{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,24]],"date-time":"2026-03-24T04:00:45Z","timestamp":1774324845446,"version":"3.50.1"},"reference-count":120,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2018,1,30]],"date-time":"2018-01-30T00:00:00Z","timestamp":1517270400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100002341","name":"Academy of Finland","doi-asserted-by":"publisher","award":["13286390 and 266152"],"award-info":[{"award-number":["13286390 and 266152"]}],"id":[{"id":"10.13039\/501100002341","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100002301","name":"Estonian Research Council","doi-asserted-by":"publisher","award":["PUT1355"],"award-info":[{"award-number":["PUT1355"]}],"id":[{"id":"10.13039\/501100002301","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100002301","name":"Estonian Research Council","doi-asserted-by":"publisher","award":["Mobilitas Pluss MOBERC-11"],"award-info":[{"award-number":["Mobilitas Pluss MOBERC-11"]}],"id":[{"id":"10.13039\/501100002301","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Ministry of Education, Youth and Sports of CR","award":["LO1415"],"award-info":[{"award-number":["LO1415"]}]},{"DOI":"10.13039\/501100001824","name":"Czech Science Foundation","doi-asserted-by":"publisher","award":["GJ17-05608Y and 17-05743S"],"award-info":[{"award-number":["GJ17-05608Y and 17-05743S"]}],"id":[{"id":"10.13039\/501100001824","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Coniferous species are present in almost all major vegetation biomes on Earth, though they are the most abundant in the northern hemisphere, where they form the northern tree and forest lines close to the Arctic Circle. Monitoring coniferous forests with satellite and airborne remote sensing is active, due to the forests\u2019 great ecological and economic importance. We review the current understanding of spectral behavior of different components forming coniferous forests. We look at the spatial, directional, and seasonal variations in needle, shoot, woody element, and understory spectra in coniferous forests, based on measurements. Through selected case studies, we also demonstrate how coniferous canopy spectra vary at different spatial scales, and in different viewing angles and seasons. Finally, we provide a synthesis of gaps in the current knowledge on spectra of elements forming coniferous forests that could also serve as a recommendation for planning scientific efforts in the future.<\/jats:p>","DOI":"10.3390\/rs10020207","type":"journal-article","created":{"date-parts":[[2018,1,30]],"date-time":"2018-01-30T12:13:37Z","timestamp":1517314417000},"page":"207","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":91,"title":["Spectral Properties of Coniferous Forests: A Review of In Situ and Laboratory Measurements"],"prefix":"10.3390","volume":"10","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6568-3258","authenticated-orcid":false,"given":"Miina","family":"Rautiainen","sequence":"first","affiliation":[{"name":"Department of Built Environment, School of Engineering, Aalto University, P.O. Box 14100, FI-00076 Aalto, Finland"},{"name":"Department of Electronics and Nanoengineering, School of Electrical Engineering, Aalto University, P.O. Box 15500, FI-00076 Aalto, Finland"}]},{"given":"Petr","family":"Luke\u0161","sequence":"additional","affiliation":[{"name":"Global Change Research Institute CAS, B\u011blidla 986\/4a, 603 00 Brno, The Czech Republic"}]},{"given":"Lucie","family":"Homolov\u00e1","sequence":"additional","affiliation":[{"name":"Global Change Research Institute CAS, B\u011blidla 986\/4a, 603 00 Brno, The Czech Republic"}]},{"given":"Aarne","family":"Hovi","sequence":"additional","affiliation":[{"name":"Department of Built Environment, School of Engineering, Aalto University, P.O. Box 14100, FI-00076 Aalto, Finland"}]},{"given":"Jan","family":"Pisek","sequence":"additional","affiliation":[{"name":"Tartu Observatory, University of Tartu, Observatooriumi 1, T\u00f5ravere, 61602 Tartumaa, Estonia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2745-1966","authenticated-orcid":false,"given":"Matti","family":"M\u00f5ttus","sequence":"additional","affiliation":[{"name":"VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 Espoo, Finland"}]}],"member":"1968","published-online":{"date-parts":[[2018,1,30]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Farjon, A. (2010). A Hand-Book of the World\u2019s Conifers, Brill.","DOI":"10.1163\/9789047430629"},{"key":"ref_2","unstructured":"(2017, November 22). Rocky Mountain Tree-Ring Research. Available online: http:\/\/www.rmtrr.org\/oldlist.htm."},{"key":"ref_3","unstructured":"Preston, R. (The New Yorker, 2006). Tall for its age, The New Yorker."},{"key":"ref_4","unstructured":"Stocker, T.F., Qin, D., Plattner, G.