Introduction

Linear cultural heritage constitutes a significant component of world cultural heritage, frequently exhibiting cross-regional or even intercontinental characteristics1. Through its unique transportation or military functions2, it links diverse cultural spheres, as exemplified by the “Southern Canal” in France and the “Myrrh Road” in Oman. Despite these notable features, global research on linear cultural heritage remains predominantly focused on tourism resource development and the establishment of administrative management policies3,4,5, with insufficient attention given to fundamental studies and applied research concerning specific heritage spaces. In the global landscape of linear cultural heritage, China holds a significant position. The Beijing-Hangzhou Grand Canal and the Great Wall, which are even visible from space, stand as the most representative examples. Nevertheless, beyond these iconic sites, there exists another ancient linear cultural heritage in southwestern China—the Shudao—primarily characterized by its transportation and military functions. From a global perspective, the Shudao is distinguished by its extensive route, complex topography, and diverse composition of landscape elements. Applying the “core-essence” relationship analysis based on the theory of landscape genes allows for a clearer understanding of the intricate connections between various landscape elements at key nodes of linear cultural heritage within complex environments. This approach carries substantial exemplary significance for the holistic preservation of cultural heritage worldwide.

With the advancement of global strategies such as cultural confidence and the protection of historical and cultural heritage in both urban and rural areas, research on and preservation of historical and cultural landscapes have been elevated to unprecedented heights. Particularly for China, one of the world’s four ancient civilizations, the importance placed on the protection of historical and cultural heritage has reached an unparalleled level. The Shudao is a quintessential linear cultural heritage site that connects the Sichuan-Chongqing region with the Guanzhong Plain. Since the time of the ancient Shu civilization, it has served as a vital conduit for economic, political, and cultural exchanges between Sichuan and the broader world6. To this day, urban development in northern Sichuan Province is predominantly concentrated along the Shudao7. This underscores the indispensable role of the Shudao in facilitating regional economic, social, and cultural development. Consequently, the significance of this research is evident8,9,10.

Currently, research on the cultural heritage of the Shudao primarily focuses on the following areas: (1) the preservation and protection of significant historical towns along the Shudao. The historical towns along the Shudao are categorized based on four criteria: protection level, urban function, historical period, and cultural type. Subsequently, their values are assessed from five dimensions—scientific, artistic, economic, historical, and social—and corresponding protection strategies are formulated. (2) Research on the Landscape Planning and Design of the Shudao. To address the common challenges faced by the Shudao, such as cultural erosion, damage to historical remains, and fragmentation of the natural environment, this study proposes corresponding protective planning and design methods. Furthermore, with the intensifying development of tourism along the Shudao, scholars are increasingly concerned with how to properly manage the conflict between protection and tourism development. Achieving a balance between protection and utilization hinges on rationally assessing the development of tourism resources, including post road remains, vegetation, buildings and structures, ancient sites, grottoes and stone carvings, and burial sites. (3) Uncovering the heritage value of the Shudao. This area of research is currently the mainstream in Shudao cultural studies. Scholars from diverse disciplines, including anthropology, sociology, economics, architecture, and urban and rural planning, have explored the 2000-year historical evolution of the Shudao and its intricate relationship with both natural and social environments. (4) Spatial characteristics of traditional settlements along the Shudao. Throughout the extensive political, economic, and military exchanges between the north and south, the areas along the Shudao became primary livelihood hubs for a significant number of residents, leading to the formation of numerous settlements and market towns. These settlements document the historical prosperity of economic trade along the Shudao and constitute an integral part of its cultural heritage. Numerous scholars have analyzed the development characteristics of these settlements from multiple perspectives, including the evolution of administrative systems, historical culture, spatial transformation, and landscape features. They have highlighted that under the influence of factors such as post stations, natural environment, and transportation hubs, village architecture, structures, and road networks exhibit distinct characteristics. (5) Spatial characteristics of plank roads. Plank roads serve as the primary transportation infrastructure along the Shudao and represent a unique cultural landscape shaped by its perilous terrain and landforms. Through the analysis of plank road spatial features, researchers can investigate the construction process of the Shudao and the ingenuity employed in adapting to challenging topography11. Additionally, seven distinct forms of plank roads have been identified, each developed under different terrain conditions. (6) Compilation and analysis of Shudao literature. By systematically organizing and analyzing historical records, poetry and prose, inscriptions, and travelogues related to the Shudao, this study aims to summarize the historical evolution and landscape characteristics of the Shudao12,13,14.

The significance and value of Shudao culture have been extensively validated by scholars, who have conducted in-depth analyses of its spatial characteristics, cultural value, and tourism development from multiple perspectives. A series of practical and effective measures have been proposed for the development and protection of the Shudao. However, regrettably, there is currently no comprehensive research that integrates and categorizes the diverse landscape elements of the Shudao, nor does existing research provide a holistic view of its landscape composition. Consequently, this has resulted in an inadequate overall understanding of the Shudao, leading to the formulation of strategies that lack systematic coherence.

Landscape genes have emerged as a concept widely embraced in the field of landscape architecture globally in recent years. Nevertheless, there exist notable discrepancies in interpretation between Chinese scholars and their international counterparts. Chinese scholars tend to approach landscape genes at a macroscopic level, emphasizing the distinctive external expressions of local landscapes, such as settlement patterns, landscape components, and architectural spaces15,16. Conversely, scholars from other countries predominantly focus on microscopic and ecological dimensions, examining biological flows within landscapes17, genetic traits of species18,19,20, and analyzing the formation of biological habitats from a genetic perspective21,22. It is evident that employing landscape genes to characterize the features of landscape elements has become a widely accepted consensus among international scholars.

