•A two-phase simulation-based framework for finding locations of biomass storages.•ALMANAC model for crop yield estimation regarding environmental dynamics.•Agent-based simulation to consider complex ...activities of actors in a supply chain.•Network partitioning to reduce computational demand of the optimization problem.•Integer programming to efficiently find locations of biomass storages.
This study presents a two-phase simulation-based framework for finding the optimal locations of biomass storage facilities that is a very critical link on the biomass supply chain, which can help to solve biorefinery concerns (e.g. steady supply, uniform feedstock properties, stable feedstock costs, and low transportation cost). The proposed framework consists of two simulation phases: (1) crop yield estimation using a process-based model such as Agricultural Land Management Alternative with Numerical Assessment Criteria (ALMANAC) and (2) biomass transportation cost estimation using agent-based simulation (ABS) such as AnyLogic® with geographic information system (GIS). The OptQuest® in AnyLogic is used as an optimization engine to find the best locations of biomass storage facilities based on evaluation results given by the two-phase simulation framework. In addition, network partitioning and integer linear programming techniques are used to mitigate computation demand of the optimization problem. Since the proposed hybrid simulation approach utilizes realistic biofuel feedstock production and considers dynamics of supply chain activities, it is able to provide reliable locations of biomass storage facilities for operational excellence of a biomass supply chain.
Large quantities of biofuel production are expected from bioenergy crops at a national scale to meet US biofuel goals. It is important to study biomass production of bioenergy crops and the impacts ...of these crops on water quantity and quality to identify environment-friendly and productive biofeedstock systems. SWAT2012 with a new tile drainage routine and improved perennial grass and tree growth simulation was used to model long-term annual biomass yields, streamflow, tile flow, sediment load, and nutrient losses under various bioenergy scenarios in an extensively agricultural watershed in the Midwestern US. Simulated results from bioenergy crop scenarios were compared with those from the baseline. The results showed that simulated annual crop yields were similar to observed county level values for corn and soybeans, and were reasonable for Miscanthus, switchgrass and hybrid poplar. Removal of 38% of corn stover (3.74Mg/ha/yr) with Miscanthus production on highly erodible areas and marginal land (17.49Mg/ha/yr) provided the highest biofeedstock production (279,000Mg/yr). Streamflow, tile flow, erosion and nutrient losses were reduced under bioenergy crop scenarios of bioenergy crops on highly erodible areas and marginal land. Corn stover removal did not result in significant water quality changes. The increase in sediment and nutrient losses under corn stover removal could be offset with the combination of other bioenergy crops. Potential areas for bioenergy crop production when meeting the criteria above were small (10.88km2), thus the ability to produce biomass and improve water quality was not substantial. The study showed that corn stover removal with bioenergy crops both on highly erodible areas and marginal land could provide more biofuel production relative to the baseline, and was beneficial to water quality at the watershed scale, providing guidance for further research on evaluation of bioenergy crop scenarios in a typical extensively tile-drained watershed in the Midwestern U.S.
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•Calibrated parameter sets for bioenergy crop growth and tile drainage were used.•Corn stover removal (38%) did not result in significant water quality impacts.•Bioenergy crops can offset adverse water quality impacts of corn stover removal.•Small bioenergy crop areas provided limited ability to improve water quality.•Results provide guidance for evaluation of bioenergy scenarios in tile-drained areas.
Quantifying Populus growth and the impacts on hydrology and water quality are important should it be widely planted. Soil and Water Assessment Tool (SWAT) tree growth algorithms and parameters for ...hybrid poplar in Midwestern US and cottonwood in Southern US were improved. Tree growth representation led to SWAT2012 code changes including a new leaf area parameter (TREED), new leaf area index algorithm, and leaf biomass algorithm. Simulated hybrid poplar LAI and aboveground woody biomass (PBIAS: 34 - 5%, NSE: 0.51–0.99, and R2: 0.72–0.99), and cottonwood aboveground biomass, runoff, sediment, and nitrate-N (PBIAS: 39 - 11%, NSE: 0.86–0.99, and R2: 0.93–0.99) from the modified SWAT were satisfactory. Improved algorithms, and parameter values and potential ranges for Populus were reasonable. Thus, the modified SWAT can be used for Populus biofeedstock production modeling and hydrologic and water quality response to its growth.
