IMPACTS OF CHANGES IN CLIMATE AND LAND USE ON WATER RESOURCES AND TERRESTRIAL ECOSYSTEMS IN THE MIDWESTERN U.S.

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 0215442
• Project Start Date: Sep 1, 2008
• Project End Date: Aug 31, 2013
• Program Code: [(N/A)]- (N/A)

Recipient Organization
UNIVERSITY OF NEBRASKA
(N/A)
LINCOLN,NE 68583

Performing Department
School of Natural Resources

Non Technical Summary
Humans have significantly altered the Earth's atmosphere, oceans, and terrestrial ecosystems via greenhouse gas emissions and changes in land cover and management. To help guide important societal choices, we must better understand how ecosystems have been perturbed, and how they may change in the future. We need basic understanding of exchanges of heat, moisture, and trace gases within the planetary boundary layer, and how land management modifies these accordingly. These fluxes are dynamic and responsive to each other, and they combine with land and ocean surface characteristics to influence atmospheric circulation, and large-scale climate patterns. In turn, the Earth's climate system affects vegetation structure, function, and global distribution. To improve understanding of these climate-biosphere feedbacks, the study of environmental change has gradually adopted an integrated approach, in which global systems are often studied in unison using numerical models. This integrated study approach is best exemplified by Dynamic Global Vegetation Models (DGVMs), a new class of ecosystem models. These models combine biogeography, soil biogeochemistry, and soil-vegetation-atmosphere-transfer components, allowing for vegetation characteristics, the soil environment, and nutrient availability to respond to atmospheric forcing and land management change. DGVMs are currently indispensable for the study of plant distribution, ecosystem structure and function, and climate feedbacks in the context of both global climate change and land use change. To respond to the need for a modeling approach that accounts for both managed and natural ecosystems within a single framework, we have implemented process-based models of agricultural row crops and management choices into an already well-tested DGVM, the Integrated Biosphere Simulator (IBIS). A new regional U.S. version of IBIS (Agro-IBIS) simulates corn, soybean, and wheat cropping system dynamics, including complete terrestrial nitrogen cycling. Agro-IBIS accounts for human management (e.g., irrigation, fertilizer application, planting and harvest date, hybrid selection) and the effects of environmental stressors (e.g., water and soil nitrogen limitations) and atmospheric CO2 on crop development and regional carbon, water, and energy exchange with the atmosphere. In this project, we propose an interdisciplinary modeling effort that will analyze the response of carbon, water, and energy cycling to multiple, interacting global change drivers within the Midwestern U.S. Specifically, we will determine the general location, timing, and magnitude of changes in water availability, vegetation distribution, and crop yields brought about by changes in: (1) atmospheric carbon dioxide (CO2), (2) regional climate (precipitation and temperature), and (3) agricultural land management. We will study the effect that these perturbations have on ecological, biophysical, and biogeochemical processes and the associated changes in ecosystem structure and functioning, both from a historical and prognostic perspective (covering the 1948 to 2100 time period across the Upper Mississippi, Missouri, and Great Lakes basins).

Animal Health Component

(N/A)

Research Effort Categories

Basic

(N/A)

Applied

(N/A)

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
111	0210	1070	40%
111	0210	2050	40%
111	0210	2070	20%

Knowledge Area
111 - Conservation and Efficient Use of Water;

Subject Of Investigation
0210 - Water resources;

Field Of Science
2070 - Meteorology and climatology; 2050 - Hydrology; 1070 - Ecology;