Fortunately, with the introduction of the concept of landscape genes, a new research paradigm has emerged for systematically summarizing the characteristics of complex linear landscapes such as the Shudao23. Landscape genes specifically refer to the inherent cultural elements that are unique to a particular landscape and distinguish it from others. These elements serve as the fundamental units of landscape “inheritance,” representing certain characteristics passed down through generations that differentiate the landscape from others24. The concept of landscape genes aligns closely with the characteristics of cultural heritage, making the landscape gene theory a reliable method for the classification and organization of cultural heritage25. Currently, numerous scholars have applied this theory to systematically classify and organize the landscape elements of traditional settlements (villages)26,27,28,29. Among the most representative studies is the work of Professor Liu Peilin and his team. They highlight that landscape genes store cultural information through the orderly arrangement and combination of genetic information, which is then transmitted along specific pathways to express unique landscapes30. The Shudao culture can also be articulated through the concept of landscape genes. Distinct Shudao landscapes are formed by different combinations of genetic elements, analogous to how variations in genetic sequences give rise to diverse biological traits. Similar to genetic replication and inheritance, the expression of landscape genes is influenced by external factors, leading to changes in the manifestation of these cultural landscapes over time. Currently, the application research31 on landscape genes primarily focuses on the following areas: (1) Coding and classification of traditional settlement landscape genes. The characteristics of landscape elements in different settlements are systematically decomposed and classified based on the principles of landscape gene coding32,33,34. Feature factors are extracted from three key dimensions—natural environment, settlement space, and architectural space—to construct a comprehensive database of traditional settlement spatial genes35,36,37,38. (2) Traditional settlement landscape pattern mapping. Based on the classification and organization of landscape elements, this step further summarizes their spatial characteristics, develops corresponding spatial prototype diagrams39,40,41, and establishes a landscape gene color system26,42,43,44. It is evident that current research on the application of landscape genes primarily concentrates on the spatial analysis of traditional settlements (villages)15,28,29. However, there remains a significant gap in the application of this approach to diverse types of cultural heritage. Particularly, the application research on the Shudao, a quintessential example of linear cultural heritage, remains notably limited. This limitation has contributed to the prolonged ambiguity surrounding the genetic characteristics of the Shudao landscape.

Although some scholars have begun to explore the connection between landscape genes and the study of the Shudao, such as Zou Weihan et al., who applied landscape gene theory to analyze traditional settlements along the Shaanxi South section of the Shudao. They established a landscape gene identification index system for traditional settlements based on four categories: traditional architectural features, settlement layout features, natural environment features, and historical and cultural features45. Using methods such as graphic extraction, element extraction, and meaning extraction, they identified prototypes of these landscape genes and constructed corresponding landscape gene maps46. However, their research remains focused primarily on traditional settlements, neglecting the importance of other landscape elements along the Shudao. Additionally, most studies concentrate on the Shaanxi South section, with relatively limited research on the Sichuan section, which requires further supplementation. More critically, the general landscape gene theory fails to fully capture the multi-element correlation characteristics of the Shudao landscape. A deeper analysis is needed, particularly from the perspective of primary and secondary relationships, to better understand the overall landscape.

In conclusion, this paper aims to construct a more systematic theoretical framework to identify and categorize the diverse landscape elements of the Shudao heritage. By analyzing the mutual influence relationships among these elements through the lens of core-periphery dynamics, the study seeks to provide comprehensive guidance for the holistic protection of the Shudao heritage.

Through this research, the landscape gene theory is expected to achieve further in-depth development. By elucidating the relationship between nuclear and cytoplasmic components, landscape genes are no longer viewed as isolated elements but rather as clusters with interconnected characteristics. The 11 landscape gene clusters and 5 representative landscape gene maps identified in this study will not only offer novel insights into the investigation of the Shudao but also pave the way for global research on linear cultural heritage.

Methods

Theoretical framework construction of NCCR

In the cells of living organisms, there exist two genetic systems: the nuclear inheritance system and the cytoplasmic inheritance system, also referred to as organelle inheritance. Nuclear genes and cytoplasmic genes share similar structures and functions, both capable of undergoing inheritance and mutation. Typically, nuclear genes dominate, while the expression of cytoplasmic genes is regulated to some extent by nuclear genes. Conversely, cytoplasmic genes also influence the activity of nuclear genes (Fig. 1). Nuclear and cytoplasmic genes exhibit mutual coordination and constraint, co-regulating the expression of an organism’s traits. This interaction can be analogized to a parent-child relationship, where parents exert overall control while children are influenced by their parents. Conversely, parents are also affected by their children. Through this bidirectional interaction, both parties contribute to the harmonious functioning of the family unit.

Fig. 1
figure 1

The relationship between “Nucleus and Cytoplasm” of cellular inheritance information.

Full size image

Landscape genes serve as the fundamental units for the inheritance of cultural landscapes, encompassing unique cultural elements that are transmitted across generations within a specific cultural landscape. During the formation of cultural landscapes, core landscape genes significantly influence the physical characteristics and appearance of the environment, including major architectural ensembles and natural features. Certain landscape genes influence specific traits or localized features of cultural landscapes, such as particular architectural details, decorative styles, or local customs. These genes are closely intertwined with core landscape genes, collectively shaping the complete morphology of the cultural landscape. This relationship is analogous to that between nuclear and cytoplasmic genes. This paper integrates these two theories and proposes a novel framework: the Nucleus-Cytoplasm Collaboration Restrict (NCCR) landscape gene cluster theory, which elucidates how core and non-core landscape genes jointly influence the formation and development of cultural landscapes. Based on this theory, this paper posits that landscape genes do not occur in isolation but rather as clusters, comprising both primary and secondary genes. These primary and secondary genes interact and constrain each other, collectively shaping regional characteristic landscape spaces and cultural phenomena. The introduction and application of this theory address the current issues of fragmented and isolated landscape gene protection, which lack a systematic approach. By treating landscape gene clusters as integrated wholes for protection, development, and inheritance, their maximum economic and social value can be fully realized. This framework offers a more comprehensive solution for the preservation and revitalization of cultural heritage.

