## 3 Results
### Wood Color
The fixed effects for the CIE L*, a*, and b* coordinates are presented separately for spruce wood in Table 18. The radial position was highly significant (\(p<0.001\)) regarding  
Figure 8: Yellowness (b*) of spruce and pine wood by log type: sapwood of burned trees on the opposite sides (concerning the intensity of forest fire) and heartwood of burned trees, sapwood, and heartwood of reference trees. Moisture content is 12%. Figure 6: Lightness (L*) of spruce and pine wood by log type: sapwood of burned trees on the opposite sides (concerning the intensity of forest fire) and heartwood of burned trees, sapwood, and heartwood of reference trees. Moisture content is 12%. Figure 7: Redness (a*) of spruce and pine wood by log type: sapwood of burned trees on the opposite sides (concerning the intensity of forest fire) and heartwood of burned trees, sapwood, and heartwood of reference trees. Moisture content is 12%. all color coordinates. Height class was significant for the L* and a* coordinates (_p_ < 0.05). The interaction between fire damage class and the radial position was very significant (_p_ < 0.001) for the L* coordinate and significant (_p_ < 0.05) for the a* coordinate. Most of the random variation was residual for all color coordinates (59.3-62.1%). The RMSE value was at its lowest, and the R\({}^{2}\) value was the highest for the L* coordinate. The fixed coefficients of the models for the color coordinates of spruce wood are presented in Table 19. Sapwood was darker and closer to green and yellow than heartwood, possibly because of the higher content of darker latewood in sapwood than in heartwood. Sapwood in the butt logs and middle logs was also darker than in the top logs. In the top logs, the a* coordinate was closer to green than in the butt and middle logs. Due to the fire damage class and radial position interaction, sapwood was darker and closer to green in the burned trees. This was explained by the most substantial effects of forest fires on the outer layer of the wood. The fixed effects for the CIE L*, a*, and b* coordinates are presented separately for pine wood in Table 20. Similar to spruce, height class was highly significant (_p_ < 0.001) for all color coordinates. The radial position was very significant (_p_ < 0.001) for the L* \begin{table}
\begin{tabular}{l r r r r r r r} \hline \hline  & **L*** & **a*** & **b*** & & **L*** & **a*** & **b*** \\ \hline
**Source** & **F** & **F** & **F** & **df1** & **df2** & **Sig.** & **Sig.** & **Sig.** \\ \hline Fire damage class & 0.084 & 0.286 & 0.093 & 2 & 234 & 0.919 & 0.751 & 0.911 \\ Height class & 4.202 & 5.974 & 0.156 & 2 & 234 & 0.016 & 0.003 & 0.856 \\ Radial position & 75.455 & 16.096 & 23.851 & 1 & 234 & \textless{}0.001 & \textless{}0.001 & \textless{}0.001 \\ Fire damage class * radial position & 12.827 & 6.100 & 0.385 & 2 & 234 & \textless{}0.001 & 0.003 & 0.681 \\ \hline
**Random effect** & **Variance** & **Variance** & **Variance** & & & & \\ \hline Stand & 6.677 & 1.481 & 9.158 & & & & \\ Tree & 0.654 & 0.046 & 0.064 & & & & \\ Residual & 10.704 & 2.427 & 15.125 & & & & \\ \hline
**Fitting statistics** & & & & & & & \\ \hline R\({}^{2}\) & 31.9\% & 16.8\% & 9.4\% & & & & \\ Bias & \(-\)0.01 & 0.00 & 0.06 & & & & \\ (0.0\%) & (0.2\%) & (0.3\%) & & & & \\ RMSE & 3.29 (3.9\%) & 1.54 & 3.91 & & & & \\  & & (62.7\%) & (18.9\%) & & & & \\ \hline \hline \end{tabular}  
* refers to interaction.  
\end{table} 
Table 19: Fixed coefficients in the linear mixed model (Equation (11)) for the color of Norway spruce and the variation in random effects. \begin{table}
\begin{tabular}{l r r r r r r} \hline \hline  & **L** & & **a*** & & **b*** & \\ \hline
**Variable** & **Estimate** & **Std. Error** & **Estimate** & **Std. Error** & **Estimate** & **Std. Error** \\ \hline Intercept & 86.309 & 2.750 & 1.446 & 1.287 & 19.544 & 3.191 \\ Fire damage class (ref: no damage) & & & & & \\ (0.0  
and b* coordinates, but not for the a* coordinate, albeit the naturally red-brown color of pine heartwood. The fire damage class was significant for the a* coordinate.