The residential landscape: fluxes of elements and the role of household decisions

Abstract

We assessed biogeochemical cycling of elements through residential household landscapes to evaluate the importance of annual to decadal household-level decisions for element fluxes that contribute to urban and regional pollution. We combined a mailed survey, vegetation measurements, and allometric and biogeochemical models to estimate fluxes and accumulation of carbon (C), nitrogen (N), and phosphorus (P) in landscapes of 360 single-family homes in the Minneapolis-Saint Paul, Minnesota metropolitan area. Carbon inputs and accumulation were strongly influenced by the presence of trees on the property. Nitrogen inputs to the landscape exceeded estimated ecosystem demand for N on average by 51% and were dominated by N fertilizer application. Because Minnesota state law restricts the use of P fertilizer, pet waste was responsible for 84% of P inputs to the landscape. The results have implications for understanding sources of urban pollution and the potential flexibility (i.e., the potential for change) in household behaviors such as tree planting, fertilization, and pet waste management that contribute to such pollution.

Contrasting nitrogen and phosphorus budgets in urban watersheds and implications for managing urban water pollution

“…The study area comprised seven urban subwatersheds of the Mississippi River in the Capitol Region Watershed (CRW) ( Table 1), building on past studies of household inputs (19,27) and storm drain exports (37). The CRW comprises just over 10,000 ha in Ramsey County, Minnesota, and includes the majority of St. Paul and small portions of neighboring suburbs.…”

“…Crop nutrient exports from the University of Minnesota St. Paul Campus Agricultural Experiment Station were from published values (64). Nutrients exported in yard waste (leaf litter and grass clippings) were estimated from a previous study in the region (19,27); all yard waste taken to county collection sites is exported from the watersheds. Nutrients exported through spring and fall municipal street sweeping were estimated from tree canopy cover over streets based on a previous study done in a nearby municipality (51).…”

“…Depending on rates of denitrification along groundwater flow paths, nitrate losses to groundwater in urban watersheds (54), denitrification, and ecosystem uptake (19) for all watersheds (each symbol represents a watershed).…”

“…18). However, past studies did not fully quantify potentially important watershed nutrient inputs, such as pet waste (17,19), nonresidential fertilizer use, and biological N fixation (BNF), or outputs, such as yard waste removal (20) and leaf litter removal via street sweeping (21). Further, most studies of watershed nutrient retention have focused on N. Although urbanization has been shown to increase surface water P export (3,4), whether such high export results from relatively high P inputs or low P retention is unknown.…”

Nitrogen and Carbon Biogeochemistry in Forest Sites along an Indirect Urban–Rural Gradient in Southeastern Michigan

“…The potentially significant effects of nitrogen addition on unmanaged ecosystems, along with increased human presence near protected areas, have fueled a number of long-term ecological studies on the effects of urbanization on biogeochemical cycles [24,37,39,40]. A recent biogeochemical field study in residential yards found that homeowner practices resulted in large fluxes of N to soils in residential neighborhoods [41], however, a recent chronosequence study of residential yards following conversion from other land uses concluded that residential soils can retain large quantities of C and N over time [42], raising the question of whether N additions in residential land would affect N cycling, and resulting changes in C storage, in protected areas nearby.…”