Recent dynamics of arctic tundra vegetation: Field observations, remote sensing, and simulation modeling

Howard Epstein, University of Virginia, hee2b@virginia.edu (Presenter)
Martha Raynolds, University of Alaska, mkraynolds@alaska.edu
Donald Walker, University of Alaska, dawalker@alaska.edu
Uma Bhatt, University of Alaska, bhatt@gi.alaska.edu
Compton Tucker, NASA Goddard, compton.j.tucker@nasa.gov
Jorge Pinzon, NASA Goddard, jorge.e.pinzon@nasa.gov
Gerald Frost, University of Virginia, gvf5y@virginia.edu
Qin Yu, University of Virginia, qy4a@virginia.ede
Gensuo Jia, Chinese Academy of Science, jiong@tea.ac.cn
Heqing Zeng, Chinese Academy of Science, zenghq@tea.ac.cn

Over the past several decades, summer air temperatures in the Arctic have increased, sea ice extent on the Arctic Ocean has declined, and tundra vegetation has “greened.” Here we summarize some of the most recent analyses of arctic tundra vegetation dynamics, arising from the various methodologies of remote sensing, field observations, and simulation modeling. From 1982-2008, the maximum Normalized Difference Vegetation Index (NDVI) increased by 9% in the North American Arctic and 2% in the Eurasian Arctic. A strong logarithmic relationship between aboveground tundra biomass and NDVI, developed from extensive field-harvested measurements of vegetation, yields aboveground biomass increases of 37% for North America and 16% for Eurasia (20% for the entire Arctic). The southernmost tundra subzones (C-E) dominate the increases in biomass, ranging from 20-26 %, although there was a high degree of heterogeneity across regions, floristic provinces, and vegetation types. Concomitant with this increase in biomass are earlier starts to the growing season, later vegetation senescence, and thus longer growing seasons overall. Field observations to date support the increased tundra biomass, with particularly strong evidence of tall shrub expansion in the southernmost tundra. Simulation modeling of warming tundra environments is also consistent with the field and remote sensing observations, however, spatial variability of soils and land management (e.g. reindeer grazing) yields varying degrees of vegetation change. An estimated total sequestration of 0.40 Pg C over the past three decades is substantive, albeit quite small relative to anthropogenic C emissions. However, the 20% average increase in aboveground biomass has major implications for nearly all aspects of tundra ecosystems including hydrology, active layer depths, permafrost regimes, wildlife and human use of arctic landscapes. While spatially extensive on-the-ground measurements of tundra biomass supported these analyses, validation is still impossible without more repeated, long-term monitoring of arctic tundra biomass in the field.

Presentation: 2011_Poster_Epstein_175_125.pdf (1218k)

Presentation Type:  Poster

Session:  Global Change Impact & Vulnerability   (Tue 11:30 AM)

Associated Project(s): 

• Walker, Skip: Adaptation to Rapid Land-Use and Climate Changes on the Yamal Peninsula, Russia: Remote Sensing and Models for Analyzing Cumulative Effects ...details
• Walker, Skip: Applications of space-based technologies to examine lLCLUC along a transect on the Yamal Peninsula and Novaya Zemlya, Russia ...details

Poster Location ID: 175