{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,28]],"date-time":"2026-04-28T15:09:54Z","timestamp":1777388994050,"version":"3.51.4"},"reference-count":65,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2018,1,3]],"date-time":"2018-01-03T00:00:00Z","timestamp":1514937600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>The focus of this analysis is on the early detection of forest health changes, specifically that of Norway spruce (Picea abies L. Karst.). In this analysis, we planned to examine the time (degree of early detection), spectral wavelengths and appropriate method for detecting vitality changes. To accomplish this, a ring-barking experiment with seven subsequent laboratory needle measurements was carried out in 2013 and 2014 in an area in southeastern Germany near Alt\u00f6tting. The experiment was also accompanied by visual crown condition assessment. In total, 140 spruce trees in groups of five were ring-barked with the same number of control trees in groups of five that were selected as reference trees in order to compare their development. The laboratory measurements were analysed regarding the separability of ring-barked and control samples using spectral reflectance, vegetation indices and derivative analysis. Subsequently, a random forest classifier for determining important spectral wavelength regions was applied. Results from the methods are consistent and showed a high importance of the visible (VIS) spectral region, very low importance of the near-infrared (NIR) and minor importance of the shortwave infrared (SWIR) spectral region. Using spectral reflectance data as well as indices, the earliest separation time was found to be 292 days after ring-barking. The derivative analysis showed that a significant separation was observed 152 days after ring-barking for six spectral features spread through VIS and SWIR. A significant separation was detected using a random forest classifier 292 days after ring-barking with 58% separability. The visual crown condition assessment was analysed regarding obvious changes of vitality and the first indication was observed 302 days after ring-barking as bark beetle infestation and yellowing of foliage in the ring-barked trees only. This experiment shows that an early detection, compared with visual crown assessment, is possible using the proposed methods for this specific data set. This study will contribute to ongoing research for early detection of vitality changes that will support foresters and decision makers.<\/jats:p>","DOI":"10.3390\/rs10010057","type":"journal-article","created":{"date-parts":[[2018,1,3]],"date-time":"2018-01-03T12:00:06Z","timestamp":1514980806000},"page":"57","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":12,"title":["Early Detection of Vitality Changes of Multi-Temporal Norway Spruce Laboratory Needle Measurements\u2014The Ring-Barking Experiment"],"prefix":"10.3390","volume":"10","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5588-9626","authenticated-orcid":false,"given":"Anne","family":"Reichmuth","sequence":"first","affiliation":[{"name":"Department of Remote Sensing, Institute of Geography and Geology, University of Wuerzburg, Am Hubland, D-97074 Wuerzburg, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Lea","family":"Henning","sequence":"additional","affiliation":[{"name":"Th\u00fcnen Institute of Forest Ecosystems, Alfred-Moeller-Strasse 1, D-16225 Eberswalde, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1978-3204","authenticated-orcid":false,"given":"Nicole","family":"Pinnel","sequence":"additional","affiliation":[{"name":"German Remote Sensing Data Center (DFD), German Aerospace Center (DLR), Muenchener Strasse 20, D-82234 Wessling, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Martin","family":"Bachmann","sequence":"additional","affiliation":[{"name":"German Remote Sensing Data Center (DFD), German Aerospace Center (DLR), Muenchener Strasse 20, D-82234 Wessling, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Derek","family":"Rogge","sequence":"additional","affiliation":[{"name":"German Remote Sensing Data Center (DFD), German Aerospace Center (DLR), Muenchener Strasse 20, D-82234 Wessling, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2018,1,3]]},"reference":[{"key":"ref_1","first-page":"42","article-title":"\u00dcberlegungen zum Risiko des Fichtenanbaus in Deutschland vor dem Hintergrund des Klimawandels","volume":"80","author":"Knoke","year":"2009","journal-title":"Forstarchiv"},{"key":"ref_2","unstructured":"Levitt, J. (1980). Water, Radiation, Salt, and Other Stresses, Band 2, Academic Press."