**5. Discussion**

The investigation above addresses an emerging issue in urban ES development and planning: the integration of stakeholder perspectives with quantitative estimates of urban ES provision to inform decisions regarding future land cover [4,16,35,44]. The new method that results is then applied to an urban neighborhood through the evaluation of existing public green space and current urban ES supply rates, the collection of resident and city-wide stakeholder priorities, and the translation of these lines of evidence into a set of alternative planting regimes.

#### *5.1. Public Green Space Inventory*

The population density and land cover distribution in the study area is broadly representative of urban residential neighborhoods in the USA [92], with lawn as the dominant vegetated land cover type (Tables S3 and S4), consistent with other urban areas studied in the USA [29] and in Europe [93]. Approximately one-eighth of this area is covered by trees, again consistent with tree coverage of European research sites [93]. At the same time, resident access to public green space is substantially above the USA average [51] (Figure S1), an unusual situation in a neighborhood with below-median income [49,50] that may partly explain the high value residents placed on numerous urban ES (Figure 4). In the evaluation of existing vegetated land cover types, the combined LiDAR and NDVI-based analysis identified tree cover with high accuracy but was less accurate in identifying shrubs (Table S2); it also obscured the co-occurrence of tree cover over herbaceous ground cover and shrubs. We, therefore, recommend the incorporation of further image analysis rules and waveform LiDAR processing in future green cover analyses for the accurate distinction of these land cover types (e.g., [94,95]).

Currently, lawn provides the majority of runoff retention and recreation value in the neighborhood, while trees and woodlands provide the majority of air purification, carbon storage, and cooling, despite their much smaller area. As a result, the question faced by those responsible for increasing urban ES in Eugene (Section 5.2.) is whether existing public lawn in the neighborhood should be replaced, and if so, with what.

#### *5.2. Stakeholder Priorities*

Alignment with local values is known to be critical to the successful planning, development, and managemen<sup>t</sup> of public urban green space [89,96], and because resident urban ES priorities are locally idiosyncratic (e.g., [40–42,97]), local input is necessary. Accordingly, Eugene's Parks and Open Space Division surveyed thousands of residents and hundreds of city governmen<sup>t</sup> and operations employees from 2015–2018, culminating in a vision and implementation plan for future green space development [48]. Although the plan focused on the recreational importance of public parks, responding to expressed desires for public gathering space and for additional sports fields [48,90], another prominent goal was to "further the parks and recreation system's capacity to serve as critical infrastructure for clean air, clean water, flood control, carbon sequestration, and climate resilience" [48] (p. 42). Strategies to provide these urban ES have not ye<sup>t</sup> been determined, but an economic assessment of current park value has been completed [98], and a \$50 million tax bond was passed in 2018 to support park operations and development in preparation for future green infrastructure development to expand urban ES delivery [99], showing the timeliness and relevance of the decision-making process we contemplate here.

#### 5.2.1. Resident Priorities

FAN residents valued urban ES highly overall, with most respondents rating 16 of the 17 listed urban ES as "moderately" to "very" important (Table S5). These primarily represented supporting or regulating services, showing the importance of ecological resilience as represented by native plant species, bird and pollinator habitat, stormwater purification, and carbon sequestration [3]. Similarly, the importance of human health and well-being was shown by the priority of air purification. These findings contrasted strongly, however, with results from Paris and Angers, France, and from Porto and Lisbon, Portugal, in which residents valued cultural and provisioning urban ES most highly [41]; Table S5. They also di ffered from the results of six cities in the USA, in which residents viewed native species and pollution mitigation as low priorities [100], and from results of Barcelona, Spain, in which pollination and biodiversity were low priorities as well [97]. Air purification, however, seems to be one of the few urban ES that shows consistently high priority among city dwellers globally, and the high priority of air quality found here is consistent with recent results from China, Portugal, Spain, France, and the Netherlands [39–41,101].

Outdoor recreation was the single cultural urban ES given high priority by FAN residents, consistent with the previous local survey [90] as well as with recent results from Finland and China [42,101]. In contrast, noise reduction and community identity were low priorities among FAN residents, consistent with findings in European cities [41] but unlike those of Guangzhou, China, in which residents ranked noise abatement as a high priority [101]. FAN residents also assigned a low priority to vegetable and fruit production, in contrast with results from cities such as Barcelona [97], revealing an unexpected lack of support given Eugene's promotion of urban farming [102,103]. Still, this result may show that the numerous community and private gardens in the neighborhood have already met this need.

