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Candidate Perennial Bioenergy Grasses Have a Higher Albedo Than Annual Row Crops Jesse N

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Candidate Perennial Bioenergy Grasses Have a Higher Albedo Than Annual Row Crops Jesse N Agronomy Publications Agronomy 2016 Candidate Perennial Bioenergy Grasses have a Higher Albedo than Annual Row Crops Jesse N. Miller University of Illinois at Urbana-Champaign Andy VanLoocke Iowa State University, [email protected] Nuria Gomez-Casanovas University of Illinois at Urbana-Champaign Carl J. Bernacchi University of Illinois at Urbana-Champaign Follow this and additional works at: http://lib.dr.iastate.edu/agron_pubs Part of the Agronomy and Crop Sciences Commons, Biogeochemistry Commons, Other Earth Sciences Commons, and the Other Environmental Sciences Commons The ompc lete bibliographic information for this item can be found at http://lib.dr.iastate.edu/ agron_pubs/110. For information on how to cite this item, please visit http://lib.dr.iastate.edu/ howtocite.html. This Article is brought to you for free and open access by the Agronomy at Iowa State University Digital Repository. It has been accepted for inclusion in Agronomy Publications by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. GCB Bioenergy (2016) 8, 818–825, doi: 10.1111/gcbb.12291 Candidate perennial bioenergy grasses have a higher albedo than annual row crops JESSE N. MILLER1 , ANDY VANLOOCKE2*,NURIAGOMEZ-CASANOVAS3 and CARL J. BERNACCHI1,2,3 1Department of Plant Biology, University of Illinois, 1201 W. Gregory Drive, 196 Madigan Lab., Urbana, IL 61801, USA, 2USDA ARS Global Change and Photosynthesis Research Unit, Urbana, IL 61801, USA, 3Energy Biosciences Institute, Institute for Genomic Biology, University of Illinois, 1206 W. Gregory Drive, Room 1400, Urbana, IL 61801, USA Abstract The production of perennial cellulosic feedstocks for bioenergy presents the potential to diversify regional economies and the national energy supply, while also serving as climate ‘regulators’ due to a number of biogeo- chemical and biogeophysical differences relative to row crops. Numerous observational and model-based approaches have investigated biogeochemical trade-offs, such as increased carbon sequestration and increased water use, associated with growing cellulosic feedstocks. A less understood aspect is the biogeophysical changes associated with the difference in albedo (a), which could alter the local energy balance and cause local to regio- nal cooling several times larger than that associated with offsetting carbon. Here, we established paired fields of Miscanthus 9 giganteus (miscanthus) and Panicum virgatum (switchgrass), two of the leading perennial cellulosic feedstock candidates, and traditional annual row crops in the highly productive ‘Corn-belt’. Our results show that miscanthus did and switchgrass did not have an overall higher a than current row crops, but a strong sea- sonal pattern existed. Both perennials had consistently higher growing season a than row crops and winter a did not differ. The lack of observed differences in winter a, however, masked an interaction between snow cover and species differences, with the perennial species, compared with the row crops, having a higher a when snow was absent and a much lower a when snow was present. Overall, these changes resulted in an average net À À reduction in annual absorbed energy of about 5 W m 2 for switchgrass and about 8 W m 2 for miscanthus rela- tive to annual crops. Therefore, the conversion from annual row to perennial crops alters the radiative balance of the surface via changes in a and could lead to regional cooling. Keywords: albedo, bioenergy, biofuel crops, corn, land-use change, miscanthus, radiative forcing, snow, soybean, switchgrass Received 16 April 2015; accepted 18 May 2015 influence regional climate via changes to surface albedo Introduction (a), roughness length, and leaf area (e.g., Georgescu et al., A primary goal of bioenergy production was to reduce 2009, 2011). The biogeophysical effects associated with the emissions of carbon dioxide into the atmosphere land-use change to perennial biofuel crops remain uncer- (EPA, 2010). Because of this focus on carbon, research tain and can be influenced by altered surface reflectivity has addressed the biogeochemical consequences of and changes in the total energy and the partitioning of changing the landscape from traditional row crops to energy into sensible, latent, and ground heat fluxes (Jør- perennial biofuel feedstocks (Melillo et al., 2009; Zeri gensen et al., 2014; Mahmood et al., 2014). Energy parti- et al., 2011; Anderson-Teixeira et al., 2012; VanLoocke tioning at the land surface can strongly influence local et al., 2012; Smith & Torn, 2013; Bagley et al., 2014a). and regional climate (Sellers et al., 1997), suggesting that Feedback associated with energy exchange between altering the land surface for bioenergy production can ecosystems and the atmosphere is strongly influenced by have implications beyond carbon cycling. the type of land cover (Sellers et al., 1997). Land-use Two perennial grass species, Miscanthus 