Abstract
Trends in the growing season MODerate resolution Imaging Spectroradiometer (MODIS) Enhanced Vegetation Index (EVI) time-series were analyzed for the period from 2000 to 2010 to understand landscape-level patterns of vegetation change in ecosystems of arctic Alaska. We compared datasets for vegetation cover types, wetland cover classes, wildfire boundaries since the 1940s, permafrost type, and elevation to identify the most likely combination of factors driving regional changes in habitat quality and ecosystem productivity. Approximately 57% of all arctic ecosystem areas in Alaska were detected with significant (p 2) were detected with significant positive growing season EVI trends. The vast majority of the arctic Alaska region detected with significant positive growing season EVI trends was classified as upland tundra cover, although non-forested wetlands (marshes, bogs, fens, and floodplains) were co-located on 8% of that area. Herbaceous wetlands were co-located on 55% of the total area detected with significant negative growing season EVI trends, mostly on the arctic coastal plain and foothills. This evidence supports the hypothesis that temperature (warming) has markedly enhanced the rates of upland tundra vegetation growth across most of arctic Alaska over recent years.
Highlights
Major changes have been observed in Alaskan ecosystems over the past several decades, including rapidlyHow to cite this paper: Potter, C. (2014) Regional Analysis of NASA Satellite Greenness Trends for Ecosystems of Arctic Alaska
57% of all area in arctic Alaska was detected with significant (p < 0.05) positive or negative MODerate resolution Imaging Spectroradiometer (MODIS) growing season Enhanced Vegetation Index (EVI) trends from 2000 to 2010 (Figure 3)
The vast majority (99%) of these non-forested wetlands with significant negative EVI trends were classified as palustrine emergent vegetation
Summary
Major changes have been observed in Alaskan ecosystems over the past several decades, including rapidlyHow to cite this paper: Potter, C. (2014) Regional Analysis of NASA Satellite Greenness Trends for Ecosystems of Arctic Alaska. (2014) Regional Analysis of NASA Satellite Greenness Trends for Ecosystems of Arctic Alaska. C. Potter melting ground ice (permafrost), ice wedge degradation, wetland drying, and increased shrub growth [1]-[4]. Along the arctic coastal plain of Alaska, permafrost temperatures have increased 5 ̊F increase since the 1980s [5]. Many areas in the continuous permafrost zone have seen increases in temperature in the seasonally active layer and a decrease in re-freezing rates. The length of the growing season (photosynthetically active period) in the Arctic has increased by 9 days per decade since 1982 [7]. Zeng and Jia [8] found greening onset was related to final snowmelt date and the end of the growing season was strongly related to the date of first snow cover
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