## 3 Results
### Wood Color
The fixed coefficients of the models for the color coordinates are presented in Table 21. As for pine, most of the random variation was residual, primarily for all color coordinates (61.0-32.4%). The R2 values were, in general, lower than in spruce. Due to the apparent color difference between earlywood and latewood, the variation in the share of earlywood and latewood in the measurement spots probably explains most of the color variation. All R2 values were relatively low. The color differences between the wood from the burned trees and reference trees is presented in Table 22 as \(\Delta\text{E}^{*}_{ab}\) values. The values were calculated based on the L, a*, and b* estimates in Tables 19 and 21. In the sapwood layer, a noticeable color difference was observed on the more damaged and less damaged sides compared with the wood from the reference trees in Norway spruce and Scots pine. In heartwood, the color change was less perceptible, especially in Norway spruce and on the less damaged side. However, due to \begin{table}
\begin{tabular}{l c c c c c c c} \hline \hline  & **L*** & **a*** & **b*** & & **L*** & **a*** & **b*** \\ \hline
**Source** & F & F & F & **df1** & **df2** & **Sig.** & **Sig.** & **Sig.** \\ \hline Fire damage class & 0.719 & 3.541 & 0.952 & 2 & 252 & 0.488 & 0.030 & 0.387 \\ Height class & 12.434 & 7.621 & 7.885 & 2 & 252 & \textless{}0.001 & \textless{}0.001 & \textless{}0.001 \\ Radial position & 13.129 & 0.233 & 31.437 & 1 & 252 & \textless{}0.001 & 0.629 & \textless{}0.001 \\ Fire damage class * radial & 1.120 & 1.673 & 2.068 & 2 & 252 & 0.328 & 0.190 & 0.129 \\ \hline
**Random effect** & **Variance** & **Variance** & **Variance** & & & & & \\ \hline Stand & 6.451 & 1.860 & 9.699 & & & & & \\ Tree & 0.000 & 0.079 & 0.446 & & & & & \\ Residual & 10.692 & 3.041 & 15.849 & & & & & \\ \hline
**Fitting statistics** & & & & & & & & \\ \hline R2 & 17.0\% & 13.4\% & 16.9\% & & & & \\ Bias & 0.00 (0.0\%) & 0.00 (0.1\%) & & 0.04 & & & \\  & & & (0.2\%) & & & & \\ RMSE & 3.32 (4.0\%) & 1.74 (53.9\%) & & 3.96 & & & \\  & & & & (16.0\%) & & & \\ \hline \hline \end{tabular} * refers to interaction.  
\end{table} 
Table 21: Fixed coefficients in the linear mixed model (Equation (11)) for color coordinates of Scots pine and variation in random effects. \begin{table}
\begin{tabular}{l c c c c c c} \hline \hline  & **L** & & **a*** & & **b*** & \\ \hline
**Variable** & **Estimate** & **Std. Error** & **Estimate** & **Std. Error** & **Estimate** & **Std. Error** \\ \hline Intercept & 86.663 & 2.633 & 1.744 & 1.423 & 19.463 & 3.251 \\ Fire damage class (ref: no damage) & & & & & & \\  More damaged side & \textless{}2.359 & 3.687 & 1.543 & 1.988 & 2.333 & 4.542 \\  Less damaged side & \textless{}1.517 & 3.680 & 0.280 & 1.984 & 0.810 & 4.533 \\  Height class (ref: top log) & & & & & & \\  Butt log & \textless{}2.925 & 0.595 & 1.255 & 0.322 & 2.906 & 0.735 \\  Middle log & \textless{}1.947 & 0.667 & 0.960 & 0.358 & 2.507 & 0.818 \\  Radial position (ref: heartwood) & & & & & & \\  Sapwood & \textless{}2.403 & 0.664 & 0.108 & 0.359 & 4.309 & 0.819 \\  Interaction of fire damage class * radial position (ref: no damage or heartwood) & & & & & & \\  More damaged side * sapwood & 1.476 & 1.034 & \textless{}0.828 & 0.557 & \textless{}2.573 & 1.272 \\  Less damaged side * sapwood & 1.039 & 1.013 & 0.165 & 0.546 & \textless{}1.354 & 1.247 \\ \hline \hline \end{tabular} * refers to interaction.  
\end{table} 
Table 20: Fixed effects in the linear mixed model (Equation (11)) for the color of Scots pine and the variation in random effects. the relatively high standard error in the estimated L, a*, and b*, caution is needed when interpreting single \(\Delta E^{*}_{ab}\) values.