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Ground-Based Hyperspectral Characterization of Alaska Tundra Vegetation along Environmental Gradients
Alfred Wegener Institute (AWI), Helmholtz Centre for Polar and Marine Research, Research Unit Potsdam, Telegrafenberg A43, D-14473 Potsdam, Germany
Alaska Geobotany Center, Institute of Arctic Biology, University of Alaska Fairbanks, P.O. Box 757000, Fairbanks, AK 99775, USA
Environmental Sciences Department, University of Virginia, 291 McCormick Road, Charlottesville, VA 22904, USA
Geography Department, Humboldt-Universität zu Berlin, Unter den Linden 6, D-10099 Berlin, Germany
* Author to whom correspondence should be addressed.
Received: 20 June 2013; in revised form: 31 July 2013 / Accepted: 5 August 2013 / Published: 9 August 2013
Abstract: Remote sensing has become a valuable tool in monitoring arctic environments. The aim of this paper is ground-based hyperspectral characterization of Low Arctic Alaskan tundra communities along four environmental gradients (regional climate, soil pH, toposequence, and soil moisture) that all vary in ground cover, biomass, and dominating plant communities. Field spectroscopy in connection with vegetation analysis was carried out in summer 2012, along the North American Arctic Transect (NAAT). Spectral metrics were extracted, including the averaged reflectance and absorption-related metrics such as absorption depths and area of continuum removal. The spectral metrics were investigated with respect to “greenness”, biomass, vegetation height, and soil moisture regimes. The results show that the surface reflectances of all sites are similar in shape with a reduced near-infrared (NIR) reflectance that is specific for low-growing biomes. The main spectro-radiometric findings are: (i) Southern sites along the climate gradient have taller shrubs and greater overall vegetation biomass, which leads to higher reflectance in the NIR. (ii) Vegetation height and surface wetness are two antagonists that balance each other out with respect to the NIR reflectance along the toposequence and soil moisture gradients. (iii) Moist acidic tundra (MAT) sites have “greener” species, more leaf biomass, and green-colored moss species that lead to higher pigment absorption compared to moist non-acidic tundra (MNT) sites. (iv) MAT and MNT plant community separation via narrowband Normalized Difference Vegetation Index (NDVI) shows the potential of hyperspectral remote sensing applications in the tundra.
Keywords: North American Arctic Transect (NAAT); Low Arctic tundra; field spectroscopy; pigment absorption; NDVI
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Buchhorn, M.; Walker, D.A.; Heim, B.; Raynolds, M.K.; Epstein, H.E.; Schwieder, M. Ground-Based Hyperspectral Characterization of Alaska Tundra Vegetation along Environmental Gradients. Remote Sens. 2013, 5, 3971-4005.
Buchhorn M, Walker DA, Heim B, Raynolds MK, Epstein HE, Schwieder M. Ground-Based Hyperspectral Characterization of Alaska Tundra Vegetation along Environmental Gradients. Remote Sensing. 2013; 5(8):3971-4005.
Buchhorn, Marcel; Walker, Donald A.; Heim, Birgit; Raynolds, Martha K.; Epstein, Howard E.; Schwieder, Marcel. 2013. "Ground-Based Hyperspectral Characterization of Alaska Tundra Vegetation along Environmental Gradients." Remote Sens. 5, no. 8: 3971-4005.