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"4","DOI":"10.1016\/S0176-1617(96)80287-2","article-title":"Vegetation Stress: An Introduction to the Stress Concept in Plants","volume":"148","author":"Lichtenthaler","year":"1996","journal-title":"J. Plant Physiol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"109","DOI":"10.1016\/0034-4257(88)90008-9","article-title":"Comparison of in situ and airborne spectral measurements of the blue shift associated with forest decline","volume":"24","author":"Rock","year":"1988","journal-title":"Remote Sens. Environ."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"677","DOI":"10.2307\/2657068","article-title":"Leaf optical properties in higher plants: Linking spectral characteristics to stress and chlorophyll concentration","volume":"88","author":"Carter","year":"2001","journal-title":"Am. J. Bot."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"239","DOI":"10.1002\/j.1537-2197.1993.tb13796.x","article-title":"Responses of Leaf Spectral Reflectance to Plant Stress","volume":"80","author":"Carter","year":"1993","journal-title":"Am. J. Bot."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"697","DOI":"10.1080\/01431169408954109","article-title":"Ratios of leaf reflectances in narrow wavebands as indicators of plant stress","volume":"15","author":"Carter","year":"1994","journal-title":"Int. J. Remote Sens."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"81","DOI":"10.1016\/0034-4257(92)90142-7","article-title":"Spectral blue-shift of red edge minitors damage class of beech trees","volume":"39","author":"Hoque","year":"1992","journal-title":"Remote Sens. Environ."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"209","DOI":"10.1080\/02772249009357575","article-title":"Studies on reflective features of Norway spruce and their possible applications in remote sensing of forest damage","volume":"27","author":"Hoque","year":"1990","journal-title":"Toxicol. Environ. Chem."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"899","DOI":"10.1016\/j.rse.2009.12.005","article-title":"Continuous wavelet analysis for the detection of green attack damage due to mountain pine beetle infestation","volume":"114","author":"Cheng","year":"2010","journal-title":"Remote Sens. Environ."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"191","DOI":"10.1080\/07038992.2015.1065707","article-title":"Hyperspectral Remote Sensing of Mountain Pine Beetle with an Emphasis on Previsual Assessment","volume":"41","author":"Niemann","year":"2015","journal-title":"Can. J. Remote Sens."},{"key":"ref_12","first-page":"308","article-title":"An angular vegetation index for imaging spectroscopy data\u2014Preliminary results on forest damage detection in the Bavarian National Park, Germany","volume":"19","author":"Fassnacht","year":"2012","journal-title":"Int. J. Appl. Earth Obs. Geoinf."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"533","DOI":"10.1016\/j.rse.2013.09.014","article-title":"Assessing the potential of hyperspectral imagery to map bark beetle-induced tree mortality","volume":"140","author":"Fassnacht","year":"2014","journal-title":"Remote Sens. Environ."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"76","DOI":"10.1016\/j.foreco.2013.07.043","article-title":"Forecasting potential bark beetle outbreaks based on spruce forest vitality using hyperspectral remote-sensing techniques at different scales","volume":"308","author":"Lausch","year":"2013","journal-title":"For. Ecol. Manag."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"2133","DOI":"10.1080\/014311698214910","article-title":"Technical note A new technique for interpolating the reflectance red edge position","volume":"19","author":"Dawson","year":"1998","journal-title":"Int. J. Remote Sens."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"181","DOI":"10.1016\/j.rse.2005.12.011","article-title":"A new technique for extracting the red edge position from hyperspectral data: The linear extrapolation method","volume":"101","author":"Cho","year":"2006","journal-title":"Remote Sens. Environ."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"34","DOI":"10.1016\/j.isprsjprs.2007.02.001","article-title":"Red edge shift and biochemical content in grass canopies","volume":"62","author":"Mutanga","year":"2007","journal-title":"J. Photogramm. Remote Sens."