is divided into distinct environmental regions before choosing sites within each region that maximize spatial distance