Residential household yard care practices along urban-exurban gradients in six climatically-diverse U.S. metropolitan areas.

Residential land is expanding in the United States, and lawn now covers more area than the country's leading irrigated crop by area. Given that lawns are widespread across diverse climatic regions and there is rising concern about the environmental impacts associated with their management, there is a clear need to understand the geographic variation, drivers, and outcomes of common yard care practices. We hypothesized that 1) income, age, and the number of neighbors known by name will be positively associated with the odds of having irrigated, fertilized, or applied pesticides in the last year, 2) irrigation, fertilization, and pesticide application will vary quadratically with population density, with the highest odds in suburban areas, and 3) the odds of irrigating will vary by climate, but fertilization and pesticide application will not.

Effects of long-term nutrient additions on Arctic tundra, stream, and lake ecosystems: beyond NPP.

Primary producers form the base of food webs but also affect other ecosystem characteristics, such as habitat structure, light availability, and microclimate. Here, we examine changes caused by 5-30+ years of nutrient addition and resulting increases in net primary productivity (NPP) in tundra, streams, and lakes in northern Alaska. The Arctic provides an important opportunity to examine how ecosystems characterized by low diversity and low productivity respond to release from nutrient limitation.

Assessment of regional variation in streamflow responses to urbanization and the persistence of physiography.

Aquatic ecosystems are sensitive to the modification of hydrologic regimes, experiencing declines in stream health as the streamflow regime is altered during urbanization. This study uses streamflow records to quantify the type and magnitude of hydrologic changes across urbanization gradients in nine U.S.

Differential Carbon and Nitrogen Controls of Denitrification in Riparian Zones and Streams along an Urban to Exurban Gradient.

Denitrification is an anaerobic microbial process that transforms nitrate (NO) to nitrogen (N) gas, preventing the movement of NO into coastal waters where it can lead to eutrophication. Urbanization can reduce the potential for denitrification in riparian zones and streams by altering the environmental conditions that foster denitrification (i.e.

Sources of variation in home lawn soil nitrogen dynamics.

Urban, suburban, and exurban lawns are an increasingly important ecosystem type in the United States. There is great concern about the environmental performance of lawns, especially nitrate (NO) leaching and nitrous oxide (NO) flux associated with nitrogen (N) fertilizer use. Previous studies of lawn N dynamics have produced conflicting results, with some studies showing high NO leaching and NO flux and others showing lower losses and high retention and cycling of N inputs.

Nitrogen deposition in and near an urban ecosystem.

Excess nitrogen (N) is a serious water-quality problem in most of the estuaries in the United States, especially those downstream of developed coastal basins. Understanding sources of N is a key first step in managing and mitigating N pollution. While the major sources of this N, atmospheric deposition, wastewater, fertilizer, and other agricultural sources are well-known, their relative importance as N sources to particular estuaries is not.

Denitrification potential in stormwater control structures and natural riparian zones in an urban landscape.

Humans have significantly altered urban landscapes, creating impervious surfaces, and changing drainage patterns that increase volume and velocity as well as frequency and timing of runoff following precipitation events. These changes in runoff have impaired streams and riparian areas that previously reduced watershed nitrogen (N) flux through uptake and denitrification. Stormwater control measures (SCM) are used most frequently to mitigate these hydrologic impacts.