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"182","DOI":"10.1016\/0034-4257(95)00235-9","article-title":"Critique of stepwise multiple linear regression for the extraction of leaf biochemistry information from leaf reflectance data","volume":"56","author":"Grossman","year":"1996","journal-title":"Remote Sens. Environ."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"145","DOI":"10.1016\/j.compag.2012.09.001","article-title":"Using vegetation index and modified derivative for early detection of soybean plant injury from glyphosate","volume":"89","author":"Yao","year":"2012","journal-title":"Comput. Electron. Agric."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"207","DOI":"10.1016\/j.rse.2004.06.002","article-title":"Use of hyperspectral derivative ratios in the red-edge region to identify plant stress responses to gas leaks","volume":"92","author":"Smith","year":"2004","journal-title":"Remote Sens. Environ."},{"key":"ref_21","unstructured":"Bayerisches Landesamt f\u00fcr Umwelt (2016). GeoFachdatenAtlas (Boden Informations System Bayern), Bayerisches Landesamt f\u00fcr Umwelt."},{"key":"ref_22","unstructured":"Bayer, A. (2013). Methodological Developments for Mapping Soil Constituents Using Imaging Spectroscopy. [Ph.D. Thesis, University Potsdam]."},{"key":"ref_23","unstructured":"Dorigo, W., Bachmann, M., and Heldens, W. (2006). AS Toolbox and Processing of Field Spectra\u2014User\u2019s Manual, German Aerospace Center. Technical Report."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"423","DOI":"10.1127\/1432-8364\/2014\/0234","article-title":"Method Analysis for Collecting and Processing in-situ Hyperspectral Needle Reflectance Data for Monitoring Norway Spruce<BR> Methodenanalyse zur Erfassung und Prozessierung hyperspektraler in-situ Nadelreflexionsdaten zum Monitoring von Fichten","volume":"2014","author":"Einzmann","year":"2014","journal-title":"Photogramm. Fernerkund. Geoinf."},{"key":"ref_25","unstructured":"Breiman, L. (1984). Classification and Regression Trees, Chapman & Hall."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"5","DOI":"10.1023\/A:1010933404324","article-title":"Random Forests","volume":"45","author":"Breiman","year":"2001","journal-title":"Mach. Learn."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"L11402","DOI":"10.1029\/2006GL026457","article-title":"Three-band model for noninvasive estimation of chlorophyll, carotenoids, and anthocyanin contents in higher plant leaves","volume":"33","author":"Gitelson","year":"2006","journal-title":"Geophys. Res. Lett."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"229","DOI":"10.1016\/S0034-4257(00)00113-9","article-title":"Estimating Corn Leaf Chlorophyll Concentration from Leaf and Canopy Reflectance","volume":"74","author":"Daughtry","year":"2000","journal-title":"Remote Sens. Environ."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"337","DOI":"10.1016\/S0034-4257(02)00010-X","article-title":"Relationships between leaf pigment content and spectral reflectance across a wide range of species, leaf structures and developmental stages","volume":"81","author":"Sims","year":"2002","journal-title":"Remote Sens. Environ."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"257","DOI":"10.1016\/S0034-4257(96)00067-3","article-title":"NDWI\u2014A normalized difference water index for remote sensing of vegetation liquid water from space","volume":"58","author":"Gao","year":"1996","journal-title":"Remote Sens. Environ."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"43","DOI":"10.1016\/0034-4257(89)90046-1","article-title":"Detection of changes in leaf water content using Near- and Middle-Infrared reflectances","volume":"30","author":"Hunt","year":"1989","journal-title":"Remote Sens. Environ."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"355","DOI":"10.1016\/S0034-4257(02)00011-1","article-title":"Remote sensing of nitrogen and lignin in Mediterranean vegetation from AVIRIS data: Decomposing biochemical from structural signals","volume":"81","author":"Serrano","year":"2002","journal-title":"Remote Sens. Environ."},{"key":"ref_33","first-page":"350","article-title":"Brown and green LAI mapping through spectral indices","volume":"35","author":"Delegido","year":"2015","journal-title":"Int. J. Appl. Earth Obs. Geoinf."