The Construction of a Protection Network for Traditional Settlements Across Regions: A Case Study of the Chengdu–Chongqing Ancient Post Road Heritage Corridor in China

Abstract

In recent years, there appears to be a notable transition towards preserving heritage on a regional scale, aiming to promote the authenticity and integrity of traditional settlements. The complex natural topography of these settlements, along with their spread-out arrangement, poses significant challenges to their protection and preservation. With the acceleration of urbanization and the implementation of the national strategy of building a twin-city economic circle in the Chengdu–Chongqing region, economic, cultural, and ecological exchanges between the twin cities have become the key dimensions of their construction. In this context, the concept of the BaShu Cultural Tourism Corridor has emerged, and the traditional settlement sites in the study area have become an important node of urban–rural integration and the BaShu Cultural Tourism Corridor. The primary objective of this study is to establish a heritage corridor protection network for traditional settlements along the Chengdu–Chongqing Ancient Post Road within the Sichuan Basin of China as an example, using the minimum cost resistance model. This approach comprises several key steps: selecting traditional settlements, analyzing their distribution traits, calculating the resistance value for the spread of traditional settlement culture, identifying potential cultural corridors, identifying cultural spaces, and, thus, constructing a protection network. The results show that the spatial distribution of traditional settlements in the study area shows obvious clustering characteristics, the core ecological space in this study is located in the mountains in the north and the southwest, and the cultural spaces are located along the central and southwestern sections, creating a linear distribution pattern. In the ecological culture corridor network, the Premier Corridor is the most extensive of the three categories, connects important cultural area, and serves as a vital conduit for developing heritage tourism strategies. This research aims to bolster the comprehensive protection and application of the region’s traditional cultural heritage, fostering the integration of urban and rural zones and enhancing regional cultural tourism. Future research directions are to integrate the conservation of traditional settlements and the surrounding environment at different planning scales with local policies and to expand the role of digital technology in the data management and visualization of ecocultural corridors.

1. Introduction

Traditional settlements have evolved over extensive historical periods, encapsulating a wealth of historical data and cultural resources [1], which result from the prolonged interaction between humans and their environment. They reflect the ancestral ingenuity and creative ability in adapting to their surroundings [2]. Protecting traditional settlements is crucial for the cultural, ecological, and economic advancement of contemporary societies. However, the natural ecological settings, diversity of cultural landscapes, and unique cultural attributes of China’s traditional settlements are under threat of degradation due to the rapid pace of modernization and urban expansion [3,4,5]. Since 2012, 8155 villages have been recognized under the Chinese Traditional Village Protection List, emphasizing their importance in preserving historical narratives and playing a critical role in local protection efforts. Additionally, protecting the cultural spaces surrounding these settlements helps preserve the coherence and structure of the traditional settlement landscape. In 1964, the Venetian Charter stated that people’s awareness that cultural heritage cannot be viewed in isolation but should be combined with the history it has witnessed and the environment in which it exists should continue to be strengthened. Therefore, the exploration of protective measures and planning for cultural spaces around settlements should consider not only the protection of specific instances but also the collective preservation of traditional settlement landscapes and cultures from a holistic perspective [3]. There are many international cases of comprehensive protection of historical heritage worth learning from, such as the Camino de Santiago, which is listed as a UNESCO World Heritage Site. The cultural heritage, religious beliefs, and natural scenery along this road have been perfectly integrated and protected. In the modern era, with the increasing number of pilgrims on this road, a new spirit of hiking culture has emerged. This makes the entire heritage of the Camino de Santiago more unique and complete over time, which offers great inspiration for the protection of similar linear cultural heritage. In addition, there are important examples of cultural heritage routes, such as the Via Francigena in Europe, the Inca Trail in South America, etc., which be considered as comparable cases at the global level, also forming linear spaces connecting important tangible and intangible cultural elements in the neighborhoods, as well as holistic conservation and tourism planning.