•We improved tree seasonal maximum LAI and dropping leaves weight simulation in SWAT.•We modified SWAT to simulate LAI and biomass yields for juvenile and mature Populus.•The modified SWAT can model biofeedstock production for Populus.•The modified SWAT can model water quantity and quality response to tree growth.•The improved algorithms and parameters are useful for other process based models.
Eastern gamagrass (Tripsacum dactyloides) is highly palatable, ideal for grazing and hay production in the United States. It is deep rooted and resilient, tolerant of flooding and drought. Objectives ...of this study were to develop plant parameters for different ecotypes of this grass. Data collected in field plots of diverse ecotypes included biomass, leaf area index (LAI), light extinction coefficient (k), and radiation use efficiency (RUE). Average LAI was 1.06 and average k was −1.05. The power response of k to LAI offers a new approach to simulating light interception at very low LAI values and throughout the range of LAI values of these ecotypes and similar grass species. The RUE values, which ranged from 1.16 to 4.31 g/MJ, highlight the immense diversity of eastern gamagrass. The high RUE values for the most productive ecotypes emphasizes the importance of this grass species for hay and grazing. While not as large as switchgrass (Panicum virgatum) values, it is still a prominent forage species that even is comparable to maize (Zea mays L.) in productivity when expressed as radiation use efficiency. These results are an important step in developing relationships and parameters to simulate the different ecotypes of this grass with process-based models.
Examining intraspecific variation in growth and function in relation to climate may provide insight into physiological evolution and adaptation, and is important for predicting species responses to ...climate change.
Under common garden conditions, we grew nine genotypes of the C4 species Panicum virgatum originating from different temperature and precipitation environments. We hypothesized that genotype productivity, morphology and physiological traits would be correlated with climate of origin, and a suite of adaptive traits would show high broad-sense heritability (H
2).
Genotype productivity and flowering time increased and decreased, respectively, with home-climate temperature, and home-climate temperature was correlated with genotypic differences in a syndrome of morphological and physiological traits. Genotype leaf and tiller size, leaf lamina thickness, leaf mass per area (LMA) and C:N ratios increased with home-climate temperature, whereas leaf nitrogen per unit mass (N
m) and chlorophyll (Chl) decreased with home-climate temperature. Trait variation was largely explained by genotypic differences (H
2 = 0.33–0.85).
Our results provide new insight into the role of climate in driving functional trait coordination, local adaptation and genetic divergence within species. These results emphasize the importance of considering intraspecific variation in future climate change scenarios.
Determining the patterns and mechanisms of natural selection in the wild is of fundamental importance to understanding the differentiation of populations and the evolution of new species. However, it ...is often unknown the extent to which adaptive genetic variation is distributed among ecotypes between distinct habitats versus along large-scale geographic environmental gradients, such as those that track latitude. Classic studies of selection in the wild in switchgrass, Panicum virgatum, tested for adaptation at both of these levels of natural variation. Here we review what these field experiments and modern agronomic field trials have taught us about natural variation and selection at both the ecotype and environmental gradient levels in P. virgatum. With recent genome sequencing efforts in P. virgatum, it is poised to become an excellent system for understanding the adaptation of grassland species across the eastern half of North America. The identification of genetic loci involved in different types of adaptations will help to understand the evolutionary mechanisms of diversification within P. virgatum and provide useful information for the breeding of highyielding cultivars for different ecoregions.
Climatic changes are already influencing the frequency, magnitude, and duration of extreme weathers (e.g. drought) in California. California is a leading state for vegetable production in United ...States (U.S.). Since vegetables are very sensitive to extreme weathers, it is critical to evaluate the effects of climate change on yield and to find the potential adaptive management strategies for the sustainable vegetable production. The objectives of this study were to develop a plant-oriented cropping model to evaluate the impacts of different cropping managements on yields under various climate condition and atmospheric CO
2
levels. To improve modeling performance, numerous previous studies that reported broccoli yields in different managements were used. After model calibration and validation, 560 scenarios under the conditions of combinations of climate changes, four broccoli cultivars, five nitrogen fertilizer application rates, and four plant densities were simulated in two study locations in Monterey County, CA where produces almost 40% of total California broccoli production. Based on results from 33,600 simulations, broccoli yields were highly related to nitrogen fertilizer application. However, at high nitrogen rates (above 75 kg N ha
−1
), yields were barely changed. In general, under stressful conditions, all cultivars produced their maximum yields at low plant density, and their yields did not respond to addition of nutrient in soil. However, CO
2
enrichment and warmer temperature under RCP8.5 pathways, yield responded positively with fertilizer application rate and plant density. It seems likely that the effects of cropping managements will depend upon CO
2
level and temperature.