During its long-term development, the Shudao Cultural Landscape has accumulated a rich and diverse array of cultural heritages and historical remains. This paper employs the NCCR landscape gene cluster theory to accurately identify the cultural landscape genes of the Shudao and further examines the cluster effect from the perspective of the “nucleus-cytoplasm” relationship. Based on the overall characteristics of the Shudao, we have delineated the features of nuclear genes and cytoplasmic genes. In practical applications, for each type of landscape gene along each Shudao, we precisely identify the gene that exhibits the strongest correlation with other landscape genes, exerts the greatest influence on them, and carries more cultural elements compared to others as the nuclear gene (nuclear inheritance) of the cluster. Other related genes that are influenced by it are classified as cytoplasmic genes (cytoplasmic inheritance) within the cluster (Fig. 2). Nuclear genes primarily refer to spatial and cultural elements within historical remains of a certain scale, characterized by their larger size, earliest construction date, most comprehensive functions, and distinct differentiation from other regions. Cytoplasmic genes, on the other hand, pertain to historical remains within the research scope that are smaller in scale, constructed later, possess singular functions, exhibit significant influence from nuclear genes in terms of spatial morphology and cultural connotation, and differ from those in other regions.Taking the landscape cluster composed of the Ancient City of Zhaohua, the Examination Hall of Zhaohua, the Yixinyuan Garden of Zhaohua, the Tomb of Bao San Niang, and the Ding Gong Shrine as an example, the Ancient City of Zhaohua is categorized as an architectural complex. The Examination Hall of Zhaohua, the Yixinyuan Garden of Zhaohua, and the Ding Gong Shrine are classified as architectural landscapes, while the Tomb of Bao San Niang is designated as a cultural heritage site. Within this cluster, the Ancient City of Zhaohua is the largest in area and has the densest concentration of buildings. The Yixinyuan Garden and Examination Hall are significant public structures within the ancient city. Their plan layout, spatial structure, decorative colors, and other architectural genes are all influenced by the overall spatial configuration of the Ancient City of Zhaohua. Conversely, their functional attributes and other architectural genes also exert an influence on the ancient city. The Tomb of Bao San Niang, located 5 kilometers outside the ancient city, is associated with Guan Suo, the adopted son of the famous Shuhan general Guan Yu from the Three Kingdoms period. The location and form of the tomb are closely linked to the cultural genes of the Ancient City of Zhaohua. The Ding Gong Shrine was constructed by Ding Gongbao during his tenure as the governor of Sichuan within the ancient city. Its spatial layout and other architectural genes are similarly influenced by the Ancient City of Zhaohua. From this analysis, it is evident that the Ancient City of Zhaohua satisfies the criteria for a core gene within the cluster. Therefore, the Ancient City of Zhaohua is designated as the core gene (nuclear inheritance), while other landscapes are classified as peripheral genes (cytoplasmic inheritance) (Fig. 3).

Fig. 2
figure 2

Example of landscape gene clusters of the Shudao.

Full size image
Fig. 3
figure 3

An Example of the “Nucleus-Substance” relationship in the Ancient City of Zhaohua.

Full size image

In addition to the primary and secondary distinctions among the Shu Dao genetic landscapes, which parallel the relationship between nuclear genes and cytoplasmic genes, there also exist collaboration relationships and restrictive relationships. Through the interaction of these nuclear and cytoplasmic genes, they collectively shape the landscape characteristics exhibited by this cluster. Taking the landscape gene cluster of Jianmen Pass as an example, the landscape gene of Jianmen Pass serves as the nuclear gene within this cluster. In contrast, the material and intangible cultural genes associated with Jianmen Pass (a military landscape) function as the cytoplasmic genes. Located at a critical break in the Dajian Mountain Range, Jianmen Pass occupies a strategically significant geographical position. It is precisely due to this topographic gene that Jianmen Pass has achieved its renowned military status of “one man guarding the pass, ten thousand cannot break through.” Historical events such as the battles between the Jingguo Army and Jingchuan Army have left indelible marks on the cultural genes of Jianmen Pass. The numerous military battlefield genes have also influenced the spatial morphology of Jianmen Pass, resulting in its distinctive Ming Dynasty architectural style characterized by “high enemy towers and dense battlements.” Moreover, Jianmen Pass, as the nuclear gene, has given rise to a wealth of valuable historical relics, including the stone statues of Liu Bei and Zhuge Liang, the Jiange Archway (a cultural landscape), and the Jinniu Bridge (a transportation landscape). These elements are not only influenced by the spatial layout of Jianmen Pass but also contribute to it. Overall, the overall layout, spatial form, and military function genes of Jianmen Pass are shaped by topographic features and historical military events. Simultaneously, the military function genes of Jianmen Pass influence the formation of surrounding landscape genes such as plank roads, ancient towns, and buildings. This interplay demonstrates a collaborative and restrictive relationship between the nuclear and cytoplasmic genes (Fig. 4).

Fig. 4
figure 4

The collaborative and restrictive relationships among the scenic clusters of Jianmen Pass.

Full size image

To further elucidate the application of NCCR theory in identifying and classifying the landscape genes of the Shudao, this paper outlines a well-defined research methodology. The Shudao, one of the earliest transportation routes established and preserved by human society, connects with both the Southern and Northern Silk Roads, serving as a significant linear cultural heritage site. Along its route, the Shudao encompasses diverse natural landscapes including forests and high mountains; material cultural elements such as settlements, passes, post stations, buildings, tombs, and cliff carvings; and intangible cultural assets like customs, dances, and handicrafts. Faced with such a diverse and extensive array of landscape genes, identifying the correlations among them and integrating these disparate elements into a cohesive and meaningful whole—akin to stringing scattered pearls into a beautiful necklace—remains an urgent challenge that requires immediate attention. Therefore, this paper leverages the robust summarizing and integrating capabilities of the NCCR landscape gene cluster theory, focusing on important historical relics along the Yinping Road, Jinniu Road, Micang Road, and Lizhi Road as primary research objects. Firstly, it employs the advanced data management and analysis functions of ArchiGIS to identify the distribution of key landscape elements along the Shudao, selecting relatively concentrated landscape clusters for initial screening while discarding isolated elements that are distant from the Shudao. Secondly, it identifies the genes of each screened landscape cluster and compares them based on their functions and influence ranges to distinguish core genes from peripheral genes, further analyzing their correlations and eliminating those with weak associations. Thirdly, it decomposes the peripheral genes a second time, distinguishing primary and secondary relationships within these genes, and constructs a hierarchical “core-peripheral” relationship until no further decomposition is possible, ultimately forming a complete and coherent cluster (Fig. 5).

Fig. 5
figure 5

Research framework for the landscape gene cluster of the Shudao based on NCCR.

Full size image

In conclusion, this study advances the landscape gene theory by deepening its application and theoretical framework. The NCCR theory we propose not only examines the characteristics of individual genes but also emphasizes the relationships between different genes, particularly the hierarchical relationship between nuclear genes and cytoplasmic genes. This approach allows us to clearly define the priorities for the future development and preservation of the Shudao. While it is true that landscape genes can be categorized into various types, their focus remains on classifying individual genes rather than exploring the intricate connections between them. The key innovation of the NCCR theory lies in its ability to conduct an integrated analysis of landscape genes within a defined spatial range, systematically analyzing the interactions between genes and identifying distinct clusters of landscape genes along the Shudao. From this perspective, this study contributes significantly to the evolution of the landscape gene theory.

Study site

The “Shudao” denotes the ancient route that has existed since the Zhou, Qin, and Han Dynasties, connecting Xi’an in Shaanxi Province to the Chengdu Plain. The Shudao culture in Sichuan boasts a profound history, with an abundance of tangible and intangible cultural heritage passed down through the centuries47. Within Sichuan Province, the Shudao comprises numerous routes, with main lines and branches forming an intricate and complex network. After systematically reviewing the historical literature on the Shudao48 and considering factors such as the identifiability of landscape genes and the accessibility of field investigations, this paper identifies four primary Shudao routes within Sichuan: Yinping Road, Jinniu Road, Micang Road, and Lizhi Road (Fig. 6). The Shudao essentially connects key towns in eastern and northern Sichuan, and is characterized by a wealth of historical remains (Table 1).

