The public nature of park green spaces determines their recognition as a form of public service. Therefore, this article draws on the research on equity in public services to clarify the content of equity in park green spaces. The following Table 1 is a compilation of research findings from scholars:

Based on the historical stages of modern societal development, this article categorizes the content of equity in park green spaces into three phases, as illustrated in Figure 1:

1. Before the 1970s, international mainstream research focused on territorial equality, specifically the comparison of per capita park green space indicators across different regions.

The article highlights that identifying the components of equity also requires corresponding to the historical stages of socio-economic development. Exploring the historical reasons behind the formation of the concept of equity is beneficial for cities in different countries and regions to recognize the current issues regarding equity based on their respective developmental stages. This understanding can assist in formulating practical and actionable strategies for future development. Therefore, it becomes essential to analyze the social context associated with these studies: before the 1970s, western societies were in a period of post-war reconstruction with government-led elite decision-making. The focus was on increasing the quantity and layout of park green spaces. However, since the 1970s, western societies have transitioned towards postmodernity, challenging elite decision-making and giving more importance to the actual needs of the public. Nevertheless, this stage also had its limitations: the understanding of public needs was relatively simplistic, and studies on the accessibility of park green spaces and the formulation of public policies often relied on a basic assumption that easy transportation would meet the public’s needs. Since the end of the 20th century, sociological research has become more complex, with social stratification and cultural diversification leading to diversified demands, and the differentiation of needs among different social groups. Identifying the needs of different groups and providing more precise services for them has become the focus of research. Besides historical reasons, the equity phased development is also associated with advancements in science and technology. In the 1990s and 2000s, continuous enhancements and optimizations of GIS technology and analytical models, along with the refinement of big data and Internet maps, made spatial fairness analysis feasible across diverse demographics. Scholars began exploring from the standpoint of various demographic needs. With the expansion of Chinese cities and an aging population, the Chinese government has proposed a strategy for common prosperity through the equalization of basic public services, incorporating green equity into residential living circle planning. The research on equity has also rapidly progressed from the first and second stages towards the third stage.

This study draws upon the Web of Science (WOS) core collection database as the primary data source. In pursuit of a comprehensive compilation of relevant literature on equity in park green space, a refined search strategy was formulated by incorporating synonymous terms associated with parks, green spaces, and equity. After several adjustments, the ultimate search string adopted was TS= (“park green space*" OR “urban green space*" OR “urban park*" OR “green space*") AND (“equity*" OR “justice*" OR “accessibility*"). The selected document types were restricted to “Article” and “Review Article”. The temporal scope spans from 2014 to December 2023, with the search conducted on 10 December 2023, 1,168 articles were retrieved through the search.

To ensure the quality and relevance of the retrieved articles, each of the three authors conducted a detailed examination of the titles and abstracts of every potential article. Articles meeting the following inclusion criteria were then downloaded:

1. The study focused on park green space, encompassing various types such as comprehensive parks, community parks, and recreational gardens (According to China’s ‘Classification Standard for Urban Green Spaces’ CJJT85-2017 (2017), a comprehensive park refers to an area with an area ≥5 h m², suitable for various outdoor activities, and equipped with comprehensive recreational and supporting management service facilities.);

Articles not meeting these criteria were excluded from the analysis. The data collection, screening, and analysis adhered to the outlined evaluation criteria, and any disputed articles were thoroughly discussed among all co-authors until a consensus was reached. Finally, 333 articles met the inclusion criteria (Figure 2A), comprising 319 articles and 14 reviews (Figure 2B).

This article will utilize CiteSpace 6.2.4 and employ both bibliometric analysis and content analysis methods to comprehensively illustrate the current research status and development trends of park green space equity from multiple perspectives. The specific structure of this paper is outlined as follows (see Figure 3). Firstly, in Section Four, a bibliometric analysis utilizing CiteSpace is employed to examine publication timelines, contributing countries, and high-frequency keywords, accompanied by brief explanations. Subsequently, Sections Five and Six adopt content analysis to systematically review selected literature in terms of research hotspots and influencing factors. Finally, Section Seven analyzes the limitations, prospects, and challenges of the study.

The bibliometric analysis of the dataset was conducted using CiteSpace 6.2.4. The “Full Record and Cited References” option was selected. Subsequently, the source data from the Web of Science (WOS) database was exported in “Plain text file” format and imported into CiteSpace. The parameter settings were configured as follows: ‘Time Slicing = From 2014, JAN To 2023, DEC' (The time range of the literature.), “Node Types = Country OR Keyword” (Selecting to conduct either country of publication analysis or keyword analysis.), “Pruning = Pathfinder AND Pruning sliced networks AND Pruning the merged network” (Trimming each slice and merging networks to highlight important network structures). All other parameters were kept at their default values.

