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Black carbon (BC) can comprise a significant fraction of the soil carbon pool in cities. However, vegetation cover and human activity influence the spatial distribution of urban soil BC. We quantified soil total carbon (TC), soil organic carbon (SOC), BC, and total nitrogen (TN) in a medium-sized city in Dallas-Fort Worth, Texas. Soils were sampled to 20 cm depth from underneath 16 paired Quercus stellata (post oak) trees and open lawns. Effects of vegetation cover, road density, and building age (a proxy for time since development) on soil C and N were analyzed. Soil OC concentrations were higher under post oak trees (5.5%) compared to open lawns (3.6%) at 0–10 cm, but not at 10–20 cm depth. In contrast, soil BC and TN did not differ by vegetation cover. There were significant interaction effects between vegetation cover and road density and vegetation cover and building age on soil BC. At 0–10 cm, soil BC concentrations, stock, and BC/SOC ratios increased more with road density under trees than lawns, indicating enhanced atmospheric BC deposition to tree canopies. Black carbon in tree soils also increased with building age as compared to lawn soils, likely due to higher BC retention under trees, enhanced BC losses under lawns, or both. Our findings show that urban tree soils are localized opportunity hotspots for BC storage in areas with elevated emissions and longer time since development. Conserving and planting urban trees above permeable surfaces and soils could contribute to long-term carbon storage in urban ecosystems. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

• Different factors influence decisions on whether to fertilize and application frequency. • Informal neighborhood effects show households conform on whether to apply fertilizer. • Households in homeowners and neighborhood associations have higher fertilizer use. Residential lawncare is understood to be a multi-scale process. In this article, we estimate a statistical model of household fertilizer decisions that characterizes household- and neighborhood-scale influences, emphasizing both informal and formal neighborhood effects. We develop a novel methodological approach that leverages spatially explicit parcel-level tax assessor data to examine informal neighborhood conforming pressures based on quantifiable metrics of property characteristics for each sampled household relative to surrounding neighbors. Using survey data from 2,635 households in the Baltimore metro region (in Maryland, USA), the statistical model is estimated for two sequenced decisions faced by households—whether to fertilize, and if so with what frequency. Results reveal that several household demographic and informal neighborhood variables are significant for one decision but not the other, demonstrating the importance of disaggregating these two decision stages. Informal neighborhood effects are primarily significant for the initial decision on whether to fertilize, perhaps because this decision is more readily observable by surrounding neighbors. Effects of formal neighborhood characteristics are significant in both fertilizer decisions but vary between homeowner and neighborhood associations and over the two sequential decisions. The widespread availability of parcel-level tax assessor data enables application of this novel approach in other regions to examine informal neighborhood pressures on fertilizer use or other lawncare behaviors. [ABSTRACT FROM AUTHOR]

Urban and suburban lawns make up a large share of land use in the US. Maintaining lawns to fulfill aesthetic norms has environmental consequences. In this analysis, we examine household decisions to apply nitrogen-containing lawn fertilizer. Using survey data of 298 households in Nashville, Tennessee, we first examine the prevalence of fertilizer use and the rate of annual nitrogen applied. We find that the resulting distribution is skewed, with the top 20% of the sample applying 56% of the total share of nitrogen. In contrast to this subset of “intensive” fertilizers, 93% of households applied at or below levels recommended by landscaping professionals, challenging the assumption that the over-application of fertilizer is widespread. We employed multi-level modeling to examine the relative importance of household- and block-level characteristics on fertilizer use and the intensity of use. Consistent with prior work, we find that the desire for a green lawn is a significant predictor of fertilizer use. However, we also find that living on a wealthy block and living near others who value a green lawn independently predict fertilizer use. In addition, we observe that intensive fertilizing households tend to be less wealthy than others on their block, suggesting the possibility of an aspirational dimension to fertilizer use. Finally, we find evidence that environmental concern is associated with less intensive fertilizer use, suggesting that households may be willing to take some steps to mitigate the impact of their lawn care on the environment. [ABSTRACT FROM AUTHOR]

Plant-parasitic nematodes are among the least understood and most difficult pests to manage on turfgrass in Florida. They are very small, and most can only be seen with the aid of a microscope. They use a stylet to puncture plant cells, to inject digestive juices into them, and to ingest plant fluids. The most reliable way to determine whether plant-parasitic nematodes are involved in a turf problem is to have a nematode assay conducted by a professional nematode diagnostic lab.

