Cities and the Environment: Eight Years of Urban Ecology Research and Practice

Since its inception, Cities and the Environment has sought to showcase a broad range of urban environmental research and practice. Thus, as we celebrate the closing of our eighth anniversary, the purpose of this paper is to remind (or, for some, introduce) researchers and practitioners of the aims and scope of the journal by describing the first eight years of its history, and to outline our vision for the next eight years

Tree Canopy Change in Coastal Los Angeles, 2009 - 2014

Los Angeles, California is prone to extreme climate events—e.g. drought, wildfires, and floods—that are only expected to increase with climate change. The establishment of green infrastructure, including a stable urban forest, is a strategy to improve resilience not only to these events, but also to contribute to other environmental, social, and economic goals. To this end, cities throughout Los Angeles County have tree planting programs and policies aimed to grow and maintain their urban forests. Despite the policy objectives and management goals of such programs, we know surprisingly little about the spatial distribution of the existing urban forest, how and where the canopy has changed over time, or the composition of the population living in places of canopy change. To examine these questions, we conducted an analysis of the Los Angeles Coast based on land cover data derived from high-resolution aerial imagery and LiDAR. In addition to characterizing the overall percentages of existing and possible tree canopy in 2014, we also characterized the change in tree canopy from 2009 to 2014 with five measures of tree canopy and change: total canopy, persistence, loss, gain, and net change. We used market segmentation data to analyze the relationship between tree canopy and the composition of communities. Results indicated that tree canopy covered about 15% of coastal Los Angeles, but this cover was unevenly distributed throughout the study area. The parcel-level analysis of change indicated that while the canopy did not change much from 2009-2014, the changes that did occur were localized and would have been missed at a coarser scale of analysis. Using geodemographic segments, we found that higher-income lifestyle groups tended to have more tree canopy and less loss over time. Change within land uses was consistent with overall change. These high-resolution, high-accuracy data and analyses can support valuable tools to guide decision-making about urban forests, especially as it relates to social equity

Contextual Considerations of Green Stormwater Infrastructure Siting

Green infrastructure increasingly is used to ameliorate water quality and quantity problems caused by runoff in cities. Studies show how the spatial distribution of these Green Stormwater Infrastructure (GSI) sites are unevenly distributed relative to socioeconomic and demographic groups. Often this is described as an indicator of perpetuated environment injustice, given the purported social and environmental benefits of GSI. To assess equity, researchers often examine either who gets what with respect to environmental ‘goods’ such as tree canopy and other green infrastructures, or investigate the procedures, decision making processes, and power structures pertaining to planning processes. This paper uses both spatial analyses to examine where GSI is located and who lives nearby in New Haven, CT, and illuminates the processes by which those locations were determined. An environmental injustice pattern was not observed: most GSI were located in low-income communities of color. However, the process that led to the siting had very little to do with who was living where. Instead, GSI siting decisions were determined by funding opportunities and their site selection criteria, flooding, combined sewer infrastructure, and avoiding infrastructure conflicts on a street segment. Future spatial analyses could consider the implicit or explicit baselines for equity in light of the processes and constraints that determine how and where GSI gets installed, and better incorporate the process of green infrastructure allocation in the chosen analytical metrics. By examining the process (ie the “how”) and the outcomes (ie the “what went where”) this study broadens the spatial analyses to include embedded knowledge from those who actually make the decisions that ultimately determine the location of GSI

Applications of Urban Tree Canopy Assessment and Prioritization Tools: Supporting Collaborative Decision Making to Achieve Urban Sustainability Goals

Urban Tree Canopy (UTC) Prioritizations can be both a set of geographic analysis tools and a planning process for collaborative decision-making. In this paper, we describe how UTC Prioritizations can be used as a planning process to provide decision support to multiple government agencies, civic groups and private businesses to aid in reaching a canopy target. Linkages to broader City-scale sustainability plans are explored. This article represents an extension and update to the UTC Canopy Goal Setting Guide by Raciti et al (2006). We conclude with recommendations for a market-like analysis of neighborhoods to better match planting initiatives to particular neighborhoods’ motivations, capacities and interests in order to improve the adoption of improved urban forestry practices

Context matters: influence of organizational, environmental, and social factors on civic environmental stewardship group intensity

Civic environmental stewardship groups actively take care of their local environment and are known to work in urban contexts. Research on the geographies of this urban environmental stewardship is young. Understanding where stewardship groups work and the associated organizational and neighborhood contexts advances the understanding of the environmental outcomes of stewardship efforts. We examine the organizational, socioeconomic, and environmental contexts associated with the number of stewardship groups at the Census block group and neighborhood scales for four diverse U.S. cities (Baltimore, MD; Chicago, IL; New York, NY; and Seattle, WA). We found relatively consistent and strong relationships with both average professionalization (staff and budget index) and diversity of groups’ focus and the number of groups’ activity areas in a block group or neighborhood, suggesting a potential density dependence effect. Overall, the number of stewardship groups correlates with social and environmental aspects at both scales across all cities, but variation across cities for specific variables indicates the need for further analyses to unpack why we observe these different patterns across cities. Strong relationships with organizational factors suggest future directions for stewardship research and that the organizational landscape may affect how many groups work in a place more than socioeconomic or environmental conditions

Prioritizing Preferable Locations for Increasing Urban Tree Canopy in New York City

