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Agricultural land in the Midwest is a source of food and fuel, as well as biodiversity.It is also a cause of excess nutrients that make their way to the Mississippi River and the Gulf of Mexico. To address unsustainable changes to biogeochemical cycles and ecosystem functions, a multidisciplinary approach involving social science, natural science, and engineering is often effective. Given the potential of second-generation biofuels, and capitalizing on the deep-rooted perennial bioenergy crops capable of thriving in poor soils, we demonstrated an integrated socio-environmental analysis of the impacts of growing switchgrass within row-crop landscapes in Illinois. In this study, we model land use scenarios that incorporate switchgrass as a biofuel crop in a Midwest corn-belt watershed using the Soil Water Assessment Tool coupled with an economic analysis for the Vermilion Basin in Illinois. We estimated the values of ecosystem services under an alternative bioenergy landscape, including commodity and bioenergy crops, changes in biogeochemistry, and recreational services. The estimated annual values of nitrate and sediment reduction attributed to bioenergy crops range from $38 million to $97 million and $16,000 to $197,000, respectively. The annual value of carbon dioxide emission reduction ranges from $1.8 million to $6.1 million based on the initial crop rotation pattern. Estimated average annual values for wildlife viewing, water-based recreation, and pheasant hunting are $1.24 million, $0.17 million, and $0.3 million, respectively. To our knowledge, this study represents the first effort to comprehensively quantify ecosystem services using a processbased model, and estimate their value in an alternative bioenergy landscape. The information we generate could aid in understanding the potential for biomass production from marginal land and the total economic value of the landscape at various spatial scales. The framework is useful in fostering alternative bioenergy landscapes with synergies in a food, energy, and conservation nexus. K E Y W O R D S carbon dioxide emission reduction, nitrate loss, nutrient recovery, sustainability, value of ecosystem services | 749 MISHRA et Al.

Locating bioenergy crops on strategically selected subfield areas of marginal interest for commodity agriculture can increase environmental sustainability. Location and choice of bioenergy crops should improve environmental benefits with minimal disruption of current food production systems. We identified subfield soils of a tile-drained agricultural watershed as marginal if they had areas of low crop productivity index (CPI), were susceptible to nitrate-nitrogen (NO-N) leaching, or were susceptible to at least two other forms of environmental degradation (marginal areas). In the test watershed (Indian Creek watershed, IL) with annual precipitation of 852 mm, 3% of soils were CPI areas and 22% were marginal areas. The Soil and Water Assessment Tool was used to forecast the impact of growing switchgrass ( L.), willow ( spp.), and big bluestem ( Vitman) in these subfield areas on annual grain yields, NO-N and sediment exports, and water yield. Simulated conversion of CPI areas from current land use to bioenergy crops had no significant ( 0.05) impact on grain production and reduced NO-N and sediment exports by 5.0 to 6.0% and 3.0%, respectively. Conversion of marginal areas from current land use to switchgrass forecasted the production of 34,000 t of biomass and reductions in NO-N (26.0%) and sediment (33.0%) exports. Alternatively, conversion of marginal areas from current land use to willow forecasted similar reductions as switchgrass for sediment but significantly ( 0.01) lower reductions in annual NO-N export (18.0 vs. 26.0%).

Abstract. Hurricanes are infrequent but influential disruptors of ecosystem processes in the southeastern Atlantic and Gulf coasts. Every southeastern forested wetland has the potential to be struck by a tropical cyclone. We examined the impact of Hurricane Hugo on two paired coastal South Carolina watersheds in terms of streamflow and vegetation dynamics, both before and after the hurricane's passage in 1989. The study objectives were to quantify the magnitude and timing of changes including a reversal in relative streamflow difference between two paired watersheds, and to examine the selective impacts of a hurricane on the vegetative composition of the forest. We related these impacts to their potential contribution to change watershed hydrology through altered evapotranspiration processes. Using over 30 years of monthly rainfall and streamflow data we showed that there was a significant transformation in the hydrologic character of the two watersheds -a transformation that occurred soon after the hurricane's passage. We linked the change in the rainfall-runoff relationship to a catastrophic change in forest vegetation due to selective hurricane damage. While both watersheds were located in the path of the hurricane, extant forest structure varied between the two watersheds as a function of experimental forest management techniques on the treatment watershed. We showed that the primary damage was to older pines, and to some extent larger hardwood trees. We believe that lowered vegetative water use impacted both watersheds with increased outflows on both watersheds due to loss of trees following hurricane impact. However, one watershed was able to recover to pre hurricane levels of evapotranspiration at a quicker rate due to the greater abundance of pine seedlings and saplings in that watershed.

