**8. Conclusions**

As a relatively young and controversial phenomenon, principally caused by the recent digital transformation, the SE generates new factors which influence the sustainable development of local communities [128]. In this viewpoint article, we have considered the impact of the sharing economy on sustainability from the perspective of urban communities. We have presented overtourism as resulting from, collating or contributing to the sharing economy. We have also reflected upon the discussion, present in the literature, on a positive and negative impact of the SE on the environmental, economic and social aspects of the urban community in the tourism context. The picture that results from this discussion is fragmented and vague, so the need to find a new theoretical viewpoint has been pointed

out. Therefore, this article suggests that SCT is the framework allowing new insight into discussion on the impact of the SE on urban communities. It transfers the evaluative character of discussion to more general dimensions of bonding and bridging character of dynamically changing conditions of actions within communities. This article leads to conclusions on the bonds between SE, social platforms and sustainability of urban communities, which we present as a conceptual model. Then, we move to the conclusions on the key relationships assumed by this model. They refer to the influence of SE on social capital and the influence of social capital on sustainability in the context of overtourism in urban communities. In this way, the article refers to Dredge and Gyimothy's [19] call to show the broader impacts of the SE on local and regional economies and communities.

By an introduction of the SCT approach, this article implies an initial framework that extends understanding of the impact of the SE on sustainability. Thus, it presents a more colourful but also more organized picture of the changes that take place at the junction of new ways of doing business imposed by sharing platforms and local communities affected by the emergence of these activities. The designation of bridging and bonding social capital shows the way the SE influences a local community. In the traditional concept of the social capital, the community—regardless of whether it is a district community or a neighborhood one—emanates bonding capital within which all the residents know or are familiar with each other. The SE community members—the so-called peers, i.e., hosts and guests—produce and transmit bridging social capital through a short-term rental disseminated by the SE platforms. Both greater liveability of the neighborhoods and unfair competition in the local market are the impacts referring to inclusive social capital. The same phenomenon is associated with consumers (potential peers, i.e., hosts and guests) who do not use existing solutions but have the awareness and tools necessary for applying them. Adopting the social capital theory to study the impact of the sharing economy on local communities in the overtourism context allowed us to construct a conceptual model which illustrates the relations among the most crucial elements in the complex process of the SE impact on the sustainable development of communities in city destinations affected by overtourism (see Figure 2).

**Figure 2.** A model for studying the impact of the SE on the sustainability of urban destinations affected by overtourism. **Source:** Own elaboration.

The model presents the SE as an initiating factor—generated and distributed through sharing platforms focusing in the accommodation sector—which influence urban destinations by modifying social capital. Additionally, the SE directly influences the other dimension of a destination's development by stimulating the economy and degrading the environment, as is exhibited on Table 2. Nevertheless, the model focuses on changes in the social sphere within local communities and

sustainability in urban destination experiencing overtourism. Overtourism is the context, not the main subject of our analysis. Social capital is the central element of the model. Being under the influence of the SE, it undergoes significant modifications and also causes changes in the last element of the model (right side of Figure 2), i.e., sustainable development of the destination. The modifications apply to bonding and bridging categories of social capital, sharpening their most significant features, discussed in Table 4 and Figure 1. Thus, a new configuration of social capital emerges, i.e., sharing platform-modified social capital. It reveals some features partly taken over from both function of social capital identified by Putnam; however, the configuration is profoundly transformative. The process of changes in social capital is identified by the arrows and the dashed lines indicating the direction of flow and the scope of the process of shaping a new configuration of social capital. Over time, this capital may become dominant, modifying the entire system of sustainable urban development. Its impact does not only concern the community, but also other components of sustainable development, i.e., the economy and the environment.

The gradual transformation of the elements of the bonding-type capital into the bridging-type capital is associated with the expanding network of social relations due to the development of sharing economy. Conversely, the transformation of some aspects of the bridging-type capital into the bonding-type capital occurs mostly due to adverse changes in the city residents' quality of living incurred by the sharing economy. These processes result in the growing number of the reconfigured elements, while the most significant impact force lies in the bridging function of social capital. However, this force is not strong enough in the confrontation with the bonding-type capital to ultimately transmute one form of capital into the other. This leads to a situation where the new elements appear and come to gain significance.