-K., Tignor, M., Allen, S.K., Boschung, J., Nauels, A., Xia, Y., Bex, V., and Midgley, P.M. (2013). Carbon and Other Biogeochemical Cycles. Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press."},{"key":"ref_5","unstructured":"United Nations Economic Commission for Europe\/Food and Agriculture Organization of the United Nations (UNECE\/FAO) (2016). Forest Products Annual Market Review 2016, UNECE. Available online: https:\/\/www.unece.org\/fileadmin\/DAM\/timber\/publications\/FPAMR2017AdvanceDraft.pdf."},{"key":"ref_6","unstructured":"Forest Europe (2015). State of Europe\u2019s Forests 2015, Forest Europe. Available online: http:\/\/www.foresteurope.org\/docs\/fullsoef2015.pdf."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"355","DOI":"10.1016\/j.rse.2004.10.010","article-title":"Simple parameterizations of the radiation budget of uniform broadleaved and coniferous canopies","volume":"94","author":"Smolander","year":"2005","journal-title":"Remote Sens. Environ."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"98","DOI":"10.1016\/j.rse.2005.02.009","article-title":"Application of photon recollision probability in coniferous canopy reflectance simulations","volume":"96","author":"Rautiainen","year":"2005","journal-title":"Remote Sens. Environ."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"399","DOI":"10.1109\/JSTARS.2013.2272890","article-title":"Minimizing measurement uncertainties of coniferous needle-leaf optical properties, part i: methodological review","volume":"7","author":"Schaepman","year":"2014","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"406","DOI":"10.1109\/JSTARS.2013.2292817","article-title":"Minimizing measurement uncertainties of coniferous needle-leaf optical properties, Part II: Experimental Setup and Error Analysis","volume":"7","author":"Malenovsky","year":"2014","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1","DOI":"10.14214\/sf.7753","article-title":"Spectral analysis of 25 boreal tree species","volume":"51","author":"Hovi","year":"2017","journal-title":"Silva Fenn."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"98","DOI":"10.1016\/j.rse.2015.10.009","article-title":"Spectral contribution of understory to forest reflectance in a boreal site: An analysis of EO-1 Hyperion data","volume":"171","author":"Rautiainen","year":"2015","journal-title":"Remote Sens. Environ."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"408","DOI":"10.1016\/j.rse.2006.04.005","article-title":"Impact of understory vegetation on forest canopy reflectance and remotely sensed LAI estimates","volume":"103","author":"Eriksson","year":"2006","journal-title":"Remote Sens. Environ."},{"key":"ref_14","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_15","doi-asserted-by":"crossref","unstructured":"Daughtry, C.S.T., and Biehl, L.L. (1984). Changes in Spectral Properties of Detached Leaves.","DOI":"10.1016\/0034-4257(85)90100-2"},{"key":"ref_16","unstructured":"Hosgood, B., Jacquemoud, S., Andreoli, G., Verdebout, J., Pedrini, A., and Schmuck, G. (2005). Leaf Optical Properties EXperiment 93 (LOPEX93), Joint Research Centre\/Institute for Remote Sensing Applications. Available online: http:\/\/ies-webarchive.jrc.ec.europa.eu\/ies\/uploads\/fileadmin\/H03\/LOPEX_Jan09.zip."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"134","DOI":"10.1016\/S0034-4257(01)00294-2","article-title":"Biochemical and reflectance variation throughout a Sitka spruce canopy","volume":"80","author":"Kupiec","year":"2002","journal-title":"Remote Sens. Environ."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"417","DOI":"10.1071\/BT04129","article-title":"A comparison of field-based and modelled reflectance spectra from damaged Pinus radiata foliage","volume":"53","author":"Coops","year":"2005","journal-title":"Aust. J. Bot."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"2004","DOI":"10.1039\/c3em00388d","article-title":"Detection of multiple stresses in Scots pine growing at post-mining sites using visible to near-infrared spectroscopy","volume":"15","author":"Klement","year":"2013","journal-title":"Environ. Sci. Process. Impacts"},{"key":"ref_20","first-page":"132","article-title":"Seasonal variation in the reflectance of photosynthetically active radiation from epicuticular waxes of Scots pine (Pinus sylvestris) needles","volume":"19","author":"Olascoaga","year":"2014","journal-title":"Boreal Environ. Res."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"667","DOI":"10.2307\/2657067","article-title":"Spectral reflectance of Picea rubens (Pinaceae) and Abies balsamea (Pinaceae) needles along an elevational gradient, Mt. Moosilauke, New Hampshire, USA","volume":"88","author":"Richardson","year":"2001","journal-title":"Am. J. Bot."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"298","DOI":"10.1016\/j.rse.2012.09.014","article-title":"Carotenoid content estimation in a heterogeneous conifer forest using narrow-band indices and PROSPECT+DART simulations","volume":"127","year":"2012","journal-title":"Remote Sens. Environ."