Replacing fossil fuel with biofuel is environmentally viable from a climate change perspective only if the net greenhouse gas (GHG) footprint of the system is reduced. The effects of replacing annual ...arable crops with perennial bioenergy feedstocks on net GHG production and soil carbon (C) stock are critical to the system-level balance. Here, we compared GHG flux, crop yield, root biomass, and soil C stock under two potential tropical, perennial grass biofuel feedstocks: conventional sugarcane and ratoon-harvested, zero-tillage napiergrass. Evaluations were conducted at two irrigation levels, 100% of plantation application and at a 50% deficit. Peaks and troughs of GHG emission followed agronomic events such as ratoon harvest of napiergrass and fertilization. Yet, net GHG flux was dominated by carbon dioxide (CO2), as methane was oxidized and nitrous oxide (N2O) emission was very low even following fertilization. High N2O fluxes that frequently negate other greenhouse gas benefits that come from replacing fossil fuels with agronomic forms of bioenergy were mitigated by efficient water and fertilizer management, including direct injection of fertilizer into buried irrigation lines. From soil intensively cultivated for a century in sugarcane, soil C stock and root biomass increased rapidly following cultivation in grasses selected for robust root systems and drought tolerance. The net soil C increase over the two-year crop cycle was three-fold greater than the annualized soil surface CO2 flux. Deficit irrigation reduced yield, but increased soil C accumulation as proportionately more photosynthetic resources were allocated belowground. In the first two years of cultivation napiergrass did not increase net greenhouse warming potential (GWP) compared to sugarcane, and has the advantage of multiple ratoon harvests per year and less negative effects of deficit irrigation to yield.
Sorghum is the world’s fifth major cereal in terms of production and acreage. It is expected that its growth will be affected by the increase in air temperature, an important component of global ...climate change. Our objective was to use the Agricultural Land Management Alternatives with Numerical Assessment Criteria (ALMANAC) model to (a) evaluate the impact of climate warming on forage and grain sorghum production in Argentina and (b) to analyze to what extent yield changes were associated with changes in water or nitrogen stress days. For model calibration, we used previous information related to the morpho-physiological characteristics of both sorghum types and several soil parameters. We then used multiyear field data of sorghum yields for model validation. Yield simulations were conducted under three possible climate change scenarios: 1, 2, and 4 °C increase in mean annual temperature. ALMANAC successfully simulated mean yields of forage and grain sorghum: root mean square error (RMSE): 2.6 and 1.0 Mg ha−1, respectively. Forage yield increased 0.53 Mg ha−1, and grain yield decreased 0.27 Mg ha−1 for each degree of increase in mean annual temperature. Yields of forage sorghum tended to be negatively associated with nitrogen stress (r = −0.94), while grain sorghum yield was negatively associated with water stress (r = −0.99). The information generated allows anticipating future changes in crop management and genetic improvement programs in order to reduce the yield vulnerability.
Eastern gamagrass (Tripsacum dactyloides) is a highly productive, highly palatable native grass tolerant to both drought and flooding. It has frequently shown great response to nitrogen (N) ...applications, but the responses of southern native ecotypes in upland and bottomland sites have yet to be reported. The objectives were to measure the responses of long-established eastern gamagrass with different N application rates in two bottomland hay pastures and two upland grazed sites, and to measure the N responses for six diverse ecotypes in a common garden. A randomized block design was used with ecotype as the main block and fertilizer rate as the subplot. In the long-established sites, 75 N peak yields were not statistically different to those of 0 N, while upland yields across the season were consistently higher for 150 N but varied for the bottomland. The common garden ecotypes had no significant difference in yield between treatments when averaged across years. Roaring Springs showed the most consistent and greatest benefit to additional N, more than doubling the dry weight of the control. All remaining ecotypes, however, had more modest responses. Eastern gamagrass responds inconsistently to applications of 75 N, whereas most applications of 150 N generally result in higher yield, though significant increases are not guaranteed.
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