Influence of sampling location on content and chemical composition of the beech native lignin (Fagus sylvatica L.)

Background and Purpose: The chemical composition of wood depends on a number of different factors, such as wood species, anatomical parts of wood, geographic location, habitation, growth, climatic characteristics, and degree of fungal and insect attacks. Recent studies report that the content of certain wood chemical components differed significantly in dependence on different sampling locations. As an extension of the mentioned studies, this study was aimed at investigating the influence of sampling locations which differ among themselves according to specific ecological factors (soil type, altitude and phytocoenoses) on the chemical composition of a wood native lignin (NL) model by Fourier-transform infrared (FT-IR) spectroscopy. Materials and Methods: The beech (Fagus sylvatica L.) sapwood NL samples from seven sampling locations were used that differ among themselves according to specific ecological factors. NL was isolated according to a modified Brauns method described in previous research, and the FT-IR transmission spectroscopic technique was used for its characterization. The content of guaiacyl (G) and syringyl units (S), as well as syringyl/guaiacyl (S/G) ratio was estimated for different sampling locations. The observed FT-IR peaks were assigned and quantified as percentages of the peak spectral heights, and the differences between NL were discussed in terms of lignin composition. Results: The results of statistical analysis of the NL contents showed significant differences between some sampling locations regarding phytocoenoses, soil type and altitude, as well as within some locations with the same sign of the mentioned ecological factors. The obtained FT-IR spectral results revealed that the observed NL composition differs in S/G ratios linked to different sampling locations, as evidenced by relative heights of FT-IR peaks at 1282-1283 cm(-1) (represent G units) and 1327-1331 cm(-1) (represent S units). The estimated relationship between the content of guaiacyl and syringyl units of the NL model structure was assigned from 63.06-36.94% and 71.62-28.38%. For different sampling locations the S/G ratios were from 0.40-0.59. Conclusions: Statistical analysis and comparison between the results of NL content for all sampling locations showed significant differences between some sampling locations with regard to phytocoenoses, soil type and altitude, as well as within some locations with the same sign of the mentioned ecological factors. Furthermore, the results of this study, such as the obtained FT-IR spectras of NL, different S/G ratios and the content of guaiacyl and siringyl units, showed the significant influence of sampling locations on the chemical composition of the wood native lignin model in terms of the content of the observed phenylpropane units.