},{"key":"ref_23","first-page":"1","article-title":"In situ measurement of Scots pine needle PRI","volume":"13","author":"Perheentupa","year":"2017","journal-title":"Plant Methods"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"79","DOI":"10.1016\/0034-4257(91)90002-N","article-title":"A comparison of spectral reflectance properties at the needle, branch, and canopy levels for selected conifer species","volume":"35","author":"Williams","year":"1991","journal-title":"Remote Sens. Environ."},{"key":"ref_25","unstructured":"Hall, F.G., Huemmrich, K.F., Strebel, D.E., Goetz, S.J., Nickeson, J.E., and Woods, K.E. (1992). Biophysical, Morphological, Canopy Optical Property, and Productivity Data from the Superior National Forest."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"545","DOI":"10.1007\/s10021-004-0144-5","article-title":"Spectral and Structural Measures of Northwest Forest Vegetation at Leaf to Landscape Scales","volume":"7","author":"Roberts","year":"2004","journal-title":"Ecosystems"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"667","DOI":"10.1080\/2150704X.2013.782112","article-title":"Optical properties of leaves and needles for boreal tree species in Europe","volume":"4","author":"Stenberg","year":"2013","journal-title":"Remote Sens. Lett."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"176","DOI":"10.1016\/0034-4257(94)90154-6","article-title":"High-spectral resolution field and laboratory optical reflectance measurements of red spruce and eastern hemlock needles and branches","volume":"47","author":"Rock","year":"1994","journal-title":"Remote Sens. Environ."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"28831","DOI":"10.1029\/97JD02560","article-title":"Seasonal variability in foliar characteristics and physiology for boreal forest species at the five Saskatchewan tower sites during the 1994 Boreal Ecosystem-Atmosphere Study","volume":"102","author":"Middleton","year":"1997","journal-title":"J. Geophys. Res."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"85","DOI":"10.1560\/IJPS.60.1-2.85","article-title":"Facultative and constitutive pigment effects on the Photochemical Reflectance Index (PRI) in sun and shade conifer needles","volume":"60","author":"Gamon","year":"2012","journal-title":"Isr. J. Plant Sci."},{"key":"ref_31","first-page":"1","article-title":"Spectral signatures of conifer needles mainly depend on their physical traits","volume":"64","year":"2016","journal-title":"Pol. J. Ecol."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"537","DOI":"10.1093\/treephys\/23.8.537","article-title":"Reflectance of Alaskan black spruce and white spruce foliage in relation to elevation and latitude","volume":"23","author":"Richardson","year":"2003","journal-title":"Tree Physiol."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"229","DOI":"10.1016\/j.rse.2016.07.014","article-title":"Leaf spectral clusters as potential optical leaf functional types within California ecosystems","volume":"184","author":"Roth","year":"2016","journal-title":"Remote Sens. Environ."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"108","DOI":"10.1080\/07038992.1997.10855193","article-title":"Optical properties of black spruce and jack pine needles at BOREAS sites in SK, Canada","volume":"23","author":"Middleton","year":"1997","journal-title":"Can. J. Remote Sens."},{"key":"ref_35","unstructured":"Hall, F.G., Huemmrich, K.F., Strebel, D.E., Goetz, S.J., Nickeson, J.E., and Woods, K.D. (2017, November 08). SNF Leaf Optical Properties: Cary-14, Available online: http:\/\/daac.ornl.gov."},{"key":"ref_36","unstructured":"Middleton, E., and Sullivan, J. (2017, November 08). BOREAS TE-10 Leaf Optical Properties for SSA Species, Available online: http:\/\/www.daac.ornl.gov."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"557","DOI":"10.1016\/j.cageo.2008.03.015","article-title":"The spectral database SPECCHIO for improved long term usability and data sharing","volume":"35","author":"Hueni","year":"2009","journal-title":"Comput. Geosci."},{"key":"ref_38","unstructured":"(2017, November 08). SPECCHIO Spectral Information System. Available online: http:\/\/www.specchio.ch\/."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"111","DOI":"10.1007\/s11284-013-1096-z","article-title":"Reflectance and transmittance spectra of leaves and shoots of 22 vascular plant species and reflectance spectra of trunks and branches of 12 tree species in Japan","volume":"29","author":"Noda","year":"2014","journal-title":"Ecol. Res."