Keywords

climate variability

climate change

land use

water resources

terrestrial ecosystems

upper midwest

crop yield

hydrology

vegetation dynamics

managed ecosystems

carbon dioxide

Goals / Objectives
The overall objective of the proposed work is to determine how past and future changes in climate and CO2 have and will impact water resources, crop yield, and ecosystem structure and function in the U.S. Upper Midwest. This can be broken down into three primary objectives: 1)Develop higher spatial resolution Agro-IBIS model driver datasets (land cover, daily climate) at 10-km resolution for 1948-2007, evaluate Agro-IBIS process formulations and output using observational datasets from AmeriFlux, FACE experiments, USGS, USDA, and other Midwest observations, and create new scenarios of future climate and atmospheric CO2 for 2008-2100. 2)Determine how previous changes in climate (temperature and precipitation), cropland management (planting dates, increasing use of nitrogen fertilizer and irrigation, and reduced tillage practices), and atmospheric CO2 have contributed to changes in vegetation (species) distributions, and changes in crop yields, forest NPP, water availability (soil moisture, evapotranspiration, runoff, etc.), and energy exchange (e.g., sensible, latent, and soil heat fluxes). 3)Determine the anticipated response of natural and managed ecosystem structure and function to future changes in land-use, climate, and atmospheric CO2 over the next 100 years, including changes in water and energy balance, and the changing availability of environmental goods and services (e.g., freshwater availability, crop yields, forest NPP), and potential vegetation distribution. As part of our work, we are keeping the following related questions in mind: 1)How have previous interactions among the complex biophysical, ecological, and biogeochemical processes acted to control water and energy cycling, crop yields, vegetation distribution, and the delivery of essential ecosystem services How might these responses change under future atmospheric conditions 2)Could ecosystems in the Midwestern U.S. appear to be stable, until they reach a threshold (e.g., "tipping point") where they will show sudden, large responses to interacting global change 3)Can we pinpoint "hot spots" of regional change in the Midwest, where the combined effects of human land use shifts and environmental drivers have been previously disruptive or will be in the future 4)How will potential forest species distributions change in the future due to the combined effects of changing climate and atmospheric CO2 We will use the Agro-IBIS model to examine scenarios of environmental change through the year 2100, but will construct simulations of the recent past (1948-2007) to examine how previous changes in climate, atmospheric CO2, and agricultural management have impacted ecosystem structure and functioning and water and energy exchange. While our model has been tested extensively across the U.S., we will perform additional validation of historical simulations of water and energy exchange to increase model confidence of both historical and future simulations. Earlier versions of the Agro-IBIS model have also been rigorously evaluated in water balance and water quality studies of the continental U.S. and Mississippi River basin.

Project Methods
We will use the Agro-IBIS model (Integrated BIosphere Simulator) to examine scenarios of environmental change through the year 2100, and we will also construct simulations of the recent past (1948-2007) to examine how previous changes in climate, atmospheric CO2, and agricultural management have impacted ecosystem structure and functioning and water and energy exchange. While our model has been tested extensively across the U.S., we will perform additional validation of historical simulations of water and energy exchange to increase model confidence of both historical and future simulations. Agro-IBIS is a process-based ecosystem model, capable of simulating managed and natural ecosystems (crops, grasslands, and forests) of North America. Agro-IBIS was developed by adapting a global terrestrial ecosystem model to explicitly model corn, soybean, and wheat crop systems across the U.S. It is currently the only such model that for the continental U.S. whereby both natural vegetation dynamics and the major row crop systems can be simulated in unison. Besides modeling short-timescale carbon, nitrogen, and water balance, and vegetation structure of natural and managed ecosystems, Agro-IBIS simulates crop transitions through key phenological stages during development (emergence, grain fill, senescence), characterizes seasonal shifts in carbon allocation to specific crop carbon pools (i.e. leaf, stem, root, and grain), and quantifies nitrogen fixation. Employing state-of-the-art models are only part of what is needed for simulating useful and realistic results. For any modeling effort attempting to look at large-scale carbon, water, and energy exchange, datasets of land cover and land management changes are crucial, especially for studies of diverse agricultural regions such as the Midwest U.S. Collaborators at the University of Wisconsin-Madison have put together global datasets of land cover, crop fractional cover and management trends such as N-fertilizer application. These will be used to assemble a comprehensive picture of regional patterns of ecosystem structure, function, and response. Agro-IBIS simulations will be performed across a 10-km x 10-km terrestrial grid using a 60-minute timestep. The model will use soil textural information as a function of soil depth (to 2.5 m) from STATSGO. Datasets of transient nitrogen fertilizer use created by merging USDA state-level survey data and county-level sales data will serve as model drivers for corn, soybeans, and wheat cropping systems at 10-km resolution. Agro-IBIS simulates complete nitrogen cycling for agricultural systems, including all the major input terms (fertilizer, atmospheric deposition, and mineralization), and uses the concentration of leaf nitrogen as a driver of plant physiological response. Therefore, we have the unique capability to simulate the effect of agronomic trends in agriculture on water and energy exchange and crop yields during the past 60 years. We will then extend the model simulations from 2008-2100 (using climate projections from the IPCC) to understand the region's response to anticipated future changes in land management, climate, and atmospheric composition.

