Effects of interactions between PC2abs1 - size (a) or PC1rel1 - crown proportions (b) or PCrel2 - slenderness (c) or PCabs2 - asymmetry (d), and percentage canopy openness (C_Open), on estimated fruit yield of rowan (F_mean); the contour plots show two-dimensional LOESS fits; the inset letters denote particular trees shown in Fig.\ref{543683} (high fruit yield in red, and low fruit yield in blue)