Soils constitute the largest sink of terrestrial carbon (C), and urban soils have the potential to provide significant soil C storage. Soils in urbanized landscapes experience a multitude of human alterations, such as compaction and management subsidies, that impact soil C dynamics. While field studies may provide data on urban soil C storage, modeling soil C dynamics under various human impact scenarios will provide a basis for identifying drivers of urban soil C dynamics and for predicting the potential for these highly altered soils to store C over time intervals not typically amenable to empirical validation. The goal of this study was to model soil C dynamics in residential lawns using CENTURY, a dynamic mechanistic model, to determine whether drivers of soil C dynamics in natural systems (e.g., soil texture) were equally useful for estimating soil C content of highly modified soils in urban residential areas. Without incorporating human impacts, we found no relationship between initial CENTURY model simulations and observed soil C ( P > 0.05). Factors that best explained soil C accumulation for the observed soil C (bulk density, r2 = 0.30; home age, r2 = 0.37; P < 0.01) differed from those found important for the CENTURY model simulations (percent sand, r2 = 0.72, P < 0.001). Therefore, we conducted a modeling exercise to test whether simulating potential construction disturbance and lawn management practices would improve modeled soil and tree C. We found that incorporating these factors did improve CENTURY's ability to model soil and tree C ( P < 0.001). The results from this analysis suggest that incorporating various human disturbances and management practices that occur in urban landscapes into CENTURY model runs will improve its ability to predict urban soil C dynamics, at least within a 100-yr time frame. Thus, enhancing our ability to provide recommendations for management and development practices that result in increasing urban soil C storage. [ABSTRACT FROM AUTHOR]

Urban land area is expanding worldwide and may contribute to long-term carbon (C) storage; however, little is known about potential drivers of soil C in urban areas. Residential areas are one of the largest urban land use zones and lawns can provide stable chronosequences for studying soil C dynamics. In residential lawns containing no trees ( n = 23), the relationships between soil C and four potential drivers [home age (1-51 years), yard maintenance practices (fertilization, irrigation, and bagging or mulching lawn clippings), soil nitrogen (N) and soil texture] were investigated. Soil C increased with home age at 0-15 cm depth by 0.026 kg C m yr, declined by −0.011 kg C m yr at 15-30 cm depth, and was stable at 30-50 cm depth. Soil C had a positive relationship with soil N ( R = 0.55) at the 0-15 cm depth. Soil C and N were not related to yard maintenance practices or soil texture. The low soil C sequestration rate and limited relationships between soil C and home age, yard maintenance, soil N and soil texture may have resulted from the positive influence of Auburn's humid, subtropical climate on residue decomposition. [ABSTRACT FROM AUTHOR]

As a dominant land use in urban ecosystems, residential yards impact water and other environmental resources. Converting thirsty lawns into alternative landscapes is one approach to water conservation, yet barriers such as cultural norms reinforce the traditional lawn. Meanwhile, the complex social and ecological implications of yard choices complicate programs aimed at changing grass and other yard features for particular purposes. In order to better understand individual landscape decisions, we qualitatively examined residents’ rationales for their preferred yard types in the desert metropolis of Phoenix, Arizona. After briefly presenting landscape choices across two survey samples, the dominant reasons for preferences are discussed: appearance, maintenance, environment, recreation, microclimate, familiarity, and health/safety. Three broader analytical themes emerged from these descriptive codes: (1) residents’ desires for attractive, comfortable landscapes of leisure encompassing pluralistic tastes, lifestyles, and perceptions; (2) the association of environmental benefits and impacts with different landscape types involving complex social and ecological tradeoffs; and (3) the cultural legacies evident in modern landscape choices, especially in terms of a dichotomous human–nature worldview among long-time residents of the Phoenix oasis. Given these findings, programs aimed at landscape change must recognize diverse preferences and rationalization processes, along with the perceived versus actual impacts and tradeoffs of varying yard alternatives. [ABSTRACT FROM AUTHOR]