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"38","DOI":"10.1562\/0031-8655(2001)074<0038:OPANEO>2.0.CO;2","article-title":"Optical properties and nondestructive estimation of anthocyanin content in plant leaves","volume":"74","author":"Gitelson","year":"2001","journal-title":"Photochem. Photobiol."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"273","DOI":"10.1016\/S0034-4257(98)00059-5","article-title":"Quantifying Chlorophylls and Caroteniods at Leaf and Canopy Scales: An Evaluation of Some Hyperspectral Approaches","volume":"66","author":"Blackburn","year":"1998","journal-title":"Remote Sens. Environ."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"494","DOI":"10.1016\/S0176-1617(96)80284-7","article-title":"Signature Analysis of Leaf Reflectance Spectra: Algorithm Development for Remote Sensing of Chlorophyll","volume":"148","author":"Gitelson","year":"1996","journal-title":"J. Plant Physiol."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"11","DOI":"10.1364\/AO.4.000011","article-title":"Spectral Properties of Plants","volume":"4","author":"Gates","year":"1965","journal-title":"Appl. Opt."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"271","DOI":"10.1016\/0034-4257(89)90069-2","article-title":"Remote-Sensing of Foliar Chemistry","volume":"30","author":"Curran","year":"1989","journal-title":"Remote Sens. Environ."},{"key":"ref_39","first-page":"55","article-title":"Plant phenolics and absorption features in vegetation reflectance spectra near 1.66 \u03bcm","volume":"43","author":"Kokaly","year":"2015","journal-title":"Int. J. Appl. Earth Obs. Geoinf."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"1775","DOI":"10.1080\/01431169008955129","article-title":"Visible and near infrared reflectance characteristics of dry plant materials","volume":"11","author":"Elvidge","year":"1990","journal-title":"Int. J. Remote Sens."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.plaphy.2013.05.009","article-title":"Plant phenolics: Recent advances on their biosynthesis, genetics, and ecophysiology","volume":"72","author":"Cheynier","year":"2013","journal-title":"Plant Physiol. Biochem."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"705","DOI":"10.1111\/j.1364-3703.2010.00625.x","article-title":"The roles of plant phenolics in defence and communication during Agrobacterium and Rhizobium infection","volume":"11","author":"Bhattacharya","year":"2015","journal-title":"Mol. Plant Pathol."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"162","DOI":"10.1007\/BF02858959","article-title":"The girdled tree","volume":"36","author":"Noel","year":"1970","journal-title":"Bot. Rev."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"28","DOI":"10.1016\/j.rse.2014.03.011","article-title":"Estimation of water-related biochemical and biophysical vegetation properties using multitemporal airborne hyperspectral data and its comparison to MODIS spectral response","volume":"148","author":"Casas","year":"2014","journal-title":"Remote Sens. Environ."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"283","DOI":"10.1016\/S0034-4257(02)00113-X","article-title":"Steady-state chlorophyll a fluorescence detection from canopy derivative reflectance and double-peak red-edge effects","volume":"84","author":"Pushnik","year":"2003","journal-title":"Remote Sens. Environ."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"69","DOI":"10.1016\/0034-4257(91)90066-F","article-title":"The effect of a red leaf pigment on the relationship between red edge and chlorophyll concentration","volume":"35","author":"Curran","year":"1991","journal-title":"Remote Sens. Environ."},{"key":"ref_47","unstructured":"Nultsch, W. (1996). Allgemeine Botanik, Thieme."},{"key":"ref_48","unstructured":"Resa, F. (1877). Ueber Die Periode der Wurzelbildung, Carthouse."},{"key":"ref_49","unstructured":"Raven, P.H., Evert, R.F., and Eichhorn, S.E. (2006). Biologie der Pflanzen, Gruyter."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"253","DOI":"10.1016\/S0378-1127(02)00134-2","article-title":"Growth and development of the root system of Norway spruce (Picea abies) in forest stands\u2014A review","volume":"175","author":"Puhe","year":"2003","journal-title":"For. Ecol. Manag."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"349","DOI":"10.1046\/j.1469-8137.2002.00482.x","article-title":"Anthocyanins in vegetative tissues: A proposed unified function in photoprotection","volume":"155","author":"Steyn","year":"2002","journal-title":"New Phytol."