Open space is a widely studied topic; as such, it is no surprise that a number of academics have put forward various definitions and classifications in relation to this subject. Tang and Wong adopt a broad definition that encompasses parks and recreational spaces, outdoor public gathering places, unroofed and undeveloped natural landscapes on urban land, adjacent spaces between villages and buildings and urban spaces, and areas open to the public and commerce (including cafes, retail markets, theme parks, sports, streets, and sidewalks) [1]. It should also be noted that open space is a form of space that continually changes in line with urban development. Mark Francis claims that in addition to the traditional public spaces of city parks, squares, neighborhood parks, and playgrounds, the significance of the value of public space gave rise to community open spaces and gardens near to nature, linear parks, waterfronts, and greenways accessible to pedestrians, so as to provide a diverse and resourceful environment for learning, manipulation, and enjoyment [2]. It should also be noted that, in urban studies research, open spaces and green spaces interact to a considerable degree.

As an aspect of urban planning, green spaces are an increasingly important factor influencing urban residents’ quality of life. Due to its significant environmental, social, and economic value, urban green space (UGS) is widely regarded as one of the most important indicators of sustainable development. Specifically, in addition to changing the physical dimensions of the city, enhancing its aesthetics, and boosting property values, UGS also provides space for recreational activities, promotes health and social well-being, fosters relations with nature, and creates beautiful landscapes [3]. Moreover, the health benefits derived from UGS are important for improving urban environments [4]. In the past two years, the perception and use of UGS have assumed a renewed importance against the backdrop of the COVID-19 pandemic, largely due to its capacity to improve mental health and physical activity levels [5]. On this basis, the importance of urban nature and open spaces as a means to prepare for pandemics cannot be understated. Although green spaces offer a multitude of benefits for urban residents, increasing UGS may trigger gentrification in neighboring areas, driving up housing prices and encouraging the development of more high-end facilities, which steadily pushes out existing residents so that more affluent individuals can move in [6].

Today, the majority of the global population live in urban areas. In 2045, there will be 6 billion urban residents, 1.5 times the 2020 urban population [7]. This shift will lead to an inevitable extension and/or increase in the density of urbanized areas and the transformation of green spaces, thereby opening up urban open spaces to dynamic change. In cities, the growth of residential and commercial areas and infrastructure has precipitated and expedited the decline of green spaces, as can be seen in the cases of Kuala Lumpur [8] and Hong Kong [9]. Elsewhere, other studies have observed that UGS are rapidly disappearing in cities located in Asian countries, such as Karachi, Pakistan [10] and Hanoi, Vietnam [11]. Anguluri and Narayanan claim that urbanization that does not also create green spaces has exerted many negative physical and social impacts on city residents. As such, there is value in studying the factors that influence the changes in urban open space [12].

However, the best way to research the formation and transformation process of open space in terms of size, shape, and function is based on urban morphology. This is because urban morphology relates to temporal conditions, and urban forms are affected by historical/periodical changes [13]. For this reason, urban morphology researchers attach importance to retrospective studies in order to understand the current situation and present conditions. In this way, the physical structure of the city can be analyzed and the evolution of the city explained by referring to both historical and contemporary research. The “morphology” of urban green space can be understood by referring to the basic levels of “form”, “distribution”, and “pattern”, as well as the correlations between the three. More importantly, there is insufficient literature available to study and understand the factors pertaining to urban green space morphology as integral research, and a focus on the interactions of individual characteristics and how they influence urban open space evolution.

2. Drivers Influencing Urban Open Space Morphology