Host and Guest Social Exchange in Developing Tourist Sites: The Case of the International Tagus Natural Park

This paper delved into host and guests’ social exchange influences on their social and economic welfare at the International Tagus Natural Park. In this developing touristic territory, a preliminary study was surveyed in-depth. Among Portuguese and Spanish bordering villages, interviews with hosts were conducted. Two focus groups were set up to analyse the host and guests’ reciprocal behaviour as well as social reciprocity in the context of a pilot participative programme. Eventually, 194 questionnaires collected among Spanish and Portuguese hosts through a structural equation modelling of causal relationships data were analysed. Theoretical and practical conclusions can be drawn from the study. Social exchange has driven hosts to focus on promoting social values, emotions, attitudes and social reciprocity to welcome guests as complementary income to raise their standard of living. Visitors provide supplemented incomes to impoverished hosts. However, the seasonal and unstable job opportunities guests create display negative effects among locals.


Introduction
Tourism is considered to be one of the most important drivers of wealth and economic growth [1]. The benefits are especially obvious in destinations that have barely enough financial resources to survive. An example of this is the International Tagus Natural Park, in the Extremadura region of Spain ( Figure 1). It was given its name in Decree 187/2005 [2].
The International Tagus National Park was declared a Portuguese national park on 18 August 2000 [3]. In 2012, Spain and Portugal signed a cooperation agreement with the aim of managing its two sections, which were separated by the border. Four years later, because of its excellent natural environment, it was designated as a Transboundary Biosphere Reserve.
The park's outstanding natural resources contrast sharply with its economy. In 2017, the gross domestic product per capita (GDPpc) in the park was the lowest in Spain-EUR 16.981 per inhabitant, compared with the Spanish average of EUR 27.558. In the same year, average personal earnings (PIBpc) in Portugal were EUR 19.209, and EUR 13.100 in the villages belonging to the park [4]. High unemployment rates and job instability characterise the territories on both sides of the border. These negative features have accelerated the decline in population in Extremadura in relative terms (with an inter-annual variation rate of −0.8% for 2016-2017) [5]. The lack of economic resources provides a framework for a study of Tagus International Park. Tourism will be crucial in the economic growth of Extremadura and Alentejo [6]. The International Tagus National Park was declared a Portuguese national park on 18 August 2000 [3]. In 2012, Spain and Portugal signed a cooperation agreement with the aim of managing its two sections, which were separated by the border. Four years later, because of its excellent natural environment, it was designated as a Transboundary Biosphere Reserve.
The park's outstanding natural resources contrast sharply with its economy. In 2017, the gross domestic product per capita (GDPpc) in the park was the lowest in Spain-EUR 16.981 per inhabitant, compared with the Spanish average of EUR 27,558. In the same year, average personal earnings (PIBpc) in Portugal were EUR 19,209, and EUR 13,100 in the villages belonging to the park [4]. High unemployment rates and job instability characterise the territories on both sides of the border. These negative features have accelerated the decline in population in Extremadura in relative terms (with an inter-annual variation rate of −0.8% for 2016-2017) [5]. The lack of economic resources provides a framework for a study of Tagus International Park. Tourism will be crucial in the economic growth of Extremadura and Alentejo [6].
Tourist activities have been seen as one of the major sources of the host´s supplementary income [7], especially the "host and guest" exchange [8]. According to Blau [9], host and guest interaction provides both parties with significant resources, which can only be provided when there is such interaction. It is therefore important to analyse how the actors involved influence social cohesion, to explain cooperative behaviour [10], and to examine the psychological factors that might positively transform residents' attitudes towards tourist activity [11][12][13].
In attempts to improve the social and economic conditions of impoverished regions, the relationship between host and guest has been widely discussed from the guest´s perspective [14]. However, little attention has been paid to the host´s point of view [15][16][17][18] nor to the impact of touristic host and guest relations in general [19].
The present study investigates the contribution made by the host and guest exchange to the host´s social and economic welfare in respect of reciprocal behaviour and social reciprocity, and the influence these have on both the host and guest´s standard of living. It is hoped that it will help in the formulation of long-term strategies for the destinations in question [20]. Tourist activities have been seen as one of the major sources of the host´s supplementary income [7], especially the "host and guest" exchange [8]. According to Blau [9], host and guest interaction provides both parties with significant resources, which can only be provided when there is such interaction. It is therefore important to analyse how the actors involved influence social cohesion, to explain cooperative behaviour [10], and to examine the psychological factors that might positively transform residents' attitudes towards tourist activity [11][12][13].

