Tchebakova Nadja M.

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Tchebakova
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Nadja M.
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  • Article
    Potential influence of climate-induced vegetation shifts on future land use and associated land carbon fluxes in Northern Eurasia
    (IOP Publishing, 2014-03-21) Kicklighter, David W. ; Cai, Y. ; Zhuang, Qianlai ; Parfenova, E. I. ; Paltsev, Sergey ; Sokolov, Andrei P. ; Melillo, Jerry M. ; Reilly, John M. ; Tchebakova, Nadja M. ; Lu, X.
    Climate change will alter ecosystem metabolism and may lead to a redistribution of vegetation and changes in fire regimes in Northern Eurasia over the 21st century. Land management decisions will interact with these climate-driven changes to reshape the region's landscape. Here we present an assessment of the potential consequences of climate change on land use and associated land carbon sink activity for Northern Eurasia in the context of climate-induced vegetation shifts. Under a 'business-as-usual' scenario, climate-induced vegetation shifts allow expansion of areas devoted to food crop production (15%) and pastures (39%) over the 21st century. Under a climate stabilization scenario, climate-induced vegetation shifts permit expansion of areas devoted to cellulosic biofuel production (25%) and pastures (21%), but reduce the expansion of areas devoted to food crop production by 10%. In both climate scenarios, vegetation shifts further reduce the areas devoted to timber production by 6–8% over this same time period. Fire associated with climate-induced vegetation shifts causes the region to become more of a carbon source than if no vegetation shifts occur. Consideration of the interactions between climate-induced vegetation shifts and human activities through a modeling framework has provided clues to how humans may be able to adapt to a changing world and identified the trade-offs, including unintended consequences, associated with proposed climate/energy policies.
  • Article
    Evapotranspiration in Northern Eurasia : impact of forcing uncertainties on terrestrial ecosystem model estimates
    (John Wiley & Sons, 2015-04-03) Liu, Yaling ; Zhuang, Qianlai ; Miralles, Diego ; Pan, Zhihua ; Kicklighter, David W. ; Zhu, Qing ; He, Yujie ; Chen, Jiquan ; Tchebakova, Nadja M. ; Sirin, Andrey ; Niyogi, Dev ; Melillo, Jerry M.
    The ecosystems in Northern Eurasia (NE) play an important role in the global water cycle and the climate system. While evapotranspiration (ET) is a critical variable to understand this role, ET over this region remains largely unstudied. Using an improved version of the Terrestrial Ecosystem Model with five widely used forcing data sets, we examine the impact that uncertainties in climate forcing data have on the magnitude, variability, and dominant climatic drivers of ET for the period 1979–2008. Estimates of regional average ET vary in the range of 241.4–335.7 mm yr−1 depending on the choice of forcing data. This range corresponds to as much as 32% of the mean ET. Meanwhile, the spatial patterns of long-term average ET across NE are generally consistent for all forcing data sets. Our ET estimates in NE are largely affected by uncertainties in precipitation (P), air temperature (T), incoming shortwave radiation (R), and vapor pressure deficit (VPD). During the growing season, the correlations between ET and each forcing variable indicate that T is the dominant factor in the north and P in the south. Unsurprisingly, the uncertainties in climate forcing data propagate as well to estimates of the volume of water available for runoff (here defined as P-ET). While the Climate Research Unit data set is overall the best choice of forcing data in NE according to our assessment, the quality of these forcing data sets remains a major challenge to accurately quantify the regional water balance in NE.