Progress 09/01/08 to 08/31/13

Outputs
Target Audience: Targeted researchers addressing hydrologic modeling and energy and mass exchange in natural and managed ecosystems. Results also shared within the academic community through seminars and undergraduate and graduate classes. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? The project entailed participation in the Agro-IBIS modeling workshops and resulted in the training of graduate students in hydrologic modeling, as well as numerous collaborations with other researchers using the Agro-IBIS modeling system How have the results been disseminated to communities of interest? Results have been disseminated through scholarly publications, presentations at professional meetings and workshops. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? To better understand how ecosystems have been perturbed, and how they may change in the future, a basic understanding of exchanges of heat, moisture, and trace gases within the planetary boundary layer is needed along with an understanding of how land management modifies these accordingly. These fluxes are dynamic and responsive to each other, and they combine with land and ocean surface characteristics to influence atmospheric circulation, and large-scale climate patterns. Model and field studies were conducted to advance our understanding of these exchanges as a result of ecosystem perturbations. The Agro-IBIS model was used to examine scenarios of environmental change through the year 2100, and simulations of the recent past (1948-2007) to examine how previous changes in climate, atmospheric CO2, and agricultural management have impacted ecosystem structure and functioning and water and energy exchange. A daily, high-resolution (~8-km), gridded dataset of incoming solar radiation was used to drive the Agro-IBIS model simulations across the Upper Midwest. These data were used along with global datasets of land cover, crop fractional cover and management, soil textural information as a function of soil, transient nitrogen fertilizer use as model drivers for corn, soybeans, and wheat cropping. The results generally show an acceleration of the water cycle in the Upper Mississippi, Missouri, Ohio, and Great Lakes basins, but with significant seasonal and spatial complexity. Over the past 24 years, evapotranspiration has increased in most regions and most seasons, particularly during the fall, which is also a time of pronounced solar brightening. Trends in runoff are characterized by distinct spatial and seasonal variations. Since recent warming has led to a greater fraction of winter precipitation falling as rain rather than snow, spring runoff in some snow-dominated regions has declined significantly since 1984. Other regions show large increases in runoff throughout all seasons, primarily as a result of increased precipitation. Sensitivity experiments show that the water balance is most linearly sensitive to solar radiation and relative humidity, followed by precipitation, air temperature and wind speed. The energy and water balance of a riparian wetland in the Republican River basin in south-central Nebraska, was studied. Due to decreases in streamflow in recent decades in the study area, invasive species such as Phragmites australis have been removed throughout the riparian corridor of the river basin in an effort to reclaim surface water and toreduce consumptive water use from evapotranspiration (ET). The results of the energy budget analysis show that the average ET rate for the wetland during the growing season is 4.4 mm per day, with a maximum rate of 8.2 mm per day occurring which is higher than some values found in previous studies (e.g., 5.0-6.9 mm per day) and is attributed to differences in plant structure/biology, environment, and regional climate. The vegetation phenology and net radiation are the two largest meteorological/vegetation drivers for the seasonal variability in ET. Remote sensing-based estimates of ET were similar to the in-situ energy balance values during full vegetation, and reveal that the ET rates from P. australis are, on average, about 28% (1.18 mm per day) greater than those for native Typha latifolia. Results of the water balance analysis reveal a reasonable correspondence between water level fluctuations and the energy budget-derived estimates of ET. Periods when the two curves do not agree imply influx (outflux) of groundwater early (late) in the growing season. Results suggest that the removal of P. australis from wetlands within the Republican River basin could potentially result in a growing season “water savings” of up to 28% if the native species of T. latifolia replaces the non-native P. australis. If a free water surface replaces P. australis, depending on wind sheltering, a “water loss” or a “water savings” could occur. We conclude that due to the general presence of wind sheltering throughout the riparian corridor of the Republican River basin, this would more likely lead to a small, but tangible amount of “water savings” if replaced by open water. Heat storage rates in the wetland were dominated by changes in water temperature (as compared to soil or canopy heat storage) and comprised a significant portion of the hourly energy balance. On daily mean timescales, changes in the rate of heat storage corresponded to ~13% of the variability in net radiation, while for the season-long average, the heat storage term was found to be essentially negligible. Analysis of the wetland water balance showed seasonal variations in water level that were similar to changes in cumulative water inputs (i.e., precipitation minus ET). In support of the field studies, groundwater was incorporated into Agro-IBIS to simulate riparian and wetland systems; the study also investigated the impact of the introduced genetic lineage of P. australis which grows alongside and out-competes its native counterpart. Gas exchange measurements revealed significant differences between the two lineages. Our results show that native P. australis has a better ability to deal with water fluctuations, water shortages, and warmer temperatures than its introduced counterpart. In contrast, the faster growth rate, higher leaf area and lower water use efficiency of the introduced lineage under cooler temperatures could result in greater carbon assimilation on a whole-plant level, giving invasive P. australis an advantage and leading to further displacement of native communities in water-saturated habitats. In another study, a combination of observed soil temperatures and the Agro-IBIS model was used to investigate how strategic residue management could reduce the risk of rhizome threatening soil temperatures. Historical (1978–2007) reconstruction of extreme minimum 10 cm soil temperatures experienced across the Midwest US and model sensitivity studies quantified the impact of crop residue on soil temperatures. Extreme minimum soil temperatures increased by 2.5C to 6C compared to bare soil when the impact of miscanthus straw thicknesses (1–5 cm) following harvest were simulated. The greatest warming was associated with thicker residue layers. The likelihood of 10 cm soil temperatures reaching -3.5C was greatly reduced with 2– 5 cm of surface residue. However, soil temperatures in portions of the Dakotas, Nebraska, Minnesota, and Wisconsin were colder than -3.5C in 50–80% of all years. These results indicate that a strategic residue management could help increase the likelihood of overwintering of rhizomes (such as those for miscanthus) in the first few years after plant establishment