},{"key":"ref_40","doi-asserted-by":"crossref","unstructured":"Noda, H. (2017, November 08). Reflectance and Transmittance Spectra of Leaves and Shoots of 22 Vascular Plant Species and Reflectance Spectra of Trunks and Branches of 12 Tree Species in Japan. Available online: http:\/\/db.cger.nies.go.jp\/JaLTER\/metacat\/metacat\/ERDP-2013-02.1.1\/default.","DOI":"10.1007\/s11284-013-1096-z"},{"key":"ref_41","unstructured":"Serbin, S. (2017, November 08). Fresh Leaf Spectra to Estimate Leaf Morphology and Biochemistry for Northern Temperate Forests. Available online: http:\/\/ecosis.org."},{"key":"ref_42","unstructured":"(2017, November 08). EcoSIS Spectral Library. Available online: https:\/\/ecosis.org\/."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"198","DOI":"10.1016\/j.rse.2014.05.004","article-title":"Spectroscopic analysis of seasonal changes in live fuel moisture content and leaf dry mass","volume":"150","author":"Qi","year":"2014","journal-title":"Remote Sens. Environ."},{"key":"ref_44","doi-asserted-by":"crossref","unstructured":"Kokaly, R.F., Clark, R.N., Swayze, G.A., Livo, K.E., Hoefen, T.M., Pearson, N.C., Wise, R.A., Benzel, W.M., Lowers, H.A., and Driscoll, R.L. (2017). USGS Spectral Library Version 7.","DOI":"10.3133\/ds1035"},{"key":"ref_45","unstructured":"(2017, November 08). USGS Spectral Library Version 7, Available online: https:\/\/speclab.cr.usgs.gov\/spectral-lib.html."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"693","DOI":"10.1007\/s11284-010-0712-4","article-title":"A review of light interception in plant stands from leaf to canopy in different plant functional types and in species with varying shade tolerance","volume":"25","author":"Niinemets","year":"2010","journal-title":"Ecol. Res."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"309","DOI":"10.3389\/fpls.2017.00309","article-title":"Spatial Variation of Leaf Optical Properties in a Boreal Forest Is Influenced by Species and Light Environment","volume":"8","author":"Atherton","year":"2017","journal-title":"Front. Plant Sci."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"283","DOI":"10.1016\/j.envexpbot.2006.02.003","article-title":"Does the azimuth orientation of Norway spruce (Picea abies L. Karst.) branches within sunlit crown part influence the heterogeneity of biochemical, structural and spectral characteristics of needles?","volume":"59","author":"Rock","year":"2007","journal-title":"Environ. Exp. Bot."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"1447","DOI":"10.1007\/s00468-015-1224-1","article-title":"Within-canopy variation in needle morphology and anatomy of vascular tissues in a sparse Scots pine forest","volume":"29","author":"Gebauer","year":"2015","journal-title":"Trees"},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"1509","DOI":"10.1080\/01431169108955186","article-title":"Seasonal patterns in leaf reflectance red-edge characteristics","volume":"12","author":"Miller","year":"1991","journal-title":"Int. J. Remote Sens."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"196","DOI":"10.1111\/nph.13251","article-title":"The photochemical reflectance index provides an optical indicator of spring photosynthetic activation in evergreen conifers","volume":"206","author":"Wong","year":"2015","journal-title":"New Phytol."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"13087","DOI":"10.1073\/pnas.1606162113","article-title":"A remotely sensed pigment index reveals photosynthetic phenology in evergreen conifers","volume":"113","author":"Gamon","year":"2016","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"291","DOI":"10.1111\/j.1469-8137.1995.tb03064.x","article-title":"Assessment of photosynthetic radiation-use efficiency with spectral reflectance","volume":"131","author":"Filella","year":"1995","journal-title":"New Phytol."},{"key":"ref_54","first-page":"2496","article-title":"Seasonal course of the spectral properties of alder and birch leaves","volume":"7","author":"Sulev","year":"2013","journal-title":"IEEE J. Sel. Top. Appl."},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"27","DOI":"10.1016\/j.rse.2006.03.002","article-title":"Reflectance quantities in optical remote sensing-definitions and case studies","volume":"103","author":"Schaepman","year":"2006","journal-title":"Remote Sens. Environ."},{"key":"ref_56","doi-asserted-by":"crossref","unstructured":"Markiet, V., Hern\u00e1ndez-Clemente, R., and M\u00f5ttus, M. (2017). Spectral Similarity and PRI Variations for a Boreal Forest Stand Using Multi-angular Airborne Imagery. Remote Sens., 9.","DOI":"10.3390\/rs9101005"},{"key":"ref_57","doi-asserted-by":"crossref","first-page":"S78","DOI":"10.1016\/j.rse.2008.10.018","article-title":"Characterizing canopy biochemistry from imaging spectroscopy and its application to ecosystem studies","volume":"113","author":"Kokaly","year":"2009","journal-title":"Remote Sens. Environ."