Anthropogenic Disturbances Affect the Relationship Between Spectral Indices and the Biometric Variables of Brazilian Savannas

Abstract

According to previous studies involving biometric variables modeling using remote sensing (RS), data did not consider the effects of anthropogenic disturbance as relevant factor. The main objective of this study was to model aboveground biomass (AGB) and total wood volume (TWV) of Brazilian Savanna biome using vegetation indices (VI) from LANDSAT 5 TM. Multiple linear regression (MLR) and random forest (RF) algorithm were applied across 641 field plots of cerrado sensu stricto of the state of Minas Gerais, Brazil, comparing two models: non-stratified, and stratified according to plot's anthropization degree. AGB and TWV obtained from non-anthropized plots presented linear relation with VIs (R 2 = 0.82 and 0.74, respectively) and, on the other hand, presented nonlinear relation when plots were affected by anthropogenic disturbances or were not stratified. This finding helps improving estimates by stratifying plots into their anthropization degree, mainly in the Brazilian Savanna biome undergoing anthropogenic disturbances.

Seasonal behavior of vegetation determined by sensor on an unmanned aerial vehicle

“…Although native remnants have a higher correlation with soil moisture (Figure 3), this was not observed in the vegetation indices. This fact may be explained by the effect of anthropogenic disturbances which are capable of affecting the spectral response of the vegetation (Pawar et al 2014, Silveira et al 2019. This was confirmed by observing the results of Forest Remnant 2, located in a highly anthropized region with roads, trails, constructions and technogenic deposits (inside and on the edges of the remnants) (Pereira et al 2010), which reported a less significant correlation when compared to Forest Remnant 1, which is located in a slightly more isolated area, and Coffea spp.…”