The SCT view which we introduce to the discussion on the SE impact on local communities leads to certain conclusions in the field of sustainability. We assume that both bonding and bridging social capital—as coexisting in social life—are favorable for the sustainability of local communities, as they are in constant pursuit of mutual balance. For urban communities, all of the forms of social capital are required to support collective actions that might transfer to perceived short-term sustainability as well as to unsustainability. In the long-term view to which sustainable development finally refers, this 'game of balance' between two types of social capital should be perceived as an representation of sustainability. Tourism is associated with the influx of tourists, so the development of the SE enriches the social capital of the destination with the elements characteristic of the bridging social capital. The social capital enrichment is deep, especially in the spheres of the development of the community, entrepreneurship and openness to the world as well as the resulting advantages (economic, social, cultural, referring to the social modernization, etc.). At the same time, the bonding capital grows in the communities affected by overtourism under the influence of the sharing economy. Its growth manifests itself in undertaking various actions which integrate local communities by generating (or enhancing) activities to protect their interests and the quality of living that is endangered due to the SE's effects. Thus, we can conclude that in both cases, we deal with the accumulation of the social capital induced by the sharing economy in the context of overtourism.

The link between the sharing platform-modified social capital and urban communities in the context of overtourism is multidirectional. On the one hand, the SE itself affects the residents' quality of living and the environment negatively, as it changes the equilibrium between the bridging and bonding capital. The new configuration of social capital might favor unsustainability, as it is not balanced by any of these two traditional types of capital. It manifests itself in a reputation system imposed by the sharing economy platform to trigger and strengthen new binary host-guest relation, at the same time 'bracketing out' other tenants and creating new disruptive geographies [33]. In this sense, an 'exclusive face' of this new social capital affects the traditional bonding capital (as shown in Table 4). However, the relationship between them does not refer to balance but rather to confrontation. This explains the negative resident perceptions and attitudes towards the SE and the unsustainability discussion of this phenomenon.

On the other hand, the sharing platform-modified social capital helps to establish the network and continuously growing social relations resulting from a growing influx of tourists and the activity of the institutions engaged in providing them with various services. Also, it brings about changes in social capital, re-uniting local communities around the protests against the negative changes it causes to their standard of living. In effect, alongside its negative impact on environment, we have to deal with the advantageous changes in two other spheres which make up sustainable development, which are society and the economy. Thus, the sharing platform-modified social capital refers not only to a certain (and moderately fixed) set of characteristics of the traditionally perceived social capital but also to the level of its saturation. It can manifest itself in openness to new ideas, higher networking of social and economic structures, an increase in entrepreneurship and a readiness to develop new business models. The new balance, and thus new exclusivity, changes the conditions of the market game. It allows and involves actors who do not exist as part of traditionally understood exclusivity. This phenomenon can be compared to a sea wave, which in a diffuse, but a successive way models the shape of the coast regardless of the assumptions of its hosts. Virtual platforms are here a new kind of a market player which, although physically inaccessible in space (like a hotel reception), sets the rules of a market game that not all the current players are aware of. In effect, we deal with the modification of the configuration of the basic elements which make up the categories of the generally conceived social capital and also—in many cases—with its new elements.

Regarding the Putnam approach to bonding social capital as important for survival and bridging social capital as being good for making progress [129], we can state that sharing platform-modified social capital is particularly crucial to 'make progress' in this very relevant branch of the sustainable development of tourist cities. At the same time, however, that capital is explicitly negative for destinations, at least concerning social and environmental sustainability. In the case of the economic aspect, the issue is more complex, yet the opinions of a negative impact can also prevail (as exhibited in Table 2), particularly in the long-term. As social capital cannot be considered selectively, concerning one community or spatial area, the impact of the SE should not be considered in these terms either. Thus, even if the SE leads to some local unsustainability, e.g., in the form of overtourism, it cannot be generalized because in a broader business landscape, sustainability may increase at the same time. However, the evaluation of this impact should include whether the social capital is treated in an autotelic or instrumental way at a given moment [130], as well as which of these two functions is regarded to be the dominating one. This is strongly emphasized by Coleman [17] in his functionalist approach and integral vision of the social realm. Schindler [130] adds that for a given situation, one can decide which function the social realm has and which elements of a social structure appear relevant, whether they serve or do harm, or whether they are neutral for a community. The article is in line with another of Schindler's opinions that it is not the amount of social capital that counts, but its specific local features and the way it is used: to what extent it serves the communities which generate it and to what extent it is instrumentalized even contrary to their interests [130]. Thus, a question appears: to what extent can entities use social capital from a local community in a way which is not necessarily compatible with a community's interests?