This paper presents a set of Geographic Information System (GIS) methods for identifying and prioritizing tree planting sites in urban environments. It uses an analytical approach created by a University of Vermont service-learning class called “GIS Analysis of New York City\u27s Ecology” that was designed to provide research support to the MillionTreesNYC tree planting campaign. These methods prioritize tree planting sites based on need (whether or not trees can help address specific issues in the community) and suitability (biophysical constraints and planting partners’ existing programmatic goals). Criteria for suitability and need were based on input from three New York City tree-planting organizations. Customized spatial analysis tools and maps were created to show where each organization may contribute to increasing urban tree canopy (UTC) while also achieving their own programmatic goals. These methods and associated custom tools can help decision-makers optimize urban forestry investments with respect to biophysical and socioeconomic outcomes in a clear and accountable manner. Additionally, the framework described here may be used in other cities, can track spatial characteristics of urban ecosystems over time, and may enable further tool development for collaborative decision-making in urban natural resource management

Hydro-bio-geo-socio-chemical interactions and the sustainability of residential landscapes

Significance statement: The paper presents major new insights into the multidisciplinary controls of nitrogen export (a widespread environmental concern) from residential landscapes. We conducted biogeochemical and social survey studies to identify locations (hotspots) or times (hot moments) with a disproportionate influence on this export. Results showed high variation in the vulnerability/sensitivity of individual parcels to cause environmental damage and in the knowledge and practices of individual managers. To the extent that hotspots are the result of management choices by homeowners, there are straightforward approaches to improve outcomes, e.g. fertilizer restrictions. If, however, hotspots arise from the configuration and inherent characteristics of parcels and neighborhoods, efforts to improve outcomes may involve more intensive and complex interventions, such as conversion to alternative ecosystem type

Ecological homogenization of oil Properties in the American Residential Macrosystem

The conversion of native ecosystems to residential ecosystems dominated by lawns has been a prevailing land-use change in the United States over the past 70 years. Similar development patterns and management of residential ecosystems cause many characteristics of residential ecosystems to be more similar to each other across broad continental gradients than that of former native ecosystems. For instance, similar lawn management by irrigation and fertilizer applications has the potential to influence soil carbon (C) and nitrogen (N) pools and processes. We evaluated the mean and variability of total soil C and N stocks, potential net N mineralization and nitrification, soil nitrite (NO2−)/nitrate (NO3−) and ammonium (NH4+) pools, microbial biomass C and N content, microbial respiration, bulk density, soil pH, and moisture content in residential lawns and native ecosystems in six metropolitan areas across a broad climatic gradient in the United States: Baltimore, MD (BAL); Boston, MA (BOS); Los Angeles, CA (LAX); Miami, FL (MIA); Minneapolis–St. Paul, MN (MSP); and Phoenix, AZ (PHX). We observed evidence of higher N cycling in lawn soils, including significant increases in soil NO2−/NO3−, microbial N pools, and potential net nitrification, and significant decreases in NH4+ pools. Self-reported yard fertilizer application in the previous year was linked with increased NO2−/ NO3− content and decreases in total soil N and C content. Self-reported irrigation in the previous year was associated with decreases in potential net mineralization and potential net nitrification and with increases in bulk density and pH. Residential topsoil had higher total soil C than native topsoil, and microbial biomass C was markedly higher in residential topsoil in the two driest cities (LAX and PHX). Coefficients of variation for most biogeochemical metrics were higher in native soils than in residential soils across all cities, suggesting that residential development homogenizes soil properties and processes at the continental scale

A Multi-City Comparison of Front and Backyard Differences in Plant Species Diversity and Nitrogen Cycling in Residential landscapes

We hypothesize that lower public visibility of residential backyards reduces households’ desire for social conformity, which alters residential land management and produces differences in ecological composition and function between front and backyards. Using lawn vegetation plots (7 cities) and soil cores (6 cities), we examine plant species richness and evenness and nitrogen cycling of lawns in Boston, Baltimore, Miami, Minneapolis-St. Paul, Phoenix, Los Angeles (LA), and Salt Lake City (SLC). Seven soil nitrogen measures were compared because different irrigation and fertilization practices may vary between front and backyards, which may alter nitrogen cycling in soils. In addition to lawn-only measurements, we collected and analyzed plant species richness for entire yards—cultivated (intentionally planted) and spontaneous (self-regenerating)—for front and backyards in just two cities: LA and SLC. Lawn plant species and soils were not different between front and backyards in our multi-city comparisons. However, entire-yard plant analyses in LA and SLC revealed that frontyards had significantly fewer species than backyards for both cultivated and spontaneous species. These results suggest that there is a need for a more rich and social-ecologically nuanced understanding of potential residential, household behaviors and their ecological consequences

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. We used multi-level models to systematically address nested spatial scales within and across six U.S. metropolitan areas—Boston, Baltimore, Miami, Minneapolis-St. Paul, Phoenix, and Los Angeles. We found significant variation in yard care practices at the household (the relationship with income was positive), urban-exurban gradient (the relationship with population density was an inverted U), and regional scales (city-tocity variation). A multi-level modeling framework was useful for discerning these scaledependent outcomes because this approach controls for autocorrelation at multiple spatial scales. Our findings may guide policies or programs seeking to mitigate the potentially deleterious outcomes associated with water use and chemical application, by identifying the subpopulations most likely to irrigate, fertilize, and/or apply pesticides