## 3 Results
### Relationship Between RS Variables and Field-Measured SAI Values  
The relationship between RS spectral indices (annual averages of BI\({}_{2}\), MCARI\({}_{\text{Sent}}\), and NDWI\({}_{\text{Gao}}\)) and _SAI_ varied across forests in both the plains and foothills landscapes. Mean annual BI\({}_{2}\) showed a significant response to _SAI_ across sites in both landscapes. Overall, mean annual BI\({}_{2}\) values increased at higher _SAI_ levels in both landscapes (Figure 3A,B; Table 5). However, values recorded in foothills sites were 25% lower than those in the plains. Specifically, in the plains landscape, sites with _SAI_ > 80% had significantly higher mean annual BI\({}_{2}\) values compared to sites with _SAI_ < 80% (Adj R\({}^{2}\) = 0.71, \(p\) < 0.0001; Figure 3A). Both mean monthly and annual BI\({}_{2}\) values exhibited the same response pattern, with a  
Figure 3: Relationship between spectral indices (annual average of BI\({}_{2}\), MCARI\({}_{\text{Sent}}\), NDWI\({}_{\text{Gao}}\)) and _SAI_ across forests on plains (blue, left) and foothills (red, right). Symbols indicate forest types: stars (mature forests, CL1-CL2), squares (closed forests with emergent, CL3-CL4), rhombuses (low closed forests, CL5), crosses (shrublands, CL6), triangles (savannas, CL7), circles (grasslands with trees, CL8). The black line represents the fitted model, with blue and red shading for the 95% confidence interval. Asterisks denote significance: * \(p\) < 0.05, ** \(p\) < 0.01, *** \(p\) < 0.001. Subfigures report BI\({}_{2}\), relation with _SAI_ values on plains (**A**), and foothills (**B**); MCARI\({}_{\text{Sent}}\), relation with _SAI_ values on plains (**C**), and foothills (**D**); NDWI\({}_{\text{Gao}}\) relation with _SAI_ values on plains (**E**), and foothills (**F**). good overall fit (Adj R\({}^{2}\) > 0.65, \(p\) < 0.0001; S3, Figure S3.1; Table S3.1). In the foothills landscape, mean annual BL\({}_{2}\) also increased with \(SAI\) (Adj R\({}^{2}\) = 0.54, \(p\) = 0.0002; Figure 3B). Similarly, mean monthly BL\({}_{2}\) responded significantly to \(SAI\) for all months except November (Figure S3.1). The fit of mean monthly BI\({}_{2}\) values for the foothills sites was lower than that for the plains, ranging from Adj R\({}^{2}\) = 0.14 to 0.65 (S3, Table S3.1). The mean annual MCARI\({}_{\text{Sent}}\) values of sites in both landscapes increased with greater \(SAI\) levels (S3, Figure S3.1; Table S3.1). However, 60% of the sites in the plains landscape fell outside the 95% confidence interval (Adj R\({}^{2}\) = 0.15, \(p\) = 0.0185; Figure 3C). The response of the mean monthly MCARI\({}_{\text{Sent}}\) to \(SAI\) varied across seasons. From February to May, MCARI\({}_{\text{Sent}}\) increased with higher \(SAI\) levels (S3, Figure S3.1). From December to January, MCARI\({}_{\text{Sent}}\) values showed no significant variation with \(SAI\) (S3, Figure S3.1; Table S3.1). In contrast, from September to November, MCARI\({}_{\text{Sent}}\) values decreased as \(SAI\) increased (S3, Figure S3.1). In the foothills landscape, mean annual MCARI\({}_{\text{Sent}}\) values also increased with higher \(SAI\) levels. The GLM for this landscape showed greater explanatory power compared to the plains, with only 40% of sites falling outside the 95% confidence interval (Adj R\({}^{2}\) = 0.39, \(p\) = 0.0070; Figure 3D). Similar to the plains, the response of monthly MCARI\({}_{\text{Sent}}\) values to \(SAI\) varied across months. From January to August, MCARI\({}_{\text{Sent}}\) increased with higher \(SAI\) levels (S3, Figure S3.1). From September to December, MCARI\({}_{\text{Sent}}\) values remained constant at increasing SAT levels (S3, Table S3.1). Mean annual values of NDWI\({}_{\text{Gao}}\) decreased with increasing \(SAI\) levels in both landscapes (Figure 3E,F). In the plains landscape, sites with high \(SAI\) levels recorded significantly lower NDWI\({}_{\text{Gao}}\) values (Adj R\({}^{2}\) = 0.71, \(p\) < 0.0001; Figure 3E).