},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"523","DOI":"10.1641\/0006-3568(2004)054[0523:UISTSE]2.0.CO;2","article-title":"Using imaging spectroscopy to study ecosystem processes and properties","volume":"54","author":"Ustin","year":"2004","journal-title":"BioScience"},{"key":"ref_59","doi-asserted-by":"crossref","first-page":"183","DOI":"10.1007\/s004420050847","article-title":"Foliage physiology and biochemistry in response to light gradients in conifers with varying shade tolerance","volume":"120","author":"Bond","year":"1999","journal-title":"Oecologia"},{"key":"ref_60","doi-asserted-by":"crossref","first-page":"2824","DOI":"10.1016\/j.rse.2008.01.013","article-title":"Estimating chlorophyll concentration in conifer needles with hyperspectral data: An assessment at the needle and canopy level","volume":"112","author":"Moorthy","year":"2008","journal-title":"Remote Sens. Environ."},{"key":"ref_61","doi-asserted-by":"crossref","first-page":"111","DOI":"10.1007\/s00468-012-0774-8","article-title":"Measurement methods and variability assessment of the Norway spruce total leaf area: Implications for remote sensing","volume":"27","author":"Kaplan","year":"2013","journal-title":"Trees"},{"key":"ref_62","doi-asserted-by":"crossref","first-page":"309","DOI":"10.1016\/0034-4257(87)90064-2","article-title":"Diffuse and specular characteristics of leaf reflectance","volume":"22","author":"Grant","year":"1987","journal-title":"Remote Sens. Environ."},{"key":"ref_63","doi-asserted-by":"crossref","first-page":"1137","DOI":"10.1093\/treephys\/27.8.1137","article-title":"Plasticity in mesophyll volume fractions modulates light-acclimation in needle photosynthesis in two pines","volume":"12","author":"Niinemets","year":"2007","journal-title":"Tree Physiol."},{"key":"ref_64","first-page":"60","article-title":"The impact of long-term CO2 enrichment on sun and shade needles of Norway spruce (Picea abies): Photosynthetic performance, needle anatomy and phenolics accumulation","volume":"188\u2013189","author":"Urban","year":"2012","journal-title":"Plant Sci."},{"key":"ref_65","first-page":"237","article-title":"Variation in needle anatomy of Picea omorika (Pinaceae) plants belonging to different gene pools in natural populations on Tara Mt. in Serbia","volume":"38","year":"2014","journal-title":"Bot. Serbica"},{"key":"ref_66","unstructured":"Ross, J., Meinander, O., and Sulev, M. (1994, January 8\u201312). Spectral scattering properties of Scots pine shoots. Proceedings of the Surface and Atmospheric Remote Sensing: Technologies, Data Analysis and Interpretation, Pasadena, CA, USA."},{"key":"ref_67","unstructured":"Gholz, H.L., Nakane, K., and Shimoda, H. (1997). The use of remote sensing in the modeling of forest productivity. Modeling Radiative Transfer through Forest Canopies: Implications for Canopy Photosynthesis and Remote Sensing, Kluwer Academic Publishers."},{"key":"ref_68","first-page":"67","article-title":"Shoot scattering phase function for Scots pine and its effect on canopy reflectance","volume":"154\u2013155","author":"Rautiainen","year":"2012","journal-title":"Agric. For. Meteorol."},{"key":"ref_69","doi-asserted-by":"crossref","first-page":"469","DOI":"10.1016\/j.rse.2011.10.019","article-title":"A note on upscaling coniferous needle spectra to shoot spectral albedo","volume":"117","author":"Rautiainen","year":"2012","journal-title":"Remote Sens. Environ."},{"key":"ref_70","doi-asserted-by":"crossref","first-page":"1038","DOI":"10.1104\/pp.79.4.1038","article-title":"Influence of shoot structure on light interception and photosynthesis in conifers","volume":"79","author":"Carter","year":"1985","journal-title":"Plant Physiol."},{"key":"ref_71","doi-asserted-by":"crossref","first-page":"656","DOI":"10.1104\/pp.47.5.656","article-title":"Reflectance and Transmittance of Light by Leaves","volume":"47","author":"Woolley","year":"1971","journal-title":"Plant Physiol."},{"key":"ref_72","first-page":"708","article-title":"Scaling PRI between coniferous canopy structures","volume":"6","author":"Rautiainen","year":"2013","journal-title":"IEEE J. Sel. Top. Appl."},{"key":"ref_73","unstructured":"Lang, M., Kuusk, A., Nilson, T., L\u00fckk, T., Pehk, M., and Alm, G. (2017, November 08). Reflectance Spectra of Ground Vegetation in Sub-Boreal Forests. Available online: http:\/\/www.aai.ee\/bgf\/ger2600\/."},{"key":"ref_74","doi-asserted-by":"crossref","first-page":"358","DOI":"10.1016\/j.foreco.2016.11.003","article-title":"Understory vegetation dynamics 15 years post-thinning in 50-year-old Douglas-fir and Douglas-fir\/western hemlock stands in western Oregon, USA","volume":"384","author":"Cole","year":"2017","journal-title":"For. Ecol. Manag."},{"key":"ref_75","doi-asserted-by":"crossref","first-page":"1389","DOI":"10.14358\/PERS.74.11.1389","article-title":"Leaf Area Index (LAI) Change Detection Analysis on Loblolly Pine (Pinus taeda) Following Complete Understory Removal","volume":"11","author":"Iiames","year":"2008","journal-title":"Photogramm. Eng. Remote Sens."