The Socioeconomic Welfare of the Community (SEW)
In attempts to improve the social and economic conditions of impoverished regions, the relationship between host and guest has been widely discussed from the guest´s perspective [14]. However, little attention has been paid to the host´s point of view [15][16][17][18] nor to the impact of touristic host and guest relations in general [19].
The present study investigates the contribution made by the host and guest exchange to the host´s social and economic welfare in respect of reciprocal behaviour and social reciprocity, and the influence these have on both the host and guest´s standard of living. It is hoped that it will help in the formulation of long-term strategies for the destinations in question [20].

The Socioeconomic Welfare of the Community (SEW)
In the recent decades, local communities have sought to improve their standard of living by promoting the leisure industry [9]. Guests not only help to maintain the host´s public services but generate better job opportunities, and higher incomes for local businesses. This encourages young people to stay in the region [10].
In the case of the Tagus International Park, budgets have been allocated to non-profit associations, institutions and local action groups. According to the tourist office, 26 initiatives were founded between 2014 and 2018. During this time, job opportunities in every municipal territory increased each year by an average of 5% [21]. However, socioeconomic benefits can have undesirable side effects [18]. More tourism means higher local taxes to pay for extra-local services for visitors, such as energy [22], security [23], water use [24] and a solid waste collection system [25].
Tourism-generated revenue has benefited foreign companies rather than the local workforce. Foreign tourism companies are hired instead of local ones [26], and the profits are not re-invested in the region. The enlistment of foreign companies is justified on the grounds that the region has insufficient Sustainability 2020, 12, 7248 3 of 18 resources [27]. Moreover, local revenue depends on external sources of technology and basic supplies. Unstable and seasonable employment and low salaries [28] are characteristic of international parks in Spanish developing territories, which are lacking financially, technologically, economically and structurally [29].
All these issues need to be translated into continuing touristic initiatives in areas that otherwise have impressive natural, cultural and social resources.

Host and Guest Social Exchange
The social exchange theory provides a means of examining, in the host communities, the social relationships between host and guest [30]. It was introduced by Blau [9], who argues that social interactions provide significant socio-economic resources when the behaviour is oriented towards objectives. Actors can only access these by interacting with others. That interdependence, based on complementary arrangements, is the key factor in social exchange.
The interdependence through social contact between guest and host is essential in economically underprivileged territories, not only as a way of increasing the standard of living [31] but also of increasing the possibility that the guest may return, to the satisfaction of both parties [32].
Social exchange theory aims to optimise the mutual benefits of the host and guest relationship by explaining to the host the impact of tourism on their territory [33]. The interaction can be positive or negative for the community, depending on the level of mutual commitments, whose rules are defined by the participants [30]. The hosts who benefit from tourism in developing tourist destinations have a more positive attitude towards tourism. They perceive a lower negative social and environmental impact than those in developed territories [34].
Social and environmental impact is affected by external factors, such as cultural, financial, environmental, political and legal issues [35]. Internal factors influence the host´s hospitality in terms of their emotions, behaviour and values [36]. Reciprocal behaviour and social reciprocity are internal factors that contribute to enhancing the host-guest social relationship.