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"S67","DOI":"10.1016\/j.rse.2008.10.019","article-title":"Retrieval of foliar information about plant pigment systems from high resolution spectroscopy","volume":"113","author":"Gitelson","year":"2009","journal-title":"Remote Sens. Environ."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1111\/j.1751-1097.1999.tb01944.x","article-title":"Environmental Significance of Anthocyanins in Plant Stress Responses","volume":"70","year":"1999","journal-title":"Photochem. Photobiol."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"395","DOI":"10.1093\/oxfordjournals.pcp.a028959","article-title":"Photosynthetic Efficiency, and Photodamage by UV and Visible Radiation, in Red versus Green Leaf Coleus Varieties","volume":"37","author":"Burger","year":"1996","journal-title":"Plant Cell Physiol."},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"855","DOI":"10.1093\/jxb\/erl123","article-title":"Hyperspectral remote sensing of plant pigments","volume":"58","author":"Blackburn","year":"2007","journal-title":"J. Exp. Bot."},{"key":"ref_56","doi-asserted-by":"crossref","unstructured":"McClure, J.W. (1975). Physiology and Functions of Flavonoids. The Flavonoids, Springer.","DOI":"10.1007\/978-1-4899-2909-9_18"},{"key":"ref_57","first-page":"78","article-title":"Non-Destructive Assessment of Chlorophyll Carotenoid and Anthocyanin Content in Higher Plant Leaves: Principles and Algorithms","volume":"263","author":"Gitelson","year":"2004","journal-title":"Pap. Nat. Resour."},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"61","DOI":"10.1046\/j.1365-3040.2000.00519.x","article-title":"Carbohydrate metabolism in a heat-girdled maize source leaf","volume":"23","author":"Jeannette","year":"2000","journal-title":"Plant Cell Environ."},{"key":"ref_59","doi-asserted-by":"crossref","first-page":"617","DOI":"10.1111\/j.1365-3040.1997.00078.x","article-title":"Internal and external photoprotection in developing leaves of the CAM plant Cotyledon orbiculata","volume":"20","author":"Barker","year":"1997","journal-title":"Plant Cell Environ."},{"key":"ref_60","doi-asserted-by":"crossref","first-page":"848","DOI":"10.1104\/pp.91.3.848","article-title":"Whole Leaf Carbon Exchange Characteristics of Phosphate Deficient Soybeans (Glycine max L.)","volume":"91","author":"Lauer","year":"1989","journal-title":"Plant Physiol."},{"key":"ref_61","doi-asserted-by":"crossref","first-page":"110","DOI":"10.1046\/j.1365-3040.1997.d01-17.x","article-title":"Sugar repression of photosynthesis: the role of carbohydrates in signalling nitrogen deficiency through source:sink imbalance","volume":"20","author":"Paul","year":"1997","journal-title":"Plant Cell Environ."},{"key":"ref_62","doi-asserted-by":"crossref","unstructured":"Larcher, W.W. (1995). Physiological Plant Ecology: Ecophysiology and Stress Physiology of Functional Groups, Springer.","DOI":"10.1007\/978-3-642-87851-0"},{"key":"ref_63","doi-asserted-by":"crossref","first-page":"273","DOI":"10.1016\/0273-1177(83)90130-8","article-title":"Red edge measurements for remotely sensing plant chlorophyll content","volume":"3","author":"Horler","year":"1983","journal-title":"Adv. Space Res."},{"key":"ref_64","doi-asserted-by":"crossref","first-page":"501","DOI":"10.1016\/S0176-1617(96)80285-9","article-title":"Detection of Red Edge Position and Chlorophyll Content by Reflectance Measurements Near 700 nm","volume":"148","author":"Gitelson","year":"1996","journal-title":"J. Plant Physiol."},{"key":"ref_65","doi-asserted-by":"crossref","first-page":"916","DOI":"10.1002\/j.1537-2197.1991.tb14495.x","article-title":"Primary and Secondary Effects of Water Content on the Spectral Reflectance of Leaves","volume":"78","author":"Carter","year":"1991","journal-title":"Am. J. Bot."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/10\/1\/57\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T14:49:55Z","timestamp":1760194195000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/10\/1\/57"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2018,1,3]]},"references-count":65,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2018,1]]}},"alternative-id":["rs10010057"],"URL":"https:\/\/doi.org\/10.3390\/rs10010057","relation":{},"ISSN":["2072-4292"],"issn-type":[{"value":"2072-4292","type":"electronic"}],"subject":[],"published":{"date-parts":[[2018,1,3]]}}}