As an influential cultural tourism brand building target in western China, the BaShu Cultural Tourism Corridor was proposed in 2020. It is necessary to further clarify the basic conditions, influencing factors, and key issues that promote the construction of the BaShu Cultural Tourism Corridor. The Chengdu–Chongqing Ancient Post Road is an essential part of the BaShu Cultural Tourism Corridor. The Chengdu–Chongqing Ancient Post Road, historically the sole route connecting Chongqing to Chengdu, served as a vital conduit for economic and cultural exchange in the BaShu region, which refers to the Sichuan Basin and its surrounding areas in southwest China. Often referred to as the precursor to the “Chengdu–Chongqing Highway”, this path stretched approximately 1200 miles. Situated to the east of Chengdu, the provincial capital, two primary ancient pathways connected these cities. The longer route was known as “Dongda Road”, while the shorter was referred to as “Dongxiao Road” [6]. For millennia, this ancient post road was a bustling artery for commercial trade, population movements, cultural interactions, and the spread of religious beliefs. Around it, various traditional settlements emerged, deeply intertwined with the post road’s culture. However, the rapid pace of contemporary urbanization has led to a significant decline in rural populations and the fading away of traditional lifestyles, inflicting irreversible harm on these traditional settlements near the ancient road. While certain sections of the ancient post road have been designated as protected cultural sites, the road itself and its adjacent settlements have not been comprehensively included in the scope of cultural heritage protection. This oversight has resulted in less-than-optimal preservation efforts for the ancient route. Research into the distribution of traditional settlements along the Chengdu–Chongqing Ancient Post Road and the construction of a unified heritage protection corridor for these settlements is crucial. Such initiatives are instrumental in forming the overall heritage route of the Chengdu–Chongqing Ancient Post Road. They hold immense value for the protection of rural landscapes, the promotion of urban–rural integration, and accelerating the construction of the BaShu Cultural Tourism Corridor, which is the area with the main cities of Chongqing and Chengdu as the core, and the high-speed railway, expressway, and urban areas (counties) along the Yangtze River water system connecting the two places as an important component.