Reciprocal Behaviour
As an internal factor, reciprocal behaviour primarily appears through host and guest emotions that are generated by the tourist experience [37]. Positive emotions lead locals and visitors to act correctly, and engage in specific goal-related social action [38].
To explain how emotions are expressed in personal behaviour, Schwartz [39] introduced the norm activation model, which has been successfully tested in tourism contexts [40]. The model begins with the knowledge of the consequences, which encourages an attitude of responsibility. The responsible behaviour leads the individual to develop norms in acting correctly. According to Heberlein [41], responsible action in the area of tourism becomes a key factor in improving the social exchange.
In economic underprivileged touristic territories, the need for economic resources moves the host to act responsibly and to create personal norms to influence the guest´s experiences. These experiences not only affect the guest´s affection towards the locals and the territory but also their loyalty, trust, mutual respect and personal attitudes [42]. Those attitudes encourage individuals to behave in a particular way towards an object that can be developed individually or socially [43].
Social exchange is also affected by traditional values [44] that influence the host´s attitudes [45]. Thus, values and attitudes not only influence reciprocal behaviour [40] but also provide a unique social relationship [29].

Social Reciprocity
A host and guest´s social relationship is based on a reciprocated response, as well as on the mutual obligation to commit themselves to each other [46]. As a result, social reciprocity plays a key role in the process of providing the necessary means of achieving those obligations. The host and guest exchange influences the social cohesion of the community. According to Ap [33], from a tourism perspective, social reciprocity is measured through a model developed between the interconnection of hosts and guests. The model defines the variables in the host and guest exchange [33]. These variables are: the need for satisfaction, the relationship of the exchange and the consequences of exchange and non-exchange. The starting point of this model is social relations, which imply an exchange of socio-economic resources between the social agents and mutual advantages. Figure 2 illustrates the positions of each party (Actor A and B) in the tourist exchange.

Social reciprocity
A host and guest´s social relationship is based on a reciprocated response, as well as on the mutual obligation to commit themselves to each other [46]. As a result, social reciprocity plays a key role in the process of providing the necessary means of achieving those obligations. The host and guest exchange influences the social cohesion of the community.
According to Ap [33], from a tourism perspective, social reciprocity is measured through a model developed between the interconnection of hosts and guests. The model defines the variables in the host and guest exchange [33]. These variables are: the need for satisfaction, the relationship of the exchange and the consequences of exchange and non-exchange. The starting point of this model is social relations, which imply an exchange of socio-economic resources between the social agents and mutual advantages. Figure 2 illustrates the positions of each party (Actor A and B) in the tourist exchange. Boxes 1 and 4 convey the balanced exchanges that represent the high and low levels of power, respectively, exercised by the two sides of the relationship. When the power of actors is high for both, the exchange is mutually beneficial. Then, when individuals have many socio-economic resources to exchange, they are more likely to be able to gain some advantage from it. It is also possible that both actors possess low levels of power (box 4). Hence, the consequences of the exchange do not produce the anticipated advantages. In this case, the resources available in the exchange have a limited value. Boxes 2 and 3 represent an unbalanced exchange where the power of actors is different. Depending on the position of power of one of the actors with respect to the other, the exchange may or may not be advantageous. According to Ap [33], the one with the greatest power holds an advantageous position at the expense of the other, who did not obtain the significant resource expected. In tourism, that interaction generates potential imbalance depending on the fair balance among individuals who are rewarded or punished depending on their response to the other [47]. From this punishing or rewarding behaviour, guidance can be provided to balance the reciprocated attitudes towards others [48]. The reciprocated response influences attitudes and behaviour when choices have to be made that can yield satisfaction by reciprocating properly with another by offering opportunities and attitudes equal to those previously received [49].
In tourism, social contact between host and guest depends on the frequency and intensity of the touristic encounter [32]. That encounter starts when touristic information is provided to the guest, influencing the guest's touristic decisions and behaviours [50]. Deeper host and guest relationships emerge when the tourist seeks to have an "intimate" social relationship based on cultural and daily life, which is genuinely perceived to be more authentic [51]. Box 1 and Box 4 convey the balanced exchanges that represent the high and low levels of power, respectively, exercised by the two sides of the relationship. When the power of actors is high for both, the exchange is mutually beneficial. Then, when individuals have many socio-economic resources to exchange, they are more likely to be able to gain some advantage from it. It is also possible that both actors possess low levels of power (box 4). Hence, the consequences of the exchange do not produce the anticipated advantages. In this case, the resources available in the exchange have a limited value. Box 2 and Box 3 represent an unbalanced exchange where the power of actors is different. Depending on the position of power of one of the actors with respect to the other, the exchange may or may not be advantageous. According to Ap [33], the one with the greatest power holds an advantageous position at the expense of the other, who did not obtain the significant resource expected. In tourism, that interaction generates potential imbalance depending on the fair balance among individuals who are rewarded or punished depending on their response to the other [47]. From this punishing or rewarding behaviour, guidance can be provided to balance the reciprocated attitudes towards others [48]. The reciprocated response influences attitudes and behaviour when choices have to be made that can yield satisfaction by reciprocating properly with another by offering opportunities and attitudes equal to those previously received [49].
In tourism, social contact between host and guest depends on the frequency and intensity of the touristic encounter [32]. That encounter starts when touristic information is provided to the guest, influencing the guest's touristic decisions and behaviours [50]. Deeper host and guest relationships emerge when the tourist seeks to have an "intimate" social relationship based on cultural and daily life, which is genuinely perceived to be more authentic [51].
In developing areas, those relationships are led by mutual interactive activities, such as farm-stays, collective meal preparation, educational tours and so on, that are characterised by small-scale and locally owned and controlled operations [52]. These activities might ultimately be amongst a host and guest's memorable and meaningful experiences [53]. It is important to find a balance between the host and guest. Hosts should avoid the invasion of guests' privacy and guests should restrain their behaviour based on obligation and restriction [54].
It is important to take into account that there are different types of attitudes held between hosts and guests. Whereas some guests are keen to interact with hosts, others abstain from starting any interaction and are only interested in consuming touristic services [55].
From that perspective, it is essential to analyse not only how social actors influence the host and guest social cohesion, but also their cooperative behaviour. Cohesion and cooperation, facets of the reciprocal behaviour between host and guest, should be managed for mutual benefit and to avoid conflict [10,19,56]. The following hypotheses were formulated in light of the above.

