{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,2]],"date-time":"2026-06-02T21:11:29Z","timestamp":1780434689593,"version":"3.54.1"},"reference-count":46,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2017,11,22]],"date-time":"2017-11-22T00:00:00Z","timestamp":1511308800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"German Federal Ministry of Economic Affairs and Energy","award":["DLR\/BMWi 50 EE 1348"],"award-info":[{"award-number":["DLR\/BMWi 50 EE 1348"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Arctic tundra ecosystems exhibit small-scale variations in species composition, micro-topography as well as significant spatial and temporal variations in moisture. These attributes result in similar spectral characteristics between distinct vegetation communities. In this study we examine spectral variability at three phenological phases of leaf-out, maximum canopy, and senescence of ground-based spectroscopy, as well as a simulated Environmental Mapping and Analysis Program (EnMAP) and simulated Sentinel-2 reflectance spectra, from five dominant low-Arctic tundra vegetation communities in the Toolik Lake Research Area, Alaska, in order to inform spectral differentiation and subsequent vegetation classification at both the ground and satellite scale. We used the InStability Index (ISI), a ratio of between endmember and within endmember variability, to determine the most discriminative phenophase and wavelength regions for identification of each vegetation community. Our results show that the senescent phase was the most discriminative phenophase for the identification of the majority of communities when using both ground-based and simulated EnMAP reflectance spectra. Maximum canopy was the most discriminative phenophase for the majority of simulated Sentinel-2 reflectance data. As with previous ground-based spectral characterization of Alaskan low-Arctic tundra, the blue, red, and red-edge parts of the spectrum were most discriminative for all three reflectance datasets. Differences in vegetation colour driven by pigment dynamics appear to be the optimal areas of the spectrum for differentiation using high spectral resolution field spectroscopy and simulated hyperspectral EnMAP and multispectral Sentinel-2 reflectance spectra. The phenological aspect of this study highlights the potential exploitation of more extreme colour differences in vegetation observed during senescence when hyperspectral data is available. The results provide insight into both the community and seasonal dynamics of spectral variability to better understand and interpret currently used broadband vegetation indices and also for improved spectral unmixing of hyperspectral aerial and satellite data which is useful for a wide range of applications from fine-scale monitoring of shifting vegetation composition to the identification of vegetation vigor.<\/jats:p>","DOI":"10.3390\/rs9111200","type":"journal-article","created":{"date-parts":[[2017,11,22]],"date-time":"2017-11-22T10:47:38Z","timestamp":1511347658000},"page":"1200","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":20,"title":["A Phenological Approach to Spectral Differentiation of Low-Arctic Tundra Vegetation Communities, North Slope, Alaska"],"prefix":"10.3390","volume":"9","author":[{"given":"Alison","family":"Beamish","sequence":"first","affiliation":[{"name":"Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Research Unit Potsdam, Telegrafenberg, A45, 14473 Potsdam, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0151-9037","authenticated-orcid":false,"given":"Nicholas","family":"Coops","sequence":"additional","affiliation":[{"name":"Integrated Remote Sensing Studio (IRSS) Faculty of Forestry, University of British Columbia, 2424 Main Mall, Vancouver, BC V6T 1Z4, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8600-5168","authenticated-orcid":false,"given":"Sabine","family":"Chabrillat","sequence":"additional","affiliation":[{"name":"Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2614-9391","authenticated-orcid":false,"given":"Birgit","family":"Heim","sequence":"additional","affiliation":[{"name":"Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Research Unit Potsdam, Telegrafenberg, A45, 14473 Potsdam, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2017,11,22]]},"reference":[{"key":"ref_1","unstructured":"Bliss, L., Heal, O.W., and Moore, J. (1981). Tundra Ecosystems: A Comparative Analysis, CUP Archive."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"267","DOI":"10.1111\/j.1654-1103.2005.tb02365.x","article-title":"The circumpolar Arctic vegetation map","volume":"16","author":"Walker","year":"2005","journal-title":"J. Veg."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"843","DOI":"10.2307\/3236198","article-title":"Plant communities of a tussock tundra landscape in the Brooks Range Foothills, Alaska","volume":"5","author":"Walker","year":"1994","journal-title":"J. Veg. Sci."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1861","DOI":"10.1080\/01431169308954008","article-title":"The relationship between tussock tundra spectral reflectance properties and biomass and vegetation composition","volume":"14","author":"Hope","year":"1993","journal-title":"Int. J. Remote Sens."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"2391","DOI":"10.1080\/01431160512331337754","article-title":"Biotic controls over spectral reflectance of arctic tundra vegetation","volume":"26","author":"Riedel","year":"2005","journal-title":"Int. J. Remote Sens."