Fig. 6
figure 6

Research scope and key nodes.

Full size image
Table 1 Main trunk lines, key towns, and notable scenic spots along the Shudao
Full size table

Data sources and management

This study focuses on the significant historical relics along the Shudao as the research object. By employing comparative and analogical methods, it systematically analyzes the landscape genetic characteristics of the Shudao and constructs the interrelationships among these genetic units. The primary data sources include: (1) Literature materials. These materials are derived from historical and geographical records, poetry and prose, stone inscriptions, and travel literature related to the Shudao, such as Chengdu County Annals, Sichuan Historical Gazetteers Collection, Shudao Gazetteers Collection, Shudao Travel Literature Collection, and Shudao Posthouse Journey Record. These sources provide detailed information on the main routes of the Shudao and its important historical relics. (2) Field investigation data. The research team conducted multiple field investigations in key towns, major historical sites, and settlements along the Shudao. Through drone aerial photography and oblique photogrammetry, they acquired detailed spatial data of the landscapes along the Shudao, extracting key elements such as spatial structure, planar features, and decorative colors of significant landscapes. Additionally, the team conducted semi-structured interviews with local residents, artisans, merchants, scenic area managers, village secretaries, and government officials to gather cultural information on historical evolution, legends and beliefs, folk activities, and traditional games.

To facilitate the retrieval and management of data in subsequent stages, this study employs ArcGIS for comprehensive data management. The coordinates, spatial characteristics, cultural attributes, and other elements of various Shudao landscapes are systematically integrated and spatially managed using ArcGIS (Fig. 7). Based on the landscape gene classification standards and identification elements provided by Professor Liu Peilin, and based on the existing research results of experts such as Zou Weihan et al. on the Shudao, it has been proposed that the landscape genes of traditional settlements along the Shudao encompass architecture, spatial layout, natural environment, and historical culture. Additionally, the book “The Shudao of China” comprehensively analyzes the landscape along the ancient Shudao from multiple dimensions, including architecture, plank roads, historical events, cultural heritage, and human geography. Based on these studies, this study categorizes the Shudao landscape into 9 major categories and 34 subcategories (Fig. 8). The principal factors and “identifiable” factors are meticulously classified. Leveraging ArcGIS for systematic management, the study facilitates computer-aided landscape identification.

Fig. 7
figure 7

GIS-Based data management of Shudao landscape elements.

Full size image
Fig. 8
figure 8

Main landscape types of the Shudao.

Full size image

The process and methodology for identifying the landscape genes of the Shudao heritage based on the NCCR theory

The objective of identifying and extracting landscape genes is to pinpoint the most representative characteristics of the Shudao. This study adheres to the overarching principles of “intrinsic uniqueness, extrinsic uniqueness, local uniqueness, and overall superiority” as proposed by Professor Liu Peilin, and employs the four landscape gene extraction methods of “element extraction, pattern extraction, structure extraction, and meaning extraction” outlined by Shen Xiuying. However, as previously discussed, the landscape of the Shudao exhibits unique characteristics and complexity: (1) The integration and synthesis of multiple linear landscapes. The Shudao forms an intricate network within Sichuan Province, with four primary routes identifiable, yet countless secondary pathways interweaving among them. Conducting landscape gene research under such complex conditions poses significant challenges. Therefore, this study proposes a category-oriented landscape gene identification index system. By conducting longitudinal comparisons across different routes, we aim to identify commonalities and differences, ultimately forming a set of common gene pools and specialized gene pools. (2) Genetic Differentiation and Clustering in Linear Multi-functional Composites. Unlike individual buildings, settlements, or isolated environments, the material and intangible landscape elements along the Shudao are intricately interconnected, forming continuous spatial entities and cultural activities shaped by special historical events, military activities, and commercial exchanges. To address the current “potted plant-like” point-based protection strategy for the Shudao landscape, this study further explores the clustering relationships of Shudao cultural genes based on gene identification and classification. By introducing the NCCR theory, it clarifies primary-secondary relationships, collaborative dynamics, restrictive interactions, and cluster associations, thereby providing more efficient guidance for the preservation of cultural landscape resources along the Shudao.

Based on this, this study, guided by the classic theory of landscape genes, has developed a systematic process and procedure for identifying landscape genes specific to the Shudao landscape (Fig. 9). First, a gene identification framework tailored to the Shudao landscape is established according to the fundamental principles of landscape gene identification. Second, the gene characteristics of the Shudao landscape are systematically identified and extracted using established landscape identification methods. Third, longitudinal comparisons of the landscape genes across different routes are conducted to construct both common gene groups and specialized gene groups. Fourth, leveraging the NCCR theory, the interrelationships and hierarchical relationships among the Shudao landscape genes are analyzed to form gene clusters, with particular emphasis on specialized gene groups. Finally, based on these gene clusters, single-core, dual-core, or multi-core landscape gene maps are generated to establish a comprehensive Shudao landscape gene network and spatial feature system.

Fig. 9
figure 9

Recognition process and program.

Full size image

Development of the identification index system

As previously discussed, the landscape genes of the Shudao primarily encompass two categories: material form and intangible form. The cultural characteristics of different routes and landscape types exhibit significant variation, rendering it challenging to provide a comprehensive summary or generalization. To address this challenge, this study established a “part-whole-part” landscape gene identification system. This system uniformly categorizes the landscape genes of the four routes into nine categories: material cultural landscapes (natural landscapes, architectural landscapes, cultural landscapes, military landscapes, and transportation landscapes) and intangible cultural landscapes (traditional customs, belief cultures, art cultures, and production and living cultures). These nine categories are further subdivided into 34 subcategories, for which specific identification indicators were developed (Fig. 10).

Fig. 10
figure 10

Index system for identifying the landscape genes of the Shudao.

Full size image

The primary elements to be identified

Based on the project team’s preliminary field investigations and literature review, detailed records have been compiled of the significant material and intangible cultural landscape remnants along the four major Shudaos, which constitute the primary focus of this study. The investigation results indicate that the Jinniu Road and Micang Road possess the richest historical remains and are therefore the key areas of emphasis in this paper. Among the diverse historical and cultural heritages, religious temples, residential buildings, tombs, stone carvings, and fortresses are particularly abundant. These elements form the core connotations of the Shudao landscape genes.

