3.1. Evolution of Scientific Production: Performance Analysis
To determine the evolution of the subject of study, some of the main bibliometric characteristics defining it were analyzed, including number of articles published, number of authors, citations, journals and countries. As shown in
Table 1, 85% of the production in this field has been published in the last decade. The increase in the number of publications (ApY) has evolved in parallel with the increase in the number of authors who publish on this subject (AupY), with 2019 standing out with 1174 authors. This is also mirrored in the evolution of the number of journals (JpY) that have published at least one article on landscape and tourism in a given year (which has increased from 1 in 1992 to a maximum of 246 in 2019) and the number of countries (CopY) that have published at least one article on the subject. This indicates that the scientific community throughout the world has shown a progressive interest in the subject of landscape and tourism, which is reflected in publications in an increasing number of journals.
As for the evolution of the average number of citations per article (∑Cpy/∑Apy), the highest figures appear in publications at the end of the 1990 s and the beginning of the 21st century, although this indicator presents more fluctuation than the previous ones.
More precisely, the number of articles published on landscape and tourism shows a clear upward trend since 1992, highlighting years such as 2002 and 2016 in which the growth in publications was even more striking (
Figure 1).
From 2006 onwards, articles about research supported by some kind of subsidy from public or private bodies began to be published and both the number of articles benefiting from this type of funding and the number of funding organizations has been progressively increasing year after year. We then considered ordinary least square (OLS) regression models with fixed effects to analyze the possible influence of the subsidies received and the funding organizations on the level of scientific production. Two regressions were carried out to explain this relationship due to the severe multicollinearity between the variables. The contrasts carried out were corrected for heteroscedasticity using the White procedure and do not show any symptoms of autocorrelation. The results are presented in
Table 2.
All of the estimators calculated for the explanatory variables of scientific production, as predicted by scientific theory in this field, show positive signs and are also highly significant, with a confidence level of 99%. Based on the results obtained in the estimates made, and with due caution, it can be stated that research grants and funding organizations appear to have been key elements in the level of scientific production in the countries over the period analyzed, with China, the United States and Spain, respectively, standing out as the countries which have received the largest number of grants for publication in this field since 1992.
In the following tables, greater detail is given about the variables analyzed in
Table 1: number of citations, journals and authors and journals.
Table 3 breaks down the citation structure of the field under study. There appears to be a high concentration of works with no or a low percentage of citations. Specifically, more than 60% of the literature on landscape and tourism has four or fewer citations. This may be because the work is not considered important enough to be cited, or because studies are too recent [
68]. Reinforcing this second explanation, 31.6% of works with four or fewer citations were published in 2019 and 2020.
In contrast, the three most important works in the field, according to the number of citations received [
57], have more than 300 citations (
Table 4).
Annals of Tourism Research is the journal with the most cited article, followed by
Ecological Economics and
Tourism. It should be noted that these three journals do not coincide with the three most productive journals in the field (
Table 5).
The three journals that published the most papers on tourism and landscape, by volume of published articles, are listed in
Table 5. Although
Sustainability does not specialize in the field of landscape and tourism, but is an interdisciplinary journal that treats sustainability from various perspectives including economic, social, cultural and environmental, it has the highest number of published articles, with 122. There is a large gap in terms of publications with the second journal,
Land Use Policy (with 65 articles), but more than double the number of citations, 1235. The third journal,
Tourism Geographies, is an international journal on tourism space, place and environment. This difference in productivity between journals can be explained, in part, by their publication volume. In
Sustainability, for example, the number of articles per issue has increased progressively since 2009, where in Vol. 1, issue 1, 8 articles were published, while 404 have been published in 2020 (Vol. 12, issue 16). In addition, from 2019 onwards, this journal publishes two issues per month, instead of one as in previous years. In contrast
, Land Use Policy publishes ten issues a year and
Tourism Geographies only five, with a volume of articles per issue far lower than the 404 published in
Sustainability.
Although papers on the topic have been published in 1338 different journals, more than 68% of the published papers are concentrated in just 30 journals.
A total of 7419 different authors have published articles related to landscape and tourism during the study period, according to data obtained from the WoS. However, more than 87% of the authors produced only a single article, indicating a low concentration in this field, and only four authors have published ten or more articles, positioning themselves as reference authors with greater specialization in the subject (
Table 6).
3.2. Conceptual Analysis: VOSViewer and SciMAT
The analysis of the keywords used in the articles shows us both the most relevant topics and the main research trends in the area [
69].
Figure 2 was constructed using VOSviewer, which makes it possible to visually demonstrate the differences in scientific production [
70]—in our case, between the keywords used by the authors.