Publications

• Type: Journal Articles Status: Published Year Published: 2010 Citation: Soylu, M. E., Istanbulluoglu, E., Lenters, J. D., and Wang, T., 2010. Quantifying the impact of groundwater depth on evapotranspiration in a semi-arid grassland region. Hydrology and Earth System Sciences Discussions, 7:6887-6923. doi:10.5194/hessd-7-6887-2010.
• Type: Journal Articles Status: Published Year Published: 2010 Citation: Ryu, J. H., Svoboda, M. D., Lenters, J. D., Tadesse, T., and Knutson, C., 2010. Potential extents for ENSO-driven hydrologic drought forecasts in the United States. Climatic Change, 101(3-4):575-597. doi:10.1007/s10584-009-9705-0.
• Type: Journal Articles Status: Published Year Published: 2011 Citation: Lenters, J. D., Cutrell, G. J., Istanbulluoglu, E., Scott, D. T., Herrman, K. S., Irmak, A., and Eisenhauer, D. E., 2011. Seasonal energy and water balance of a Phragmites australis- dominated wetland in the Republican River basin of south-central Nebraska (USA). Journal of Hydrology, 408, 19-34. doi:10.1016/j.hydrol.2011.07.010.
• Type: Journal Articles Status: Published Year Published: 2012 Citation: Herrman, K. S., Scott, D. T., Lenters, J. D., Istanbulluoglu, E., 2012. Nutrient loss following Phragmites australis removal in controlled soil mesocosms. Water, Air, and Soil Pollution. 223(6), 3333-3344. doi:10.1007/s11270-012-1113-9.
• Type: Journal Articles Status: Published Year Published: 2012 Citation: Istanbulluoglu, E., Wang, T., Wright, O. M., and Lenters, J. D., 2012. Interpretation of hydrologic trends from a water balance perspective: The role of groundwater storage in the Budyko hypothesis. Water Resources Research. v. 48, W00H16, doi:10.1029/2010WR010100.
• Type: Journal Articles Status: Published Year Published: 2013 Citation: Kucharik, C.J., VanLoocke A., Lenters J.D., Motew M.M., 2013. Miscanthus Establishment and Overwintering in the Midwest USA: A Regional Modeling Study of Crop Residue Management on Critical Minimum Soil Temperatures. PLoS ONE 8(7): e68847. doi:10.1371/journal.pone.0068847
• Type: Theses/Dissertations Status: Published Year Published: 2010 Citation: Cutrell, G. J., 2010. Seasonal energy and water balance of a Phragmites australis-dominated wetland in the Republican River basin (southwestern Nebraska, USA). Masters Thesis, University of Nebraska-Lincoln, 128 pp
• Type: Theses/Dissertations Status: Published Year Published: 2010 Citation: Walters, S. G., 2010. Carbon dynamics in a Phragmites australis invaded riparian wetland. Masters thesis, University of Nebraska-Lincoln, 53 pp
• Type: Theses/Dissertations Status: Published Year Published: 2012 Citation: Dong, B. 2012. Impacts of climate change on the surface water balance of the central United States, 1984-2007. Masters Thesis, University of Nebraska-Lincoln
• Type: Theses/Dissertations Status: Published Year Published: 2012 Citation: Mykleby, P. 2012. Water and energy balance response of a riparian wetland to the removal of Phragmites australis. Masters Thesis, University of Nebraska-Lincoln