Corridors were originally a concept in landscape ecology as linear landscape units that facilitate the movement of species between habitat fragments [7]. In recent years, the scope of research in heritage protection has expanded from individual sites to consist of broader concepts such as corridors [8,9,10] and networked dimensions [11,12]. This shift reflects the evolution of the heritage corridor idea, which draws inspiration from the emergence of greenways and heritage areas in the United States during the 20th century. A landmark moment came in 1984 when the Illinois and Michigan Canal was recognized by the United States Congress as the first National Heritage Corridor, officially bringing the heritage corridor concept into formal recognition [13]. The concept of a heritage corridor emphasizes the cultural significance and natural values of a heritage site. It is a multi-objective conservation planning approach that incorporates heritage conservation, regional revitalization [14], recreation, physical and mental regeneration of residents [15], and cultural tourism [12,16,17]. Heritage corridors serve a dual purpose. On one hand, they connect isolated heritage or natural sites into a cohesive spatial arrangement, thereby amplifying the collective value of these sites to surpass the mere addition of individual values. On the other hand, much of the current research on the preservation of heritage and culture in traditional settlements has been narrowly focused on the commemorative importance of significant sites and historical structures [18]. This focus tends to be confined to specific items and a defined geographical boundary, overlooking the wider historical context and environment that lies beyond these confines [19]. Scholars specializing in historical landscapes argue that cultural qualities are ubiquitous, rendering it necessary to identify the landscape characteristics and cultural spaces of various traditional settlements in the region from an overall perspective [20]. The research on the construction of heritage corridors is currently in the exploratory stage. Currently, the relevant domestic research consists of three main aspects: (1) Corridor structures are established based on existing heritage elements, such as rivers, walls, railways, traffic roads, and other historical activities. For example, the construction of an intangible cultural heritage corridor along the Great Wall [21], a linear cultural heritage corridor for the Shanxi Tea Ceremony [22], and a Jingdezhen heritage corridor have been studied. (2) Starting from the existence of spaces or nodes with historical activity significance, corridors are established through the summary of historical activities. For example, the integration of traditional settlement landscapes in the southwestern Wuling Mountain area [3]. (3) The construction of corridors are studied from the perspective of ecological landscape value assessment and the influence diffusion capacity of important nodes. For example, the study of the Zhangye Silk Road corridor assessed the value of the cultural ecological landscape through participatory mapping, demonstrating CES spatial mapping [23]. The Silk Road in Yunnan [24] and traditional village cultural heritage corridor in Mentougou district [25] were quantified by evaluating the value and impact of each node. The above studies provide an essential theoretical framework and reference for such studies in various aspects of corridor construction. From an overall conservation perspective, due to the complex terrain of the Chengdu–Chongqing Ancient Post Road, the preservation and development of traditional settlements need to be connected through the surrounding landscape. Therefore, it is necessary to construct the cultural-influence range of traditional settlements to better guide the construction of corridors. There has been an increasing emphasis on the conservation of valuable cultural heritage, relics, and geological heritage in traditional settlements [26]. Regarding research methodology, most studies adopt qualitative analysis to study various aspects, such as the historical and cultural environment, intervillage cultural logics, and the formation of an ancient village system [12,27,28]. This approach guides the holistic conservation of the region’s cultural heritage and identifies important ecological and cultural spaces for the purpose of building tourism corridors [29]. This paper primarily utilizes the minimum cost resistance (MCR) model and the Linkage Mapper current model, focusing on traditional settlements along the Chengdu–Chongqing Ancient Post Road. By combining historical research with spatial analysis, we aim to integrate the resources of these settlements and establish a scientifically grounded and logically structured heritage protection network for the Chengdu–Chongqing Ancient Post Road. Our research seeks to address several overarching questions: (1) What are the regional distribution characteristics of traditional settlements? (2) How do we construct the settlement heritage corridor in the region? (3) Based on the analysis results of the MCR model, how do we construct cultural space as a cultural source? Addressing these questions will significantly broaden our understanding of how we can construct a network of heritage corridors that spans across regions. This, in turn, will support future planning for regional heritage and tourism spaces by offering data support and practical recommendations. This study integrates the cultural units and tourism elements around the Ba Shu cultural corridor, connecting them in a series, akin to stringing beads; strengthens regional cooperation; breaks down administrative barriers; realizes resource sharing and complementary advantages; promotes the evolution of the natural and historical functions of the cultural tourism belt in the Ba Shu region to the actual function from a holistic perspective; forms a comprehensive resource value system of virtual and real coexistence and interweaving time and space; and realizes the coordinated development of regional economy, culture, and ecology based on a cultural strategy in the Ba Shu region. Moreover, our findings are expected to provide valuable insights and guidance for the conservation and restoration of other transregional heritage cultural spaces, structures, and networks.

2. Materials and Methods

2.1. Study Area

The area chosen for this study comprises the administrative regions (cities/districts) along the main routes of Dongda Road and Dongxiao Road in the Chengdu–Chongqing Ancient Post Road network. This includes parts of eastern Sichuan Province and a section of Chongqing (Figure 1), covering 2 provinces, 25 districts, and several counties, over an area of 24,630.18 square kilometers.

Historically, during the Tang and Song dynasties, the Chengdu–Chongqing area was served by a few minor trade routes, which were the precursors to Dongda Road. However, by the Ming and Qing Dynasties, as the political and economic focus of the Sichuan Basin moved eastward and southward, Chongqing’s political importance rose to match that of Chengdu. This shift facilitated more frequent economic and cultural exchange between the two cities, leading to the flourishing of Dongda Road and the emergence of the ‘Dongda Road Economic Belt’ between Chengdu and Chongqing [6]. Migration and economic growth in this region spurred population increases and trade development, which, in turn, led to the growth in the number and size of trade-related settlements. Over time, these developments contributed to the formation of the “line + settlement” spatial pattern of the heritage corridor.

