## 3 Results and Discussion
It is noticeable that there is one outlier in the monodominant plot with a considerably higher biomass than any other sampled plot. This is attributed to the existence of mahogany, which is an exotic tree species for Indonesia (being native to the Caribbean), growing up to 30 m high and with a large spherical crown and many heavy branches [100], facts which indicate a species with a high biomass. A closer look at the field data reveals that the only four plots with biomasses higher than 150 ton/ha are all comprised of mahogany as the dominant species. When investigating the statistical distribution of the plot biomass as a function of the dominant species (Figure 4a), it becomes apparent that mahogany-dominated plots contain a higher amount of biomass. Moreover, when separating between monodominant and monodominant cases (Figure 4b), the same trend is observed; the single monodominant mahogany plot exhibits a considerably higher value of biomass. The biomass levels for acacia and teak are at similar levels; however, the standard deviation for acacia is considerably lower for both cases of monodominant and non-monodominant plots. The current study focused on investigating the relationship between the plot biomass and the Sentinel-1 and Sentinel-2 band combinations. The R\({}^{2}\) map for each experiment was derived and the statistically most important scenarios are presented in Figures 5-7. Figure 5 depicts the results when considering the entire dataset of the 30 field plots. It is evident that there are two spectral regions where the correlations seem to be significant. Specifically, the Ri/Rj combinations of bands 2-5 and bands 6-8A correlate with R\({}^{2}>\) 0.5 (max R\({}^{2}\) = 0.70 for the band combination 2/8). This is an indication that spectral bands constructed based on the visible and near-infrared bands correlate strongly for this private forest. Interestingly, there is a second spectral region at the combined bands of the near-infrared with the SWIR bands (i.e., 11 and 12) which also yields similar correlation (0.62 \(\leq\) R\({}^{2}\)\(\leq\) 0.66). Both of these spectral windows indicate a low \(p\)-value and therefore are statistically significant. This is in agreement with a study which also utilized the complete band combinations of Sentinel-2 to estimate AGB in a boreal forest [44], which found a low correlation (R\({}^{2}\) = 0.24) based on the NDSI combination of bands 8a and 10, 6 and 11, and 3 and 12; nevertheless, all band combinations had similarly low values and the aforementioned bands cannot be considered as a suggestion of AGB proxy. Relatedly, band 8a was also the feature of all bands and \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Species** & **Number of Trees** & **Circumference Range (cm)** & **Height Range (m)** & **Biomass Range (kg)** \\ \hline Teak & 550 & 20–98 & 1.23–23.98 & 4.63–486.27 \\ Earleaf acacia & 165 & 19–100 & 4–60–25.66 & 9.00–699.18 \\ Mahogany & 268 & 25–94 & 4.00–23.98 & 41.98–829.65 \\ Others & 20 & 27–100 & 5–19 & 12.08–129.41 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Cumulative number and species of trees sampled in the 30 plots and their structural characteristics. indices with the highest relative importance in a prediction model that [PERSON] et al. [19] used to estimate AGB in a sub-tropical forest in Nepal. Moreover, it is worth noting that the R\({}^{2}\) of the combinations of the visible and SWIR regions overall perform poorly and are, for all cases, below 0.5. Figure 2: Histogram distribution of the diameter (**a**), height (**b**), and biomass (**c**) of individual trees categorized by the three main dominant species encountered at the 30 plots of field sampling. The white bins refer to the cumulative samples while the colored curves correspond to individual major species. The data correspond to 983 trees out of 1003 trees sampled in total. Figure 4: Box-and-whisker plots of biomass (per plot) measured during fieldwork categorized by the dominant species encountered (**a**) and grouped by the existence of monodominance (**b**).