Fig. 3

Selection of optimal wavelengths by successive projections algorithm. Distributions of important variables (marked with ‘filled circle’) for cellulose (a), hemicellulose (b) and lignin (c); final number of selected variables for cellulose (d), hemicellulose (e) and lignin (f) determined on the basis of the root mean square error (RMSE) of validation set of multiple linear regression models