Local-scale mapping of tree species in a lower mountain area using Sentinel-1 and -2 multitemporal images, vegetation indices, and topographic information

Frontiers in Forests and Global Change

Forests and Global Change

Constantin Irinel Greșiță¹  Iosif Vorovencii¹  Codrin-Leonid Codrean¹  Sanda Chima¹  Ion Gavrilescu¹  Lucian Dincă²  Cristian Cătălin²  Vlad Crișan²  Ruxandra-Georgiana Postolache³ 

[1]Faculty of Silviculture and Forest Engineering, Transilvania University of Brașov, Brașov, Romania

[2]National Institute for Research and Development in Forestry “Marin Drăcea”, Brașov, Romania

[3]National Institute for Research and Development in Forestry “Marin Drăcea”, Brașov, Romania

[4]Forestry Faculty, Stefan cel Mare University of Suceava, Suceava, Romania

关键词: random forest;    Sentinel-2;    topographic features;    vegetation indices;    datasets;    tree species;    mountain area;   

DOI  :  10.3389/ffgc.2023.1220253

 received in 2023-05-10, accepted in 2023-09-29,  发布年份 2023

来源: Frontiers

【 摘 要 】

IntroductionMapping tree species is an important activity that provides the information necessary for sustainable forest management. Remote sensing is a effective tool that offers data at different spatial and spectral resolutions over large areas. Free and open acces Sentinel satellite imagery and Google Earth Engine, which is a powerful cloud computing platform, can be used together to map tree species.MethodsIn this study we mapped tree species at a local scale using recent Sentinel-1 (S-1) and Sentinel-2 (S-2) time-series imagery, various vegetation indices (Normalized Difference Vegetation Index - NDVI, Enhanced Vegetation Index - EVI, Green Leaf Index - GLI, and Green Normalized Difference Vegetation Index - GNDVI) and topographic features (elevation, aspect and slope). Five sets of data were used, in different combinations, together with the Random Forest classifier in order to determine seven tree species (spruce, beech, larch, fir, pine, mixed, and other broadleaves [BLs]) in the studied area.Results and discussionDataset 1 was a combination of S-2 images (bands 2, 3, 4, 5, 6, 7, 8, 8a, 11 and 12), for which an overall accuracy of 76.74% was obtained. Dataset 2 comprised S-2 images and vegetation indices, leading to an overall accuracy of 78.24%. Dataset 3 included S-2 images and topographic features, which lead to an overall accuracy of 89.51%. Dataset 4 included S-2 images, vegetation indices, and topographic features, that have determined an overall accuracy of 89.36%. Dataset 5 was composed of S-2 images, S-1 images (VV and VH polarization), vegetation indices, and topographic features that lead to an overall accuracy of 89.68%. Among the five sets of data, Dataset 3 produced the most significant increase in accuracy, of 12.77%, compared to Dataset 1. Including the vegetation indices with the S-2 images (Dataset 2) gave an accuracy increase of only 1.50%. By combining the S-1 and S-2 images, vegetation indices and topographic features (Dataset 5) there was an accuracy increase of only 0.17%, compared with the S-2 images plus topographic features combination (Dataset 3). However, the input brought by the S-1 images was apparent in the increase in classification accuracy for the mixed and other BL species that were mostly found in hilly locations. Our findings confirm the potential of S-2 images, used together with other variables, for classifying tree species at the local scale.

【 授权许可】

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Copyright © 2023 Vorovencii, Dincă, Crișan, Postolache, Codrean, Cătălin, Greșiță, Chima and Gavrilescu.