Inter-annual variability of NDVI in response to long-term warming and fertilization in wet sedge and tussock tundra |
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Authors: | Email author" target="_blank">Natalie?T?BoelmanEmail author Marc?Stieglitz Kevin?L?Griffin Gaius?R?Shaver |
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Institution: | (1) Lamont-Doherty Earth Observatory, Columbia University, 61 Route 9W, Palisades, NY 10964, USA;(2) Present address: Department of Global Ecology, Carnegie Institution of Washington, 260 Panama Street, Stanford, CA 94305, USA;(3) Georgia School of Civil and Environmental Engineering and School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA;(4) Marine Biological Laboratory, The Ecosystems Center, Woods Hole, , MA 02543, USA |
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Abstract: | This study explores the relationship between the normalized difference vegetation index (NDVI) and aboveground plant biomass
for tussock tundra vegetation and compares it to a previously established NDVI–biomass relationship for wet sedge tundra vegetation.
In addition, we explore inter-annual variation in NDVI in both these contrasting vegetation communities. All measurements
were taken across long-term experimental treatments in wet sedge and tussock tundra communities at the Toolik Lake Long Term
Ecological Research (LTER) site, in northern Alaska. Over 15 years (for wet sedge tundra) and 14 years (for tussock tundra),
N and P were applied in factorial experiments (N, P and N+P), air temperature was increased using greenhouses with and without
N+P fertilizer, and light intensity was reduced by 50% using shade cloth. during the peak growing seasons of 2001, 2002, and
2003, NDVI measurements were made in both the wet sedge and tussock tundra experimental treatment plots, creating a 3-year
time series of inter-annual variation in NDVI. We found that: (1) across all tussock experimental tundra treatments, NDVI
is correlated with aboveground plant biomass (r
2=0.59); (2) NDVI–biomass relationships for tussock and wet sedge tundra communities are community specific, and; (3) NDVI
values for tussock tundra communities are typically, but not always, greater than for wet sedge tundra communities across
all experimental treatments. We suggest that differences between the response of wet sedge and tussock tundra communities
in the same experimental treatments result from the contrasting degree of heterogeneity in species and functional types that
characterize each of these Arctic tundra vegetation communities. |
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Keywords: | Aboveground biomass Arctic tundra Normalized difference vegetation index |
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