Abstract
Abstract. The free to use Sentinel-2 (S2) sensors with 5-day revisit time at high spatial resolution in 10 spectral bands is a revolution in the remote sensing domain. Including 6 spectral bands in the near infrared, with 3 dedicated for the red-edge (where the vegetation significatively increases), these european satellites are very promising for mapping tree species distribution at a national scale. Here, we study the contribution of three one-year S2 Satellite Image Time Series (SITS) for mapping deciduous species distribution in the southwest of France. The annual cycle of vegetation (called phenology) can contribute to the identification of tree species. For some specific dates, species can have different phenological behaviours (senesence, flowering…). To train and validate the maps, we used the Support Vector Machine algorithm with a spatial cross-validation method. To train the algorithm with the same number of samples per species, we decided to undersample each class to the smallest class using a K-means clustering method. Moreover, a Sequential Feature Selection (SFS) has been implemented to detect the optimal dates per species. Our results are promising with high accuracy for Red oak andWillow (average score of the three one-year respectively F1 = 0.99, F1 = 0.94) based on the optimal dates. However, it appears that the performances when using the each full SITS are far below the optimal dates models (average ΔF1 = 0.32). We did not find, except for Willow and Red oak, that the optimal dates were the same for each year. Perspectives is to find an algorithm robust to temporal or spectral noise and to smooth the time series.
Highlights
In the context of global warming and biodiversity loss, forests are one of the most important ecosystems to protect (Thompson et al, 2011)
Thanks to the two Sentinel-2 satellites, it has been possible to acquire a significant number of images for year 2017, 2018 and 2019
Using optimal dates based on the Sequential Feature Selection, high performances were observed for Red oak and Willow
Summary
In the context of global warming and biodiversity loss, forests are one of the most important ecosystems to protect (Thompson et al, 2011). The share of the world’s forests is decreasing year after year and is being replaced by agriculture or grazing with serious consequences on biodiversity (Brockerhoff et al, 2008). These previous authors pointed out that the replacement of natural or semi-natural forests by forest plantations is always preferable to other land covers, with the exception of the original forest. Whether it is degradation or deforestation, there are solutions to slow down these losses. We protect the flora and fauna biodiversity
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More From: ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences
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