Methodology and workflow for identifying landscape genes

Landscape gene identification is a systematic and comprehensive process, particularly for the Shudao landscape, which exhibits diverse and complex characteristics. This necessitates the establishment of a scientific and rigorous identification methodology. Based on existing research, the identification of landscape genes primarily comprises two key components: resource management and operational identification. For resource management, this study leverages the robust data management capabilities of ArcGIS to construct a Shudao landscape resource database, enabling real-time retrieval and precise spatial positioning of landscape resources. The identification operation process primarily focuses on specific landscape elements of the Shudao. Based on a comprehensive collection and analysis of relevant research materials, this study examines the distinct landscape features of Shudao culture. Utilizing methods such as element extraction, pattern extraction, structure extraction, and meaning extraction, the workflow for identifying these features is systematically established. Furthermore, this paper incorporates a longitudinal comparative analysis of the same type of landscape genes across different Shudao routes, based on the unique characteristics of the Shudao. This additional step allows for the classification of extracted landscape genes into common gene groups and distinctive gene groups (Fig. 11). Furthermore, the core focus of this study is the identification and differentiation of nuclear genes and cytoplasmic genes within a defined spatial range. The detailed methodology is outlined below: (1) First, the standard deviation ellipse function in ArcGIS is employed to identify and cluster significant landscape gene groups along the Shudao. The area of the standard deviation ellipse reflects the degree of concentration or dispersion of historical remains, enabling determination of whether they belong to the same landscape gene cluster. The azimuth angle indicates the predominant direction of historical remains distribution, and the positional relationships between different remains can be used to preliminarily assess genetic connections within the cluster. (2) Point data for historical remains are collected, and Thiessen polygons are generated using the Create Thiessen Polygons tool in GIS. The Add Geometry Attributes tool is then applied to calculate attributes such as polygon area and perimeter, which provide insights into the distances and communication costs between landscape genes. A smaller polygon perimeter suggests lower communication costs. If a gene within a cluster exhibits the smallest polygon perimeter relative to other genes, it can be classified as a nuclear gene, while the remaining genes are categorized as cytoplasmic genes. (3) When quantitative data alone cannot distinguish between nuclear and cytoplasmic genes, supplementary methods such as historical literature review, field survey data collection, and semi-structured interviews with local villagers can be utilized. These approaches help identify the largest-scale, earliest-built, and most functionally complete landscape gene as the nuclear gene, with all others classified as cytoplasmic genes.

Fig. 11
figure 11

Workflow of landscape gene identification for the Shudao.

Full size image

Results

Common genomes and special genomes

Based on the research framework, this study systematically identifies and screens the landscape genes of the four main Shudaos according to their categories. Given the varying natural and socio-cultural environments along these roads, the landscape genes exhibit distinct characteristics. Consequently, this study conducts a comparative analysis of the landscape genes across different types of landscapes on the four Shudao Roads. This process allows for the extraction of both common and special gene pools, which form the foundation for subsequent NCCR landscape cluster research. Research indicates that the common landscape genes of the Shudao primarily encompass the following aspects: (1) In terms of natural landscapes, significant topographic relief and deep V-shaped cross-sections are defining features, while extensive forests constitute another key common gene; (2) Regarding architectural landscapes, residential buildings and settlements exhibit numerous shared characteristics; (3) Concerning cultural landscapes, there is a resonance in themes related to the Three Kingdoms period and the commemoration of historical figures; (4) With respect to military landscapes, construction techniques utilizing local materials are notably similar; (5) Pertaining to transportation landscapes, terrain constraints and dual functions for trade and military purposes are common traits among the four Shudaos; (6) For intangible cultural landscape genes, the close integration with regional cultures along the Shudao is a shared characteristic (Table 2).

Table 2 Common genomic sequences
Full size table

Through comparative analysis, it is evident that among the landscape genes of the Shudao, certain genes are unique to specific sections of particular routes and are thus categorized as special gene groups. Their main characteristics are as follows: (1) The Jinniu Road is distinguished by settlements, transportation infrastructure, and tombs. Due to variations in its natural and cultural environment, this section exhibits a significant number of distinctive genes; (2) Handicrafts on the Micang Road differ markedly from those on other sections of the Shudao, particularly with the Magic Grottoes featuring an unusual eave-style architecture; (3) The Lizhi Road, located in northeastern Sichuan and influenced by Tujia culture, displays notable differences in its intangible cultural landscape genes. It also features a unique combination of tombs and stone carvings; (4) Although the Yinping Road is relatively short within Sichuan Province, its distinct stone carving style and folk activities such as bullfighting, influenced by Tibetan culture, constitute important special genes of the Shudao (Table 3).

Table 3 Special genomic sequences
Full size table

The NCCR cluster of landscape genes of the Shudao

Using the aforementioned research methods, the research team has systematically identified the genetic elements of the Shudao and organized and summarized the landscape clusters based on NCCR theory. Given the extensive and lengthy routes of the Shudao, the associated workload is substantial. Constrained by research time, personnel limitations, and paper length, this study initially selected several key landscape clusters for detailed investigation, mapping, and gene extraction and summarization. Consequently, 11 landscape gene clusters were identified (Fig. 12). Future research will continue to explore and comprehensively extract the landscape gene characteristics and significant clusters of the Shudao.

Fig. 12
figure 12

Typical Landscape Gene Clusters of the Shudao.

Full size image

Cluster 1: Qingxi Ancient Town Group. In this cluster, the overall spatial layout of Qingxi Ancient Town serves as the core gene. Under its influence, several quality genes have emerged, including the planar form of the Qingxi Ancient Town Wall, the spatial layout of Huayan Temple in Guangyuan, the spatial structure of surrounding settlements such as Luoyigou Village and Yinping Village, the location and orientation of the Eight Scenic Spots Tower, and the subject matter depicted on the Writing Cliff. This demonstrates the dominant role of Qingxi Ancient Town in shaping other landscape elements. Additionally, the decorative colors, spatial layouts, and development patterns of these quality genes also influence the expression of the core gene, illustrating the mutual constraints described in the NCCR theory.

Cluster 2: Zhaohua Ancient Town Group. This cluster, located on the Jinniu Road, centers around the spatial layout of Zhaohua Ancient Town. It encompasses a diverse range of landscape elements, including the Zhaohua Examination Hall, Zhaohua Yixinyuan, Fei Yi’s Tomb, Bao San’niang’s Tomb, and Jiameng Pass. The expression of various landscape genes within this cluster is shaped by the overall layout, decorative colors, and military fortification functions of Zhaohua Ancient Town, thereby presenting the distinctive landscape genes characteristic of the Shudao. For example, the formation, spatial configuration, and functional attributes of Jiameng Pass are all closely tied to the influence of Zhaohua Ancient Town.

