Natural Resources of Tourism: Towards Sustainable Exploitation on a Regional Scale

Modern tourism studies focus largely on sociological perspectives on tourist activities [...]


Introduction
Modern tourism studies focus largely on sociological perspectives on tourist activities [1][2][3][4][5] and environmental aspects of tourism development [6][7][8][9][10]. In other words, tourism is considered as a social phenomenon with an evident ecological impact. However, such a vision is somewhat biased, because tourism itself is impossible without a valuable resource basis, and natural resources are often vital for tourism development on a given territory. These ideas have become especially clear together with the rise of such an innovative, nature-dependent direction of tourism as geotourism in the 2010s [11][12][13][14][15][16][17].
A vast amount of knowledge on the natural resources of tourism, i.e., natural objects, systems, landscapes, processes, and events, which can be employed for the purposes of tourism development, has been accumulated, but this knowledge is often neglected as something too obvious. The relevant publications are not so infrequent, but these often appear in 'marginal' and even difficult-to-access scientific media. Evidently, this situation is challenging. There are many 'fresh' examples demonstrating how a correct understanding of natural resources, their localization, and their true value facilitates tourism growth and contribute to sustainable development in particular geographical loci-countries, regions, and natural domains [18][19][20][21][22].
The natural resources of tourism constitute a very broad category, and their diversity has to be addressed. They can be classified depending on the dominant and most useful (to tourists) landscape elements. If so, geomorphological (landforms), geological (minerals, rocks, and fossils), hydrological (rivers, lakes, and seas), and biological (animals and plants) resources should be distinguished. The natural resources of tourism can also be classified depending on their functionality. They are related to tourism, recreation, hospitality, and infrastructure, and these can be used either directly or indirectly. Finally, it is possible to classify the natural resources of tourism depending on their state. They can be judged static and dynamic, as well as physical, culturally-interpreted, and aesthetic. Undoubtedly, these tentative classifications need further improvements and justifications to become more universal, which is an important task for further investigations.
Our understanding of the natural resources of tourism depends on the analytical depth and geographical breadth of the relevant research. Well-performed case studies of various aspects of the natural resources of tourism in different places of the world are required in order to improve this understanding and to make it really adequate. Tourism studies are not only about tourists, hotels, and transport. Attractions that allow tourism growth need to be carefully inventoried, and their useful properties must be revealed, to determine the tourism potential of each given object. In the case of tourism's natural resources, such studies become often inter-or even multidisciplinary because they require the involvement of experts from several branches of science, including biologists, geographers, archaeologists, etc., as well as economists, sociologists, and, indeed, tourism experts.

Volume Overview
This special issue focuses on the characteristics of the various natural resources of tourism. Its main purposes are (1) to provide examples from very different places of the world, (2) to clarify the possibility of exploiting these resources for the purposes of the tourism industry, and (3) to focus on the regional dimension of nature-based tourism development and governance. In this special issue, a broad understanding of regions is allowed, i.e., these can be geographical domains, provinces of any country, or geopolitical macroregions (depending of the preferences of the contributing experts). Special attention is paid to how natural resources can contribute to the sustainable development of tourism on a regional scale. In other words, this special issue is nothing less than an attempt to make the contemporary tourism science more resource-and region-focused.
The contributions to this special issue address the above-mentioned purposes, and the proposed tasks are achieved in very different contexts. Taken together, these contributions reveal the complexity of the idea of tourism's natural resources and put it into a multidimensional framework. Below, the content of this special issue is briefly explained, and a logical arrangement of the contributions is undertaken (Table 1). In order to accomplish the latter, the 14 contributions are assigned to four main themes, namely geotourism resources, rural versus urban resources, recreational resources, and natural resources in tourism networks. Table 1. Logically arranged content of this special issue.