The Chengdu–Chongqing Ancient Post Road and its nearby traditional settlements demonstrate a remarkable understanding of ecological wisdom of adaptation and coexistence. This adaptability is evident through the strategic regional positioning, the organized hierarchical system, and the trade function layouts that are both inspired by and in tune with nature. As a significant ancient transportation network, the Chengdu–Chongqing Ancient Post Road comprises a system of roads, postal stations, commercial towns, and other key points. Rivers, too, play a vital role in this comprehensive transportation network. Travelers moving from Neijiang to Zizhou through the Dongda Road would navigate across the Tuojiang River at Tangming, illustrating the integrated relationship between the road and its neighboring environments. From the Qin and Han dynasties onwards, the flourishing state of transport was complexly associated with various societal, political, economic, and hydrological considerations. The evolution of the Chengdu–Chongqing Ancient Post Road significantly impacted the development of and decline in urban and rural settlements situated along its path [6]. The surge in east–west commerce led to increased population densities in towns along the ancient post road, fostering continual enhancements in settlement conditions and the emergence of numerous commercial hubs.

2.2. Data Source and Processing

This research incorporates an array of data concerning the Chengdu–Chongqing Ancient Post Road, including historical route information, details on traditional settlements in proximity to the road, and fundamental geographic data relevant to the area under study. The methodology for data collection and analysis is outlined below:

The historical route data are primarily sourced from relevant ancient books, ancient maps, writings, official archives, and personal travel notes regarding the Sichuan Basin. We first read the written records of the names of the ancient post road in these books and examined the position of the present ruins of these ancient stations. Second, the road was annotated in Google Maps to obtain accurate geographic coordinate data, which were imported into ArcGIS 10.8 to concatenate the coordinates of the stations and were finally compiled into a .shp file. Notably, works such as Tang and Song Sichuan Post-house Huikao (1990) and Sichuan Post-station Huikao in Yuan Dynasty (1997) by Lanyong offer comprehensive details on traffic junctions and the distances between these points. These records are invaluable for the analysis of the evolution of the Chengdu–Chongqing Ancient Post Road’s transportation pathways across various periods. The information regarding the positioning of traditional settlements leverages the national preservation catalog, on-site surveys, the Sichuan Ancient Town and Ancient Village Digital Museum [30], and the official site of the Chongqing Municipal Government (including provincial historical and cultural towns, provincial historical and cultural villages, traditional villages, and other data). A selection of 65 traditional settlements, characterized by their unique local cultural attributes, was made considering aspects such as the settlements’ functions, architectural distinctiveness, connections to the ancient post road, both tangible and intangible cultural heritage, and their protection status (

Table 1. Traditional settlement information database along Chengdu–Chongqing Ancient Post Road (partial data).

Route	Current Place Names	Ancient Places	Dynasty	Historical Function
Dongxiao Road	Luodai Ancient Town	Zhenzi Field	Qing dynasty (1616–1912 CE)	Major trading town
	Shuangjiang Ancient Town	Shuangjiang Commune	Late Ming–early Qing (1600–1700 CE)	Ancient town
	Anju Ancient Town	Anju River	Ming dynasty (1368–1644 CE)	Ancient town
Dongda Road	Lianchipu Village	Lianchi Shop	Qing dynasty (1616–1912 CE)	Ancient post
	Nanjin Town	Nanjin Post Station	-	Ancient post
	Yujian Community	Yujian Old Street	Qing dynasty (1616–1912 CE)	Distribution center
	Shipan Town	Shipan Shop	Ming dynasty (1368–1644 CE)	Ancient post
	Yunshan Town	Yinshan Town	Tang dynasty (618–907 CE)	Ancient town
	Zouma Ancient Town	Zouma Post Station	Han dynasty (202 BCE–220 CE)	Major trading town
	Chaotian Men	Chaotian Post Station	Tang dynasty (618–907 CE)	Water wharf

).

Primary geographic information data primarily include the 30 m spatial resolution digital elevation model (DEM), alongside data on rivers, roads, and the quality of the ecological environment in the study area. This information was procured from the Geospatial Data Cloud portal of the Computer Network Information Center at the Chinese Academy of Sciences (http://www.gscloud.cn/, accessed on 12 March 2023). The research integrates the historical pathways of the Chengdu–Chongqing Ancient Post Road with assessments of current transportation infrastructure and hydrographic distribution. It involves the creation of Euclidean distances from traditional settlements to rivers and roadways and the transformation of vectorized road data of varying classifications into raster format (30 m spatial resolution) to simplify the analysis of spatial distances between traditional settlements and these geographic features.