Progress 10/01/11 to 09/30/12

Outputs
OUTPUTS: Together with two graduate students, we have been using the Agro-IBIS model to simulate the impacts of climate variability and change on water resources in the Upper Midwest. One of the graduate students recently completed his thesis, which focused on the impacts of Phragmites australis removal on the surface energy and water balance of a wetland site in south-central Nebraska. A second graduate student also completed his thesis, in which he used the Agro-IBIS model to simulate the surface energy and water balance of the Upper Midwest for the period 1984-2007. The students participated in two land surface hydrology (Agro-IBIS) modeling workshops - one at Iowa State University and the other at the University of Minnesota. PARTICIPANTS: We have two graduate students (Bo Dong, Phillip Mykleby) at the University of Nebraska-Lincoln (UNL) that worked on this project during the past year. Their duties were to analyze field data and perform model simulations and analysis using the Agro-IBIS terrestrial ecosystem model. We have four collaborators at three other academic institutions. This includes Dr. Chris Kucharik from the University of Wisconsin-Madison, Drs. Tracy Twine and Peter Snyder from the University of Minnesota, and Dr. Brian Hornbuckle from Iowa State University. Training has been provided to the two UNL graduate students through coursework and research group meetings. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Field and growth chamber measurements have allowed us to refine and improve our simulations of the water balance in Agro-IBIS. Results of this study have been published in a student thesis and are also in preparation for submission to a peer-reviewed journal. Participation in Agro-IBIS modeling workshops has resulted in the training of graduate students in hydrologic modeling, as well as numerous collaborations with other researchers using the Agro-IBIS modeling system. Finally, we have graduated two recent M.S. students associated with this project.

Publications

• Herrman, K. S., Scott, D. T., Lenters, J. D., Istanbulluoglu, E. (2012) Nutrient loss following Phragmites australis removal in controlled soil mesocosms. Water, Air, and Soil Pollution. 223(6), 3333-3344. doi:10.1007/s11270-012-1113-9.
• Istanbulluoglu, E., Wang, T., Wright, O. M., and Lenters, J. D. (2012) Interpretation of hydrologic trends from a water balance perspective: The role of groundwater storage in the Budyko hypothesis. Water Resources Research. v. 48, W00H16, doi:10.1029/2010WR010100.
• Soylu, M. E., Lenters, J. D., Istanbulluoglu, E., and Loheide, S. P. (2012) On evapotranspiration and shallow groundwater fluctuations: A Fourier-based improvement to the White method. Water Resources Research, v. 48, W06506, doi:10.1029/2011WR010964.

