{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,26]],"date-time":"2026-02-26T23:56:34Z","timestamp":1772150194889,"version":"3.50.1"},"reference-count":64,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2018,2,23]],"date-time":"2018-02-23T00:00:00Z","timestamp":1519344000000},"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>Understanding the vertical pattern of leaf traits across plant canopies provide critical information on plant physiology, ecosystem functioning and structure and vegetation response to climate change. However, the impact of vertical canopy position on leaf spectral properties and subsequently leaf traits across the entire spectrum for multiple species is poorly understood. In this study, we examined the ability of leaf optical properties to track variability in leaf traits across the vertical canopy profile using Partial Least Square Discriminatory Analysis (PLS-DA). Leaf spectral measurements together with leaf traits (nitrogen, carbon, chlorophyll, equivalent water thickness and specific leaf area) were studied at three vertical canopy positions along the plant stem: lower, middle and upper. We observed that foliar nitrogen (N), chlorophyll (Cab), carbon (C), and equivalent water thickness (EWT) were higher in the upper canopy leaves compared with lower shaded leaves, while specific leaf area (SLA) increased from upper to lower canopy leaves. We found that leaf spectral reflectance significantly (P \u2264 0.05) shifted to longer wavelengths in the \u2018red edge\u2019 spectrum (685\u2013701 nm) in the order of lower &gt; middle &gt; upper for the pooled dataset. We report that spectral bands that are influential in the discrimination of leaf samples into the three groups of canopy position, based on the PLS-DA variable importance projection (VIP) score, match with wavelength regions of foliar traits observed to vary across the canopy vertical profile. This observation demonstrated that both leaf traits and leaf reflectance co-vary across the vertical canopy profile in multiple species. We conclude that canopy vertical position has a significant impact on leaf spectral properties of an individual plant\u2019s traits, and this finding holds for multiple species. These findings have important implications on field sampling protocols, upscaling leaf traits to canopy level, canopy reflectance modelling, and subsequent leaf trait retrieval, especially for studies that aimed to integrate hyperspectral measurements and LiDAR data.<\/jats:p>","DOI":"10.3390\/rs10020346","type":"journal-article","created":{"date-parts":[[2018,2,23]],"date-time":"2018-02-23T12:41:40Z","timestamp":1519389700000},"page":"346","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":48,"title":["Impact of Vertical Canopy Position on Leaf Spectral Properties and Traits across Multiple Species"],"prefix":"10.3390","volume":"10","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8134-4849","authenticated-orcid":false,"given":"Tawanda W.","family":"Gara","sequence":"first","affiliation":[{"name":"Faculty of Geo-Information Science and Earth Observation (ITC), University of Twente, P.O. Box 6, 7500 AA Enschede, The Netherlands"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7512-0574","authenticated-orcid":false,"given":"Roshanak","family":"Darvishzadeh","sequence":"additional","affiliation":[{"name":"Faculty of Geo-Information Science and Earth Observation (ITC), University of Twente, P.O. Box 6, 7500 AA Enschede, The Netherlands"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7446-8429","authenticated-orcid":false,"given":"Andrew K.","family":"Skidmore","sequence":"additional","affiliation":[{"name":"Faculty of Geo-Information Science and Earth Observation (ITC), University of Twente, P.O. Box 6, 7500 AA Enschede, The Netherlands"},{"name":"Department of Environmental Science, Macquarie University, Sydney, NSW 2106, Australia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1138-8464","authenticated-orcid":false,"given":"Tiejun","family":"Wang","sequence":"additional","affiliation":[{"name":"Faculty of Geo-Information Science and Earth Observation (ITC), University of Twente, P.O. Box 6, 7500 AA Enschede, The Netherlands"}]}],"member":"1968","published-online":{"date-parts":[[2018,2,23]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"295","DOI":"10.1111\/j.1654-1103.2004.tb02266.x","article-title":"The plant traits that drive ecosystems: Evidence from three continents","volume":"15","author":"Diaz","year":"2004","journal-title":"J. Veg. Sci."