Hypothesis 1 (H1).
Reciprocal behaviours (RB) positively affect the social and economic welfare of the community (SEW).

Hypothesis 2 (H2).
Social reciprocity (SR) between the host and guest positively affects the social and economic welfare of the community (SEW).

Host and Guest Touristic Participative Plan (TPP)
Scholars have studied the impact of tourist plans on hosts and guests [57,58]. They have found that those programmes are not only related to the quality of tourism services provided [35,59] but also to host and guest interaction within a participative plan [10,60].
A general tourist plan alone is not enough of a solution to make traditional rural industries more attractive to the host and guest community. Touristic plans should reinvest in guests' feedback to involve hosts in the promotion of their own touristic resources [61]. This connection allows hosts to participate in touristic activities detailed in the touristic participative programmes [62].
Touristic programmes are not only a matter of accommodating and entertaining the visitors [63] but of making improvements to touristic activities according to the host and guests' feedback [61], by introducing improvements to the current development and management of tourism [60] through the collection of well-informed opinions from the touristic initiatives [64].
In Extremadura, natural and cultural touristic activities are approved through the Tourism Plan of Extremadura (2017-2020) and regulated by Decree 187/2005 [2]. As Law 7/1985 [65] states, every municipality is competent enough to govern its own touristic initiatives. Local governments invest funds to maintain and update cultural-natural tourist places as well as to promote studies to improve the relationship between host and guest as a way of increasing the host´s socio-economic welfare.
The studies that have promoted these relationships are well aligned with the host and guest social exchange, which is vital to ensure and encourage the success of tourists' visits to the territory [66]. The points raised above reveal several relationships that allow the formulation of the following hypotheses.
Hypothesis 6 (H6). Touristic participative planning (TPP) positively affects the social and economic welfare of the community (SEW).