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"3971","DOI":"10.3390\/rs5083971","article-title":"Ground-based hyperspectral characterization of Alaska tundra vegetation along environmental gradients","volume":"5","author":"Buchhorn","year":"2013","journal-title":"Remote Sens."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Bratsch, S., Epstein, H., Buchhorn, M., and Walker, D. (2016). Differentiating among four Arctic Tundra plant communities at Ivotuk, Alaska using field spectroscopy. Remote Sens., 8.","DOI":"10.3390\/rs8010051"},{"key":"ref_8","first-page":"1","article-title":"Remote sensing of arctic vegetation: Relations between the NDVI, spatial resolution and vegetation cover on Boothia Peninsula, Nunavut","volume":"6","author":"Laidler","year":"2008","journal-title":"Arctic"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"4823","DOI":"10.1080\/01431160701268996","article-title":"Short-term response of arctic vegetation NDVI to temperature anomalies","volume":"28","author":"Olthof","year":"2007","journal-title":"Int. J. Remote Sens."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"281","DOI":"10.1016\/j.rse.2003.10.018","article-title":"Remote sensing of vegetation and land-cover change in Arctic tundra ecosystems","volume":"89","author":"Stow","year":"2004","journal-title":"Remote Sens. Environ."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"44","DOI":"10.1191\/0309133303pp358ra","article-title":"Biophysical remote sensing of arctic environments","volume":"27","author":"Laidler","year":"2003","journal-title":"Progress Phys. Geogr."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"414","DOI":"10.1007\/s00442-003-1198-3","article-title":"Response of NDVI, biomass, and ecosystem gas exchange to long-term warming and fertilization in wet sedge tundra","volume":"135","author":"Boelman","year":"2003","journal-title":"Oecologia"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"2921","DOI":"10.1080\/014311699211543","article-title":"Landsat MSS-derived land-cover map of northern Alaska: Extrapolation methods and a comparison with photo-interpreted and AVHRR-derived maps","volume":"20","author":"Muller","year":"1999","journal-title":"Int. J. Remote Sens."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"127","DOI":"10.1016\/0034-4257(79)90013-0","article-title":"Red and photographic infrared linear combinations for monitoring vegetation","volume":"8","author":"Tucker","year":"1979","journal-title":"Remote Sens. Environ."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"123","DOI":"10.1016\/0034-4257(95)00198-0","article-title":"Effects of standing litter on the biophysical interpretation of plant canopies with spectral indices","volume":"55","author":"Huete","year":"1996","journal-title":"Remote Sens. Environ."},{"key":"ref_16","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_17","first-page":"1027","article-title":"Plant carotenoids: Pigments for photoprotection, visual attraction, and human health","volume":"7","author":"Bartley","year":"1995","journal-title":"Plant Cell"},{"key":"ref_18","unstructured":"Alscher, R.G., and Cummings, J.R. (1990). Carotenoids and stress. Stress Responses in Plants: Adaptation and Acclimation Mechanisms, Wiley."},{"key":"ref_19","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_20","doi-asserted-by":"crossref","first-page":"149","DOI":"10.1663\/0006-8101(2003)069[0149:TEOFA]2.0.CO;2","article-title":"The ecophysiology of foliar anthocyanin","volume":"69","author":"Close","year":"2003","journal-title":"Bot. Rev."},{"key":"ref_21","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_22","doi-asserted-by":"crossref","first-page":"1261","DOI":"10.1046\/j.1365-3040.2002.00905.x","article-title":"Do anthocyanins function as antioxidants in leaves? Imaging of H2O2 in red and green leaves after mechanical injury","volume":"25","author":"Gould","year":"2002","journal-title":"Plant Cell Environ."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"8830","DOI":"10.3390\/rs70708830","article-title":"The EnMAP Spaceborne Imaging Spectroscopy Mission for earth observation","volume":"7","author":"Guanter","year":"2015","journal-title":"Remote Sens."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"25","DOI":"10.1016\/j.rse.2011.11.026","article-title":"Sentinel-2: ESA\u2019s Optical High-Resolution Mission for GMES Operational Services","volume":"120","author":"Drusch","year":"2012","journal-title":"Remote Sens. Environ."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"27","DOI":"10.1080\/07038992.2016.1143330","article-title":"Spectral wavelength selection and detection of two invasive plant species in an urban area","volume":"42","author":"Chance","year":"2016","journal-title":"Can. J. Remote Sens."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"351","DOI":"10.1109\/JSTARS.2012.2203796","article-title":"Invasive species mapping in Hawaiian rainforests using multi-temporal hyperion spaceborne imaging spectroscopy","volume":"6","author":"Somers","year":"2013","journal-title":"IEEE J. Sel. Top. Appl. Earth Observ. Remote Sens."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"5549","DOI":"10.1080\/01431160903311305","article-title":"An automated waveband selection technique for optimized hyperspectral mixture analysis","volume":"31","author":"Somers","year":"2010","journal-title":"Int. J. Remote Sens."