2.3. Research Methods

2.3.1. Kernel Density Estimation Method

Kernel density estimation stands out as a highly regarded non-parametric method for analyzing spatial point patterns [31]. In this research, kernel density is employed to illustrate the spatial clustering of traditional settlements [32]. The methodology utilizes the following formula:

$$f_n\left(x\right)={\displaystyle \frac{1}{nh}}\sum _{i=1}^{n}k[\frac{x-x_i}{h}]$$

(1)

In the formula, $k[\frac{x-x_i}{h}]$ is called the kernel function; $h$ is the bandwidth and $h$ > 0; and $(x-x_i)$ represents the distance from the estimated point to sample point $x_i$.

2.3.2. The Nearest Neighbor Index Analysis Method

The principle underlying the nearest neighbor index analysis method revolves around selecting a point randomly from the actual dataset and comparing the average distance $\overline{D_O}$ from this point to its nearest neighbor with the expected average distance to the nearest neighbor distance $\overline{D_E}$ in a hypothetical random distribution [33]. This comparison, conducted using a ratio, serves to assess the spatial aggregation of the “point” [34]. The formula for calculating the actual observed average distance to the nearest neighbor is as follows:

$$\overline{D_O}={\displaystyle \frac{1}{n}}\sum _{i=1}^n{d}_i$$

(2)

In the formula, $d_i$ is the distance between the $i$-th point and its nearest neighbor point; $n$ is the number of points. The expected nearest neighbor average distance is calculated as follows:

$$D_E={\displaystyle \frac{1}{2}}\sqrt{n/A}$$

(3)

In the formula, $n_2$ is the number of points of traditional settlements; $A$ is the area of the study area; and when the neighborhood ratio (NNI) is less than 1, it indicates that traditional settlements are clustered. As the NNI nears 1, the distribution of these settlements appears more random. An NNI above 1 suggests a uniform distribution across the area. The method further involves calculating Z-values and their confidence levels through standard distribution tests to quantify the deviation between the observed and expected average distances [35].

2.3.3. Minimum Cumulative Resistance and Current Theory

The minimum cumulative resistance (MCR) model is designed to quantify the effort required by species to navigate through varying landscape resistances as they move from ecological origins to destinations [36,37]. Yu Kongjian et al. have applied the MCR model to evaluate the viability of heritage corridors [38]. The model’s formula is as follows:

$$MCR={\int }_{min}\sum _{j=n}^{i=m}(D_{ij}\times R_i)$$

(4)

In the formula, MCR is the minimum cumulative resistance value; $D_{ij}$ is the empirical spatial distance from the environmental element I to the legacy source j; and $Ri$ is the drag coefficient experienced by the environmental element I during the spatial motion.

At present, the MCR model enjoys broad application across ecological research areas, including species protection and landscape pattern analysis, as well as ecological network construction [39] and land suitability evaluation [40], where circuit theory constitutes a prominent computational framework.

In the field of circuit theory, it is understood that charge behaves in a manner similar to a random walk [41], aligning with the randomness or semi-randomness observed in the communication processes of this specific region. This research, therefore, employs both circuit and graph theory to create networks that are regionally interconnected (Figure 2). In particular, the landscape is approached as a conductive surface. Leveraging graph theory alongside circuit theory, the diverse landscape is conceptualized as a circuit made up of nodes and resistors, symbolizing a significant cultural influence [42]. This study was guided by parameters such as the resistance threshold, the extent of the circuit, the minimum resistance value (200.0), and the distribution scope of key settlements. Drawing on additional relevant studies, the corridors’ maximum width was established at 5 km to facilitate the creation of corridors that impede flow, which were analyzed and specialized with Linkage Mapper 3.1.0 software for circuit landscapes.