A Preliminary Study
To ascertain the level of impact of tourism on hosts, eighteen municipalities were randomly selected on both sides of the Targus International Park. Between the 1st and 15th November 2019, 70 Spanish and 72 Portuguese hosts were randomly chosen to participate in the study; 56% were under 50 years of age, 57% were currently working and nearly 66% had only studied to high school level. Table 1 shows the demographic data. To measure the host´s perception of the tourist contribution to the local economy, several items were covered: the general improvement of standard of living of the host [67], generation of companies, improvement in the employment rate and young people´s exodus from the villages [68]. Questions were ranked between 1 (not important at all) and 10 (extremely important). Table 2 shows that guests' contribution to the hosts' economic conditions were lower in Portuguese villages (8.28) than Spanish ones (9.26) because the former received a lower numbers of visitors and possessed relatively fewer economic resources than the former [5].  From the study population, a pilot participative programme was set up in two municipalities at the Tagus International Natural Park to apply the social exchange theory and to consider it from a host´s perspective. Using an interactive methodology, proposals were disseminated, and tourist offices in Alcántara and Brozas became the centre for dynamic participative methods after March 2019. Over a period of six months, tourism initiatives were assessed by hosts as well as guests.
During that time, feedback about tourist plans were collected and sent to the decision-makers. A summary of the feedback was shared with locals at those tourist offices. Since the pilot project began, two surveys have been organised. These measured the economic role that tourism and social relationships played in these impoverished and subsidised villages. In this scenario, tourism is a highly valued mechanism to supplement income.
To measure the development of the participants from September 2019 to March 2020, four questions related to the host´s standard of living were made. They were ranked from 0 (not important all) to 10 (extremely important). A total of 475 responses were collected from a population of 3530; of these, 55% were from guests and 45% were from hosts. Table 3 shows that economic and social exchange is highly valued. Amongst the answers, host and guest feedback had the least relevance for both locals and visitors. However, it saw the highest increase in six months, compared with the trend in the other items which remained almost the same.

Variables and Model
For the pilot programme, two focus groups were set up to discuss what variables should be selected to analyse the guests' contributions to the hosts' economic welfare. From the debate organised in the first meeting, 16 items were presented and discussed in the second meeting. The variables originally proposed were addressed in the first meeting and introduced to hosts: host´s socioeconomic welfare (SEW); reciprocal behaviour (RB); social reciprocity (SR); and touristic participative plan (TPP). According to the results, two items were eventually deleted, for two reasons. Not only were public institutions and maintenance services not mentioned, but undesirable economic and environmental side effects for hosts were not significant enough to be taken into account. Similarly, 12 items were corrected and modified. Eventually, the participants approved the list of attributes (see Table 4).
The final items from the four variables were supported by the literature review. From the delineated items, a Likert scale was used based on Teye et al. [69]. The questions were validated by a group of 15 hosts and 30 guests chosen at random from five villages. No variation was implemented. From September 2019 to March 2020, 194 questionnaires were collected in 18 villages within the park. The questionnaires were approved through the "ethical clearance" process of the University of Extremadura (Document 039-19). Based on the variables and the items, the model is presented according to the hypotheses drawn from the literature review ( Figure 3). The questionnaires were approved through the "ethical clearance" process of the University of Extremadura (Document 039-19).
Based on the variables and the items, the model is presented according to the hypotheses drawn from the literature review (Figure 3).

SEM-PLS Methodology
To answer the question of how the host and guest relationship contributes to socioeconomic welfare in developing territories and, to formulate strategic theories to provide solutions, an SEM-PLS methodology was adopted [70]. This is recommended for analysis in social science [71] because of its predictive accuracy. The model visually presents the relationships between variables. It also helps to prioritise resources to improve the hosts' socioeconomic welfare in underdeveloped territories, and could be replicated in other similar scenarios [72].
PLS-SEM is the most commonly used application for the analysis of quantitative data. SmartPLS (version 3.2.7) Software assesses the path coefficients to better understand the relationship between Model. Note: SEW: host socioeconomic welfare; RB: reciprocal behaviour; SR: social reciprocity; TPP: touristic participative plan.

SEM-PLS Methodology
To answer the question of how the host and guest relationship contributes to socioeconomic welfare in developing territories and, to formulate strategic theories to provide solutions, an SEM-PLS methodology was adopted [70]. This is recommended for analysis in social science [71] because of its predictive accuracy. The model visually presents the relationships between variables. It also helps to prioritise resources to improve the hosts' socioeconomic welfare in underdeveloped territories, and could be replicated in other similar scenarios [72].
PLS-SEM is the most commonly used application for the analysis of quantitative data. SmartPLS (version 3.2.7) Software assesses the path coefficients to better understand the relationship between the exogenous constructs such as reciprocal behaviour; social reciprocity; touristic participative plan factors; and hosts' socioeconomic welfare as the endogenous latent variable [70].

