A Phenological Approach to Spectral Differentiation of Low-Arctic Tundra Vegetation Communities, North Slope, Alaska

被引:15
|
作者
Beamish, Alison Leslie [1 ]
Coops, Nicholas [2 ]
Chabrillat, Sabine [3 ]
Heim, Birgit [1 ]
机构
[1] Helmholtz Ctr Polar & Marine Res, Alfred Wegener Inst, Res Unit Potsdam, A45, D-14473 Potsdam, Germany
[2] Univ British Columbia, Fac Forestry, IRSS, 2424 Main Mall, Vancouver, BC V6T 1Z4, Canada
[3] GFZ German Res Ctr Geosci, Helmholtz Ctr Potsdam, D-14473 Potsdam, Germany
来源
REMOTE SENSING | 2017年 / 9卷 / 11期
关键词
low-Arctic; tundra vegetation; hyperspectral remote sensing; spectroscopy; HYPERSPECTRAL MIXTURE ANALYSIS; REFLECTANCE SPECTROSCOPY; CHLOROPHYLL CONTENT; PLANT-LEAVES; RED; ANTHOCYANINS; INDEXES; BIOMASS; PHOTOPROTECTION; VARIABILITY;
D O I
10.3390/rs9111200
中图分类号
X [环境科学、安全科学];
学科分类号
08 ; 0830 ;
摘要
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.
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页数:21
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