Cluster 3: Langzhong Ancient Town Group. Located in the northwest of Sichuan, Langzhong Ancient Town serves as a crucial gateway for entering and exiting Sichuan Province. It is rich in Shudao culture, with a diverse array of material and intangible landscape genes. Under the influence of its overall spatial structure gene, which follows a layout around mountains and water, numerous quality genes such as Zhang Fei Temple, Dafosi Temple, Babasi Mosque, Northern Sichuan Provincial Examination Hall, Tengwang Pavilion, Yong’an Temple, Baoning Pressed Wine production, Baoning Vinegar production, and Wulong Temple exhibit spatial expressions closely tied to the Shudao. These elements are highly consistent with the development direction of Langzhong Ancient Town. In particular, there is a strong connection between the functional characteristics and thematic content of these different landscape elements.

Cluster 4: The White Robe Ancient Town Group. This cluster is located on the Lizhi Road. Established during the Qin and Han Dynasties, the White Robe Ancient Town has long been an important market town along the Shudao. Centering around this ancient town, numerous landscape elements of the Shudao have developed, including the Ling Shan Wu Family Courtyard, the Double Bamboo Hall Archway, the Black Horse Mountain Tomb Cluster, Buddha Head Fort, and the Pingchang Hanzhong Ancient Road. The spatial layout, morphology, decorative colors, transportation functions, and commercial activities of these elements are all significantly influenced by the White Robe Ancient Town.

Cluster 5: Luocheng Ruins. This cluster, located closest to Chengdu, is the largest in scale and encompasses numerous landscape elements such as the Dujiacun Cliff Tombs, Yilan Shrine, the Central Hall of Longju Temple, Fanghu Lake, and the Sanxingdui Ruins. The overall spatial layout of the Luocheng Ruins exhibits a clear connection with other elements within this cluster. For example, the orientation and scale of the Dujiacun Cliff Tombs are significantly influenced by the spatial configuration of the Luocheng Ruins.

Cluster 6: Pingliangcheng Ruins Group. This cluster is located on the Micang Road and primarily comprises stone carvings and grottoes as its main quality genes. The core-quality relationship is prominently reflected in the functional influence and the thematic content of the statues. Additionally, spatially, Pingliangcheng is closely associated with the Nan Kan Cliff Carvings, Xi Kan Cliff Carvings, and Longmenshan Grottoes.

Cluster 7: The Baimaguan Group. This cluster, centered around a military pass, comprises a rich and diverse array of landscape genes, including Luofeng Slope (ancient battlefield), Jingle Palace (palace), Luojiang Wanfo Temple (temple), Pang Tong’s Tomb (tomb), Pang Tong’s Shrine (shrine), and Luojiang Kuixing Pavilion (public building). Spatially, these elements are arranged around the core gene of Baimaguan. Additionally, they exhibit close connections with Baimaguan in terms of decoration, color, spatial form, and functional attributes.

Cluster 8: The Jianmen Pass Group. Jianmen Pass, the most significant pass on the Jinniu Road, forms a crucial landscape gene cluster along the Shudao. Within this cluster, the strategic location of Jianmen Pass influences the orientation and positioning of the Kongming Stele. Additionally, the decorative and morphological genes of Jianmen Pass shape the architectural space of the Pingxiang Houci. Furthermore, key landscape elements such as Jianxi Bridge and Jinniu Bridge are constructed in reliance on Jianmen Pass and functionally interact with it.

Cluster 9: Fule Mountain Group. This cluster is centered on the spatial layout of the natural environment of Fule Mountain, which serves as its core gene. This core gene influences the orientation, form, and material composition of tombs such as those of Jiang Wan and Song Zheyuan. It also constrains the scale of the Li Du Shrine and the height of the Pingyang Military Command Post. Furthermore, it has facilitated the creation of remarkable features like the cliff carvings at Bishui Temple. Consequently, it is evident that under the influence of Fule Mountain’s unique topography and geomorphology genes, the expression of corresponding humanistic landscape genes is significantly impacted.

Cluster 10: Thousand Buddha Cliff Grottoes. This cluster is a quintessential landscape gene cluster centered on stone carving art. Its influence extends to the Jiamen Shudao, the Huangze Temple cliff carvings, and the Dushan Bridge in Xiaoxinchang, all of which exhibit unique characteristics of the Shudao landscape. The historical events associated with the Jiamen Shudao are closely intertwined with the thematic content of the Thousand Buddha Cliff Grottoes. The Huangze Temple cliff carvings share remarkable similarities with the Thousand Buddha Cliff Grottoes in terms of form, content, and artistic techniques. Moreover, the transportation function of the Dushan Bridge in Xiaoxinchang plays a crucial role in the context of the Thousand Buddha Cliff Grottoes. Consequently, within this cluster, the absence of any component gene would significantly impact the overall spatial expression, thereby affecting the integrity of the Shudao landscape genes.

Cluster 11: The Historical and Cultural Group of Northern Sichuan. This cluster is a typical landscape gene network centered on intangible culture. Influenced by the overall development history and characteristics of Northern Sichuan’s historical civilization, this cluster exhibits distinct Shudao features in various elements. Specifically, it includes the spatial form and decorative patterns of the General’s Mansion, the construction history and spatial layout of Du Sheng’s Former Residence, the unique morphology of Du Family’s Bell Mouth, the overall arrangement and form of the Du Family Bell Mouth Burial Group, the spatial characteristics of Jieyuan Temple, the historical origins of Guihua Hall, and historical remains such as the Ba People’s Cave in Baishiyuan. Conversely, the expression of these qualitative genes also significantly influences the connotation and developmental trajectory of Northern Sichuan’s historical civilization.

The NCCR theory-oriented landscape gene map network of the Shudao

To further emphasize the research theme and elucidate the characteristics of the landscape gene clusters, this study developed a nonlinear network-based landscape gene map. This map not only illustrates the spatial attributes of different landscape genes but also categorizes them into “core” and “periphery,” connecting them through a network structure to more intuitively demonstrate the spatial relationships among genes within the landscape clusters. Due to the limitations of the paper’s length, it is not feasible to comprehensively present the gene map networks for all landscape clusters. Therefore, this article selects five representative gene clusters centered on settlements, natural environments, stone carvings, passes, and intangible cultural landscapes to illustrate the map networks.