Results
A structural equation model (SEM) was used to explain how the host perceives tourist activity in the International Tagus Natural Park. This method is convenient when observable variables or indicators measured by latent variables are related [73]. This approach is based on structural equation modelling to visually examine the relationships between unobservable or latent variables such as the conveyed in the hypotheses [74]. As was noted above, it is recommended for social science analysis is predictive accuracy, which means that the model could be replicated in other scenarios [74]. According to Hair, Hult, Ringle and Sarstedt [72], reliability and validity should be examined.
PLS path modelling is a well-established method for analysing structural equations. It has been used by various researchers in organisation and business management and tourism [73,[75][76][77]. It first determines the estimation of the measurement model and second, the structural model [78]. This technique is less rigid concerning minimum requirements on sample size and the nature of the scales of measurement compared with other methods based on covariances [72]. To structure the data, SmartPLS software version 3.2.3 was used [78].

Analysis of the Measurement Model
The measurement model, employing only reflective measures, yielded satisfactory results after deleting the item TPP1. Its original value was 0.663 < 0.7 [79], so it was deleted. After running the model again, all items loaded as expected and were significant at the p < 0.05 level ( Table 5). The evaluation of the measurement model is shown in Table 6. According to Chin [80], the model is considered acceptable if the loads are greater than 0.5. Fornell and Larcker [81] establish the values of the composite reliability through the extracted mean variance (AVE). It should exceed the recommended limits of 0.7 and 0.5, as is demonstrated. In accordance with Fornell and Larcker [81], the discriminant validity and the Heterotrait-Monotrait method were analysed [82]. The first indicator evaluated the discriminant validity through the comparison between the square root of each AVE on the diagonal and the correlation coefficients. The values of the diagonal were higher than rows and columns, and therefore the discriminant validity was approved. In relation to the second Heterotrait-Monotrait (HTMT) indicator, values obtained should be less than 0.90 [83], so they were accepted (Table 7).   [71]. These indicate a good overall fit for the model.

Analysis of the Structural Model
Once the convergent and discriminant validity of the measurement model was confirmed, the relations between constructs were tested, by obtaining the different statistical parameters using the bootstrapping method (5000 sub-samples). Support for the hypotheses was based on the sign, the value and the significance of the t-values in each of the path coefficients (β) [74]. As we can see in Table 9, the hypotheses were significant.  According to Chin [80] R 2 values were described as 0.67, 0.33 and 0.19 and as substantial, moderate and weak, respectively. The inner path model was described as substantial (R 2 = 77.5). It meant that SEW was substantially explained by the three exogenous variables: RB, SR and TPP.
The predictive relevance of dependent constructs was also significant. It was obtained by calculating the value of Q 2 (cross-validated redundancy index) through "blindfolding" [84]. Q 2 (SEW = 0.334) > 0, so the model had predictive capacity (Table 10) [85]. To complete the analysis of the structural model, the goodness-of-fit was calculated from the goodness-of-fit (GoF) indicator from the standardised root mean square residual (SRMR) proposed by Hu and Bentler [86]. In our case, the value of SRMR was 0.63, which was below the 0.08 recommended by Henseler et al. [85], so it can be said that the model had a good quality.

