The Impact Of Decadal Land Cover Change On The Global Warming Potential Of Beringian Arctic Tundra

• Main Author: Lin, David Hwei-Len
• Format: Text
• Language: English
• Published: ScholarWorks@UTEP 2012
• Subjects: carbon dioxide; climate change; global warming potential; land cover change; methane; Biogeochemistry; Ecology and Evolutionary Biology; Arctic; Chukotka; Climate change; Global warming; Sea ice; Tundra; Alaska; Beringia
• Online Access: https://scholarworks.utep.edu/open_etd/2126; https://scholarworks.utep.edu/cgi/viewcontent.cgi?article=3125&context=open_etd

Arctic terrestrial ecosystems play an important role in the global carbon cycle. If arctic warming continues to rise as projected, large amounts of soil carbon stored in these ecosystems could be released to the atmosphere as carbon dioxide or methane and positively enhance greenhouse warming. Thus, improving understanding of the likely future state and fate of arctic soil carbon, and the carbon uptake potential of arctic terrestrial ecosystems are well recognized research priorities. At the pan-arctic scale, decadal increases in NDVI (Normalized Difference Vegetation Index), an index of vegetation productivity, have been observed from satellite imagery, indicating a general greening of the Arctic. Although the increase in NDVI has been linked to summer warming and sea ice loss in coastal areas and expansion of shrubs inland, these changes do not explain NDVI trends in the Beringian arctic. Here, shrubs do not dominate many tundra landscapes, regional warming has occurred, and NDVI has mostly increased in Alaska and decreased in Chukotka. This discrepancy highlights an important gap in current understanding of the Arctic system. The overarching goal of this study is to (1) determine how land cover in the Beringian Arctic changed in the last half century; (2) assess what biophysical properties control peak growing season land-atmosphere CO2 and CH4 exchange in multiple landscapes and land cover classes in Beringia; and (3) model how decadal land cover change in Beringia has altered peak growing season CO2 and CH4 exchange and global warming potential. Using a campaign-style, snapshot sampling approach sixteen sites were visited in ten different landscapes throughout the Beringian Arctic between 2005 and 2008. Sites represented a broad range of arctic terrestrial ecosystems, and data collection included CO2 exchange, CH4 exchange, and a number of biophysical and spectral properties for the purpose of spatial scaling and model development. For seven landscapes, ground-truthed land cover maps were created from ...