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"S143","DOI":"10.1086\/374368","article-title":"The evolution of plant functional variation: Traits, spectra, and strategies","volume":"164","author":"Reich","year":"2003","journal-title":"Int. J. Plant Sci."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"737","DOI":"10.1111\/ele.12462","article-title":"Functional traits, convergent evolution, and periodic tables of niches","volume":"18","author":"Winemiller","year":"2015","journal-title":"Ecol. Lett."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"957","DOI":"10.1111\/nph.12210","article-title":"Next-generation dynamic global vegetation models: Learning from community ecology","volume":"198","author":"Scheiter","year":"2013","journal-title":"New Phytol."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"403","DOI":"10.1038\/523403a","article-title":"Environmental science: Agree on biodiversity metrics to track from space","volume":"523","author":"Skidmore","year":"2015","journal-title":"Nature"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"277","DOI":"10.1126\/science.1229931","article-title":"Essential biodiversity variables","volume":"339","author":"Pereira","year":"2013","journal-title":"Science"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"406","DOI":"10.1016\/j.isprsjprs.2007.07.004","article-title":"Can nutrient status of four woody plant species be predicted using field spectrometry?","volume":"62","author":"Ferwerda","year":"2007","journal-title":"ISPRS J. Photogramm. Remote Sens."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"153","DOI":"10.1016\/S0034-4257(00)00163-2","article-title":"Investigating a physical basis for spectroscopic estimates of leaf nitrogen concentration","volume":"75","author":"Kokaly","year":"2001","journal-title":"Remote Sens. Environ."},{"key":"ref_9","first-page":"72","article-title":"Evaluation of SPOT imagery for the estimation of grassland biomass","volume":"38","author":"Dusseux","year":"2015","journal-title":"Int. J. Appl. Earth Obs. Geoinf."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"2592","DOI":"10.1016\/j.rse.2007.12.003","article-title":"Inversion of a radiative transfer model for estimating vegetation LAI and chlorophyll in a heterogeneous grassland","volume":"112","author":"Darvishzadeh","year":"2008","journal-title":"Remote Sens. Environ."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"92","DOI":"10.1016\/S0034-4257(02)00196-7","article-title":"Spectral discrimination of vegetation types in a coastal wetland","volume":"85","author":"Schmidt","year":"2003","journal-title":"Remote Sens. Environ."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"151","DOI":"10.1016\/S0924-2031(01)00113-8","article-title":"Discrimination, classification, identification of microorganisms using FTIR spectroscopy and chemometrics","volume":"26","author":"Mariey","year":"2001","journal-title":"Vib. Spectrosc."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"88","DOI":"10.1016\/j.isprsjprs.2015.09.003","article-title":"Combining leaf physiology, hyperspectral imaging and partial least squares-regression (PLS-R) for grapevine water status assessment","volume":"109","author":"Rapaport","year":"2015","journal-title":"ISPRS J. Photogramm. Remote Sens."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"273","DOI":"10.1016\/j.isprsjprs.2015.05.005","article-title":"Optical remote sensing and the retrieval of terrestrial vegetation bio-geophysical properties\u2014A review","volume":"108","author":"Verrelst","year":"2015","journal-title":"ISPRS J. Photogramm. Remote Sens."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.ecocom.2013.06.003","article-title":"Review of optical-based remote sensing for plant trait mapping","volume":"15","author":"Clevers","year":"2013","journal-title":"Ecol. Complex."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1029","DOI":"10.1080\/01431160701281023","article-title":"Canopy chlorophyll concentration estimation using hyperspectral and LiDAR data for a boreal mixedwood forest in northern Ontario, Canada","volume":"29","author":"Thomas","year":"2008","journal-title":"Int. J. Remote Sens."