Discussion
This research analysed the influence of host and guest social exchanges on the communities' social and economic welfare at the International Tagus Natural Park. The underprivileged natural territory contains communities with earnings under the average in Spain and Portugal. This situation has persuaded hosts to find ways of supplementing their incomes to improve their socioeconomic welfare.
Based on 194 hosts´questionnaires in 18 villages, a model was presented. It shows that reciprocal behaviour (RB) and social reciprocity (SR), as well as the touristic participative plan (TPP), have become powerful tools to open up the economically underprivileged territory to new visitors. Its substantial explanatory capacity (R 2 = 77.5%) conveyed the fact that host and guest social exchange has become a crucial way of increasing the social and economic welfare of the community. As a result, tourism has become an important element in helping to ensure the economic growth of Extremadura and Alentejo, which was one of the aims of the present study [6]. The hosts considered tourist activity as one of the major sources of supplementary income [7]. The results also showed that the participative programme amongst hosts, who proposed and designed the items, was central in attaining the high significance of the model presented. Similarly, the predictive capacity of the dependent variable SEW was also high (Q 2 = 0.461). These are convincing reasons why the model should be applied to international parks with similar socioeconomic conditions.
Significantly, all the hypotheses were confirmed; reciprocal behaviour (RB) between hosts and guests (RB → SEW: β = 0.362; t = 3.575) and social reciprocity (SR→SEW: β = 0.344; t = 3.449) positively influenced the community´s socioeconomic welfare. According to Sinkovics and Penz [31], social contact between guests and hosts is essential in developing territories if the latter are to increase their standard of living. That reciprocity affects both guest intention to return and host satisfaction [30]. The results showed that social exchange theory encourages the interaction between the parties (host and guest) as a way to implement a cost-benefit analysis.
The results also revealed that, in low income territories, reciprocal behaviour (RB) and social reciprocity (SR) optimise the guests' and hosts´mutual benefits and social relationship by providing socioeconomic reasons to guide these relationships [33]. As a result, the host´s experiences, values, attitudes and behaviour are considered relevant as a way of promoting the touristic encounter, which helps to upgrade that deprived territory. In other words, from the survey it can be deduced that the costs of the host and guest relationship are lower than the rewards the settled community receive from guests. Efforts are reciprocated within the park. Table 11 shows that host and guest relationships in the Portuguese municipalities promote that reciprocity more than Spanish ones because those areas are less economically developed [6]. Supplemented incomes are needed relatively more in the Portuguese territories, so there is a greater need for them to develop their economies. Portuguese hosts consider their traditional values as of assistance in providing a high-quality service to guests (9.4) as well as in fulfilling their touristic obligations (9.3). As Eusebio, Kastenholz and Breda [87] highlight the relevance of the traditional values to provide a professional service to guest. That touristic service amongst tourism stakeholders such as visitors, public and private agents of products and services and hosts are measured according to their behaviour, satisfaction, host-guest interaction and perceptions of the tourism phenomenon and its implications on the villages' development. Residents are very pleased with tourism in the village, and are willing to attract more visitors and encourage the emergence of new tourist activities. They tend to view tourism as a positive activity that has contributed to the revitalisation of the village, therefore being in favour of tourism development. Residents suggest the creation of recreational activities as well as the improvement of commercial and other services to make tourists stay longer. Table 11. Host´s perception of guest's touristic activities.

Items P S
Host's perception of the host and guest hospitality experiences 9.0 7.8 Host´s attitude towards guests are driven towards gaining the guest´s affection, loyalty and mutual respect 8.9 7.9 Host´s traditional values are essential to provide a high-quality service to guests 9.4 7.4 Host´s interest to reduce the social distance with guests 8. As Table 11 indicates, on the Spanish side, hosts are especially committed to fulfilling their professional obligations (8.5) and their involvement in touristic activities and local authority planning (8.4). That engagement is well explained by Canoves, Villarino, Priestley and Blanco [88]. There is a need to sustain population levels in Spanish rural areas in the face of rapid depopulation. The new rural economy was based on family businesses and, as in the rest of Europe, constituted a strategy for the diversification of farm and economic activities. The strategy for the survival of small family farms has been focused on specialising in new products, or providing complementary touristic activities. At this stage the engagement has been mainly promoted by the female members of the family who welcomed the guests into rural homes, promoted the values of the local culture and organised food and accommodation [89].
Therefore, host and guest integration in this developing territory is not only positive but also affirms that their mutual commitments [20,45] are balanced in terms of costs and benefits for the community [89].
A tourist participative plan not only positively affects the host´s socioeconomic welfare (TPP → SEW: β = 0.331; t = 3.169) but also mediates its effect on the reciprocal behaviour between host and guest (TPP →RB: β = 0.509; t = 6.928) as well as their social relationship (TPP →SR: β = 0.372; t = 3.370). Even though the participative plan is applied to the Spanish side only, data show that hosts are willing to work on a participative plan scenario by contributing to surveys to improve local tourism [10,61].
There are grounds to say that tourism at the International Park responds to hosts' expectations by promoting social exchange between host and guest despite the social and economic uncertainty and the seasonality of the occupation.