},{"key":"ref_76","doi-asserted-by":"crossref","first-page":"1077","DOI":"10.1139\/cjfr-2014-0538","article-title":"Variation in understory and canopy reflectance during stand development in Finnish coniferous forests","volume":"45","author":"Kuusinen","year":"2015","journal-title":"Can. J. For. Res."},{"key":"ref_77","doi-asserted-by":"crossref","first-page":"95","DOI":"10.1080\/01431169008955002","article-title":"Remote sensing of temperate coniferous leaf area index: The influence of canopy closure, understory vegetation, and background reflectance","volume":"11","author":"Spanner","year":"1990","journal-title":"Int. J. Remote Sens."},{"key":"ref_78","doi-asserted-by":"crossref","first-page":"205","DOI":"10.1016\/S0034-4257(98)00087-X","article-title":"Characterization of the reflectance anisotropy of three boreal forest canopies in spring\u2013summer","volume":"67","author":"Deering","year":"1999","journal-title":"Remote Sens. Environ."},{"key":"ref_79","doi-asserted-by":"crossref","first-page":"3615","DOI":"10.1016\/j.rse.2011.08.022","article-title":"NDVI responses to the forest canopy and floor from spring to summer observed by airborne spectrometer in eastern Siberia","volume":"115","author":"Suzuki","year":"2011","journal-title":"Remote Sens. Environ."},{"key":"ref_80","doi-asserted-by":"crossref","first-page":"312","DOI":"10.1016\/j.rse.2006.07.023","article-title":"Retrieving forest background reflectance in a boreal region from Multi-angle Imaging SpectroRadiometer (MISR) data","volume":"107","author":"Canisius","year":"2007","journal-title":"Remote Sens. Environ."},{"key":"ref_81","doi-asserted-by":"crossref","first-page":"2172","DOI":"10.1016\/j.rse.2009.05.017","article-title":"Forest canopy height from the Multiangle Imaging Spectro-Radiometer (MISR) assessed with high resolution discrete return lidar","volume":"113","author":"Chopping","year":"2009","journal-title":"Remote Sens. Environ."},{"key":"ref_82","doi-asserted-by":"crossref","first-page":"499","DOI":"10.1109\/TGRS.2009.2024756","article-title":"Mapping forest background in a boreal region using multiangle Compact Airborne Spectrographic Imager data","volume":"48","author":"Pisek","year":"2010","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_83","doi-asserted-by":"crossref","first-page":"11936","DOI":"10.3390\/rs61211936","article-title":"A simple method for retrieving understory NDVI in sparse needleleaf forests in Alaska using MODIS BRDF data","volume":"6","author":"Yang","year":"2014","journal-title":"Remote Sens."},{"key":"ref_84","doi-asserted-by":"crossref","first-page":"32257","DOI":"10.1029\/98JD02462","article-title":"Synergistic algorithm for estimating vegetation canopy leaf area index and fraction of absorbed photosynthetically active radiation from MODIS and MISR data","volume":"D103","author":"Knyazikhin","year":"1998","journal-title":"J. Geophys. Res."},{"key":"ref_85","doi-asserted-by":"crossref","first-page":"3020","DOI":"10.1016\/j.rse.2011.06.005","article-title":"Seasonal reflectance dynamics of common understory types in a northern European boreal forest","volume":"115","author":"Rautiainen","year":"2011","journal-title":"Remote Sens. Environ."},{"key":"ref_86","doi-asserted-by":"crossref","first-page":"332","DOI":"10.1016\/j.rse.2007.03.002","article-title":"Coupling forest canopy and understory reflectance in the Arctic latitudes of Finland","volume":"110","author":"Rautiainen","year":"2007","journal-title":"Remote Sens. Environ."},{"key":"ref_87","doi-asserted-by":"crossref","first-page":"190","DOI":"10.1016\/0034-4257(94)90155-4","article-title":"Visible-near infrared spectral reflectance of landscape components in western Oregon","volume":"47","author":"Goward","year":"1994","journal-title":"Remote Sens. Environ."},{"key":"ref_88","doi-asserted-by":"crossref","first-page":"29475","DOI":"10.1029\/97JD02558","article-title":"Seasonal change in the understory reflectance of boreal forests and influence on canopy vegetation indices","volume":"102","author":"Miller","year":"1997","journal-title":"J. Geophys. Res."},{"key":"ref_89","doi-asserted-by":"crossref","first-page":"33","DOI":"10.1016\/j.agrformet.2004.05.004","article-title":"Simulation of the reflectance of ground vegetation in sub-boreal forests","volume":"126","author":"Kuusk","year":"2004","journal-title":"Agric. For. Meteorol."},{"key":"ref_90","first-page":"84","article-title":"Spectral reflectance patterns and seasonal dynamics of common understory types in three mature hemi-boreal forests","volume":"43","author":"Nikopensius","year":"2015","journal-title":"Int. J. Appl. Earth Obs. Geoinf."},{"key":"ref_91","doi-asserted-by":"crossref","first-page":"238","DOI":"10.1016\/j.rse.2006.08.011","article-title":"Reflectance seasonality and its relation to the canopy leaf area index in an eastern Siberian larch forest: Multi-satellite data and radiative transfer analyses","volume":"106","author":"Kobayashi","year":"2007","journal-title":"Remote Sens. Environ."