Number
Contribution Geographical Focus

Russia
The importance of the first theme, namely geotourism resources, is dictated by its methodological value. Unique geological and geomorphological features constitute an important tourism resource, although its value has been realized relatively recently and its clarity to potential tourists is not always high. Moreover, attention to this resource has been paid more by geologists. As a result of these circumstances, the geotourism-related research has developed, from the beginning, with an emphasis on resource assessment. Apparently, this research stimulates a shift of the international tourism research community towards paying more attention to resources in addition to the sociological and environmental aspects of tourism. This special issue hosts six contributions on geotourism resources, which solve three notable tasks. First, they demonstrate the equal importance of geosites and geoparks to geotourism. Second, they relate geotourism to geoconservation and various types of protected areas. Third, they pay attention to geotourism's benefits to local communities.
The second theme is linked to the importance of natural resources to both rural and urban tourism. Its urgency is determined by the overall high value of tourism to the sustainable development of cities/towns and countryside. Undoubtedly, natural resources can be found and effectively exploited on both rural and urban areas. This special issue hosts four contributions devoted to rural or urban tourism employing natural resources. They solve two particular tasks. First, they explain the role of traditional human-nature interactions in tourism development. Second, they indicate the broad availability of natural elements in rural and urban areas, whose tourism-related use depends partly on public perceptions. More generally, these contributions reveal the presence of a specific resource, which can be termed "nature-rooted resource". It results from modifications or interpretations of products and landscapes with evident natural constituents. This resource seems to be essential for linking tourism and sustainable development.
The third theme is represented by a single contribution of great importance. Evidently, coastal landscapes and their aesthetic properties interpreted by visitors constitute an important natural resource to be used in both tourism sensu stricto and various resort activities. This resource is always under significant anthropogenic pressure and requires preservation. The contribution raises the important question of whether the people (residents and visitors) are ready to cover the costs of this preservation, and it also demonstrates the determinants of the people's willingness-to-pay for the related activities.
Finally, the fourth theme addresses the most complex issues and explains generally the importance of natural resources to the development of tourism networks. This theme is not unexpected because of the high complexity of tourism environments, where each element does not only determine the general meaning of a given environment, but can also trigger changes in this meaning. Moreover, tourism networks create new resources and/or re-elaborate pre-existing resources. This special issue hosts three contributions to this theme, and they solve two particular tasks. First, they relate natural resources to the socioeconomic context of tourism. Second, they emphasize the influence of spatial parameters (including spatial connectivity) determined by the natural peculiarities of territories where tourism is growing. Evidently, these tasks are closely tied to the sustainability-related research agenda.
It should be stressed that the contributions to this special issue provide examples from many parts of the word, including East and South Europe, Central and East Asia, North Africa, and Latin America (Table 1). These examples represent very different natural and cultural contexts. Therefore, the entire special issue appears to be globally representative to a certain degree, which confirms the importance of paying more attention to the natural (and not only) resources of tourism.

Concluding Remarks
This special issue achieves two general aims. First, it reveals the complexity of the nature-space-culture-tourism-sustainability nexus. Natural resources are not only geographical elements important to direct use. The contributions reveal their diverse functions. Second, this special issue demonstrates the urgency of paying close attention to tourism resources in general. In addition to natural resources, the other broad categories are cultural (also historical) and resort (also balneological) resources, and their distinction from natural resources is not always strict (transitional categories can be outlined). These meanings emphasize the importance of multidisciplinary approaches in tourism studies, where geographical, biological, and other analytical tools should not be abandoned.
Indeed, no special issue addressing so diverse and complex questions can pretend to be really comprehensive. For instance, there are some other topics which could also be considered in the context of this special issue. They include, for instance, wildlife resources [23], cross-border natural resources management for the purpose of tourism [24], food-environment-hospitality relationships [25], environmental state of important touristic locations and geographical domains [26][27][28], and the state governance of nature-based tourism [29]. Nonetheless, it is hoped that the present special will lead to further research in these and other topics within the resource frame. Acknowledgments: I am grateful for the opportunity to edit this special issue for "Sustainability". To achieve this challenging task would not have been possible without the support of the MDPI's editorial team and, particularly, Allie Shi, nor without the enthusiastic work of many experts who agreed to serve as reviewers. All scientists who contributed to this special issue are specially acknowledged. I deeply thank the administration of the K.G. Razumovsky Moscow State University of Technologies and Management (the First Cossack University) (Moscow, Russia), under whose 'umbrella' I have been able to accomplish this project.

Conflicts of Interest:
The author declares no conflict of interest.