Conclusions
According to Ap [33], the main reason to initiate the host and guest exchange, from the resident's point of view, is the improvement of the social and economic well-being of the community. Host perceptions and attitudes are predictors of behaviour towards tourism in host-guest exchanges in the tourism sector. As the most impoverished region in Spain and Portugal, the International Tagus Natural Park has recently designed a pilot tourist strategy not only to improve hosts' social and economic welfare but also to promote the outstanding natural and touristic resources of the area, such as travelling by ship along the Tagus River, visiting local villages with castles, dolmens, necropolises, roman granite tombs and historical ruins, birdwatching and visiting the environmental interpretation centre and the Roman Bridge (2nd century BC) in Santiago de Alcántara, as well as other tourist hotspots and natural resources.
However, in contrast to other studies [69], economic uncertainty in this destination has added a new positive perspective in the social exchange theory. Touristic aspects such as the perception of tourists saturating the towns, the lack of preservation of local traditions [44] and the negative touristic and environmental impact on welfare have been appropriately balanced by the actions of the community at the park [84]. Here, a tourist-related plan has been appropriately organised and managed according to the host expectations [84].
Hosts at this impoverished site are found to be engaged with tourism development, not only improving the level of resident hospitality [47] based on respectful attitudes towards visitors, but also changing their attitudes towards encounters with guests, who respond reciprocally and positively to this behaviour [46]. It is also worth noting the high level of acceptance amongst hosts of new strategies designed to enhance tourism through participative decision-making [42,59] and the involvement of the locals in the process [55]. Such findings may help to formulate long-term strategic theories in these destinations [20].
The differences in perspective between Spanish and Portuguese hosts should be pointed out. Whereas the economic view of tourism is highly ranked amongst Spanish hosts, social exchange is highly valued by the Portuguese locals. This is because visitor numbers are lower in the western part of the park. Social exchange may therefore be seen as the best way to sustain tourism in the area.
Overall, the positive host and guest relationship in the park has decisively helped the community to develop economically and socially, turning the loss of population into job opportunities in every municipal territory [5]. It has improved the quality of life [10].
The present study has a number of limitations. It is a pilot project, and there is no prior evidence with which to compare the results. No similar research has ever been carried out in any of Spain's seventeen regions. Second, the regional authorities were not cooperative; a response from those quarters would have enriched the discussion. Future research might compare the host, guest and local and regional authorities' responses to the social exchange theory. Third, even though the touristic participative plans added a new dimension to decision making, they did not include the potentially adverse socio-cultural and environmental effects of unsustainable practices in such underprivileged territories. The objectives of sustainable tourism were not addressed when the long-term strategic decisions were being designed. Fourth, the collaborative planning between host and guest omitted an explanation of the main challenges the territory faced. Finally, some key issues were absent from the tourist participative programme. They were: measuring the host and guest´s level of motivation in providing solutions for a socioeconomic "upgrade" of the territory; a readiness on the part of all parties (local and regional government, hosts, guests and so on) to work towards implementing plans proposed by the local authorities; the level of hosts' commitment to future tourist programmes; and clear lines of responsibility for stakeholders.
Future research will include a study that, in accordance with social exchange theory, compares the host and guest involvement in upgrading the territory with the local and regional authorities' attitudes towards providing solutions. Second, the host and guest´s prosocial behaviour will be examined to ascertain their level of agreement on the decisions arising from the participative pilot programme. In accordance with Schwartz [39], host and guest attitudes, norms, responsibilities and behaviour will be analysed. Using Schwartz´s theory [90], personal beliefs, moral obligation and behaviour could be linked as part of the effort to improve the park region's economic status [91].