**1. Introduction**

Preserving greenspace quantity and quality in the face of increasing urbanization is a pressing global challenge [1]. Greenspaces provide invaluable ecosystem services to humans that are important to plan for in cities [2]. Economic motives and urban neoliberal policies are liable explanations behind the loss of public space in many cities [3,4]. Public greenspace is an important component of public space [5] and could be defined as "any vegetation found in the urban environment, including parks, open spaces, residential gardens, or street trees" [6] (p. 113). Here, by public space is meant spaces in cities that are "owned by the government, accessible to everyone without restriction, and/or fosters communication and interaction" [7] (p. 9). This definition encapsulates Louis Wirth's notion of urbanism [8], taking into account how individuals interact with one another and with spaces. Public spaces facilitate human exchange and interaction, as in the form of urban squares and market places that traditionally have served as arenas for public communication and social interaction [9]. However, there is a massive shift towards the privatization of public land and resources in many cities today [3,10], a ffecting green spaces in a multitude of ways with repercussion for long-term managemen<sup>t</sup> of ecosystem services. While urbanization causes the direct loss of urban greenspace, comprising habitat fragmentation that involves both loss and/or the breaking apart of habitats [11], there exist more subtle forms of greenspace loss that ultimately are linked to property-rights arrangements. We here refer to such loss as incremental, occurring over a series of gradual declines or small steps but experienced at the cognitive level of urban space as 'baseline shifts' among urban residents.

Based on the literature related to institutions, economic geography, urban ecology, and social theory, we present a set of subtle drivers for why public green spaces gradually erode in cities. This gradual erosion, we argue, is often "invisible" in that it can almost exclusively be revealed by high spatial resolution remote sensing data [12] and that their e ffect can be translated into high social-ecological<sup>1</sup> costs that impinge negatively on human wellbeing [13,14]. Based on a set of examples of incremental greenspace change, this paper briefly discusses how urban planning authorities should avoid 'day-to-day planning' [15] and be more long-term oriented to meet an ever-increasing unpredictable future. Property rights theory in relation to natural resource managemen<sup>t</sup> emphasizes institutions at the interface between social and natural systems [16,17], where the term 'institutions' signifies the rules and conventions of society that facilitate coordination among people regarding their behavior [18]. At a more general level, institutions are made up of formal constraints (rules, laws, constitutions), informal constraints (norms of behavior, conventions, and self-imposed codes of conduct), and their enforcement characteristics; thus, they shape incentives in human exchange, whether political, social, or economic [18]. Ecologically oriented scholars define institutions simply as working-rules or rules-in-use, meaning "the set of rules actually used by a set of individuals to organize repetitive activities" [19] (p. 19). Thus, property rights link people to nature, and have the potential to coordinate the social and natural systems in a complementary way for both ecological and human long-term objectives [20].

Property-rights could also be viewed as slow variables in urban transformation; however, their monoculturalization in favor of urban privatization schemes may gradually erode urban resilience (i.e., 'bu ffering capacity' to deal with disturbance and novel events) and make planning bodies and local authorities less pertinent to propel urban growth along more sustainable trajectories that value ecosystem services as risk insurance and as adaptive capacity for responding to known and unknown disturbances. The paper concludes by proposing common property systems as a viable alternative for local governments to survive economic disruptions and in turning public spaces into places that urban residents themselves can manage for improving and protecting greenspace and associated ecosystem services.

#### **2. Urban Green Space Dynamics and Reasons for Their Incremental Demise**

The availability of public green spaces is foremost linked to the geographical location of a city [21]. However, urban expansion in many cities takes place almost exclusively at the expense of farmland [22], with changes in greenspace predominantly occurring in the urban-rural periphery [12]. Urban greenspace consists mainly of semi-natural areas, such as di fferent gardens, road and rail networks and their associated land, airfields, golf courses, parks, allotment areas, urban agriculture, etc. that together with formally protected nature reserves and Natura 2000-sites contribute to the generation of urban ecosystem services [23].

Quantifying spatiotemporal patterns of urban greenspace at more precise levels is reliant upon modern remote sensing techniques. Hence, more steadfast comprehensive assessments of detailed greenspace change are scarce in the ecological literature related to urban systems [24]. Previous studies have also come to di fferent results. For example, Kabisch and Haase [6] could not find a significant change in Western and Southern European cities between 1990 and 2000; but found a significant increase of greenspace in the period from 2000 to 2006. In a study of 386 European cities, Fuller and Gaston [1] found a dramatic drop in per capita green space provision in cities with high population

<sup>1</sup> By the term 'social-ecological' is here meant a set of critical natural, socioeconomic, and cultural resources (or, capitals) whose flow and use is regulated by a combination of ecological and social systems.

density, likely due to more people being packed into the urban matrix rather than buildings replacing existing green spaces. They also found that access to greenspace rapidly declines as cities grow, decreasing opportunities for people to experience nature. Following post-socialist changes many East-European cities have experienced a decline in greenspace [25,26]. Similarly, McDonald et al. [24] found an open space loss between 1990 and 2000 for all the examined 274 metropolitan areas in the contiguous United States. While many Chinese cities show mixed results, with both increases and decreases, cities in many developing countries are losing green spaces at a rapid pace [12].

