Seasonal Biochemical Changes in Betula tortuosa Ledeb. Annual Rings in Alpine Forest-Tundra of Kuznetsk Ala Tau Mountains

Abstract

Woody vegetation growth conditions have marked effects on hemicellulose, cellulose and lignin formation. In this study, we analyzed the climatic responses of these major cell wall polymers in Betula tortuosa. We studied 35 annual rings (1980-2015) of B. tortuosa trees growing in the alpine forest-tundra of Kuznetsk Ala Tau using Fourier-transform infrared (FTIR) spectroscopy and pyrolysis gas chromatography mass spectrometry (Py-GC/MS). Our analysis of the correlation of the resulting spectra and Py-GC/MS values with mean air temperature and precipitation showed that the polymeric composition of B. tortuosa was mainly determined by June-August climate. The major factor limiting the development of the “unique” cell wall polymer composition of B. tortuosa found in alpine forest-tundra of Kuznetsk Ala Tau was a deficit of heat. At the end of the growing season, precipitation had largely a negative impact on polymer formation in B. tortuosa cell walls. We believe that combining FTIR spectroscopy and Py-GC/MS is an effective approach to quantifying the consequences of current climate trends for Siberian forest ecosystems.