@article {180,
	title = {Innovation in Outcomes-Based Water Quality Policy: A Case Study from the Yahara Watershed, Wisconsin, USA},
	journal = {Case Studies in the Environment},
	year = {2018},
	month = {2018/01/01},
	abstract = {This case examines the risks and opportunities for stakeholders involved in an experimental water quality management program in Wisconsin, USA. This program pays for pounds of pollution reduced through soil conservation practices on farm fields and other high-runoff areas across the landscape{\textemdash}nonpoint sources of pollution{\textemdash}by redirecting funds from the sewerage plant and municipal point sources of pollution. Uncertain monitoring and modeling of pollution sources used for program payments and accountability create perceived and real risks to program participants and the environment, including the threat of regulatory enforcement, lost revenue, and failure to achieve environmental outcomes. On the other hand, in this case study, regulatory flexibility also opened a space for stakeholder dialog and programmatic cooperation that could lead to more adaptive and locally acceptable watershed pollution control in the future.},
	doi = {10.1525/cse.2018.001222},
	url = {http://cse.ucpress.edu/content/early/2018/08/20/cse.2018.001222.abstract},
	author = {Wardropper, Chloe and Gillon, Sean and Rissman, Adena}
}
@article {164,
	title = {The Influence of Legacy P on Lake Water Quality in a Midwestern Agricultural Watershed},
	journal = {Ecosystems},
	year = {2017},
	month = {2017//},
	pages = {1 - 15},
	abstract = {Decades of fertilizer and manure applications have led to a buildup of phosphorus (P) in agricultural soils and sediments, commonly referred to as legacy P. Legacy P can provide a long-term source of P to surface waters where it causes eutrophication. Using a suite of numerical models, we investigated the influence of legacy P on water quality in the Yahara Watershed of southern Wisconsin, USA. The suite included Agro-IBIS, a terrestrial ecosystem model; THMB, a hydrologic and nutrient routing model; and the Yahara Water Quality Model which estimates water quality indicators in the Yahara chain of lakes. Using five alternative scenarios of antecedent P storage (legacy P) in soils and channels under historical climate conditions, we simulated outcomes of P yield from the landscape, lake P loading, and three lake water quality indicators. Legacy P had a significant effect on lake loads and water quality. Across the five scenarios for Lake Mendota, the largest and most upstream lake, average P yield (kg~ha-1) varied by -41 to +22\%, P load (kg~y-1) by -35 to +14\%, summer total P (TP) concentration (mg~l-1) by -25 to +12\%, Secchi depth (m) by -7 to +3\%, and the probability of hypereutrophy by -67 to +34\%, relative to baseline conditions. The minimum storage scenario showed that a 35\% reduction in present-day loads to Lake Mendota corresponded with a 25\% reduction in summer TP and smaller reductions in the downstream lakes. Water quality was more vulnerable to heavy rainfall events at higher amounts of P storage and less so at lower amounts. Increases in heavy precipitation are expected with climate change; therefore, water quality could be protected by decreasing P reserves.},
	isbn = {1435-0629},
	doi = {10.1007/s10021-017-0125-0},
	url = {http://dx.doi.org/10.1007/s10021-017-0125-0},
	author = {Motew, Melissa and Chen, Xi and Booth, Eric G. and Carpenter, Stephen R. and Pinkas, Pavel and Zipper, Samuel C. and Loheide, Steven P. and Donner, Simon D. and Tsuruta, Kai and Vadas, Peter A. and Kucharik, Christopher J.}
}
@article {134,
	title = {Invasive species triggers a massive loss of ecosystem services through a trophic cascade},
	journal = {Proceedings of the National Academy of Sciences},
	year = {2016},
	month = {2016/03/21},
	abstract = {Despite growing recognition of the importance of ecosystem services and the economic and ecological harm caused by invasive species, linkages between invasions, changes in ecosystem functioning, and in turn, provisioning of ecosystem services remain poorly documented and poorly understood. We evaluate the economic impacts of an invasion that cascaded through a food web to cause substantial declines in water clarity, a valued ecosystem service. The predatory zooplankton, the spiny water flea (Bythotrephes longimanus), invaded the Laurentian Great Lakes in the 1980s and has subsequently undergone secondary spread to inland lakes, including Lake Mendota (Wisconsin), in 2009. In Lake Mendota, Bythotrephes has reached unparalleled densities compared with in other lakes, decreasing biomass of the grazer Daphnia pulicaria and causing a decline in water clarity of nearly 1 m. Time series modeling revealed that the loss in water clarity, valued at US$140 million (US$640 per household), could be reversed by a 71\% reduction in phosphorus loading. A phosphorus reduction of this magnitude is estimated to cost between US$86.5 million and US$163 million (US$430{\textendash}US$810 per household). Estimates of the economic effects of Great Lakes invasive species may increase considerably if cases of secondary invasions into inland lakes, such as Lake Mendota, are included. Furthermore, such extreme cases of economic damages call for increased investment in the prevention and control of invasive species to better maximize the economic benefits of such programs. Our results highlight the need to more fully incorporate ecosystem services into our analysis of invasive species impacts, management, and public policy.},
	doi = {10.1073/pnas.1600366113},
	url = {http://www.pnas.org/content/early/2016/03/16/1600366113.abstract},
	author = {Walsh, Jake R. and Carpenter, Stephen R. and Vander Zanden, M. Jake}
}
@article {123,
	title = {Importance of landscape heterogeneity in sustaining hydrologic ecosystem services in an agricultural watershed},
	journal = {Ecosphere},
	volume = {6},
	year = {2015},
	month = {2015/11/01},
	pages = {art229},
	abstract = {The sustainability of hydrologic ecosystem services (freshwater benefits to people generated by terrestrial ecosystems) is challenged by human modification of landscapes. However, the role of landscape heterogeneity in sustaining hydrologic services at scales relevant to landscape management decisions is poorly understood. In particular, the relative importance of landscape composition (type and proportion of land cover) and configuration (spatial arrangement of cover types) is unclear. We analyzed indicators of production of three hydrologic services (freshwater supply, surface and ground water quality) in 100 subwatersheds in an urbanizing agricultural landscape (Yahara Watershed, Wisconsin, USA) and asked: (1) How do landscape composition and configuration affect supply of hydrologic services (i.e., does spatial pattern matter)? (2) Are there opportunities for small changes in landscape pattern to produce large gains in hydrologic services? Landscape composition and configuration both affected supply of hydrologic services, but composition was consistently more important than configuration for all three services. Together landscape composition and configuration explained more variation in indicators of surface-water quality than in freshwater supply or groundwater quality (Nagelkerke/adjusted R2: 86\%, 64\%, and 39\%, respectively). Surface-water quality was negatively correlated with percent cropland and positively correlated with percent forest, grassland and wetland. In addition, surface-water quality was greater in subwatersheds with higher wetland patch density, disaggregated forest patches and lower contagion. Surface-water quality responded nonlinearly to percent cropland and wetland, with greater water quality where cropland covered below 60\% and/or wetland above 6\% of the subwatershed. Freshwater supply was negatively correlated with percent wetland and urban cover, and positively correlated with urban edge density. Groundwater quality was negatively correlated with percent cropland and grassland, and configuration variables were unimportant. Collectively, our study suggests that altering spatial arrangement of land cover will not be sufficient to enhance hydrologic services in an agricultural landscape. Rather, the relative abundance of land cover may need to change to improve hydrologic services. Targeting subwatersheds near the cropland or wetland thresholds may offer local opportunities to enhance surface-water quality with minimal land-cover change.The sustainability of hydrologic ecosystem services (freshwater benefits to people generated by terrestrial ecosystems) is challenged by human modification of landscapes. However, the role of landscape heterogeneity in sustaining hydrologic services at scales relevant to landscape management decisions is poorly understood. In particular, the relative importance of landscape composition (type and proportion of land cover) and configuration (spatial arrangement of cover types) is unclear. We analyzed indicators of production of three hydrologic services (freshwater supply, surface and ground water quality) in 100 subwatersheds in an urbanizing agricultural landscape (Yahara Watershed, Wisconsin, USA) and asked: (1) How do landscape composition and configuration affect supply of hydrologic services (i.e., does spatial pattern matter)? (2) Are there opportunities for small changes in landscape pattern to produce large gains in hydrologic services? Landscape composition and configuration both affected supply of hydrologic services, but composition was consistently more important than configuration for all three