Landscape gene map centered on settlements: A case study of the ancient city of Zhaohua. This gene cluster focuses on the planar layout of the Ancient City of Zhaohua as its core, establishing connections with the spatial layouts of Zhaohua Yixinyuan and other homologous genes. It further explores the intricate relationships between the core and peripheral elements through the spatial expression of detailed genes. For example, the architectural style of the examination hall from the Ming and Qing Dynasties in Zhaohua is highly consistent with the overall architectural style of the Ancient City of Zhaohua (Fig. 13).

Fig. 13
figure 13

Genetic cluster map of the ancient city of Zhaohua.

Full size image

Landscape gene map centered on natural environment: A case study of Fule Mountain. This gene cluster centers on the natural environment of Fule Mountain, which supports artificial structures, as the core gene, while related elements such as tombs and pavilions serve as peripheral genes. Through the construction of this gene map, it becomes evident that the evolution of the natural environment is influenced by human activities, and conversely, human behavior is constrained by the characteristics of the natural environment. This fully illustrates the coordinated and restrictive relationship between the core and peripheral elements in the NCCR theory (Fig. 14).

Fig. 14
figure 14

Map of the Fuleshan gene cluster group.

Full size image

Landscape gene map centered on stone carvings - Taking the Thousand Buddha Cliff Grottoes as an example. This cluster centers on the Thousand Buddha Cliff Grottoes, incorporating key elements such as the Dushan Bridge in Xiaoxinchang, the Shudao at Jiamen, and the Grottoes of the Imperial Grace Temple. These elements form a closely interconnected gene cluster. Notably, the two sets of grotto carvings exhibit significant similarities in content and subject matter, particularly in their predominant depiction of Maitreya Buddha statues. This observation suggests that within this gene cluster, spatial expressions are influenced by mechanisms analogous to cellular genetics. This finding further corroborates the applicability and scientific validity of the NCCR theory in the study of landscape genes along the Shudao (Fig. 15).

Fig. 15
figure 15

Gene Cluster Map of the Thousand Buddha Cliff Cliff Carvings.

Full size image

Landscape gene map centered on passes - A case study of Jianmen Pass. Passes constitute a critical element of the military landscape along the Shudao and serve as the most concentrated carriers of its landscape genes. Historically, the Shudao has been a strategic stronghold for military operations, endowing it with a distinctive military culture that sets it apart from other linear landscapes. Specifically, Jianmen Pass exemplifies this unique characteristic. The design and features of the pass and its city walls are deeply influenced by the natural environment and regional culture, making Jianmen Pass an essential gene carrier of the Shudao (Fig. 16).

Fig. 16
figure 16

Map of the Jianmen Pass gene cluster group.

Full size image

Landscape gene map centered on intangible cultural landscapes: A case study of the historical civilization in northern Sichuan. Northern Sichuan, as an important passage along the Shudao and a significant human geographical region in Sichuan Province, has developed a distinctive historical and cultural identity under the dual influence of regional culture and Shudao culture. This cluster, centered on its unique intangible cultural heritage, uses numerous related historical relics as quality genes, forming a distinctive “culture-space” bidirectional interactive gene expression model (Fig. 17).

Fig. 17
figure 17

Map of historical civilization gene clusters in northern Sichuan.

Full size image

In conclusion, guided by the NCCR theoretical framework, this study conducted an initial exploration of the composition and internal relationships of 11 landscape gene clusters. Among these, five representative clusters were selected to construct a landscape gene map with a clearly defined “core-periphery” relationship. These clusters can inform future research on the Shudao theory, while the landscape gene map provides actionable guidance for the conservation and tourism development of towns and key heritage sites along the Shudao.

Discussion

This research, underpinned by the NCCR theory, investigates the landscape genes of the Shudao. It serves as a critical advancement for the existing research on the Shudao, uncovering the correlation features of its landscape genes at a more profound level. Consequently, it puts forward an integrated protection framework, thereby advancing the preservation and transmission of the Shudao’s cultural heritage from a broader and more systematic perspective.

The Shudao corridor is renowned for its diverse heritage and serves as a significant cultural repository for humanity. Extensive existing research has highlighted the significant heritage value of the Shudao and proposed corresponding conservation measures, particularly achieving notable outcomes in the protection and development of traditional settlements along the route. For instance, some scholars have assessed the overall development of the Jianmenguan area from the perspective of tourism development suitability. While the study considered various factors, such as the density of heritage site, the number of 3 A and higher-rated scenic area, the proportion of cultural tourism and sports in total expenditure, the normalized vegetation index (NDVI, and other tourism- and environment-related factors49, it failed to explicitly establish the correlations among these factors. Moreover, the study did not emphasize that the protection plan for Jianmenguan should integrate landscape elements, including surrounding mountains, famous statues, and bridges, into a holistic preservation strategy. This represents the core argument of this research. Building on this substantial body of research, this paper systematically categorizes and refines the types of cultural landscapes associated with the Shudao heritage from multiple dimensions, including settlements, natural environments, and transportation networks. It also constructs a comprehensive Shudao heritage resource database.

The study of landscape clusters serves as an essential tool for accurately assessing the value of the Shudao heritage. The Shudao heritage is a linear corridor formed by transportation routes, which has prompted many scholars to adopt a linear approach in their research and summaries, focusing on issues such as the route’s orientation, connectivity, and overall coherence. Apart from spatial analysis, the existing theoretical studies predominantly draw upon historical records, including travelogues and ancient texts. For instance, Ferdinand von Richthofen’s “Diary of China” and “Hand-drawn Maps of China: The History of Chinese Architecture Recorded by Japan”7,50 have been utilized to systematically organize the historical background and theoretical frameworks related to the Shudao. Nevertheless, such research remains inadequate. Undoubtedly, the spatial investigation of the Shudao continues to be a key area of scholarly focus. Scholars have overlooked a critical aspect: while the Shudao heritage exhibits a predominantly linear distribution, it also features numerous nodes of varying scales along the route. These nodes do not exist in isolation but are intricately linked to specific natural environments and historical events. Based on this, some scholars proposed a method grounded in the current historical remains and the minimum resistance model to re-plan, evaluate, and categorize the Shudao routes6. Additionally, they analyzed natural elements such as land use types10, topography, geomorphology, and hydrological systems to emphasize the scientific validity of the newly reconstructed routes. However, while this study strengthened the connections between the remnants of the Shudao, it overlooked the historical authenticity of the routes. Moreover, when considering key influencing factors, it failed to account for the correlations between the landscape genes of the Shudao ‘s historical remains and their surrounding natural and cultural elements. This represents one of the significant advancements achieved in this study. Consequently, the nodes on the Shudao display rich and diverse characteristics, and the heritage elements are multifaceted and interconnected. This study systematically examines the temporal sequence and spatial relationships of various heritage elements, drawing on the concept of nuclear genes and mitochondrial genes to deeply explore the intrinsic connections among different heritage landscapes at the nodes of the Shudao. Consequently, it identifies several landscape gene clusters along the Shudao Compared with traditional “display-oriented” landscape gene maps, this approach represents a significant advancement.