Progress 10/01/10 to 09/30/11

Outputs
OUTPUTS: Together with three graduate students, we have been working with the Agro-IBIS model to simulate the impacts of climate variability and change on water resources in the Upper Midwest. One of the graduate students recently completed a paper in which groundwater was incorporated into Agro-IBIS to simulate riparian and wetland systems. A second graduate student has completed both field and growth chamber experiments to measure physiological parameters for an invasive plant species (P. australis), which have been incorporated into Agro-IBIS. The third graduate student has completed the calibration of a daily, high-resolution, gridded dataset of incoming solar radiation that is being used to drive the Agro-IBIS model simulations across the Upper Midwest for the entire study period (1948-2007). We participated in two land surface hydrology (Agro-IBIS) modeling workshops - one at the University of Nebraska-Lincoln and the other at the University of Wisconsin-Madison. Participants included three UNL grad students and collaborators from four other universities. PARTICIPANTS: We have three graduate students (Bo Dong, Phillip Mykleby, Evren Soylu) at the University of Nebraska-Lincoln (UNL) that have worked on this project during the past year. Their duties are to analyze field data and perform model simulations and analysis using the Agro-IBIS terrestrial ecosystem model. We have four collaborators at three other academic institutions. This includes Dr. Chris Kucharik from the University of Wisconsin-Madison, Drs. Tracy Twine and Peter Snyder from the University of Minnesota, and Dr. Brian Hornbuckle from Iowa State University. Training has been provided to the three UNL graduate students through coursework and research group meetings. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
The Agro-IBIS modeling results for riparian/wetland systems have been found to compare well with observations (and other models), and this study has now been published in Hydrology and Earth System Science Discussions (an online and open-access EGU journal). The field and growth chamber measurements (as well as the incorporation of groundwater) have allowed us to refine and improve our simulations of the water balance in Agro-IBIS. Publications describing these results are in preparation. The new solar radiation dataset has allowed us to examine trends in cloud cover that are impacting water resources in the U.S. Upper Midwest. Participation in the Agro-IBIS modeling workshops has resulted in the training of graduate students in hydrologic modeling, as well as numerous collaborations with other researchers using the Agro-IBIS modeling system. Finally, we have graduated one Ph.D. student associated with this project, and two more will be graduating in 2012.

Publications

• Soylu, M. E., Lenters, J. D., and Istanbulluoglu, E. (2011) On evapotranspiration and shallow groundwater fluctuations: A Fourier-based improvement to the White method. Water Resources Research. Accepted for publication.
• Lenters, J. D., Cutrell, G. J., Istanbulluoglu, E., Scott, D. T., Herrman, K. S., Irmak, A., and Eisenhauer, D. E. (2011) Seasonal energy and water balance of a Phragmites australis- dominated wetland in the Republican River basin of south-central Nebraska (USA). Journal of Hydrology, 408, 19-34. doi:10.1016/j.hydrol.2011.07.010.

Progress 09/01/09 to 08/31/10

Outputs
OUTPUTS: Together with three graduate students, we have been working with the Agro-IBIS model to simulate the impacts of climate variability and change on water resources in the Upper Midwest. One of the graduate students recently completed a paper in which groundwater was incorporated into Agro-IBIS to simulate riparian and wetland systems. A second graduate student has been collecting field data and planning growth chamber experiments to measure physiological parameters for an invasive plant species (P. australis), which will then be incorporated into Agro-IBIS. The third graduate student is compiling a daily, high-resolution, gridded dataset of incoming solar radiation that will be used to drive the Agro-IBIS model simulations across the Upper Midwest for the entire study period (1948-2007). We participated in two land surface hydrology (Agro-IBIS) modeling workshops - one at Iowa State University and the other at the University of Minnesota. Participants included three UNL grad students and collaborators from five other universities. PARTICIPANTS: We have five graduate students (Gregory Cutrell, Bo Dong, Phillip Mykleby, Evren Soylu, and Steven Walters) and two postdoctoral researchers (Kyle Herrman and Tiejun Wang) at the University of Nebraska-Lincoln (UNL) that have worked on this project during the past year. Their duties are to analyze field data and perform model simulations and analysis using the Agro-IBIS terrestrial ecosystem model. We have five collaborators at four other academic institutions. This includes Dr. Chris Kucharik from the University of Wisconsin-Madison, Drs. Tracy Twine and Peter Snyder from the University of Minnesota, Dr. Brian Hornbuckle from Iowa State University, and Dr. Simon Donner from the University of British Columbia. Training has been provided to the five UNL graduate students and the UNL postdoctoral researchers through coursework and research group meetings. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
The Agro-IBIS modeling results for riparian/wetland systems were found to compare well with observations (and other models), and this study has now been published in Hydrology and Earth System Science Discussions (an online and open-access EGU journal). The field and growth chamber measurements (as well as the incorporation of groundwater) will allow us to refine and improve our simulations of the water balance in Agro-IBIS. Finally, since net radiation is a primary driver of evapotranspiration and other water balance components, it is important that we include a quality solar radiation dataset as one of our model drivers. The new solar radiation dataset will also allow us to examine trends in cloud cover that are impacting water resources in the U.S. Upper Midwest. Participation in the Agro-IBIS modeling workshops has resulted in the training of graduate students in hydrologic modeling, as well as numerous collaborations with other researchers using the Agro-IBIS modeling system.

