气候变化领域集成服务门户(CCPortal): Early detection of forest stress from European spruce bark beetle attack, and a new vegetation index: Normalized distance red & SWIR (NDRS)

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DOI	10.1016/j.rse.2020.112240
	Early detection of forest stress from European spruce bark beetle attack, and a new vegetation index: Normalized distance red & SWIR (NDRS)
	Huo L.; Persson H.J.; Lindberg E.
发表日期	2021
ISSN	00344257
卷号	255
英文摘要	The European spruce bark beetle (Ips typographus [L.]) is one of the most damaging pest insects of European spruce forests. A crucial measure in pest control is the removal of infested trees before the beetles leave the bark, which generally happens before the end of June. However, stressed tree crowns do not show any significant color changes in the visible spectrum at this early-stage of infestation, making early detection difficult. In order to detect the related forest stress at an early stage, we investigated the differences in radar and spectral signals of healthy and stressed trees. How the characteristics of stressed trees changed over time was analyzed for the whole vegetation season, which covered the period before attacks (April), early-stage infestation (‘green-attacks’, May to July), and middle to late-stage infestation (August to October). The results show that spectral differences already existed at the beginning of the vegetation season, before the attacks. The spectral separability between the healthy and infested samples did not change significantly during the ‘green-attack’ stage. The results indicate that the trees were stressed before the attacks and had spectral signatures that differed from healthy ones. These stress-induced spectral changes could be more efficient indicators of early infestations than the ‘green-attack’ symptoms. In this study we used Sentinel-1 and 2 images of a test site in southern Sweden from April to October in 2018 and 2019. The red and SWIR bands from Sentinel-2 showed the highest separability of healthy and stressed samples. The backscatter from Sentinel-1 and additional bands from Sentinel-2 contributed only slightly in the Random Forest classification models. We therefore propose the Normalized Distance Red & SWIR (NDRS) index as a new index based on our observations and the linear relationship between the red and SWIR bands. This index identified stressed forest with accuracies from 0.80 to 0.88 before the attacks, from 0.80 to 0.82 in the early-stage infestation, and from 0.81 to 0.91 in middle- and late-stage infestations. These accuracies are higher than those attained by established vegetation indices aimed at ‘green-attack’ detection, such as the Normalized Difference Water Index, Ratio Drought Index, and Disease Stress Water Index. By using the proposed method, we highlight the potential of using NDRS with Sentinel-2 images to estimate forest vulnerability to European spruce bark beetle attacks early in the vegetation season. © 2020 Elsevier Inc.
英文关键词	Early detection; Sentinel-1; Sentinel-2; Spruce bark beetle infestation; Vegetation indices
语种	英语
scopus关键词	Decision trees; Vegetation; Established vegetations; Forest vulnerability; Linear relationships; Normalized difference water index; Random forest classification; Spectral differences; Spectral separability; Spruce bark beetles; Forestry; backscatter; bark; beetle; detection method; pest control; radar imagery; satellite imagery; seasonality; Sentinel; vegetation index; visible spectrum; vulnerability; Sweden; Coleoptera; Hexapoda; Ips typographus
来源期刊	Remote Sensing of Environment
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/178948
作者单位	Department of Forest Resource Management, Swedish University of Agriculture Sciences, Umeå, SE-901 83, Sweden
推荐引用方式 GB/T 7714	Huo L.,Persson H.J.,Lindberg E.. Early detection of forest stress from European spruce bark beetle attack, and a new vegetation index: Normalized distance red & SWIR (NDRS)[J],2021,255.
APA	Huo L.,Persson H.J.,&Lindberg E..(2021).Early detection of forest stress from European spruce bark beetle attack, and a new vegetation index: Normalized distance red & SWIR (NDRS).Remote Sensing of Environment,255.
MLA	Huo L.,et al."Early detection of forest stress from European spruce bark beetle attack, and a new vegetation index: Normalized distance red & SWIR (NDRS)".Remote Sensing of Environment 255(2021).