2.3.4. Analytic Hierarchy Process (AHP)

The construction of traditional settlements and heritage corridors along the Chengdu–Chongqing Ancient Post Road is differently influenced by various resistance factors.

Building on prior research and analysis [42], both the Delphi method (an expert evaluation method) and the analytic hierarchy process (AHP) were applied to assess the significance of different resistance factors. Therefore, seven resistance factors—elevation, slope, aspect, terrain undulation, rivers, roads, and proximity to the ancient post road—were evaluated using Yaahp 12.12 software, and their significance was established following consistency checks. These seven factors form the basis of the resistance model employed in this study.

2.4. Research Framework

The construction of heritage corridors in traditional settlements primarily comprises the identification of key traditional settlement sites, the construction of corridor spaces in related areas, and identifying areas with unique cultural landscapes (Figure 3).

2.4.1. Selection of Traditional Settlement Points

Following the acquisition of the traditional settlement sites within the study area, they were categorized based on an expert survey and review (with verbal consent from all participants prior to the study), according to the protection status of the traditional settlement and the importance of the cultural heritage [28].

Currently, there are 65 officially recognized traditional Chinese settlements along the Chengdu–Chongqing ancient stagecoach route, according to the Ministry of Housing and Urban–Rural Development and the State Administration of Cultural Heritage. Of these, 41 are in Sichuan and 24 are in Chongqing, with the earliest settlements dating back to the Qin dynasty. The original features of 38 traditional settlements in the region are relatively well preserved. Among them, we selected the 12 most influential villages, which were rated as having a high level of protection and a large spatial correlation with ancient ways. Therefore, the 65 ancient villages studied were categorized into four classes: a total of 12 verified traditional Chinese settlements were classified as Class 1 settlements, 16 settlements with better preserved original features were classified as Class 2 settlements, and the remaining 27 ancient villages were classified as Class 3 and Class 4 traditional settlements.

2.4.2. Construction of the Corridor Space of the Connected Areas

This study includes critical habitation locations and environmentally significant sites along the ancient post road. It integrates key factors such as road and water networks to establish a corridor that connects traditional settlements through both cultural and ecological landscapes. This corridor will also incorporate significant historic and cultural waterways found in the research zone. To analyze mobility patterns under a certain resistance limit, circuit models are applied, selecting suitable resistance factors and values tailored for this research’s objectives. Thereafter, a regional connectivity corridor is designed based on the calculated total resistance area. The importance of these corridors is assessed using the tool Centrality Mapper, and the overall length of each potential ecocultural corridor is determined.

2.4.3. Identifying Characteristic Ecocultural Landscape Areas

The MCR model identifies vital ecological and cultural hubs near the settlements. This research evaluates how various natural factors affect the spread of traditional settlements (in percentage terms) to determine combined resistance values and weights.

In this study, ecological spaces are defined as areas with high integrated ecological value, such as forests, bodies of water, and fertile lands, all of which maintain a strong connection to traditional settlements. Cultural source areas consist of traditional settlements, tangible and intangible cultural heritage connected to the ancient post road, serving to identify key cultural landscape areas as cultural reference points for traditional settlements. A total of 56 national cultural relics protection units and 121 provincial cultural relics protection units were analyzed, resulting in the identification of 264 cultural sources. We employ the cost distance tool in GIS alongside the ISO unsupervised classification tool to highlight key ecological and cultural areas. To differentiate the significant levels of cultural spaces, they were categorized using the natural breakpoint method, leading to the formation of a stratified ecocultural space of varying importance.

The construction of heritage corridors in traditional settlements primarily requires the selection of vital traditional settlement points, the formation of corridor spaces in pertinent areas, and the identification of unique cultural landscape areas.

2.5. Comparison of Research Methods

We sorted out the methods commonly used to construct the heritage cultural corridor network, and the results of other researchers are shown in

Table 2. Main approaches to the construction of cultural heritage corridors.

