Modeling the impacts of temperature and precipitation changes on soil CO2 fluxes from a Switchgrass stand recently converted from cropland.

Switchgrass (Panicum virgatum L.) is a perennial C4 grass native to North America and successfully adapted to diverse environmental conditions. It offers the potential to reduce soil surface carbon dioxide (CO2) fluxes and mitigate climate change. However, information on how these CO2 fluxes respond to changing climate is still lacking. In this study, CO2 fluxes were monitored continuously from 2011 through 2014 using high frequency measurements from Switchgrass land seeded in 2008 on an experimental site that has been previously used for soybean (Glycine max L.) in South Dakota, USA. DAYCENT, a process-based model, was used to simulate CO2 fluxes. An improved methodology CPTE [Combining Parameter estimation (PEST) with "Trial and Error" method] was used to calibrate DAYCENT. The calibrated DAYCENT model was used for simulating future CO2 emissions based on different climate change scenarios. This study showed that: (i) the measured soil CO2 fluxes from Switchgrass land were higher for 2012 which was a drought year, and these fluxes when simulated using DAYCENT for long-term (2015-2070) provided a pattern of polynomial curve; (ii) the simulated CO2 fluxes provided different patterns with temperature and precipitation changes in a long-term, (iii) the future CO2 fluxes from Switchgrass land under different changing climate scenarios were not significantly different, therefore, it can be concluded that Switchgrass grown for longer durations could reduce changes in CO2 fluxes from soil as a result of temperature and precipitation changes to some extent.

[1]  W. Parton,et al.  Analysis of factors controlling soil organic matter levels in Great Plains grasslands , 1987 .

[2]  Johan Six,et al.  Simulating greenhouse gas budgets of four California cropping systems under conventional and alternative management. , 2010, Ecological applications : a publication of the Ecological Society of America.

[3]  F. Chapin,et al.  Global Warming and Terrestrial Ecosystems: A Conceptual Framework for Analysis , 2000 .

[4]  Michael Bahn,et al.  Soil Carbon Dynamics - an Integrated Methodology , 2010 .

[5]  B. Emmett,et al.  Effects of experimental drought on microbial processes in two temperate heathlands at contrasting water conditions , 2003 .

[6]  W. Parton,et al.  Life-cycle assessment of net greenhouse-gas flux for bioenergy cropping systems. , 2007, Ecological applications : a publication of the Ecological Society of America.

[7]  J. Schimel,et al.  Microbial response to freeze-thaw cycles in tundra and taiga soils , 1996 .

[8]  J. Arnold,et al.  HYDROLOGICAL MODELING OF THE IROQUOIS RIVER WATERSHED USING HSPF AND SWAT 1 , 2005 .

[9]  W. Schlesinger,et al.  The global carbon dioxide flux in soil respiration and its relationship to vegetation and climate , 1992 .

[10]  Richard A. Birdsey,et al.  Modeling Carbon Stocks in a Secondary Tropical Dry Forest in the Yucatan Peninsula, Mexico , 2014, Water, Air, & Soil Pollution.

[11]  Yiqi Luo,et al.  Response of soil CO2 efflux to water manipulation in a tallgrass prairie ecosystem , 2002, Plant and Soil.

[12]  Ming Xu,et al.  Heterotrophic Soil Respiration in Relation to Environmental Factors and Microbial Biomass in Two Wet Tropical Forests , 2006, Plant and Soil.

[13]  M. B. Kirkham,et al.  Elevated Carbon Dioxide: Impacts on Soil and Plant Water Relations , 2011 .

[14]  Zhe Zhang,et al.  Predominant role of water in regulating soil and microbial respiration and their responses to climate change in a semiarid grassland , 2009 .

[15]  S. Marhan,et al.  Field-scale manipulation of soil temperature and precipitation change soil CO2 flux in a temperate agricultural ecosystem , 2013 .

[16]  David S. Powlson,et al.  Evaluation of Soil Organic Matter Models , 1996 .

[17]  Yiqi Luo,et al.  Source components and interannual variability of soil CO2 efflux under experimental warming and clipping in a grassland ecosystem , 2007 .

[18]  Soroosh Sorooshian,et al.  Status of Automatic Calibration for Hydrologic Models: Comparison with Multilevel Expert Calibration , 1999 .

[19]  S. B. McLaughlin,et al.  Projecting Yield and Utilization Potential of Switchgrass as an Energy Crop , 2006 .

[20]  Lynn L Wright,et al.  Historical Perspective on How and Why Switchgrass was Selected as a "Model" High-Potential Energy Crop , 2007 .

[21]  R. Monson,et al.  Differential controls by climate and substrate over the heterotrophic and rhizospheric components of soil respiration , 2006 .

[22]  X. Wang,et al.  Combined PEST and Trial-Error approach to improve APEX calibration , 2015, Comput. Electron. Agric..

[23]  Evan H. DeLucia,et al.  Comparative Biogeochemical Cycles of Bioenergy Crops Reveal Nitrogen-Fixation and Low Greenhouse Gas Emissions in a Miscanthus × giganteus Agro-Ecosystem , 2010, Ecosystems.

[24]  W. Parton,et al.  DAYCENT and its land surface submodel: description and testing , 1998 .

[25]  R. M. Lehman,et al.  Nitrogen fertilizer and landscape position impacts on CO2 and CH4 fluxes from a landscape seeded to switchgrass , 2015 .

[26]  K. Regina,et al.  Fluxes of N2O, CH4 and CO2 in a meadow ecosystem exposed to elevated ozone and carbon dioxide for three years. , 2007, Environmental pollution.

[27]  J. Scurlock,et al.  The development and current status of perennial rhizomatous grasses as energy crops in the US and Europe , 2003 .

[28]  Robert P. Anex,et al.  Nitrous Oxide Emissions from Cropland: a Procedure for Calibrating the DayCent Biogeochemical Model Using Inverse Modelling , 2013, Water, Air, & Soil Pollution.

[29]  Leif T. Jensen,et al.  A comparison of the performance of nine soil organic matter models using datasets from seven long-term experiments , 1997 .

[30]  J. Arnold,et al.  VALIDATION OF THE SWAT MODEL ON A LARGE RWER BASIN WITH POINT AND NONPOINT SOURCES 1 , 2001 .

[31]  J. Nash,et al.  River flow forecasting through conceptual models part I — A discussion of principles☆ , 1970 .

[32]  Doris Do The Effects of Temperature and Precipitation on Carbon Dioxide Flux from California Grassland Soil , 2008 .

[33]  M. Bahn,et al.  On the ‘temperature sensitivity’ of soil respiration: Can we use the immeasurable to predict the unknown? , 2010, Soil biology & biochemistry.

[34]  J. Fike,et al.  The Biology and Agronomy of Switchgrass for Biofuels , 2005 .

[35]  William J. Parton,et al.  The CENTURY model , 1996 .

[36]  Shelie A. Miller,et al.  Using DAYCENT to quantify on-farm GHG emissions and N dynamics of land use conversion to N-managed switchgrass in the Southern U.S. , 2011 .

[37]  Jeffrey G. Arnold,et al.  Model Evaluation Guidelines for Systematic Quantification of Accuracy in Watershed Simulations , 2007 .