Abstract
Abstract. The objective of this study is to evaluate the spectral difference between and within 11 tree species belonging to Brazilian Atlantic Forest located in the countryside of São Paulo State, Brazil. Tree species with different development stages may have different reflectance spectra because of the structural and phenological influence on it. Tree structure can affect the crown spectra due to the differences in geometry of view and density of shadow and sunlight pixels. Additionally, reflectance spectra can be similar between tree species belonging from different species, which affect the classification accuracy of these targets. In this sense, we evaluate the spectral difference between highly diverse Atlantic Forest using two different features extracted from individual tree crowns (ITCs). Mean reflectance spectra and mean normalized reflectance spectra of each ITC were used. They were computed from hyperspectral images acquired with sensor onboard unmanned aerial vehicle. Differences between tree species and within-species were calculated. Wilcoxon-Mann-Whitney test was applied in order to statistically evaluate whether the reflectance spectra were different. Results showed that the normalized values are more propense to increase the classification accuracies than using the mean values since it reduces the variability within-species and present a higher number of different values between-species.
Highlights
Tropical Atlantic forest is an interesting research topic because of its biodiversity wealth in contrast with its deforestation and degradation over the years (Myers et al, 2000)
Tree species reflectance is affected by a series of factors such as leaves disposal and shape, structure, soil reflectance and geometry of view (Asner, 1998)
Mean reflectance factor spectra of each tree species are given in Figure 1, where it is possible to see that the highest differences are in the red-edge region
Summary
Tropical Atlantic forest is an interesting research topic because of its biodiversity wealth in contrast with its deforestation and degradation over the years (Myers et al, 2000). Most of the remnant of Brazilian Atlantic forest are fragmented (Ribeiro et al, 2009). This type of forest protection and restoration is an important key to protect the ecosystem services (Rezende et al, 2018). Hyperspectral data can provide detailed information about targets which are valuable to classification purposes. Especially when working with targets like vegetation where the reflectance spectra can be similar (Price, 1994). Tree species reflectance is affected by a series of factors such as leaves disposal and shape, structure, soil reflectance and geometry of view (Asner, 1998). The same tree species can have different spectra depending on its stage of development and location, which can be a challenging factor when producing tree species maps
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