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"75","DOI":"10.1016\/j.fcr.2012.11.017","article-title":"Non-uniform vertical nitrogen distribution within plant canopy and its estimation by remote sensing: A review","volume":"142","author":"Li","year":"2013","journal-title":"Field Crops Res."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"1077","DOI":"10.1093\/treephys\/tpw043","article-title":"How vertical patterns in leaf traits shift seasonally and the implications for modeling canopy photosynthesis in a temperate deciduous forest","volume":"36","author":"Coble","year":"2016","journal-title":"Tree Physiol."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"520","DOI":"10.1007\/BF00378977","article-title":"Maximizing daily canopy photosynthesis with respect to the leaf nitrogen allocation pattern in the canopy","volume":"72","author":"Hirose","year":"1987","journal-title":"Oecologia"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"63","DOI":"10.1007\/BF00321192","article-title":"Coordination theory of leaf nitrogen distribution in a canopy","volume":"93","author":"Chen","year":"1993","journal-title":"Oecologia"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"521","DOI":"10.1093\/aob\/mci050","article-title":"Leaf canopy as a dynamic system: Ecophysiology and optimality in leaf turnover","volume":"95","author":"Hikosaka","year":"2005","journal-title":"Ann. Bot."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"564","DOI":"10.1093\/treephys\/tpu016","article-title":"Canopy position affects the relationships between leaf respiration and associated traits in a tropical rainforest in far north Queensland","volume":"34","author":"Weerasinghe","year":"2014","journal-title":"Tree Physiol."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"170","DOI":"10.1016\/j.eja.2015.11.017","article-title":"Estimating canopy leaf nitrogen concentration in winter wheat based on multi-angular hyperspectral remote sensing","volume":"73","author":"He","year":"2016","journal-title":"Eur. J. Agron."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"324","DOI":"10.1016\/j.envpol.2015.05.028","article-title":"Leaf reflectance variation along a vertical crown gradient of two deciduous tree species in a Belgian industrial habitat","volume":"204","author":"Khavaninzadeh","year":"2015","journal-title":"Environ. Pollut."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"4626","DOI":"10.3390\/rs70404626","article-title":"Remote estimation of leaf and canopy water content in winter wheat with different vertical distribution of water-related properties","volume":"7","author":"Liu","year":"2015","journal-title":"Remote Sens."},{"key":"ref_26","first-page":"185","article-title":"A field study on solar-induced chlorophyll fluorescence and pigment parameters along a vertical canopy gradient of four tree species in an urban environment","volume":"466\u2013467","author":"Alonso","year":"2014","journal-title":"Sci. Total Environ."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"17","DOI":"10.1111\/wre.12274","article-title":"Effects of leaf position on reflectance, transmittance and absorption of red and far-red light in tomato, chenopodium album and amaranthus retroflexus leaves","volume":"58","author":"Ma","year":"2018","journal-title":"Weed Res."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"123","DOI":"10.1016\/j.ecolind.2013.03.025","article-title":"Developing and validating novel hyperspectral indices for leaf area index estimation: Effect of canopy vertical heterogeneity","volume":"32","author":"Li","year":"2013","journal-title":"Ecol. Indic."},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Yu, K.-Q., Zhao, Y.-R., Li, X.-L., Shao, Y.-N., Liu, F., and He, Y. (2015). Hyperspectral imaging for mapping of total nitrogen spatial distribution in pepper plant. PLoS ONE, 9.","DOI":"10.1371\/journal.pone.0116205"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"0735751","DOI":"10.1117\/1.JRS.7.073575","article-title":"Comparison of spectral indices and wavelet transform for estimating chlorophyll content of maize from hyperspectral reflectance","volume":"7","author":"Liao","year":"2013","journal-title":"APPRES"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"111","DOI":"10.1016\/j.agrformet.2012.10.004","article-title":"Canopy vertical heterogeneity plays a critical role in reflectance simulation","volume":"169","author":"Wang","year":"2013","journal-title":"Agric. Meteorol."