Fig. 3. Spatial distribution covering the period 1981–2006 for principal components (A) prin1, (B) prin2, (C) print3, and (D) prin4. Shading indicates positive values in two levels, i.e. 0–1 (grey) and >1(black). Positive values indicate higher than average performance for each respective principal component and for its associated species (Backhaus et al., 1990).