9 giganteus change from annual row crops to perennial biofuel crops (miscanthus) and Panicum virgatum (switchgrass), have can alter the land-atmosphere exchange and strongly been proposed as candidate cellulosic biofuel crops for the Midwestern United States (McLaughlin & Kszos, *Present address: Department of Agronomy, Iowa State University, 2005; Heaton et al., 2008a,b). These species emerge Ames, IA, USA before and senesce after the annual row crops, Zea mays (maize) and Glycine max (soybean), that currently domi- Correspondence: Carl J. Bernacchi, 1201 W. Gregory Drive, 196 nate the Midwestern U.S. landscape. Because vegetation ERML, Urbana, IL 61801, USA, tel. +1 217 333 8048, a fax +1 217 244 7246, e-mail: [email protected] has a higher than soil, the longer growing season © 2015 The Authors. Global Change Biology Bioenergy Published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License, 818 which permits use, distribution and reproduction in any medium, provided the original work is properly cited. ALBEDO, ANNUAL AND PERENNIAL BIOENERGY CROPS 819 associated with the perennial grasses could lead to crops (maize and soybean) to perennial feedstocks higher a during early spring and late fall when less soil (miscanthus and switchgrass) over multiple years repre- is exposed relative to the row crops (Burba & Verma, senting a wide range of climatic conditions. From the a 2001). The presence or absence of vegetation is, how- measurements, radiative forcing (RF) will be calculated ever, only one of many land surface factors that can to assess how potential changes in a can influence the influence a (Pielke, 2001). For example, the presence of surface energy balance. In this study, we test the predic- snow cover, with an a that approaches unity, is an tions that (i) transitioning from annual crops to perennial important determinant of a (Cherubini et al., 2012). grasses will increase annual a because perennials emerge However, the presence of litter or standing biomass, before and senesce after soybean and maize and (ii) dif- with a relatively lower a, might intercept light before it ferences in management between crops, such as the reaches snow and alter the radiation balance of the sur- length of time biomass is left standing in the field during face (e.g., Twine et al., 2004; Kucharik et al., 2013). Fur- winter, will alter the radiative properties of the surface, thermore, perennial and annual crops are managed especially with regard to snowfall events. Specifically, differently, with perennial fields usually left with stand- we predict that when snow cover is present, annuals, ing biomass into the winter, which can provide more which are harvested before winter and have relatively opportunities for masking snowfall in the perennial little litter, will have a higher a than perennials, which ecosystems compared to row crops that are typically are typically left standing through the winter and have harvested before winter starts. Finally, differences in high amounts of plant litter. These predictions are tested leaf properties can alter a among species. For example, with direct a measurements from multiple locations leaf area index (LAI) between crops could be similar, across central Illinois over maize, soybean, miscanthus, but lower leaf nitrogen content of perennials relative to and switchgrass fields over a 5-year time period. annuals (Nabity et al., 2012) could give perennials a higher a (Bartlett et al., 2011; Wicklein et al., 2012). Materials and methods Therefore, land-use change from annual to perennial species is likely to influence a. Site description Several modeling studies have investigated the poten- tial climate impact of altering a due to transitioning The study was conducted at three locations in Central Illinois, from annual row crops to perennial grasses (Lobell located in the Midwest U.S. ‘Corn-belt’: 1) University of Illinois’ et al., 2006; Davis et al., 2009; Georgescu et al., 2009, Energy Farm (UIEF) near Champaign, IL (40.064°N, 88.197°W), 2011; Loarie et al., 2011; Bright et al., 2012; Anderson 2) University of Illinois South Farms/SoyFACE research facility ° ° et al., 2013; Bagley et al., 2014a). Model simulations of (UISF) near Champaign, IL (40.042 N, 88.235 W), and 3) Univer- sity of Illinois Dudley Smith Farms (UIDS) near Pana, IL the conversion from annual row crops to bioenergy (39.441°N, 89.121°W). Typical of much of the Midwestern crops in the Midwestern U.S. predict a shift in energy ‘Corn-belt’, the climate of these sites is highly seasonal, with partitioning and altered surface reflectivity, which monthly average temperatures in winter below 0 °C and above together have a cooling effect that is several times stron- 20 °C in summer months (Zeri et al., 2011). Experimental plots ger than the potential cooling that would result from at UIEF (described in Zeri et al., 2011) consisted of 0.4 Ha plots reduced carbon emissions (Georgescu et al., 2011). This of miscanthus, switchgrass, and a rotation sequence of maize cooling was modeled based on a small increase in a (2008, 2009, 2011, 2012) and soybean (2010).
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