CNH-L: Multi-Scale Coupled Natural-Human System Dynamics of Nitrogen in Residential Landscapes

人们早就知道，来自城市和郊区景观的径流对接收这些排放的溪流的水质有重大影响。在这一领域，一个特别令人关切的问题是，在草坪上使用化肥会导致过量的硝酸盐出口，这可能会促进接收水域中的藻类或微生物生长。最近的研究表明，这种硝酸盐出口低于预期，但原因尚不清楚。该项目将调查可能调节草坪中氮的保留和排放的自然过程，以及影响房主对草坪管理水平决策的社会力量。研究结果将被纳入一个模型，该模型将确定径流中硝酸盐含量高的地点和时段，以确定人类决策和自然过程如何共同控制这些浓度。这些结论将适用于全国各种各样的城市和郊区地点，该项目将直接有利于切萨皮克湾环境健康的管理。该项目模拟了住宅景观中氮的多尺度、耦合系统动力学，以确定生物地球化学、水文和人类行为过程如何相互作用，以控制住宅生态系统和景观中的氮出口。这些模型将协调来自家庭调查、现有数据和地理信息系统分析的信息，以评估草坪管理和水文敏感性的相互关联的空间格局。最重要的假设是，大规模的社会和制度影响往往会导致房主的草坪护理实践与房主的偏好相反，但行为的重大变化可以通过系统激励来激发。将对不同土地利用历史（森林与农业）、场地管理（肥料投入）和年龄的地块进行实地研究，以检验关于草坪土壤剖面中氮封存极限的假设。利用生态水文模型分析地理、生物地球化学和社会科学数据，对流域尺度上草坪肥料出口的潜在热点进行空间分析。然后可以严格评估替代政策和房主做法对土地管理和氮出口的影响。

Runoff from urban and suburban landscapes has long been known to have a significant effect upon the water quality of streams that receive this discharge. A particular concern in this area is the export of excess nitrate from the use of fertilizers on lawns, which can promote algal or microbial growth in receiving waters. Recent research has indicated that such nitrate export is less than expected, but the reasons for this are unclear. This project will investigate both the natural processes that may regulate the retention and discharge of nitrogen from lawns, as well as the sociological forces that influence the decisions of homeowners concerning the level of lawn management. The results will be incorporated into a model that will identify the locations and episodes of high nitrate in runoff in order to determine how human decisions and natural processes work together to control these concentrations. The conclusions will be applicable to a wide variety of urban and suburban locations across the country and the project will have direct benefit to the management of the environmental health of Chesapeake Bay. This project models multi-scale, coupled-system dynamics of nitrogen in residential landscapes to determine how biogeochemical, hydrologic, and human behavioral processes interact to control nitrogen exports from residential ecosystems and landscapes. These models will coordinate information from household surveys, existing data, and geographic information system analyses to evaluate interconnected spatial patterns of lawn management and hydrologic sensitivity. The overarching hypothesis is that large-scale social and institutional influences often induce homeowner lawn-care practices contrary to homeowner preferences, but that significant changes in behavior can be motivated via systematic incentives. Field studies on plots varying in land use history (forest versus agriculture), site management (fertilizer input) and age will be established to test hypotheses about the limits of nitrogen sequestration in lawn soil profiles. Geographic, biogeochemical, and social-science data will be analyzed using ecohydrological models to produce spatial analyses of potential hotspots of lawn fertilizer export at the watershed scale. The effect of alternative policies and homeowner practices on land management and nitrogen exports can then be evaluated rigorously.