How can understanding preferences for seasonal change inform bioretention planting design?

Kelsey Broich

The University of Georgia

Co-Authors: J. Calabria, B. Orland, M. Risse, J. Brown

While research suggests bioretention and wetland environments are important, it also suggests that they may lack visual interest. Understanding perceptions of bioretention seasonality may improve planting design. This study explored perceptions of seasonal change in bioretention practices. Respondents in the Southeastern Coastal Plain, USA, (n=985) replied to an online survey comparing actual photos of five different bioretention sites taken throughout the year. The photo-based discrete choice experiment (DCE) captures the decision making process by estimating weighted factors based on the respondents’ chosen preferences. Unsurprisingly, results revealed a preference for the growing season over the dormant season (X2 (4, n = 985) = 928.490, p<0.01) and suggested specific design recommendations to improve the visual appreciation of bioretention practices, such as intentional year-round seasonal planting design.

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6 thoughts on “How can understanding preferences for seasonal change inform bioretention planting design?

  1. Very nice presentation. Your poster is beautiful! I had a couple of questions. 1) Did any of the bioretention areas in your surveys have evergreen plants, or were they pretty uniformly brown in winter? 2) Do these results align with other work that may have looked at other landscapes (e.g. not bioretention) and found people preferred them in the growing season? Thanks!

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    1. Thank you for your question! While the winter photos were mostly brown, there was a little variety in greenery. Some of the greenery came from ornamental grasses, rushes, turf grass and an evergreen shrub.
      After reviewing the literature, there seems to be only a few studies looking into seasonal preferences. One study had similar findings when comparing preferences between across the seasons for a woodland walk (Kuper 2015). Many designers and researchers present landscapes in their peak season (spring or summer). A few studies (outside of bioretention) found preferences for greenery and flowering plants (Jorgensen, Hitchmough and Dunnett 2006; Hoyle, Hitchmough and Jorgensen 2017). I think it would be interesting if the study were replicated either with different landscapes or people to understand preferences for characteristics of winter vegetation.

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  2. Most landscapes are less aesthetic in the dormant season compared to the growing season and also tend to require less maintenance. So I am curious if a seasonal aesthetics preferences lead to long term lack of stewardship? Or does stewardship return during the growing season (for instance a group has a bioretention clean-up day in the fall and spring but ignores it in the winter)?

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    1. Thank you for your question. My topic started from conversations about improving the management of bioretention practices and how recognizable these practices are to someone who may not be familiar with stormwater management. One article recounted a situation at a commercial site where bioretention practices were added, but when the site received new ownership, the practices were removed because the new owners did not recognize them as a designed space. The literature suggests that people perceive wetland plants as messy and unkempt (Gobster et al. 2007). One researcher developed the concept of “cues to care”, or deliberate human interventions in the landscape to help communicate stewardship. If messy ecosystems are paired with orderly frames (such as a mown edge), people are more likely to associate them with stewardship (Nassauer 1995).
      My study primarily focused on whether or not seasonality impacted preferences for bioretention practices in order to contribute to a broader goal of informing stewardship. Perhaps seasonality could act as a “cue to care”, or improve the visibility of bioretention practices. If bioretention practices exhibit year-round seasonal interest, will people recognize them as a designed space, find them more beautiful, and therefore, take care of them? While my study was a preliminary step toward understanding relationships between preference and stewardship, I think your question is important for future research. How does stewardship compare across the seasons? In addition, how does stewardship compare between a landscape without intentional winter design and one with intentional winter interest? The results of the survey suggest that bioretention practices may be most at risk of improper management during dormant seasons when they lack most preference, but further research is needed to draw that conclusion.

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  3. Very nice work, Kelsey. I’m curious if you also included control pictures of natural areas in each season? It seems that natural areas (forests etc) would broadly be “uglier” in the winter as well. I wonder whether respondents find bioretention systems less aesthetically pleasing than natural areas and whether this varies by season.

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  4. Hi Ryan, thank you. I only showed photos of bioretention areas. In the pilot study, I presented photos from 6 different sites. One of the sites had a drastically different design when compared to the others. It contained large trees and few grasses. The site was found to be a significant factor driving preference. Because of the overwhelming preference for the one site, we decided to and removed it from the later survey to help focus the test on seasonality. Showing other environments could introduce many other factors that could influence preferences.

    In the literature, wetland environments are often cited as being misunderstood or lacking aesthetically (Herzog 1985; Gobster et al. 2007; Meyer 2008). I did come across some studies comparing other waterscapes and sites with open or rushing water were most preferred, while swamps and less spacious environments were least preferred (Herzog 1985). Another study found that respondents preferred trees with leaves over dormant bare trees (Palmer 1990). I think continuing these explorations in the context of seasonality would be excellent for future research. In my discussion, I mentioned the importance of gaining a deeper understanding of the respondent’s reaction to characteristics of the vegetation. My study primarily tested for preference across seasons, but further research can begin to explore comparisons (as you mentioned) between different environments, designs and kinds of vegetation. Understanding preferred characteristics can help inform planting design recommendations.

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