*2.7. Accuracy Assessment*

The accuracy of the estimated AGB was assessed using the adjusted coefficient of determination (*R*2) and root-mean-square error (*RMSE*). The *R*<sup>2</sup> and *RMSE* were calculated using following equations:

$$\mathcal{R}^2 = 1 - \frac{\left(n - 1\right) \sum\_{i=1}^n \left(\mathbf{x}\_i - \mathbf{x}\_i\right)^2}{\left(n - 2\right) \sum\_{i=1}^n \left(\mathbf{x}\_i - \overline{\mathbf{x}}\right)^2} \tag{1}$$

$$RMSE = \sqrt{\frac{\sum\_{i=1}^{n} (\mathbf{x}\_i - \mathbf{x}\_i)^2}{n-2}} \tag{2}$$

where *xi* is the observed mangrove AGB, *x*ˆ*i* is the predicted AGB based on the random forest model built with the training data, *x* is the average AGB of all validation plots, and *n* is the number of validation plots.