The networked development of landscape gene maps is a critical pathway for advancing in-depth research on landscape genes. Landscape genes are a widely adopted concept in contemporary human geography. The map serves as a critical tool for visualizing landscape genes. At present, landscape gene maps are predominantly applied to relatively straightforward and easily interpretable village landscapes26. Through the use of these maps, the location distribution, spatial structure, landscape elements, and architectural characteristics of traditional villages can be systematically depicted30. However, their map presentations often exhibit fragmented and point-like characteristics, lacking systematic integration. This study, by applying the concept of landscape gene clusters, develops a networked landscape gene map that establishes connections between spatial elements. Consequently, this approach enables landscape gene research to transcend its previously simplistic nature and advance towards a more comprehensive and systematic direction. Therefore, the primary contribution of this study lies in breaking the fragmented research trend on the landscape genes of the Shudao and striving to construct a more systematic and integrated research framework. This, in turn, offers more scientifically grounded and practically effective guidance for the conservation of the Shudao’s cultural heritage.

Although this study has made new attempts in gene integration and map construction, it still relies on the established processes and procedures of previous scholars for landscape gene identification, resulting in a lack of targeted research methods. Therefore, the primary contribution of this study is its interpretation and application of the NCCR theory. Nevertheless, there remains a need for more innovative techniques and methodologies in the identification and summarization of landscape genes. Addressing this gap will be a key focus of our future research efforts. Additionally, constrained by research time and thesis length, the current research team has only conducted summarization, investigation, mapping, interviews, and cartography for selected clusters of the Shudao landscape. This limits the ability to fully reflect the true situation of the Shudao’s landscape gene clusters. In the next phase of the research, the project team will continue to advance follow-up work, aiming to complete the comprehensive sorting and field investigation of all landscape gene clusters along the Shudao as soon as possible. Subsequently, they will develop a more comprehensive landscape gene map to support the practical application of the theoretical research findings. In terms of spatial analysis, the lack of comprehensive spatial surveys has limited our ability to provide essential spatial analysis diagrams for examining “nuclear-cytoplasmic” gene relationships. These include the spatial axis alignment between nuclear and cytoplasmic genes, spatial morphological connections, and structural form associations. Additionally, regarding the interpretation of cultural connotations, deeper analysis is needed, particularly in understanding the links between cliff carving themes and historical narratives, which currently lack sufficient supporting evidence. Addressing these gaps will be a critical focus in future research.

In summary, the main contributions of this study can be highlighted in the following five aspects: (1) A theoretical framework for the “core-periphery” relationship of NCCR landscape genes was developed; (2) The primary landscape elements along the Shudao were systematically identified and organized; (3) Using the NCCR theory, the corresponding landscape genes of the Shudao were systematically summarized, forming multiple gene clusters; (4) Eleven typical landscape gene clusters were selected for in-depth analysis; (5) Based on the NCCR theoretical framework, gene maps were constructed for five representative landscape gene clusters.

By leveraging the biological theory of the mutual influence between nuclear and cytoplasmic genetic information, this paper integrates this concept into landscape gene research, developing a systematic NCCR (Nuclear-Cytoplasmic Coordinated Relationship) landscape gene cluster theory. This theory is then applied to the rich and diverse landscape genes of the Shudao. In the process of identifying and extracting these landscape genes, the study conducts a comprehensive summary and integration, distilling both common and distinctive genes. Furthermore, it selectively constructs 10 landscape gene clusters and corresponding types of typical nonlinear gene map networks as a preliminary step. Through the above research, this paper draws the following conclusions: (1) The landscape of the Shudao primarily comprises five categories of material cultural landscapes—namely, natural landscapes, architectural landscapes, cultural landscapes, military landscapes, and transportation landscapes—and four categories of intangible cultural landscapes, including traditional customs, belief culture, art culture, and production and living practices. (2) The common genetic traits of the Shudao landscape are primarily reflected in several key aspects: topography and landforms, military and commercial functions, settlement spatial forms influenced by major historical events and figures, decorative colors, tomb sizes and shapes, themes and scales of ancestral temples, and the spatial characteristics of passes and fortresses.

(3) The NCCR landscape gene cluster theory can effectively summarize and integrate the landscape genes of the Shudao, elucidate the “nucleus-cytoplasm” co-constraint relationship among them, and provide a theoretical foundation for the concentrated and contiguous protection of the Shudao landscape. This study, within the framework of the NCCR theory, identified 11 unique landscape gene clusters. The landscape elements within each cluster are closely interrelated, with nuclear genes determining the expression of quality genes and quality genes, in turn, influencing the evolution of nuclear genes. Together, they form cultural heritage nodes along the ancient road within specific spatial extents. (4) The nonlinear gene map constructed in this study can clearly delineate the spatial relationships among different landscape genes, thereby offering practical and actionable guidance for government decision-making bodies and planning and design entities in the sustainable development of the Shudao landscape. This study has generated maps for five typical landscape gene clusters. Through the spatial representation of these maps, it is evident that nuclear genes exert influence on quality genes in areas such as cultural connotation expression, spatial alignment, and landscape control, while quality genes, in turn, impact the development and evolution of nuclear genes concerning theme expression, color, artistic form, and natural landforms.

This research project aims to propose a novel method for summarizing landscape genes and apply it to the study of the Shudao. By integrating fragmented research on the landscape genes of the Sichuan Road, this study seeks to construct multiple landscape gene clusters along its route. Through mapping landscape genes from the perspective of gene clusters and establishing spatial relationships among them, this research provides a solid foundation for the conservation of cultural heritage and sustainable tourism development along the Shudao.

Linear cultural heritage is a valuable asset to all of humanity and a focal point of global concern. In particular, within the modern context of global cultural integration and the development of economic corridors, fully harnessing the connectivity function of cultural heritage corridors can strengthen economic and cultural exchanges between nations, foster global harmony and peaceful development, and holds significant importance.