Summing up, this article contributes to the discussion on sustainability of SE by adopting the SCT framework to explain its role and extent of impact on local communities in relation to overtourism syndrome. As the tourism industry is one of several spheres where the SE is diffusing, the study's results can be helpful for understanding the way that SE influences social capital and contributes to sustainability within urban communities. Following this approach, this article contributes to the discussion on overtourism by focusing on the relations between the SE and local communities, instead of only identifying the effects of the SE. Thus, it provides the new conceptual framework for studying the implications resulting from overtourism, which is in line of suggestions of Koens et al.'s [26] and Dodds and Butler's [74] calls for more in-depth insight into both SE sustainability and overtourism. Moreover, it supports Rodriguez-Giron and Vanneste's [103] suggestions that SCT may be helpful

in understanding the gap between intentions and efforts, as well as what can contribute to the improvement of a destination's ability to handle the impact of SE in more sustainable ways.

This article also contributes to discussion on social tensions that manifest themselves in the phenomenon of overtourism. The 'sharing effect' takes place in the sphere of accommodation host–neighbor relationships, i.e., business activities of flats/homes owners, the consequences of these activities for other tenants and their mutual inter-reactions. The tourist effect refers to the fact the accommodation is rented by tourists who are culturally-distant and use them for a short term and for leisure purposes, and therefore it is based on the interactions among them and other members of the neighborhood. Thus, medium-term problems arise (the long-term issues could not be observed yet) which affect local communities in many ways [26,27,74,92]. Applying Putnam's approach to the SCT, we can explain the role of the SE in the rise and growth of overtourism in urban communities as a gate through which the new configuration of social capital flows and emerges in a traditional community, enhancing the bridging side of social capital but confronting its bonding side. Overtourism, as a negatively assessed and perceived but short-term phenomenon, is fueled by the new configuration of social capital introduced by the SE in local communities. The dynamics of the violent growth of the SE in urban communities highlights the unsustainable sharing platform-driven social capital and pushes its inclusiveness to the background, causing the calls for laws and regulations [21,32,39,51].

The picture of the relations among analyzed phenomena and their effects is largely simplified, as the research in this field is still rare and underdeveloped. Similarly, our considerations have limitations resulting from the fact that they were based on a literature review and the area of the SE limited to the accommodation sector, although it certainly affects the overtourism to the most significant extent. Additionally, only the English-language studies indexed in the Web of Science and Scopus databases were selected for the systematic analysis. It can be expected that the research conducted in other countries and published in other languages could enrich the material and thus affect the cognitive and explanatory values of this work in a positive way.

This study puts forward several suggestions for further studies. To name a few, we start with sharpening of the discussion about what contemporary bridging and bonding SC becomes under the influence of SE in the area of tourism. Identification of the interplay between bridging, bonding and the new configuration of social capital affected by SE is sets the next issue that awaits identification. Having this in mind, we recommend further studies on the mechanisms and effects of the sharing economy and overtourism on the sustainable development of destinations and their communities using the concept of sharing platform-modified social capital and the matrix for identifying and analyzing the impact of the SE on the social capital of urban destinations. Understanding the factors that moderate generation of new configurations of social capital could be beneficial for academic and practical discussion. Finally, in the context of overtourism, studies could focus on finding ways of improving a destination's social capital-related capacity to self-determine its development path when it is affected by SE. As this article is strictly of a theoretical nature—which is its main limitation—the arguments and conclusions should be verified empirically by studying the impact of the SE on a selected community affected by overtourism. Analysis of the impact of the SE on the sustainability of a urban community using Putnam's approach of SCT in other sectors of the tourism industry and other spheres of social activity is also suggested.

**Author Contributions:** This article is a joint work of the four authors. Conceptualization, P.Z. and A.W.; literature review, P.Z., A.W. and W.A.; writing—original draft preparation, P.Z., G.L., A.W. and W.A.; writing—review and editing, P.Z. and G.L.; visualization, P.Z. and W.A.; supervision, P.Z. and G.L. All authors have read and agreed to the published version of the manuscript."

**Funding:** This research has been supported by a Poznan University of Economics and Business internal grant program called PUEB for Science—Novel directions in the field of economics". Project title: "Evolution of inter-organisational relationships as the result of the sharing economy's development: micro, meso and macroeconomic implications."

**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

## **Appendix A**