Publications

• Soylu, M. E., Istanbulluoglu, E., Lenters, J. D., and Wang, T., 2010. Quantifying the impact of groundwater depth on evapotranspiration in a semi-arid grassland region. Hydrology and Earth System Sciences Discussions, 7:6887-6923. doi:10.5194/hessd-7-6887-2010.
• Ryu, J. H., Svoboda, M. D., Lenters, J. D., Tadesse, T., and Knutson, C., 2010. Potential extents for ENSO-driven hydrologic drought forecasts in the United States. Climatic Change, 101(3-4):575-597. doi:10.1007/s10584-009-9705-0.
• Cutrell, G. J., 2010. Seasonal energy and water balance of a Phragmites australis-dominated wetland in the Republican River basin (southwestern Nebraska, USA). Master's Thesis, University of Nebraska-Lincoln, 128 pp.
• Walters, S. G., 2010. Carbon dynamics in a Phragmites australis invaded riparian wetland. Master's thesis, University of Nebraska-Lincoln, 53 pp.

Progress 09/01/08 to 08/31/09

Outputs
OUTPUTS: This report summarizes progress made during the first full year of this Hatch project. Since the initiation of this project on September 1, 2008, significant progress has been made toward the project goals. Accomplishments to date include the following: 1) A high-resolution (~8-km) climate dataset was produced and purchased from ZedX, Inc. for use in our Agro-IBIS model simulations. This dataset covers the entire continental United States (and portions of southern Canada) and includes observations of daily air temperature, precipitation, solar radiation, relative humidity, and wind speed for the period 1948-2007. Preliminary analysis of this new dataset indicates that it provides very reliable estimates of critical atmospheric variables at high enough resolution to be meaningful for regional scale studies, such as the current project. 2) Two new graduate students have been recruited to the University of Nebraska-Lincoln (UNL) to work on the project. Together with an existing third graduate student and a postdoctoral researcher, these individuals are receiving training on the Agro-IBIS model. This is helping to further the education of these individuals and prepare them for making future contributions to the project. 3) An Agro-IBIS workshop was organized and scheduled to be held in Madison, Wisconsin in October of 2009. This workshop will include scientists from the University of Wisconsin-Madison, the University of Minnesota, Iowa State University, and UNL. The objective of the workshop is to explore the various applications that Agro-IBIS is currently being used for, and to share ideas, technical skills, and software for analyzing the data and model outputs. PARTICIPANTS: We have three graduate students (Bo Dong, Phillip Mykleby, and Evren Soylu) and one postdoctoral researcher (Tiejun Wang) at the University of Nebraska-Lincoln (UNL) that are currently working on this project. Their duties are to analyze climatic input data and perform model simulations and analysis using the Agro-IBIS terrestrial ecosystem model. We have three collaborators at two other academic institutions. This includes Dr. Chris Kucharik from the University of Wisconsin-Madison and Drs. Tracy Twine and Peter Snyder from the University of Minnesota. Training has been provided to the three UNL graduate students and the UNL postdoctoral researcher through coursework and research group meetings. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
As we have just completed the first year of the project, there are limited outcomes and impacts to report. The most significant outcome is the availability of the new high resolution climate dataset, which will be useful not only for our model simulations, but also for use in other research projects that require the use of detailed climate observations over the past 60 years. An additional impact of the project is that we are currently training three graduate students in the area of hydroclimatology, and specifically in the use of Agro-IBIS for understanding the impacts of climate variability and change on water resources across the U.S. Upper Midwest.

Publications

• No publications reported this period

Progress 09/01/07 to 08/31/08

Outputs
OUTPUTS: This project was initiated on 9/1/2008, and so there is no progress to report at this time. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
This project was initiated on 9/1/2008, and so there is no progress to report at this time.

Publications

• No publications reported this period