},{"key":"ref_92","unstructured":"Peterson, U. (1989). Seasonal Reflectance Profiles for Forest Clearcut Communities at Early Stages of Secondary Succession, Academy of Sciences of the Estonian SSR. Section of Physics and Astronomy; Preprint A-5."},{"key":"ref_93","doi-asserted-by":"crossref","first-page":"3203","DOI":"10.5194\/bg-8-3203-2011","article-title":"Greenhouse gas flux measurements in a forestry-drained peatland indicate a large carbon sink","volume":"8","author":"Lohila","year":"2011","journal-title":"Biogeosciences"},{"key":"ref_94","doi-asserted-by":"crossref","first-page":"2943","DOI":"10.1016\/j.rse.2010.08.031","article-title":"Forest structure and aboveground biomass in the southwestern United States from MODIS and MISR","volume":"115","author":"Chopping","year":"2011","journal-title":"Remote Sens. Environ."},{"key":"ref_95","doi-asserted-by":"crossref","first-page":"343","DOI":"10.1016\/j.rse.2004.10.009","article-title":"BRDF measurement of understory vegetation in pine forests: Dwarf shrubs, lichen and moss","volume":"94","author":"Peltoniemi","year":"2005","journal-title":"Remote Sens. Environ."},{"key":"ref_96","doi-asserted-by":"crossref","first-page":"474","DOI":"10.5589\/m09-040","article-title":"Spectral reflectance of multispecies herbaceous and moss canopies in the boreal forest understory and open field","volume":"35","author":"Hallik","year":"2009","journal-title":"Can. J. Remote Sens."},{"key":"ref_97","doi-asserted-by":"crossref","first-page":"275","DOI":"10.5194\/bg-6-275-2009","article-title":"Towards spatial assessment of carbon sequestration in peatlands: Spectroscopy based estimation of fractional cover of three plant functional types","volume":"6","author":"Limpens","year":"2009","journal-title":"Biogeosciences"},{"key":"ref_98","doi-asserted-by":"crossref","first-page":"98","DOI":"10.1016\/j.rse.2016.05.013","article-title":"Photon recollision probability in modelling the radiation regime of canopies\u2014A review","volume":"183","author":"Stenberg","year":"2016","journal-title":"Remote Sens. Environ."},{"key":"ref_99","doi-asserted-by":"crossref","first-page":"2627","DOI":"10.1016\/j.rse.2007.12.005","article-title":"Multi-angular reflectance properties of a hemiboreal forest: An analysis using CHRIS PROBA data","volume":"112","author":"Rautiainen","year":"2008","journal-title":"Remote Sens. Environ."},{"key":"ref_100","doi-asserted-by":"crossref","first-page":"2341","DOI":"10.1016\/j.rse.2007.11.001","article-title":"Angular sensitivity analysis of vegetation indices derived from CHRIS\/PROBA data","volume":"112","author":"Verrelst","year":"2008","journal-title":"Remote Sens. Environ."},{"key":"ref_101","doi-asserted-by":"crossref","first-page":"1072","DOI":"10.1109\/36.700992","article-title":"Multi-angle Imaging SpectroRadiometer (MISR) instrument description and experiment overview","volume":"36","author":"Diner","year":"1998","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_102","doi-asserted-by":"crossref","first-page":"1512","DOI":"10.1109\/TGRS.2004.827260","article-title":"The PROBA\/CHRIS mission: A low-cost smallsat for hyperspectral multiangle observations of the Earth surface and atmosphere","volume":"42","author":"Barnsley","year":"2004","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_103","doi-asserted-by":"crossref","first-page":"5105","DOI":"10.1109\/TGRS.2016.2554466","article-title":"Tracking the seasonal dynamics of boreal forest photosynthesis using EO-1 Hyperion reflectance: sensitivity to structural and illumination effects","volume":"54","author":"Kolari","year":"2016","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_104","doi-asserted-by":"crossref","first-page":"940","DOI":"10.2307\/2446360","article-title":"Variability in leaf optical properties among 26 species from a broad range of habitats","volume":"85","author":"Knapp","year":"1998","journal-title":"Am. J. Bot."},{"key":"ref_105","doi-asserted-by":"crossref","first-page":"189","DOI":"10.1016\/j.rse.2002.06.002","article-title":"Needle chlorophyll content estimation through model inversion using hyperspectral data from boreal conifer forest canopies","volume":"89","author":"Miller","year":"2004","journal-title":"Remote Sens. Environ."},{"key":"ref_106","doi-asserted-by":"crossref","first-page":"108","DOI":"10.1016\/j.rse.2004.12.007","article-title":"Spectral sensing of foliar water conditions in two co-occurring conifer species: Pinus edulis and Juniperus monosperma","volume":"96","author":"Stimson","year":"2005","journal-title":"Remote Sens. Environ."},{"key":"ref_107","doi-asserted-by":"crossref","first-page":"5315","DOI":"10.1080\/01431160600762990","article-title":"Applicability of the PROSPECT model for Norway spruce needles","volume":"27","author":"Clevers","year":"2006","journal-title":"Int. J. Remote Sens."