Fig. 4From: Chemical composition of lignocellulosic biomass in the wood of Abies religiosa across an altitudinal gradientPrincipal component analysis (PCA) of ATR-FTIR characterization: a Contribution and square cosines of the study variables; b–d graphs of the loadings of PC1, PC2 and PC3 (Principal Component 1, 2 and 3) along the altitude gradient, where the points are average values (n = 6 ± standard error), NS (nonsignificant) and ** (statistically significant)Back to article page