Method	Main Processes	Pros and Cons
Legacy resource rating	Cultural heritage resource determination; cultural heritage resource rating; cultural heritage potential corridor construction	Data acquisition is convenient and belongs to qualitative research. It can only take into account the heritage sites that have been investigated, without considering the ecological factors; no concrete corridor can be formed.
Analysis of multidimensional network connectivity	Extract single-dimensional nodes; optimize single-dimensional space; superpose to form an integrated network	Considering the time, space, national culture, religious culture, altitude difference, and other hierarchical factors of landscape patches. However, the connection mode is direct connection, and no specific corridor is formed.
The minimum cumulative resistance method (MCR)	Analysis of basic data (ecological, cultural resources, etc.); simulation of resistance values of various elements; formation of comprehensive resistance surface; determination of cultural heritage source points; formation of corridor network	It can directly form specific corridors and judge the importance of corridors. However, the resistance value calculation index is subjective and can only be determined by referring to other studies.
Participatory mapping to assess the value of cultural ecosystem services	Distribution of questionnaires; digitizing all plotted points; kernel density analysis; spatial clustering of individual CES	It can directly reflect the public perception of regional heritage and protection work. However, the participatory mapping survey needs to issue a large number of questionnaires, and the preliminary research workload is large.

.

In the common construction methods of cultural heritage corridors, the minimum cumulative resistance (MCR) method is the most used method. The advantage of this method is that it is convenient to obtain data and can generate specific potential corridor information.

3. Results

3.1. Spatial Distribution Characteristics of Traditional Settlements Along the Chengdu–Chongqing Ancient Post Road

Utilizing the analytical capabilities of the ArcGIS10.8 nearest neighbor index tool alongside the Euclidean distance calculation method, we determine the spatial distribution patterns of traditional settlement points linearly. The findings indicate that the nearest neighbor ratio is below 1 (Figure 4a). By integrating the p-values and z-values, it is determined that the distribution pattern of traditional settlements leans towards clustering, successfully passing the significance test. Additionally, Ripley’s K-function has been employed to assess variations in traditional settlements across different spatial dimensions. The distribution map of traditional settlements in the vicinity of the Chengdu–Chongqing Ancient Post Road, generated through Crimestat3.3 calculations, reveals (Figure 4b) that the x-axis distance denotes the scale of distance, whereas the y-axis L(d) signifies the clustering pattern, boasting a confidence level of approximately 99.9%. This pattern suggests that traditional settlements, regarded as point factors, exhibit dual behaviors of outward diffusion and inward clustering across spatial extents, with clusters forming in the 0 to 39 km range and a more even distribution observed beyond the 39 km mark.

The kernel density estimation method was applied to visually represent the spatial distribution traits of traditional settlements (Figure 5). It is observed that the primary concentration areas of traditional settlements span the Longchang–Rongchang–Yongchuan–Bishan region, with Zizhong County also hosting a significant cluster. A limited number of traditional settlements are discovered along Dongxiao Road.

3.2. Construction of Ecocultural Integrated Resistance Surfaces in Traditional Settlements

3.2.1. Construction of Ecological Spaces

In the analysis of the designated study area, the classification of land use highlights areas with significant ecosystem service functions—specifically, water bodies and forest lands—as primary focal points for the MSPA analysis. Conversely, agricultural lands, barren terrains, and construction land are used as the backdrop for this study. Utilizing Guidos 3.3 software, this study employs an eight-neighborhood approach to analyze a binary grid layout measuring 30 m by 30 m. This process yields seven morphological types, with their respective sizes and percentages catalogued. The findings exhibit that the core area covers 308.57 km², which represents 10.82% of the overall study region and 43.38% of the combined forest and water areas. This zone is mainly distributed in Longquan Mountains in the north and Jinyun Mountains in the southwest. Further analysis demonstrates 9302 individual patches in the core zone, including 207 patches exceeding 10 hm², collectively spanning 240.10 km² or 77.8% of the core’s total extent. The strategy for ecological space construction aims to isolate patches with fragmented core areas while preserving those of significant ecological merit. This approach is instrumental in fostering ecological processes, thereby protecting the stability and functionality of the ecosystem for further research.