Based on the content analysis and extension in Section 2.2, it is evident that the analysis of park green space equity based on primary social fairness primarily focuses on the disparities in the ability and opportunity of different groups to access park green space services. The analytical approach is based on the multidimensional characteristics of park green spaces, such as quantity, quality, and type, as well as the demographic attributes of social groups within spatial units, to assess the ease of access to park green spaces for different social groups (whether different social groups can fairly enjoy access to park green spaces), thus determining equity.

The conclusions can be broadly categorized into two main types (see Table 4). The most common finding is the inequity of park green spaces, manifested in lower accessibility for the elderly, children, immigrants, and ethnic minority groups. Areas with higher housing prices tend to have higher accessibility to park green spaces, and park green space accessibility is higher in city centers compared to suburbs. However, very few studies fail to confirm the existence of park green space inequity. Some scholars attribute this to the different spatial scales used in research. Common research scales include streets, neighborhoods, and residential areas. Different spatial scales within the same city may yield different results, especially when the area of aggregation units far exceeds residents’ walking distances, which may lead to erroneous conclusions. Therefore, accessibility analysis should be conducted at finer scales whenever possible.

The focus of research on park green space equity has gradually shifted towards socially vulnerable groups such as low-income individuals, migrant workers, as well as physiologically vulnerable groups including children, the elderly, and women. Studies suggest that residents with lower socioeconomic status (SES) spend more time using parks and green spaces (Shen et al., 2017). Moreover, Black residents have access to more parks than White residents, but the per capita park area is lower for Black residents. This phenomenon is attributed to parks in predominantly Black communities being more crowded, especially in metropolitan areas (Julia et al., 2021). Faced with this inequality, if the government constructs a large number of parks and green spaces in areas lacking greenery, it can make surrounding residences more attractive, leading to an increase in housing prices, escalating living costs, and even displacement of original residents, ultimately resulting in gentrification (Boone et al., 2009). Noteworthy examples include the High Line park in the United States (Brisman, 2012) and the Cheonggyecheon Stream restoration project in South Korea (Lim et al., 2013). To address this issue, scholars propose the “Just green enough” strategy, advocating for the construction of small-scale, dispersed parks and green spaces rather than large expanses (Curran and Hamilton, 2012).

Chinese scholars, however, present two divergent views on this matter. One perspective suggests that vulnerable groups are gradually moving away from parks and green spaces. For instance, research indicates that park accessibility is negatively correlated with building age and positively correlated with housing prices (Yu et al., 2020). Community parks built in earlier years exhibit higher accessibility, but in recent housing development, the elderly are increasingly distancing themselves from parks and green spaces. The other perspective contends that compared to ordinary residents, vulnerable groups such as immigrants, the unemployed, and residents of welfare housing are more likely to live in areas with better park usage rights (Nesbitt et al., 2019). Two main reasons account for this: first, it is related to the urban green space planning strategy of Shanghai, which emphasizes even distribution of public green space; second, vulnerable groups reside in high-rise buildings in the city center, and although they have better park green space accessibility, their living conditions are extremely poor due to poor economic conditions. Concurrently, with the increasingly severe aging population in China, the elderly face a serious shortage of park green space usage. Studies reveal that different modes of transportation and varying park green space sizes can influence the degree of fairness in elderly people’s access to these spaces (Meng et al., 2020). Addressing this issue, some scholars advocate for greater government leadership in planning, giving priority to the interests of vulnerable groups (Hewko et al., 2002).

The research is primarily categorized into two main areas: the relationship between park green space accessibility and health, and the relationship between park green space ecological services and health.

According to Table 5, research on the relationship between park green space accessibility and health in China mainly focuses on large cities such as Beijing and ice and snow cities such as Harbin, as well as in Western countries like the United States, the United Kingdom, and Canada. Health data is primarily obtained through questionnaire surveys, face-to-face interviews, and publicly available databases. Some scholars have studied the relationship between park green space equity and resident health from the perspectives of accessibility, distance, and coverage. The majority of research findings indicate a positive effect of park green space equity on residents’ psychological and physiological health (Wolch et al., 2014; Dadvand et al., 2016; Rigolon, 2016). Park green space accessibility is negatively correlated with the incidence of various diseases among residents (Kaczynski and Henderson, 2007), particularly cardiovascular and cerebrovascular diseases (Haiya, 2011). However, individual studies suggest no correlation between park green space accessibility, proportion, supply-demand ratio, and health.