Figure 2 illustrates the most frequently used keywords in the different papers, and these keywords indicate the most studied topics. Due to the high number of keywords used by the authors, only keywords that occurred a minimum of 20 times have been used. Using this criterion, a total of 40 items were found, grouped into five clusters (differentiated by color) with a total of 349 links between them. The most frequently recurring keywords are represented in larger nodes. The shorter the distance between the different nodes, the stronger the relationship between the keywords [
52].
As expected, “landscape” (with 365 occurrences and 38 links to other keywords) and “tourism” (569 occurrences and 37 links) are the keywords that recurred the most, which means that they are at the center of the network. However,
Figure 2 also highlights the importance of “cultural heritage” and “sustainability”, both present in more than 200 documents and with more than 30 links to other keywords. These four words, therefore, constitute the nucleus of four of the five clusters identified. Cluster 1 (sustainability) is the most numerous, consisting of 18 items such as national park, land use, conservation, biodiversity or protected area. Cluster 2 (landscape) is made up of nine items including identity, rural, authenticity, local development and place-attachment. Cluster 3 (tourism) is made up of five items, such as urban or linguistic landscape. Finally, clusters 4 and 5 are made up of four items each, such as development, environment and geotourism in the first, and architecture, perception and nature, in the second. It should be noted that in four of the five clusters a node has appeared relating to the country in which the different analyses are carried out, with Mexico belonging to cluster 1, Italy to cluster 2, China to cluster 3 and Spain to cluster 4.
From this first approach to the main keywords used in this research topic throughout the period analyzed, a much more detailed analysis can be made, subdividing the period of study in different stages. As previously mentioned, despite the positive trend of growth in the publication of publications on landscape and tourism, changes in productivity can be observed both in 2002 and 2016 (
Figure 1), which allows us to identify three stages of research [
57].
The first period (1992–2002), which we can call the “initial stage”, contains a total of 76 articles published (almost seven articles per year). The year 2001 stands out with 13 articles published. A second “developmental stage” (2003–2016), in which more than 132 articles were published per year, witnessed a total of 1859 publications. In this stage, the year 2010 and after showed above average productivity. Finally, there has been an “expansionary stage” (2017–1 September 2020) with more than 351 articles per year and a total of 1405 published. This last stage of barely four years represents 51% of the total production of literature in the field to date.
Figure 3 shows the bibliometric map of the evolution of the research topics during the three time periods. The inclusion index has been used to detect the links between the different themes (represented by circles) and to define the thematic areas (lines). The size of the circle corresponds to the number of documents in each theme.
In the first column of
Figure 3, six research topics can be identified in the first period, 1992–2002. It can therefore be said that the subject studied began to be considered based on analyses focusing on “cultural heritage”, “sustainability”, “management”, “post-war/industrial tourism”, “soil” and “landscape assessment”. The “cultural heritage” cluster includes terms related to “cultural landscape”, “cultural tourism” and “cultural ecosystem services”. The cluster “sustainability”, is a wide and transversal concept, but as a cluster is basically made up of two main components: sustainable tourism and sustainable development. “Management” is also a broad term encompassing coastal, tourism, landscape and territorial management, as well as waste management. The cluster of “post-war/industrial tourism” includes work centered on postwar tourism and post-industrial landscapes, referring to the Cold War, the Vietnam War, the First World War and the phenomenon of post-colonialism. Finally, under the term “soil” there are keywords fundamentally related to soil erosion, as well as the relationship of the soil with flora and fauna. The last group, “landscape assessment”, is the most homogeneous, as it is made up mainly of the keyword which gives the group its name, as well as other, similar keywords that refer to landscape assessment.
However, during the second period, 2003–2016, a greater diversity of 24 total themes related to the previous ones appeared. Of these 24, only “management” from the previous period was conserved, with other important themes such as “national park”, “climate”, “forest” and “rural” appearing. A distinction can be made between themes with strong connections to those from period one (continuous lines)—such as “national park”, “heritage”, “forest”, “management”, “conservation”, “visual analysis”, “globalization”, “alpine landscape” and “tourist beaches”—and other themes that have a weaker connection (dotted lines) sharing keywords with the previous period but not indicating the main research topic, such as “climate”, “rural”, “urban”, “place attachment”, “geotourism”, “human” and “GIS” (this corresponds to the acronym for the geographical information system, a computer system for capturing, storing, checking, and displaying data related to positions on Earth” s surface). The groups “urban” and “rural” refer, fundamentally, to the type of tourism and the development of these territories, and the term “human” encompasses all types of impact that human activity has on a territory (e.g., footprint, pressure, transhumance).
