Altitudinal sampling model on Pico Island (Ah-Peng et al. 2012 and Gabriel et al. 2014): (a) 200 m elevation steps, two plots (black squares, 10 m x 10 m) are placed within 10 m to 15 m from each other; (b) each plot is divided into 25 quadrats (grey squares, 2 m x 2 m), from which three are sampled; (c) and (d) – each quadrat is thoroughly examined for different substrata and three microplots (red rectangular shapes, 5 cm x 10 cm) are collected on every microhabitat, except on trees, where nine replicates are made, at three different height levels. (Source: