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dc.contributor.authorAnderson, Helen
dc.contributor.authorNilsen, Lennart
dc.contributor.authorTømmervik, Hans
dc.contributor.authorKarlsen, Stein Rune
dc.contributor.authorNagai, Shin
dc.contributor.authorCooper, Elisabeth J.
dc.identifier.citationRemote Sensing 2016, 8(10)nb_NO
dc.description.abstractTo remotely monitor vegetation at temporal and spatial resolutions unobtainable with satellite-based systems, near remote sensing systems must be employed. To this extent we used Normalized Difference Vegetation Index NDVI sensors and normal digital cameras to monitor the greenness of six different but common and widespread High Arctic plant species/groups (graminoid/Salix polaris; Cassiope tetragona; Luzula spp.; Dryas octopetala/S. polaris; C. tetragona/D. octopetala; graminoid/bryophyte) during an entire growing season in central Svalbard. Of the three greenness indices (2G_RBi, Channel G% and GRVI) derived from digital camera images, only GRVI showed significant correlations with NDVI in all vegetation types. The GRVI (Green-Red Vegetation Index) is calculated as (GDN 􀀀��������� RDN)/(GDN + RDN) where GDN is Green digital number and RDN is Red digital number. Both NDVI and GRVI successfully recorded timings of the green-up and plant growth periods and senescence in all six plant species/groups. Some differences in phenology between plant species/groups occurred: the mid-season growing period reached a sharp peak in NDVI and GRVI values where graminoids were present, but a prolonged period of higher values occurred with the other plant species/groups. Unlike the other plant species/groups, C. tetragona experienced increased NDVI and GRVI values towards the end of the season. NDVI measured with active and passive sensors were strongly correlated (r2 > 0.70) for the same plant species/groups. Although NDVI recorded by the active sensor was consistently lower than that of the passive sensor for the same plant species/groups, differences were small and likely due to the differing light sources used. Thus, it is evident that GRVI and NDVI measured with active and passive sensors captured similar vegetation attributes of High Arctic plants. Hence, inexpensive digital cameras can be used with passive and active NDVI devices to establish a near remote sensing network for monitoring changing vegetation dynamics in the High Arctic. NDVI; greenness index; RGB camera; vegetation; phenology; active sensor; passive sensor; Svalbardnb_NO
dc.rightsNavngivelse-Ikkekommersiell 3.0 Norge*
dc.subjectgreenness indexnb_NO
dc.subjectRGB cameranb_NO
dc.subjectactive sensorsnb_NO
dc.subjectpassive sensornb_NO
dc.titleUsing ordinary digital cameras in place of near-infrared sensors to derive vegetation indices for phenology studies of high arctic vegetationnb_NO
dc.typeJournal articlenb_NO
dc.typePeer reviewednb_NO
dc.subject.nsiVDP::Mathematics and natural science: 400::Zoology and botany: 480nb_NO
dc.source.journalRemote Sensingnb_NO

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Navngivelse-Ikkekommersiell 3.0 Norge
Except where otherwise noted, this item's license is described as Navngivelse-Ikkekommersiell 3.0 Norge