Finally, in the third and final period, 2017–1 September 2020, there is a small decrease in the number of research topics, to 19, with eight of the topics from the previous period remaining (national park, rural, urban, place attachment, geotourism, linguistic landscape, religious tourism and tourist beaches), with “management” (present in the first two stages) disappearing, while “cultural heritage” reappears from the first stage. In addition, ten new themes emerge for this period: “ecosystem services”, “planning”, “environment”, “spatial analysis”, “mountain”, “settlement”, “collaborative economy”, “tourism destination”, “3D models” and “sensitive analysis”.
It is necessary to clarify that the “heritage” group (which appears in the second stage) is created to differentiate it from the “cultural heritage” group (first and third stages), a group with a complete identity and explicit reference to culture, while “heritage” includes a diversity of themes related to the subject, such as preservation, interpretation, modernization and policies. Nevertheless,
Figure 3 illustrates the strong interrelationship of these two groups, which are united through continuous lines. The different themes identified in
Figure 3 for each period are represented in a strategic diagram, in which the size of the circle is proportional to the number of documents linked to each research theme. The h-index for each theme is provided next to each one (
Figure 4).
For the first decade (1992–2002), three fundamental themes stand out in this field, with the greatest number of documents published and the highest h-index: “sustainability”, “cultural heritage” and “management”. The first theme is the most central, but it can be said that all three are highly developed and essential in the construction of the research area. Although “sustainability” will not appear again in the following periods of the field’s evolution, it is a transdisciplinary concept [
71,
72] which, as can be seen in its network of keywords (
Figure 5), is related to 11 other keywords: “ecotourism”, “recreation”, “planning”, “conservation”, “agriculture”, “destination”, “islands”, “land use”, “resources”, “environment” and “globalization”. Although “sustainability” does not appear in the conceptual maps of the following stages, most of these keywords do, so it cannot be said that sustainability is not being addressed after 2003, but rather that it is being worked on in a less direct and more transversal way in conjunction with various other themes.
In the second period (2002–2016), “management” continues to appear at least partially as the driving theme with greater relevance to the subject than in the previous period (centrality), but a lower degree of subject development (density); instead of “cultural heritage”, another driving theme closely related to it appears, but much broader: “heritage”. “National park”, “climate”, “human” and “visual analysis” can also be included as driving themes in the second period. This is also the period in which the greatest number of essential themes concern the countryside as an area and in which various emerging themes also arise (lower right quadrant) such as “rural”, “urban” or “forest”, as well as general and transversal themes, such as “globalization” or analysis of territories in “Spain” and “China”.
In the last period (2017–1 September 2020), “geotourism” appears to have gained great moment, after first appearing as a specialized theme at the periphery of the research area in the previous period, in this third stage it becomes, together with “national park” (maintaining its position from the previous period), of key importance. It is possible that “geotourism” will evolve in the same manner as “national park”, becoming a subject of interest over the long term and serving to motivate a large part of the future research in this field, but it is also possible that it could evolve like other driving themes from the two previous periods, gradually allowing the interest of researchers to shift from this theme to others that will become new driving forces. In this period, other new themes also appear which are very attractive, although not as developed as the driving theme. These new themes include “ecosystem services”, “planning” (in which spatial, landscape and tourism planning are dealt with) and “environment” (a very broad theme that covers education, perception, protection, impacts, policies, etc.). Other highly topical and innovative subjects such as “collaborative economy”, “3D models” or “sensitive analysis” also appear, but these are quite specialized and therefore present internal and external connections with other weaker keywords. “Cultural heritage” is no longer the driving force it was in the first period, and is now located finally in the lower right quadrant, which indicates it can be interpreted as a theme in decline.
Many of the emerging themes from the previous period remain in the same quadrant, although with slight changes that bring them closer to potentially becoming driving themes for future stages, as is the case with “rural” and “spatial analysis”. There is also continuity of some of the second stage themes in the same upper left quadrant during this third period, as in the case of “religious tourism”, “tourist beaches,” and “linguistic landscape”. Although a priori they are not very relevant to the field, the fact that they are present in both stages suggests that they are mature, although not innovative, themes which have been recurrent throughout the discipline for a group of researchers (this assumption is reinforced by the fact that “linguistic landscape” is shown in
Figure 2, which analyses the whole period). It is therefore likely that these issues will continue to appear in the same quadrant in future research.
Finally, it should be noted that a considerable number of articles deal with issues that are not included in the different strategic diagrams. These include research focused on territorial development (especially at a local level), human impact (e.g., ecological footprint, conservation and impact at a social level) and waste (solid, liquid) management and planning. That these issues do not appear in the strategic diagrams may be because these are subjects whose development has not been the focus in a specific period (of the three analyzed), but they are subjects in which the researchers show a continuous interest throughout the whole period of study, with the articles concentrating on them being scattered throughout.