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1603","DOI":"10.1016\/j.rse.2011.03.003","article-title":"Endmember variability in spectral mixture analysis: A review","volume":"115","author":"Somers","year":"2011","journal-title":"Remote Sens. Environ."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"222","DOI":"10.1016\/j.rse.2014.12.009","article-title":"Oil detection in the coastal marshes of Louisiana using MESMA applied to band subsets of AVIRIS data","volume":"159","author":"Peterson","year":"2015","journal-title":"Remote Sens. Environ."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"238","DOI":"10.1111\/j.1600-0587.1989.tb00844.x","article-title":"Terrain, vegetation and landscape evolution of the R4D research site, Brooks Range Foothills, Alaska","volume":"12","author":"Walker","year":"1989","journal-title":"Ecography"},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Bliss, L.C., and Matveyeva, N.V. (1992). Circumpolar arctic vegetation. Arctic Ecosystems in a Changing Climate: An Ecophysiological Perspective, Academic Press.","DOI":"10.1016\/B978-0-12-168250-7.50010-9"},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Tenhunen, J.D., Lange, O.L., Hahn, S., Siegwolf, R., and Oberbauer, S.F. (1992). The ecosystem role of poikilohydric tundra plants. Arctic Ecosystems in a Changing Climate: An Ecophysiological Perspective, Academic Press.","DOI":"10.1016\/B978-0-12-168250-7.50016-X"},{"key":"ref_33","unstructured":"Lehnert, L.W., Meyer, H., and Bendix, J. (2016). Hsdar: Manage, Analyse and Simulate Hyperspectral Data in R, R Package."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"6329","DOI":"10.1029\/JB089iB07p06329","article-title":"Reflectance spectroscopy: Quantitative analysis techniques for remote sensing applications","volume":"89","author":"Clark","year":"1984","journal-title":"J. Geophys. Res. Solid Earth"},{"key":"ref_35","unstructured":"Clark, R.N., and King, T. (1987, January 15). Automatic Continuum Analysis of Reflectance Spectra. Proceedings of the 3rd Airborne Imaging Spectrometer Data Analysis Workshop, Denver, CO, USA."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"1183","DOI":"10.1016\/j.rse.2009.02.003","article-title":"Nonlinear hyperspectral mixture analysis for tree cover estimates in orchards","volume":"113","author":"Somers","year":"2009","journal-title":"Remote Sens. Environ."},{"key":"ref_37","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_38","doi-asserted-by":"crossref","first-page":"169","DOI":"10.1017\/S003224740001367X","article-title":"NDVI, biomass, and landscape evolution of glaciated terrain in northern Alaska","volume":"31","author":"Walker","year":"1995","journal-title":"Polar Rec."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"5103","DOI":"10.1080\/01431160210153129","article-title":"Assessment of different spectral indices in the red-near-infrared spectral domain for burned land discrimination","volume":"23","author":"Chuvieco","year":"2002","journal-title":"Int. J. Remote Sens."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"234","DOI":"10.1016\/S0034-4257(98)00014-5","article-title":"Biophysical and biochemical sources of variability in canopy reflectance","volume":"64","author":"Asner","year":"1998","journal-title":"Remote Sens. Environ."},{"key":"ref_41","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_42","doi-asserted-by":"crossref","first-page":"1459","DOI":"10.1080\/01431169408954177","article-title":"The red edge position and shape as indicators of plant chlorophyll content, biomass and hydric status","volume":"15","author":"Filella","year":"1994","journal-title":"Int. J. Remote Sens."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"293","DOI":"10.1016\/0098-8472(90)90041-2","article-title":"Spectral characteristics of ozone-treated conifers","volume":"30","author":"Ustin","year":"1990","journal-title":"Environ. Exp. Bot."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"2691","DOI":"10.1080\/014311697217558","article-title":"Remote estimation of chlorophyll content in higher plant leaves","volume":"18","author":"Gitelson","year":"1997","journal-title":"Int. J. Remote Sens."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"272","DOI":"10.1562\/0031-8655(2002)075<0272:ACCIPL>2.0.CO;2","article-title":"Assessing Carotenoid Content in Plant Leaves with Reflectance Spectroscopy","volume":"75","author":"Gitelson","year":"2002","journal-title":"Photochem. Photobiol."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"366","DOI":"10.1007\/s00442-002-0905-9","article-title":"Seasonal patterns of reflectance indices, carotenoid pigments and photosynthesis of evergreen chaparral species","volume":"131","author":"Stylinski","year":"2002","journal-title":"Oecologia"}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/9\/11\/1200\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T18:50:44Z","timestamp":1760208644000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/9\/11\/1200"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2017,11,22]]},"references-count":46,"journal-issue":{"issue":"11","published-online":{"date-parts":[[2017,11]]}},"alternative-id":["rs9111200"],"URL":"https:\/\/doi.org\/10.3390\/rs9111200","relation":{},"ISSN":["2072-4292"],"issn-type":[{"value":"2072-4292","type":"electronic"}],"subject":[],"published":{"date-parts":[[2017,11,22]]}}}