Despite the massive shift towards privatization of public land and resources [3,10], comprehensive studies that have examined the relationship between loss of green spaces and ownership regimes are greatly lacking. However, it may not be far-fetched to assume that much of the privatization of public space involves greenspace. While this loss comprises direct habitat loss and the breaking apart of habitats [11], few scholars have addressed more subtle causes behind urban greenspace loss, but see Mensah [27]. In the following we present a set of examples of incremental demise of public urban greenspace.

#### *2.1. Lack of Financial Support*

One of the major reasons behind the privatization of public space is financially strained local governmen<sup>t</sup> budgets, that strain results in the outsourcing and the alienation of land to private interests and the privatization of services that previously were publicly delivered. There exist plenty of examples of how tightening budgets are leading to declines in the quality of green spaces and loss of ecosystem services, due to the lack of staff and maintenance resources [27,28]. The Heritage Lottery Fund—a large funder of heritage in the UK—reported in 2013 that almost half of the local park authorities were considering selling parks and green spaces or transferring their managemen<sup>t</sup> to private entrepreneurs [29]. Considering the current recession due to the Covid-19 pandemic, one can only imagine how this situation will worsen.

There has also been an increase in long-term leaseholds to allow the transfer of public land, such as parks and other green spaces, to not-for-profit trusts and to resident-led managemen<sup>t</sup> bodies [30]. While public land may be alienated from the ownership of local governments, privatization predominantly takes place through a mixture of transfers of governance and managemen<sup>t</sup> responsibility from the public sector to a number of other actors in the private, voluntary, and community sectors [7,30], and with the degree of privatization ranging from full to partial outsourcing of responsibilities [4].

Public–private partnerships (PPP) constitute a well-known example of 'contractual governance', which increasingly is used to re-develop and manage public spaces, especially as capital investments [30]. Through a PPP, a local authority or a central-government agency sign a long-term contractual arrangemen<sup>t</sup> with a private supplier for the delivery of services and taking of responsibility for building infrastructure, financing the investment, and managing and upholding the facility [31]. PPPs are increasing across Europe, Canada, and the United States, as well in some developing countries [31]. Business improvement districts (BIDs) are an example of a PPP in which a local authority and a business community together develop schemes to benefit a local district area [32]. The services provided through this type of contractual arrangemen<sup>t</sup> could, for example, include improvements and attractiveness of physical areas [7] and managemen<sup>t</sup> of public parks [33,34].

#### *2.2. The Separation of Attributes*

A critical fate that can affect underfinanced public spaces is the separation of attributes, which in economic theory can be expected when it is cost-effective and if sufficient demands for this exist [3]. In an overcrowded public domain, markets and governments will strive towards a separation of rights to land according to different attributes. This may be done in order to reduce potential conflicts and to lower transaction costs related to the governance of public space. In this way, the rights to different attributes of a park can be separated and granted to various user groups, such as devising demarcated land for leisure, habitats for wildlife, sporting areas, etc. [35]. Separation of attributes can also involve

alienation or leaseholds of bits and pieces of public greenspace. There exist several cases where underfinanced public parks have been opened up to private interests, such as to restaurants, cafés and other social spaces. While local governments can reinvest the revenues from rents and/or property taxes for restoring degraded greenspace, profits are often instead used for other purposes [28,35].

#### *2.3. Increased Private Control*

Another subtle form of driver linked to urban greenspace change is the increased control and surveillance of public space [7,36]. Increased surveillance and policing over public space will likely intensify with an increased number of terror attacks as witnessed in many parts of the world. Today, much control of public space is outsourced to private corporations, making the boundary between public and private policing complex [37]. New York and Tokyo are telling examples of cities that lose much public space [36]. With increasing fear of terrorism after the Tokyo sarin gas attack in 1995 and the 9/11 attack in New York, many places where people formerly could relax from stress and annoyance have been eradicated [38]. Not only has an increased fear of terrorism acted as a vindication for imposing restrictions on the use of public sidewalks and plazas, but also in the use of natural habitats [38]. During the Covid-19 pandemic, the lack of public space in New York City prompted the banning of cars on certain streets in order to provide more space for pedestrians to upkeep social distancing. In contrast, green spaces in Sweden served as vital areas for social distancing [14].

Control of public space could be in the form of private police and/or surveillance equipment. While it may not directly lead to the loss of public space it can affect public space in more indirect ways, such as making people feel monitored and subsequently avoiding such spaces. The integrity of peoples' personal lives is increasingly also becoming jeopardized as digitalization is increasing in many cities [39]. While control can affect public green spaces the same way as it affects any other type of monitored public space, it especially can affect people's accessibility and use of urban green space. Many dwellers in urban areas display a fear of nature due to cultural reasons [40]. Lush green area habitats may be frightening for people due to lack of safety; hence, such habitats are sometimes replaced for safety reasons, e.g., increasing the width of sidewalks or increasing the occurrence and brightness of street lights, [41] thereby affecting greenspace negatively.