services. Together landscape composition and configuration explained more variation in indicators of surface-water quality than in freshwater supply or groundwater quality (Nagelkerke/adjusted R2: 86\%, 64\%, and 39\%, respectively). Surface-water quality was negatively correlated with percent cropland and positively correlated with percent forest, grassland and wetland. In addition, surface-water quality was greater in subwatersheds with higher wetland patch density, disaggregated forest patches and lower contagion. Surface-water quality responded nonlinearly to percent cropland and wetland, with greater water quality where cropland covered below 60\% and/or wetland above 6\% of the subwatershed. Freshwater supply was negatively correlated with percent wetland and urban cover, and positively correlated with urban edge density. Groundwater quality was negatively correlated with percent cropland and grassland, and configuration variables were unimportant. Collectively, our study suggests that altering spatial arrangement of land cover will not be sufficient to enhance hydrologic services in an agricultural landscape. Rather, the relative abundance of land cover may need to change to improve hydrologic services. Targeting subwatersheds near the cropland or wetland thresholds may offer local opportunities to enhance surface-water quality with minimal land-cover change.},
	keywords = {agricultural landscape, land management, landscape ecology, nonlinearity, spatial configuration, Spatial heterogeneity, sustainability, synergies, tradeoffs},
	isbn = {2150-8925},
	doi = {10.1890/ES15-00312.1},
	url = {http://dx.doi.org/10.1890/ES15-00312.1},
	author = {Qiu, Jiangxiao and Turner, Monica G.}
}
@article {72,
	title = {Influence of groundwater on plant water use and productivity: Development of an integrated ecosystem - Variably saturated soil water flow model},
	journal = {Agricultural and Forest Meteorology},
	volume = {189},
	year = {2014},
	pages = {198-210},
	abstract = {Plant physiology influences the energy and water balance of the soil-plant-atmosphere continuum. However, impacts of soil water dynamics on plants in shallow groundwater environments are not completely understood, partially due to the limited ability of current models to simulate groundwater vegetation interactions. In this study, we analyzed the influence of groundwater-induced soil temperature change on plant phenology, and the impact of variable depth to the water table on the net primary productivity (NPP), evapotranspiration and stomatal response, by integrating an advanced dynamic agroecosystem model (Agro-IBIS) and a variably saturated soil water flow model (Hydrus-1D) into a single framework. The model is first evaluated using field observations of soil moisture and temperature as well as annual NPP and weekly LAI measurements collected from three replicated maize plots at the Arlington Agricultural Research Station near Arlington, Wisconsin, USA. Comparisons showed reasonable agreement for each dataset without site-specific prior calibration. We then simulated the influence of groundwater on plant physiological responses as well as the energy, carbon, and water balance at the land surface. The model sensitivity analyses indicated that physiological functions of plants are sensitive to water table depth, and the aridity of a particular production site. For example, shallow groundwater limits water stress during dry years, helping to mitigate decreased NPP associated with water deficits. However, if the water table is persistently too close to the surface during the growing season, photosynthesis is negatively affected through oxygen stress on roots regardless of the aridity. To further explore factors influencing plant physiology other than oxygen stress, we designed simulations without oxygen stress effects. Results showed that under shallow groundwater conditions: (1) higher leaf level relative humidity causes higher water use efficiency because of a lower vapor pressure deficit between the leaf and atmosphere: (2) due to delayed corn plant emergence caused by cooler springtime soil temperatures reduces NPP. Our results suggest that models designed to more mechanistically simulate groundwater vegetation interactions may lead to a more realistic representation of feedbacks between plant phenology, soil moisture, temperature, anoxia, NPP and ET. However, until critical data are collected to assess simulated feedbacks and advance our understanding of groundwater vegetation interactions, model confidence will likely remain somewhat limited. (C) 2014 Elsevier B.V. All rights reserved.},
	issn = {0168-1923},
	doi = {10.1016/j.agrformet.2014.01.019},
	url = {http://dx.doi.org/10.1016/j.agrformet.2014.01.019},
	author = {Soylu, M. E. and Kucharik, C. J. and Loheide, S. P.}
}
