The influence of temperature on latewood lignin content in treeline Norway spruce compared with maximum density and ring width

The latewood lignin content, maximum density and total ring width of ten consecutive annual increments were determined in treeline Norway spruce (Picea abies [L.] Karst.) using ultraviolet (UV) microscopy and radio-densitometry, respectively. A positive correlation between the total ring width and the mean temperature of mid-July to August was identified, as was one between the maximum density and the temperature of August-September. Lignin content in the secondary cell wall layer of the terminal latewood tracheids was positively correlated with the temperature for the period running from the beginning of September until the third week of October. It can, therefore, be concluded that lignification of the cell wall is susceptible to the influence of climatic variability, as is the case with ring width and maximum density.