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1029\/2010JG001407","article-title":"Evaluation of leaf-to-canopy upscaling methodologies against carbon flux data in North America","volume":"117","author":"Sprintsin","year":"2012","journal-title":"J. Geophys. Res. Biogeosci."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"700","DOI":"10.1111\/2041-210X.12510","article-title":"Using discrete-return airborne laser scanning to quantify number of canopy strata across diverse forest types","volume":"7","author":"Wilkes","year":"2016","journal-title":"Methods Ecol. Evolut."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"2014","DOI":"10.3390\/rs5042014","article-title":"Characterization of canopy layering in forested ecosystems using full waveform LiDAR","volume":"5","author":"Whitehurst","year":"2013","journal-title":"Remote Sens."},{"key":"ref_35","unstructured":"ASD Inc (2008). Integrating Sphere User Manual, Analytical Spectral Devices, Inc. (ASD)."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"1627","DOI":"10.1021\/ac60214a047","article-title":"Smoothing and differentiation of data by simplified least squares procedures","volume":"36","author":"Savitzky","year":"1964","journal-title":"Anal. Chem."},{"key":"ref_37","unstructured":"Opti-Sciences, Inc (2011). CCM-300 Chlorophyll Content Meter, Opti-Sciences, Inc."},{"key":"ref_38","unstructured":"ADC-BioScientific Ltd (2013). Am350 Portable Leaf Area Meter, ADC BioScientific Ltd."},{"key":"ref_39","unstructured":"Perkin-Elmer, Inc (2005). 2400 Series II CHNS\/O Elemental Analysis, Perkin Elmer, Inc."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"322","DOI":"10.1016\/j.rse.2016.08.003","article-title":"Linking seasonal foliar traits to VSWIR-TIR spectroscopy across California ecosystems","volume":"186","author":"Meerdink","year":"2016","journal-title":"Remote Sens. Environ."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"3172","DOI":"10.1109\/JSTARS.2015.2422734","article-title":"Leaf nitrogen content indirectly estimated by leaf traits derived from the prospect model","volume":"8","author":"Wang","year":"2015","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"99","DOI":"10.2307\/3001913","article-title":"Comparing individual means in the analysis of variance","volume":"5","author":"Tukey","year":"1949","journal-title":"Biometrics"},{"key":"ref_43","doi-asserted-by":"crossref","unstructured":"Quinn, G.P., and Keough, M.J. (2002). Experimental Design and Data Analysis for Biologists, Cambridge University Press.","DOI":"10.1017\/CBO9780511806384"},{"key":"ref_44","first-page":"32","article-title":"Hyperspectral reflectance of leaves and flowers of an outbreak species discriminates season and successional stage of vegetation","volume":"24","author":"Carvalho","year":"2013","journal-title":"Int. J. Appl. Earth Obs. Geoinf."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"109","DOI":"10.1016\/S0169-7439(01)00155-1","article-title":"PLS-regression: A basic tool of chemometrics","volume":"58","author":"Wold","year":"2001","journal-title":"Chemom. Intell. Lab. Syst."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"388","DOI":"10.1016\/j.oregeorev.2016.04.014","article-title":"Partial least squares-discriminant analysis of trace element compositions of magnetite from various VMS deposit subtypes: Application to mineral exploration","volume":"78","author":"Makvandi","year":"2016","journal-title":"Ore Geol. Rev."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"104","DOI":"10.1016\/j.aca.2016.08.002","article-title":"Paper spray mass spectrometry and PLS-DA improved by variable selection for the forensic discrimination of beers","volume":"940","author":"Pereira","year":"2016","journal-title":"Anal. Chim. Acta"},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"26","DOI":"10.18637\/jss.v028.i05","article-title":"Building predictive models in R using the caret package","volume":"28","author":"Kuhn","year":"2008","journal-title":"J. Stat. Softw."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"111","DOI":"10.1016\/j.fcr.2013.12.018","article-title":"Improving estimation of summer maize nitrogen status with red edge-based spectral vegetation indices","volume":"157","author":"Li","year":"2014","journal-title":"Field Crops Res."