#### 5.2.2. Delphi Analysis

The perspectives of stakeholders who would either be involved in making and influencing green infrastructure development decisions, or responsible for implementing and maintaining any changes, di ffered from each other substantially in the first round but partly converged during the second round, reflecting the exchange of ideas allowed by the Delphi procedure (Supplementary Materials Section S2; Table S8) and showing the promise of this method in reaching consensus among other diverse stakeholder groups. Among the consensus priorities, Delphi participants valued air and stormwater purification most highly, reflecting current urgen<sup>t</sup> needs for these services at the city level (Section 2.1.). Although residential neighborhoods typically contribute fewer total suspended solids and other stormwater pollutants than do roads with heavy tra ffic [104], low-density development typically contributes greater runo ff volume and a ffects more of its watershed than high-density development [105]. Delphi respondents also assigned high value to carbon sequestration, natural beauty, and native plant species (Table 1), but the prospect of dense vegetation raised safety concerns (Table S8), illustrating an internal conflict in the responses that would require eventual resolution.

In contemplating land cover changes, Delphi participants described the recreational and ease-of-maintenance benefits of lawn in neighborhood and city parks; one participant noted that city operations managemen<sup>t</sup> is currently converting long-established landscape beds into lawn to realize these benefits, adding that lawn is viewed as "neat-looking". These views, combined with the acknowledgment of lawn's minimal delivery of regulating and supporting services, are consistent with those found among municipal land managers in three Swedish cities [106]; however, Delphi participants did not express concern about the costs and greenhouse gas emissions of mowing, as Swedish stakeholders did [106]. Instead, most Delphi participants viewed the "cost and complexity" associated with the installation and maintenance of alternative planting regimes as a greater set of barriers, although they did not elaborate (Table S8). Still, most Delphi participants (>85%) supported the conversion of some public lawn to alternative plantings to increase regulating and supporting services, agreeing that the primary limitation would be the preservation of sightlines along right-of-way planting strips.

#### 5.2.3. Resident and Delphi Comparison

The di fferences between resident and Delphi urban ES priorities appear to have reflected their frames of reference: while Delphi participants contemplated the city scale, residents considered only their own neighborhood, as intended. Illustrating distinctly city-level concerns, one Delphi participant explained:

"What drives public agencies such as our Public Works Department is regulatory requirements—meeting the Federal Clean Water Act and our NPDES Permit requirements (e.g., reducing pollution into local waterways, reducing flooding, and improving air quality). Other items are secondary to the basic welfare and safety of the general public." (Supplementary Materials Section S3, p. 17).

Consistent with the diversity of stakeholder opinion found in related studies, the partial divergence among Delphi and resident priorities supports the inclusion of neighborhood-level input even in city-wide urban ES planning.

A notable discrepancy was found in the stakeholders' view of cost barriers: while Delphi participants agreed that the cost of lawn conversion was an important barrier (Table S7), over 85% of residents expressed willingness to pay for green infrastructure development that would increase urban ES delivery through tax measures or private donations (Figure 5; Table S6). While stated willingness is not a guarantee of future payment, these findings are consistent with survey results regarding willingness to pay for urban ES in Palm Beach, FL, USA, involving biodiversity, outdoor recreation, and flood protection [107], as well as in Wuhan, Changsha, and Nanchang, China, involving climate regulation, cultural services, air quality, erosion prevention, and habitat services [108]. In each of these cases, the willingness to pay exceeded the expected cost per capita despite heterogeneity in the responses. In contrast, residents of Veneto, Italy expressed a willingness to pay for recreational services but felt that biodiversity conservation and landscape quality should be provided without taxes [109], illustrating the importance of personal history and the governmental context in such attitudes [110] and suggesting that urban planners survey their target neighborhoods before assuming particular cost barriers.

#### *5.3. Integration of Stakeholder Priorities with Potential for Local Benefit*

Recent studies have emphasized the need to integrate the ES priorities of multiple stakeholder groups with the quantitative and qualitative potential for the desired ES to be realized [2,16,35,37,44], but none have explored this further. Here, we found that such integration could be readily accomplished by evaluating questions typical of a green space planning process (Section 4.1.) in light of the corresponding stakeholder survey and urban ES supply rate evidence, yielding a set of alternative planting regimes representing each line of evidence. The ability of each vegetated land cover type to provide multiple urban ES then facilitated the creation of an integrated scheme with limited compromise to stakeholder priorities (Section 4.2.). Of central importance, the contrasts among the individual lines of evidence (i.e., quantitative considerations, resident priorities, and Delphi priorities) illustrated the value of consulting all three. In particular, safety and sightline concerns of Delphi participants moderated the extent of woodland required to maximize air and water quality services, while cost concerns limited stormwater planter area; likewise, residents' outdoor recreation priorities limited the conversion of lawn-based playing fields and emphasized widespread inclusion of native flowering shrubs, carrying particular importance because of residents' financial responsibility for any changes as well as their willingness to bear additional costs. As a result, the Integration planting regime is one that could not have been found by any one approach alone, adding strong support to previous recommendations that diverse stakeholder views and quantitative evidence should be considered together in developing urban ES delivery plans [37].
