## 2 Results  
### Seasonal Dynamics of Fine Root Biomass  
Cumulative fine root biomass and its distribution pattern were estimated at stand level with five samplings times (one year from March 2018-2019) covering three seasons (dry, rainy, and foggy cool). Fine root biomass was strongly affected by season and soil depth (\(p<0.001\)) based on the mixed-effect model (Table 1). The linear mixed effect model showed no interaction between the cropping systems (monoculture Vs. intercropping). Meanwhile, the Post-hoc Tukey test showed a significant difference between stand ages at each seasonal interval and between two cropping systems (Figure 1). It was found that seasons \(\times\) soil depth and stand age \(\times\) soil depths had a significant (\(p<0.001\)) effect on fine root biomass. The fine root biomass exhibited a contrasting result in the intercropping systems, i.e., intercropping systems had lower fine root biomass than rubber monoculture systems, except under 15-year-old intercropping systems during S3 (Figure 1). Fine root biomass negatively correlated with the increasing stand age; the young age (12 years) plantation contributed to greater fine root biomass than the 15- and 24-years old stands. However, fine root biomass significantly increased during S1 and S5 monoculture systems (Figure 1). Similarly, the intercropping system's highest fine root biomass was observed in 12 years during S5. The relationship of fixed effect in the mixed model explained the 0.76 (marginal R\({}^{2}\)) of the total variances, and the random effects explained 0.82 of the total variances (conditional R\({}^{2}\)) (Table 1).  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Effects**} & \multicolumn{4}{c}{**Fine Roots Biomass**} & \multicolumn{2}{c}{**Available Nitrogen**} & \multicolumn{2}{c}{**Available Phosphorus**} & \multicolumn{2}{c}{**Available Potassium**} \\  & \multicolumn{4}{c}{**(Mg:\(\mathbf{h^{-1}}\))**} & \multicolumn{2}{c}{**(mg:\(\mathbf{kg^{-1}}\))**} & \multicolumn{2}{c}{**(mg:\(\mathbf{kg^{-1}}\))**} & \multicolumn{2}{c}{**(mg:\(\mathbf{kg^{-1}}\))**} & \multicolumn{2}{c}{**(mg:\(\mathbf{kg^{-1}}\))**} \\ \hline
**Factors** & _df_ & **SSq** & **F** & \(p\)** & **Value** & **SSq** & **F** & \(p\)** & **Sq** & **F** & **\(p\)** \\  & & **Value** & **Value** & **Value** & **Value** & **Value** & **Value** & **Value** & **Value** & **Value** & **Value** & **Value** & **Value** \\ \hline Season (S) & 4 & 2.13 & 5.03 & 0.001 & 5.43 & 70.59 & 0.001 & 17.42 & 12.94 & 0.001 & 0.62 & 5.02 & 0.001 \\ Management & 1 & 0.25 & 2.39 & 1.00 & 0.00 & 0.16 & 0.695 & 24.14 & 71.72 & 0.001 & 0.93 & 30.09 & 0.001 \\ (M) & 2 & 0.5 & 2.38 & 1.00 & 0.98 & 25.38 & 0.001 & 114.64 & 170.27 & 0.001 & 0.46 & 7.49 & 0.01 \\ Depths (D) & 5 & 191.89 & 362.47 & 0.001 & 28.94 & 300.82 & 0.001 & 95.8 & 56.92 & 0.001 & 7.28 & 47.22 & 0.001 \\ S \(\times\) D & 20 & 4.87 & 2.3 & 0.001 & – & – & – & – & – & – & – & – & – \\ A \(\times\) D & 10 & 2.87 & 2.71 & 0.003 & – & – & – & 17.16 & 5.1 & 0.001 & – & – & – \\ S \(\times\) M & 4 & 0.4 & 0.95 & 0.433 & 0.25 & 3.29 & 0.05 & 13.75 & 10.21 & 0.001 & 0.79 & 6.38 & 0.001 \\ S \(\times\) A & 8 & 1.19 & 1.4 & 0.196 & 1.44 & 9.34 & 0.001 & 35.84 & 77.82 & 0.001 & 0.96 & 3.9 & 0.001 \\ M \(\times\) A & 2 & 0.16 & 0.77 & 1.00 & 0.1 & 2.6 & 0.102 & 52.39 & 77.82 & 0.001 & 0.67 & 10.84 & 0.001 \\ M \(\times\) D & 5 & 0.54 & 1.03 & 0.402 & – & – & 1.14 & 0.67 & 0.643 & & – & – \\ S \(\times\) M \(\times\) A & 8 & 0.93 & 1.1 & 0.362 & 1.031 & 6.69 & 0.001 & 17.74 & 6.59 & 0.001 & 1.43 & 5.81 & 0.001 \\ R\({}^{2}\) & – & – & – & – & 0.78 & – & 0.85 & – & – & 0.64 & – & – \\ R\({}^{2}\) c & – & 0.82 & – & – & 0.79 & – & – & 0.87 & – & – & 0.77 & – & – \\ \hline \hline \end{tabular}
\end{table}
Table 1: Linear mixed-effect model values attained testing effects of different management systems (M), stand age (A), seasons (S), and soil depths (D) on fine root biomass and available nutrients.