},{"key":"ref_108","doi-asserted-by":"crossref","first-page":"106","DOI":"10.1016\/j.rse.2006.08.001","article-title":"Canopy spectral invariants for remote sensing and model applications","volume":"106","author":"Huang","year":"2007","journal-title":"Remote Sens. Environ."},{"key":"ref_109","doi-asserted-by":"crossref","first-page":"296","DOI":"10.5589\/m08-030","article-title":"Retrieving chlorophyll content in conifer needles from hyperspectral measurements","volume":"34","author":"Zhang","year":"2008","journal-title":"Can. J. Remote Sens."},{"key":"ref_110","doi-asserted-by":"crossref","first-page":"3041","DOI":"10.1080\/01431160802558725","article-title":"Spectral identification of ozone-damaged pine needles","volume":"30","author":"Biging","year":"2009","journal-title":"Int. J. Remote Sens."},{"key":"ref_111","doi-asserted-by":"crossref","first-page":"889","DOI":"10.1016\/j.rse.2009.01.005","article-title":"A dataset for the validation of reflectance models","volume":"113","author":"Kuusk","year":"2009","journal-title":"Remote Sens. Environ."},{"key":"ref_112","doi-asserted-by":"crossref","first-page":"128","DOI":"10.1016\/j.rse.2013.02.006","article-title":"Modelling leaf chlorophyll content in broadleaf and needle leaf canopies from ground, CASI, Landsat TM 5 and MERIS reflectance data","volume":"133","author":"Croft","year":"2013","journal-title":"Remote Sens. Environ."},{"key":"ref_113","doi-asserted-by":"crossref","first-page":"31","DOI":"10.1080\/17550874.2012.754512","article-title":"Spectral characteristics of pine needles at the limit of tree growth in subarctic Finland","volume":"6","author":"Dengel","year":"2013","journal-title":"Plant Ecol. Divers."},{"key":"ref_114","doi-asserted-by":"crossref","first-page":"368","DOI":"10.1093\/treephys\/tpv133","article-title":"A comparison of methods to estimate photosynthetic light absorption in leaves with contrasting morphology","volume":"36","author":"Olascoaga","year":"2016","journal-title":"Tree Physiol."},{"key":"ref_115","doi-asserted-by":"crossref","unstructured":"Pot\u016f\u010dkov\u00e1, M., \u010cerven\u00e1, L., Kupkov\u00e1, L., Lhot\u00e1kov\u00e1, Z., Luke\u0161, P., Hanu\u0161, J., Novotn\u00fd, J., and Albrechtov\u00e1, J. (2016). Comparison of reflectance measurements acquired with a contact probe and an integration sphere: Implications for the spectral properties of vegetation at a needle-level. Sensors, 16.","DOI":"10.3390\/s16111801"},{"key":"ref_116","doi-asserted-by":"crossref","unstructured":"Homolov\u00e1, L., Janoutov\u00e1, R., Luke\u0161, P., Hanu\u0161, J., Novotn\u00fd, J., Brovkina, O., and Loyaza Fernandez, R.R. (2017). In situ data collection supporting remote sensing estimation of spruce forest parameters at the ecosystem station B\u00edl\u00fd K\u0159\u00ed\u017e. Beskydy, under review.","DOI":"10.11118\/beskyd201710010075"},{"key":"ref_117","first-page":"384","article-title":"Determination of accurate extinction coefficients and simultaneous equations for assaying chlorophylls a and b extracted with four different solvents: Verification of the concentration of chlorophyll standards by atomic absorption spectroscopy","volume":"975","author":"Porra","year":"1989","journal-title":"Biochem. Biophys. Acta"},{"key":"ref_118","doi-asserted-by":"crossref","first-page":"350","DOI":"10.1016\/0076-6879(87)48036-1","article-title":"Chlorophylls and carotenoids: Pigments of photosynthetic membranes","volume":"148","author":"Lichtenthaler","year":"1987","journal-title":"Method Enzymol."},{"key":"ref_119","doi-asserted-by":"crossref","first-page":"15","DOI":"10.5194\/isprs-archives-XLI-B1-15-2016","article-title":"Potential of airborne imaging spectroscopy at CzechGlobe","volume":"XLI-B1","author":"Fajmon","year":"2016","journal-title":"Int. Arch. Photogramm. Remote Sens. Spat. Inf. Sci."},{"key":"ref_120","doi-asserted-by":"crossref","first-page":"2631","DOI":"10.1080\/01431160110115834","article-title":"Geo-atmospheric processing of airborne imaging spectrometry data. Part 2: Atmospheric\/topographic correction","volume":"23","author":"Richter","year":"2002","journal-title":"Int. J. Remote Sens."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/10\/2\/207\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T14:53:07Z","timestamp":1760194387000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/10\/2\/207"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2018,1,30]]},"references-count":120,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2018,2]]}},"alternative-id":["rs10020207"],"URL":"https:\/\/doi.org\/10.3390\/rs10020207","relation":{},"ISSN":["2072-4292"],"issn-type":[{"value":"2072-4292","type":"electronic"}],"subject":[],"published":{"date-parts":[[2018,1,30]]}}}