The relationship between park green space ecological services and health has been explored by scholars. Some researchers (Zhang et al., 2021c) have conducted a review and summary of international research findings, outlining the promotion benefits of green spaces on health, factors influencing the effectiveness of health impacts, and mechanisms by which green spaces promote health. Others have delved into the physiological, psychological, and social correlations between green spaces and human health, proposing the concept of green medicine and discussing auxiliary approaches to maintaining the physical and mental health of urban residents (Kaczynski et al., 2008).

The influence of regional economy on the equity of park green spaces is primarily manifested in the level of supply. In China, as a vast country with uneven development, significant disparities exist between urban and rural areas, as well as between eastern and western regions, and between the north and south. In economically developed areas, local governments often possess more financial resources, enabling them to provide more park green space resources, thereby ensuring relatively sufficient supply in these areas (Li et al., 2018). For instance, the central and southeastern coastal regions typically maintain higher levels of park green space coverage. However, in areas with harsh geographical conditions or relatively underdeveloped economies, such as mountainous or desert regions, constraints on park green space construction are considerable, resulting in inadequate supply, and in some cases, levels even below the national average (Chen and Wang, 2013; Zhao et al., 2013). Conversely, in Western countries like the United States, park green space construction is typically funded through mechanisms such as property taxes. Nevertheless, due to limited local funds, there is often a need to seek financial support from non-profit organizations, institutions, and federal governments at the national and state levels (Harnik and Barnhart, 2015). This competitive allocation of funds may exacerbate inequalities (Joassart-Marcelli et al., 2011), with affluent areas receiving more support, further aggravating disparities in park green space distribution.

Government planning plays a crucial role in the spatial layout and construction of park green spaces. Unlike Western countries, where park green spaces are typically planned and constructed by the government and open to the public free of charge, in China, traditional planning tends to rely on metrics like per capita park area to gauge the level of supply. Consequently, park green spaces are often densely concentrated in areas with high population density, while areas with lower population density experience shortages (Liyan et al., 2023). Furthermore, some local governments, in pursuit of political achievements and prestige, may excessively prioritize increasing park green space coverage, investing heavily in superficial projects, thereby neglecting the actual needs and usage patterns of park green spaces (Zhao et al., 2013). This detachment between park green space planning and residents’ demands exacerbates the disparities between planning intentions and community needs (Chen et al., 2017).

In China, park green spaces are often closely linked to high-quality housing, with high-quality parks typically adjacent to upscale residences, while lower-quality parks are connected to relatively lower-end housing. Higher-income groups usually have the ability to purchase premium housing, thus enjoying access to better-quality park green spaces. Conversely, lower-income groups may only reside in environments with poorer-quality housing, leading to disparities in park green space utilization among residents of different socioeconomic statuses, further exacerbating spatial inequalities in park green space distribution (Chen et al., 2020; Wu and Rowe, 2022). Studies in Western countries have also confirmed this observation, showing that in capitalist societies, higher socioeconomic status (SES) groups typically have access to larger and higher-quality park green spaces, while lower SES groups often lack equivalent opportunities (Zhu and Zhang, 2008; Alessandro and Jeremy, 2018; 2020; Browning et al., 2022).

Racial discrimination and segregation are also significant factors contributing to the inequitable distribution of park green spaces (Wolch et al., 2014; Rigolon, 2016). Historically, due to the dominant position of white people, public facilities such as parks were predominantly located in affluent areas, while industrial zones and high-density housing were situated in areas inhabited by people of color and low-income individuals, a legacy that continues to have profound effects. Racial discrimination and segregation make it more difficult for communities of color to access park green spaces (Dai, 2011), even when they reside closer to them. Issues such as smaller park areas, poor quality, and environmental pollution discourage residents from utilizing these spaces (Alessandro and Jeremy, 2018), exacerbating the inequities in park green space distribution (Wolch et al., 2013).

(1) Equity of Parks and Green Spaces for Different User Groups: Future research should focus on the fairness of park green space usage among different demographic groups, especially vulnerable populations such as the elderly (Guo et al., 2019), children, and low-income individuals.

• This study has limitations regarding the selection of databases: The literature was derived from the WOS core database. The choice of databases may result in the omission of some relevant literature, posing a risk of literature gaps. Future research could consider expanding the scope of database selection, such as incorporating Scopus, PubMed, and others, to obtain a more comprehensive literature review.

These limitations should be addressed and rectified in subsequent research to enhance the comprehensiveness and objectivity of the study. Additionally, a more detailed content analysis of relevant literature is warranted to gain a deeper understanding of the current status and trends in the field of equity in park green space.