Lawns are a common ecosystem type in human-dominated landscapes which can have negative impacts on water quality due to fertilizer applications, but also host a range of ecosystem services. While many studies have addressed water and nitrogen (N) dynamics in lawns, few have considered how topography interacts with human behaviors to control these dynamics. Our overarching objective was to determine if mesoscale topography (hillslopes within lawns) interacts with human behavior (fertilizer use) influencing patterns of N mobilization and removal in lawns. To that end, we measured several hydrobiogeochemical characteristics associated with N dynamics along topographic gradients in fertilized and unfertilized residential and institutional lawns. We found topographic gradients affect the hydrobiogeochemistry of lawns, with significant effects of landscape position (top versus toe slope versus bottomland swales), but with direction and strength of the effect often varying among different lawn types (exurban versus suburban front yards versus suburban backyards versus institutional). Fertilizer application did not affect the hydrobiogeochemical properties of lawns. Rather, results from this study suggest lawns in suburban front yards were at greatest risk of N mobilization due to a complex suite of characteristics including proximity to impervious surfaces, swales with low saturated infiltration rates, and potential vulnerability to N deposition from vehicles. This study highlights the need to consider landscape controls of water and N fluxes and how they interact with human behaviors to better understand how these landscapes function. These results contribute to the emerging understanding of the structure, function and environmental impacts of lawns.

中文翻译：

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城市草坪氮循环的景观方法揭示了地形与人类行为之间的相互作用

草坪是人类主导景观中常见的生态系统类型，由于施肥会对水质产生负面影响，但也提供一系列生态系统服务。虽然许多研究都涉及草坪中的水和氮 (N) 动态，但很少有人考虑地形如何与人类行为相互作用以控制这些动态。我们的首要目标是确定中尺度地形（草坪内的山坡）是否与人类行为（肥料使用）相互作用，影响草坪中氮的动员和清除模式。为此，我们测量了与施肥和未施肥住宅和机构草坪中沿地形梯度的氮动态相关的几种水生地球化学特征。我们发现地形梯度会影响草坪的水生地球化学，具有显着的景观位置影响（顶部与脚趾坡度与底部洼地），但效果的方向和强度通常因不同的草坪类型而异（远郊与郊区前院与郊区后院与机构）。施肥不影响草坪的水生地球化学特性。相反，这项研究的结果表明，由于一系列复杂的特征，包括靠近不透水表面、饱和渗透率低的洼地以及车辆氮沉积的潜在脆弱性，郊区前院的草坪面临着最大的氮动员风险。这项研究强调需要考虑水和氮通量的景观控制以及它们如何与人类行为相互作用，以更好地了解这些景观的功能。