},{"key":"ref_50","first-page":"344","article-title":"Remote estimation of crop and grass chlorophyll and nitrogen content using red-edge bands on Sentinel-2 and -3","volume":"23","author":"Clevers","year":"2013","journal-title":"Int. J. Appl. Earth Obs. Geoinf."},{"key":"ref_51","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":"ISPRS J. Photogramm Remote Sens."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"252","DOI":"10.1046\/j.1365-2435.2001.00517.x","article-title":"Canopy-level photosynthetic compensation after defoliation in a tropical understorey palm","volume":"15","author":"Anten","year":"2001","journal-title":"Funct. Ecol."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"995","DOI":"10.2307\/2260229","article-title":"Light variation and carbon gain in rain forest understorey palms","volume":"74","author":"Chazdon","year":"1986","journal-title":"J. Ecol."},{"key":"ref_54","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_55","first-page":"66","article-title":"Estimating leaf functional traits by inversion of prospect: Assessing leaf dry matter content and specific leaf area in mixed mountainous forest","volume":"45","author":"Ali","year":"2016","journal-title":"Int. J. Appl. Earth Obs. Geoinf."},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"1157","DOI":"10.1093\/treephys\/22.15-16.1157","article-title":"Leaf respiration at different canopy positions in sweetgum (Liquidambar styraciflua) grown in ambient and elevated concentrations of carbon dioxide in the field","volume":"22","author":"Tissue","year":"2002","journal-title":"Tree Physiol."},{"key":"ref_57","doi-asserted-by":"crossref","first-page":"1052","DOI":"10.1111\/j.1365-3040.2007.01683.x","article-title":"Photosynthesis and resource distribution through plant canopies","volume":"30","author":"Niinemets","year":"2007","journal-title":"Plant Cell Environ."},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"1249","DOI":"10.1093\/treephys\/20.18.1249","article-title":"Photosynthetic nitrogen-use efficiency in evergreen broad-leaved woody species coexisting in a warm-temperate forest","volume":"20","author":"Hikosaka","year":"2000","journal-title":"Tree Physiol."},{"key":"ref_59","doi-asserted-by":"crossref","first-page":"24","DOI":"10.1046\/j.1365-2435.1999.00292.x","article-title":"Acclimation of photosynthesis to light: A mechanistic approach","volume":"13","author":"Kull","year":"1999","journal-title":"Funct. Ecol."},{"key":"ref_60","doi-asserted-by":"crossref","first-page":"11072","DOI":"10.3390\/s101211072","article-title":"Scaling up semi-arid grassland biochemical content from the leaf to the canopy level: Challenges and opportunities","volume":"10","author":"He","year":"2010","journal-title":"Sensors"},{"key":"ref_61","doi-asserted-by":"crossref","first-page":"85","DOI":"10.1016\/0034-4257(88)90007-7","article-title":"Remote sensing of forest canopy and leaf biochemical contents","volume":"24","author":"Peterson","year":"1988","journal-title":"Remote Sens. Environ."},{"key":"ref_62","doi-asserted-by":"crossref","unstructured":"Luo, J., Ma, R., Feng, H., and Li, X. (2016). Estimating the total nitrogen concentration of reed canopy with hyperspectral measurements considering a non-uniform vertical nitrogen distribution. Remote Sens., 8.","DOI":"10.3390\/rs8100789"},{"key":"ref_63","first-page":"84","article-title":"Canopy foliar nitrogen retrieved from airborne hyperspectral imagery by correcting for canopy structure effects","volume":"54","author":"Wang","year":"2017","journal-title":"Int. J. Appl. Earth Obs. Geoinf."},{"key":"ref_64","doi-asserted-by":"crossref","first-page":"152","DOI":"10.1016\/j.agrformet.2016.08.016","article-title":"Canopy leaf water content estimated using terrestrial LiDAR","volume":"232","author":"Zhu","year":"2017","journal-title":"Agric. For. Meteorol."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/10\/2\/346\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T14:56:08Z","timestamp":1760194568000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/10\/2\/346"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2018,2,23]]},"references-count":64,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2018,2]]}},"alternative-id":["rs10020346"],"URL":"https:\/\/doi.org\/10.3390\/rs10020346","relation":{},"ISSN":["2072-4292"],"issn-type":[{"value":"2072-4292","type":"electronic"}],"subject":[],"published":{"date-parts":[[2018,2,23]]}}}