TY - JOUR
T1 - Contrasting changes in gross primary productivity of different regions of North America as affected by warming in recent decades
AU - Mekonnen, Zelalem A.
AU - Grant, Robert F.
AU - Schwalm, Christopher
N1 - Funding Information:
Funding was provided by NSERC Discovery Frontiers (DF) grant through Arctic Development and Adaptation to Permafrost in Transition (ADAPT). We acknowledge the Multi-scale Synthesis and Terrestrial Model Intercomparison Project (MsTMIP; http://nacp.ornl.gov/MsTMIP.shtml ) for providing support in environmental driver data. Funding for MsTMIP activity was provided through NASA ROSES Grant # NNX10AG01A . Data management support for preparing, documenting, and distributing model driver and output data was performed by the Modeling and Synthesis Thematic Data Center at Oak Ridge National Laboratory (ORNL; http://nacp.ornl.gov ), with funding through NASA ROSES Grant # NNH10AN681 . Data products in this study are archived at the ORNL DAAC ( http://daac.ornl.gov ). Computational facility for ecosys was provided by WestGrid supercomputing infrastructure ( https://www.westgrid.ca ).
Publisher Copyright:
© 2015 Elsevier B.V.
PY - 2016/3/15
Y1 - 2016/3/15
N2 - Ecosystem responses to the increasing warming in recent decades across North America (NA) are spatially heterogeneous and partly uncertain. Here we examined the spatial and temporal variability of warming across different eco-regions of NA using long-term (1979-2010) climate data (North America Regional Reanalysis (NARR)) with 3-hourly time-step and 0.25° × 0.25° spatial resolution and run a comprehensive mathematical process model, ecosys to study the impacts of this variability in warming on gross primary productivity (GPP). In a site scale test of model results, annual GPP modeled for pixels which corresponded to the locations of 20 eddy covariance flux towers correlated well (R2 = 0.76) with annual GPP derived from the towers in 2005. At continental scale, long-term annual average modeled GPP correlated well (geographically weighed regression R2 = 0.8) with MODIS GPP. GPP modeled in eastern temperate forests and most areas with lower mean annual air temperature (Ta), such as those in northern forests and Taiga, increased due to early spring and late autumn warming observed in NARR and these eco-regions contributed 92% of the increases in NA GPP over the last three decades. However, modeled GPP declined in most southwestern regions of NA (accounting >50% of the ecosystems with declining GPP), due to water stress from rising Ta and declining precipitation, implying that further warming and projected dryness in this region could further reduce NA carbon uptake. Overall, NA modeled GPP increased by 5.8% in the last 30 years, with a positive trend of +0.012 ± 0.01 Pg C yr-1 and a range of -1.16 to +0.87 Pg C yr-1 caused by interannual variability of GPP from the long-term (1980-2010) mean. This variability was the greatest in southwest of US and part of the Great Plains, which could be as a result of frequent El Niño-Southern Oscillation' events that led to major droughts.
AB - Ecosystem responses to the increasing warming in recent decades across North America (NA) are spatially heterogeneous and partly uncertain. Here we examined the spatial and temporal variability of warming across different eco-regions of NA using long-term (1979-2010) climate data (North America Regional Reanalysis (NARR)) with 3-hourly time-step and 0.25° × 0.25° spatial resolution and run a comprehensive mathematical process model, ecosys to study the impacts of this variability in warming on gross primary productivity (GPP). In a site scale test of model results, annual GPP modeled for pixels which corresponded to the locations of 20 eddy covariance flux towers correlated well (R2 = 0.76) with annual GPP derived from the towers in 2005. At continental scale, long-term annual average modeled GPP correlated well (geographically weighed regression R2 = 0.8) with MODIS GPP. GPP modeled in eastern temperate forests and most areas with lower mean annual air temperature (Ta), such as those in northern forests and Taiga, increased due to early spring and late autumn warming observed in NARR and these eco-regions contributed 92% of the increases in NA GPP over the last three decades. However, modeled GPP declined in most southwestern regions of NA (accounting >50% of the ecosystems with declining GPP), due to water stress from rising Ta and declining precipitation, implying that further warming and projected dryness in this region could further reduce NA carbon uptake. Overall, NA modeled GPP increased by 5.8% in the last 30 years, with a positive trend of +0.012 ± 0.01 Pg C yr-1 and a range of -1.16 to +0.87 Pg C yr-1 caused by interannual variability of GPP from the long-term (1980-2010) mean. This variability was the greatest in southwest of US and part of the Great Plains, which could be as a result of frequent El Niño-Southern Oscillation' events that led to major droughts.
KW - Carbon flux
KW - Ecosys
KW - Ecosystem modeling
KW - North America GPP
KW - Warming
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U2 - 10.1016/j.agrformet.2015.11.016
DO - 10.1016/j.agrformet.2015.11.016
M3 - Article
AN - SCOPUS:84960427548
SN - 0168-1923
VL - 218-219
SP - 50
EP - 64
JO - Agricultural and Forest Meteorology
JF - Agricultural and Forest Meteorology
ER -