V. Kelly Turner

Outdoor heat mitigation strategies such as trees, shade structures, and reflective pavement are widely deployed in cities, but the cooling benefits attributed to them depend on two analytical choices that are rarely examined together: the spatial scale at which performance is evaluated and the temperature metric used to assess it. Most assessments rely on a single scale or single metric, and how these choices jointly shape conclusions about intervention performance remains poorly understood. This question is consequential in schoolyards, where heat-vulnerable children spend time outdoors and major cooling investments are underway. We address this gap using high-resolution microclimate modeling, validated against field measurements, to evaluate four interventions (clustered trees, dispersed trees, artificial shade structure, and reflective pavement) across four nested functional spatial scales reflecting how children use schoolyard space and three temperature metrics at an elementary school in Los Angeles, California. Both dimensions reordered intervention rankings. Across spatial scales, the best-performing intervention for mean radiant temperature (MRT) shifted from dispersed trees at the whole-school scale (-1.2 °C) to clustered trees at the point scale (-24.5 °C), while reflective pavement increased MRT at every scale (up to +3.0 °C). At the schoolyard scale, reflective pavement ranked first for reducing surface temperature (-1.5 °C) but last for MRT. Air temperature responses were negligible (≤0.2 °C). These results demonstrate that conclusions about which interventions cool most effectively depend jointly on spatial scale and temperature metric, and that human-centered evaluation requires aligning both with how heat is experienced.

Planners often regard streets as targets for mitigating urban heat across cities by virtue of being abundant, publicly-owned, low-albedo, low-vegetation surfaces. Few studies, however, have assessed the role streets play in contributing to urban heat, and the scale of their effect relative to the built environment around them. We examine the relationship between road area and land surface temperature across a variety of biophysical regions through the urban areas of Los Angeles and San Bernardino Counties in Southern California. Our results show that wide streets have no consistent, detectable effect on urban heat. Rather, vegetation is the primary cooling mechanism for urban areas. In the absence of trees, concrete highways are the coolest surfaces, though particular hot or cool pockets (e.g., airports, industrial centers, parks) can dominate neighborhood temperature signatures. In considering LST mitigation strategies, these hotspots might outweigh the cumulative effects of road surface changes.

The paper examines relationships between stormwater control measure (SCM) priorities and environmental value orientations among stormwater managers in Cleveland, Ohio and Denver, Colorado, metro regions with contrasting environmental conditions and policy contexts. While studies show that governance explains differences in broad SCM priorities, less is known about what motivates individual “street level bureaucrats” who influence decisions at the project level. Drawing from cognitive social science perspectives, this study surveyed stormwater professionals (n = 185) about primary and co‐benefit SCM priorities and environmental value orientation. Results revealed different primary SCM priorities by region: Cleveland and Denver respondents prioritized quantity and quality goals, respectively, reflecting regional context. Co‐benefit priorities correlated to two environmental value orientation clusters — “Traditional Technocrats” with relatively anthropocentric orientations and “Champions” with relatively ecocentric orientations — who were equally abundant in both regions. Findings suggest that environmental value orientation influences co‐benefit priorities, which may have implications for project level articulation of policy.

Heat has become a central concern for cities everywhere, but heat governance has historically lagged behind other climate change hazards. This study examines 175 municipal plans from the 50 most populous cities in the United States to understand which aspects of urban heat are included or not in city plans and what factors explain inclusion. We find that a majority of plans mention heat, but few include strategies to address it and even fewer cite sources of information. The term ‘extreme heat event’ (EHE) is significantly more likely to be paired with institutional actions as a part of hazard planning, while ‘urban heat island’ (UHI) is more likely to be paired with green and grey infrastructure interventions as a part of general planning. Disparity and thermal comfort framings are not significantly related to any solutions and are used least. Plan type, followed by environmental networks (e.g. C40, Urban Sustainability Directors Network, Rockefeller 100 Resilient Cities), explain variation in plan content; social and environmental context do not. Findings point to the emergence of two independent heat governance systems, EHE and UHI, and several gaps in heat planning: integration, specificity, solutions, disparity, economy, and thermal comfort.

Regional land surface temperature (LST) maps derived from remote sensing data are most available to cities to assess and respond to heat. Yet, LST only captures one dimension of urban climate. This study investigates the extent to which remote sensing derived estimates of LST are a proxy for multiple climate variables at hyper-local scales (<10s of meters). We compare remotely sensed estimates of LST (RS-LST) to field and simulated LST, MRT, and air temperature (AT), in a neighborhood in Tucson, Arizona, USA. We find that LST, MRT, and ST follow different diurnal trends masked by RS-LST. We also find that three-dimensional urban design is a better predictor of MRT than two-dimensional land cover and albedo – a known determinant of RS-LST. Shade is a better predictor of both simulated LST and MRT than RS-LST. We conclude that RS-LST is not adequate for guiding heat mitigation at hyper-local scales in cities.

Problem, research strategy, and findings: Residential landscapes are homogenizing the ecology of cities, and decisions about yard structure and management practices are the result of a complex mix of actors and institutions operating at multiple scales. In this study we examine how one such institution, the homeowners association (HOA), homogenizes yard ecology at the neighborhood scale through formal institutional rules. We examine a random sample of publicly recorded covenants, codes, and restrictions (CCRs) documents and a nonrandom sample of private architecture and landscaping guidelines for HOAs in Maricopa County (AZ). We find landscaping rules in CCRs have increased over time but are relatively small in number and generic in content, sometimes repeated municipal rules, and increasingly outsourced rules to architectural and landscaping guidelines. Rules about yard aesthetics or maintenance were required, whereas rules relating to environmentally sensitive landscaping were encouraged. We propose HOAs facilitate ecological homogenization by aggregating heterogeneous rule types to formulate a club good. Takeaway for practice: Our findings suggest planners can enact ordinances that influence residential landscape ecology in HOAs via statutory mandates because CCRs reinforce existing rules at the neighborhood scale. However, HOAs potentially inhibit adoption of voluntary programs directly or indirectly via approvals and restrictions. Moreover, the finding that HOAs are increasingly shifting regulations from publicly recorded CCRs to private documents reveals a challenge for planners because private contract law allows land use provisions in HOAs to remain “hidden” from the public domain.

Berardo, R., V. K. Turner, and S. Rice. 2019. Systemic coordination and the problem of seasonal harmful algal blooms in Lake Erie. Ecology and Society 24(3):24. https://doi.org/10.5751/ES-11046-240324

Homeowners’ Associations (HOAs) dictate landscape structure and management through legally enforceable land covenants at the neighborhood scale in the USA. Determining the location and spatial extent of HOAs is critical for examining its influence. However, such analysis is confounded by the lack of spatial data at the appropriate unit for such analysis. The purpose of this paper is to develop and realize an open source implementation to automate land parcel classification, which is an initial step towards the goal of determining the impact of HOAs on urban land management. Using Maricopa County, Arizona as a testbed, we found that parcel merging processes reduce the number of subdivisions from 26,042 to 17,269, such that boundaries better align with neighborhood units to which rule sets like land covenants apply. Moreover, after an initial training period, this process was completed in just over 7 hours. This research is an important first step in enabling a number of analysis including determining the location and spatial extent of HOAs regionally and, eventually, nationally and determining proposed links between HOAs and land management outcomes.