Objective As a vital part of urban green spaces, urban parks provide essential venues for older adults, which can help promote the latter’s physical and mental well-being. Compared to other age groups, older adults have a greater need for engaging in activities within green spaces, and their perception of these environments significantly influences their activity behaviors. Understanding the nonlinear relationship between the elderly’s perception of urban park green spaces and their activity characteristics is essential for guiding age-friendly park renovations and effective urban green space planning. Previous research has examined the impact of green space environments on the elderly’s activities, but the focus is primarily on objective environmental characteristics rather than on subjective perceptions. To address this gap, the present research employs the Extreme Gradient Boosting (XGBoost) model to explore the complex relationship between the elderly’s perception of urban park green spaces and their activity behaviors. The research aims to construct a theoretical model that captures the nonlinear dynamics between these variables, using data from urban parks in Fuzhou for validation. By analyzing the contribution of different perception indicators to older adults’ activity levels, the research seeks to identify threshold effects and provide insights for age-friendly park design and renovation, ultimately supporting the high-quality development of urban green spaces.
Methods In this research, the elderly’s perception of urban park green spaces is set as an independent variable, while their activity levels in green spaces are defined as a dependent variable. The independent variable, i.e., the elderly’s perception of urban parks, includes 12 indicators incorporated into the formal questionnaire adopted in the research: accessibility, sense of security, rationality of fitness facilities, rationality of recreational facilities, sanitary conditions, green space quality, maintenance, ecological environment, sound environment comfort, air quality, sense of attachment, and sense of place. These indicators are measured using a 7-point Likert scale. The dependent variable includes four indicators related to the elderly’s activity levels in green spaces: weekly activity frequency, weekly activity duration, activity diversity, and total weekly activity amount. A total of 779 valid questionnaires are collected from five urban parks in Fuzhou. The collected data are statistically analyzed using Excel 2013 and SPSS 26.0 to evaluate the elderly’s perception of urban green spaces and their activity levels. In addition, Spearman correlation analysis is conducted to identify the relationship between the independent and dependent variables. For the significant variable group, an interpretable XGBoost machine learning model is constructed to explore the relative importance of various perception indicators and the nonlinear relationship between the elderly’s perception and their activity characteristics.
Results Research results are summarized as follows. 1) The elderly generally have a positive perception of the green space environment, especially in terms of air quality and ecological environment. There exist no significant differences in green space perception between different genders and age groups. However, individuals exhibit large differences in their total activity amount, which might be associated with their health conditions, personal interests, and accessibility to green spaces. 2) Sense of place and sense of attachment are the most crucial factors influencing the frequency of the elderly’s green space usage, while ecological environment and green space quality significantly impact the duration of use. Additionally, air quality is the most important factor affecting the diversity of activity types, and the ecological environment is the most significant factor influencing the total weekly activity levels. 3) There is a significant nonlinear relationship between the elderly’s weekly activity frequency, duration, activity type diversity, and total activity level and several perception characteristics. Among these, sense of place, ecological environment, and green space quality are found to significantly influence activity frequency and duration. Specifically, sense of place has the most pronounced effect on activity levels, while improvements in the ecological environment exhibit an inverse U-shaped effect, indicating that continuous improvement of the ecological environment may reduce activity levels after a certain threshold. Moreover, air quality and sound environment are shown to play essential roles in promoting activity frequency and type diversity.
Conclusion This research, based on data from elderly populations in five urban parks in Fuzhou, utilizes the XGBoost model to reveal the nonlinear relationship between the elderly’s perception of green spaces and their outdoor activity characteristics. By exploring this relationship from a nonlinear perspective, the research addresses the limitations of traditional research, which often relies on linear analysis models. The findings indicate that factors such as sense of place, ecological environment, air quality, facility rationality, and green space quality are crucial in shaping the elderly’s activity patterns in green spaces. Among these, sense of place has the most significant impact on activity frequency and duration. Additionally, improvements in the ecological environment and green space quality significantly promote outdoor activity participation, while continuous optimization of the ecological environment may lead to a reduction in activity levels, exhibiting an inverted U-shaped relationship. Moreover, air quality and acoustic environment further confirm the importance of environmental comfort in enhancing activity frequency and diversity. The rational arrangement and maintenance of fitness and recreational facilities also have multiple impacts on activity duration and variety, with both excessive and insufficient facilities potentially suppressing elderly participation. The research identifies the varying weights and marginal effects of these factors on the elderly’ green space activities, offering a new theoretical perspective for understanding the driving mechanisms behind green space usage. Additionally, the research expands the understanding of the relationship between environmental comfort and activity behavior, providing a new analytical framework and direction for future research. Although this research elucidates the nonlinear relationship between the elderly’s perception of green spaces and their activities, offering scientific evidence for green space usage among the elderly, it is limited by the cross-sectional nature and coverage of the data collected. Future research should incorporate longitudinal designs and cross-regional comparisons to explore the dynamic patterns of the elderly’s green space usage behavior and validate and extend the conclusions of this research. Overall, this research not only clarifies the complex relationship between the elderly’s perception of green spaces and their activity characteristics, but also provides scientific support for understanding and optimizing age-friendly urban green space design. Furthermore, it offers policy and practical references for the age-friendly renovation of urban parks, contributing to the high-quality development of green spaces and ultimately promoting the elderly’s health and well-being, as well as sustainable social development.
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