Sustainability GHG emissionsNitrate leachate Marginal landsNutrient recovery a b s t r a c t Current and future demand for food, feed, fiber, and energy require novel approaches to land management, which demands that multifunctional landscapes are created to integrate various ecosystem functions into a sustainable land use. We developed an approach to design such landscapes at a field scale to minimize concerns of land use change, water quality, and greenhouse gas emissions associated with production of food and bioenergy.This study leverages concepts of nutrient recovery and phytoremediation to place bioenergy crops on the landscape to recover nutrients released to watersheds by commodity crops. Crop placement is determined by evaluating spatial variability of: 1) soils, 2) surface flow pathways, 3) shallow groundwater flow gradients, 4) subsurface nitrate concentrations, and 5) primary crop yield. A 0.8 ha bioenergy buffer was designed within a 6.5 ha field to intercept concentrated surface flow, capture and use nitrate leachate, and minimize use of productive areas. Denitrification-Decomposition (DNDC) simulations show that on average, a switchgrass (Panicum Virgatum L.) or willow (Salix spp.) buffer within this catchment according to this design could reduce annual leached NO 3 by 61 or 59% and N 2 O emission by 5.5 or 10.8%, respectively, produce 8.7 or 9.7 Mg ha À1 of biomass respectively, and displace 6.7 Mg ha À1 of corn (Zea mays L.) grain. Therefore, placement of bioenergy crops has the potential to increase environmental sustainability when the pairing of location and crop type result in minimal disruption of current food production systems and provides additional environmental benefits. (H. Ssegane), negri@anl.gov (M.C. Negri), quinnj@anl.gov (J. Quinn), demirtasmu@anl.gov (M. Urgun-Demirtas).

Landscape design has been embraced as a promising approach to holistically balance multiple goals related to environmental and resource management processes to meet future provisioning and regulating ecosystem services needs. In the agricultural context, growing bioenergy crops in specifi c landscape positions instead of dedicated fi elds has the potential to improve their sustainability, provide ecosystem services, and minimize competition with other land uses. However, growing bioenergy crops in sub-productive or environmentally vulnerable parts of a fi eld implies more complex logistics as small amounts of biomass are generated in a distributed way across the landscape. We present a novel assessment of the differences in production and logistic costs between business as usual (BAU, dedicated fi elds), and distributed landscape production of shrub, or short-rotation willow for bioenergy within a US Midwestern landscape. Our fi ndings show that regardless of the mode of cropping, BAU or landscape design, growing shrub willows is unlikely to provide positive revenues (-$67 to -$303 ha -1 yr -1 at a biomass price of $46.30 Mg wet -1 ) because of high land rental costs in this agricultural region. However, when translated into a practice cost per unit of N removed at the watershed scale (range: $1.8-37.0 kg N -1 yr -1 ), the net costs are comparable to other conservation practices. The projected opportunity cost of growing willows instead of corn on underproductive areas varied between -$14 and $49 Mg wet -1 . This highlights the potential for willows to be a cost effective choice depending on the intra-fi eld grain productivity, biomass price and desirable concurrent ecosystem services.

Paired watershed studies are used around the world to evaluate and quantify effects of forest and water management practices on hydrology and water quality. The basic concept uses two neighboring watersheds (one as a control and another as a treatment), which are concurrently monitored during calibration (pre-treatment) and post-treatment periods. A statistically significant relationship between the control and treatment watersheds is established during calibration period such that any significant shift detected in the relationship during treatment is attributed to the treatment effects. The approach assumes that there is a consistent, quantifiable, and predictable relationship between watershed response variables. This study tests the hypothesis that the hydrologic relationships between control and treatment watersheds for daily water table elevation (WTE) and daily flow data were similar without any statistically significant difference during two different calibration (1988-1989 and 2007-2008) and treatment periods (1995-1996 and 2009), when the control and treatment watersheds were interchanged. The watersheds are two artificially drained loblolly pine forests (D1: 24.7 ha and D2: 23.6 ha) located in coastal North Carolina. Results depicted significantly similar WTE regression relationships during the two calibration periods but significantly different WTE relationships during the two treatment periods with reversed control and treatment watersheds. Calibration and treatment flow relationships, and the mean treatment effects on WTE and flow, before and after treatment reversal were significantly different (α = 0.05). The study also discusses causes of differences in hydrologic relationships and treatment effects for such reversal of treatments during a 21-year span of the study on these two similar and adjacent watersheds. The observed differences in the hydrologic relationships between control and treatment watersheds before and after treatment reversal may be attributed to climate or hydrologic non-stationarity which may affect the reliability of paired watershed approach especially when the calibration periods are short.

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