Plant diversity, preference, and psychological well-being

Wu, Chia-Ching

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https://hdl.handle.net/2142/127325 Copy

Description

Title

Plant diversity, preference, and psychological well-being

Author(s)

Wu, Chia-Ching

Issue Date

2024-10-11

Director of Research (if dissertation) or Advisor (if thesis)

• Sullivan, William C.
• Chang, Chun-Yen

Doctoral Committee Chair(s)

Sullivan, William C.

Committee Member(s)

• Deal, Brian
• O’Keefe, Joy
• Li, Dongying

Department of Study

Landscape Architecture

Discipline

Landscape Architecture

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Urban nature
• biodiversity
• plant species richness
• landscape preference
• attention restoration
• stress reduction

Abstract

Urban green spaces that harbor a variety of vegetation and wildlife are vital for fostering residents’ health and well-being and for strengthening their connections with nature. Extensive research has indicated that higher vegetation cover is associated with elevated landscape preferences and improved health outcomes. However, when vegetation becomes denser and appears in wilder, more natural forms, these benefits and preferences for the landscape may diminish. This decline could be attributed to concerns regarding safety, unwanted contact with wildlife, or decreased perceived aesthetics of urban nature. Therefore, while green spaces often positively impact human health and well-being, they can also have negative associations when the vegetation density and diversity are increased. A growing body of research investigated the relationships among plant diversity in natural landscapes, aesthetic perceptions, and health outcomes. These studies, however, reported mixed effects—positive, no relation, and negative. Furthermore, studies that examined the health effects of plant species richness almost always did not differentiate the effects of plant cover. Hence, the independent relationships between plant species richness and health benefits remain unclear. To fill these gaps, this dissertation aims to explore the extent to which varying levels of plant diversity affect landscape preferences, short-term attentional functioning, and stress levels. I specifically examined the effects of plant species richness on these landscape perceptions and health outcomes while accounting for vegetation density. To address these research questions, I conducted a systematic review and two empirical studies: the Preference Survey Study and the Health Experimental Study. In the systematic review chapter (Chapter 2), I reviewed 41 empirical studies on the relationships between biodiversity and health from 2018 to 2024. By reviewing these research articles, I answered four questions: 1) synthesize and describe the relationships between the variability of biodiversity composition and human health; 2) depict the pathways through which these relationships have been examined; 3) assess the extent to which subjectively perceived biodiversity aligns with objectively measured biodiversity; and 4) describe any known relationships between subjectively perceived biodiversity and health outcomes. In the Preference Survey Study (Chapter 3), I investigated the extent to which plant species influence landscape preferences when the plant cover, defined as green view, is controlled. To do so, I created one hundred simulations to manipulate both plant species richness and green view at none, low, medium, and high levels. I built online surveys asking about preferences for these landscapes and the perceived plant diversity distributed via Amazon Mechanical Turk. In the Health Experimental Study (Chapter 4), I assessed the extent to which plant species richness impacts the recovery speed from attentional fatigue and stress while holding green view levels constant. This study generated ten video interventions from the ten groups of simulations used in the Preference Survey Study. During the experiment, I exposed participants to stressful conditions and randomly presented them with one of the ten videos. I measured participants’ short-term attentional functioning, self-reported stress, and objective stress responses at each phase, comparing the pre- and post-intervention differences in health measurements across varying levels of plant species richness. I also examined whether personal characteristics, such as daily attentional functioning, chronic stress, and degree of nature relatedness, moderate the relationships between plant species richness, green view levels, and health outcomes. In the Preference Survey Study, I collected 341 valid sample sizes. The findings presented that both plant species richness and green view were positively correlated with landscape preferences. Additionally, plant species richness was shown as a significant predictor after accounting for green view levels. Associations among plant species richness, green view, and landscape preference were best described with curvilinear relationships. In the Health Experimental Study, with 145 valid datasets, I found that neither plant species richness nor green view showed negative or positive effects on recovery from attentional fatigue and stress, except that the increased green view significantly led to higher relaxation levels. Moreover, my results demonstrated significant moderation effects of daily attentional functioning, chronic stress, and nature relatedness on the relationships between plant diversity and landscape preferences, recovery from mental fatigue, and stress. These two studies expand our understanding by demonstrating that plant species richness, composed of varying types of vegetation such as tree canopy, shrubs, flowering plants, and ground cover across different urban settings, is positively associated with landscape preferences with green view levels controlled. Additionally, these two studies present that increased plant species richness or green view does not negatively affect short-term health outcomes measured by objective health indicators. Considering the proven indirect influences of other ecosystem services on health and well-being, my research supports the implication that diverse vegetation in urban green spaces can produce beneficial effects for both urban residents and wildlife.

Graduation Semester

2024-12

Type of Resource

Thesis

Handle URL

https://hdl.handle.net/2142/127325

Copyright and License Information

Copyright 2024 Chia-Ching Wu

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