The analysis, facilitated by Conefor 2.6 software, calculates the overall landscape connectivity index (IC) and the patch significance index (dPC) for critical landscape patches in the study zone. These indicators serve to measure the landscape’s connectivity level. Adopting a distance threshold of 2000 m and a connectivity probability of 0.5, as suggested by the related literature [39,40,43,44], enables the calculation of the patch importance index across each core zone. This assessment, in conjunction with the dimensions of each ecological patch, lays the groundwork for establishing evaluation and ranking guidelines for core areas (

Table 3. Graded assessment of the regional ecological space of the Chengdu–Chongqing Ancient Post Road.

Area (hm2)	Importance Index (dPC)
	dPC ≥ 2	2 > dPC ≥ 1	1 > dPC ≥ 0.1	dPC ≤ 0.1
S ≥ 200	Ecological source	Ecological source	First-level core area	First-level core area
200 > S ≥ 50	Ecological source	First-level core area	First-level core area	Second-level core area
50 > S ≥ 20	First-level core area	First-level core area	Second-level core area	Third-level core area
S ≤ 20	Second-level core area	Second-level core area	Third-level core area	Third-level core area

). Through this classification, core areas are classified into ecological source areas and primary, secondary, and tertiary core areas. Additionally, connector zones identified through MSPA 2.3 software are designated as structural ecological corridors in the study area.

This study identified a total of 13 ecological sources, comprising 25 first-level core areas, 35 second-level core areas, and 131 third-level core areas (Figure 6b). These ecological sources primarily consist of wetlands, lakes, rivers, and scenic spots. In terms of spatial distribution, these sources are unevenly spread across the region, with a significant concentration in the southeast and northwest, while the central area exhibits a scarcity of ecological sources.

3.2.2. Construction of Cultural Space

The Chengdu–Chongqing Ancient Post Road has historically played a crucial role in facilitating commercial trade and migration. Therefore, the surrounding settlements are dotted with buildings and landscape structures that have direct ties to these activities. These sites of material cultural heritage have been recognized as either provincial or national cultural heritage protection units. Collectively, they form a cultural space that not only enriches the traditional settlements but also highlights the historical significance of the ancient post road [3].

In assessing the influence of various cultural sources, the MCR model was employed. This research categorizes cultural dissemination into five levels, ranging from low to high influence (Figure 7,

Table 4. Number of traditional settlements and cultural source points in different levels of cultural space.

Cultural Dissemination Zone Level	Area (km2)	Percentage	Number of Settlement Points	Cultural Source Points
I	125.8754469	0.51%	11	92
II	295.9238255	1.20%	21	79
III	379.3567502	1.54%	22	69
IV	743.1246573	3.02%	11	19
V	3999.74432	16.24%	0	5
Total	5544.025	22.52%	65	264

). Area I and Area II represent the central zones for the transmission of traditional settlement culture, including 32 traditional settlements and 171 cultural heritage protection units. These areas account for 49.23% and 64.77% of all cultural sources, respectively. District III serves as a secondary zone, containing 33.846% of the total settlements. Meanwhile, District IV includes only 11 traditional settlements, and District V lacks traditional settlements entirely, featuring only a few associated cultural sources.

The cultural spaces in the study area are predominantly situated in the central and southwestern sections along the ancient road, creating a linear distribution pattern. The focal points of this distribution are Longchang City and Rongchang District. Other cultural spaces are dispersed across the southwestern region of Zizhong County and the northern regions adjacent to the Chengdu–Chongqing Ancient Post Road, including Lezhi County, Anyue County, Anju District, Tongnan District, etc. (Figure 8).

3.2.3. Construction of Ecocultural Integrated Resistance Surfaces in Traditional Settlements

The minimum cumulative drag model identifies the most efficient path by calculating the path with the lowest overall drag distance between the starting point and the destination. This approach more accurately represents the potential movement of material energy across the landscape and the migration patterns of biological species across different habitat areas. The levels and resistance values of each resistance coefficient are listed (

Table 5. Ecocultural heritage corridor resistance factors and their weights and relative resistance.

Resistance Surface Type	Weight	Representation	Number of Traditional Settlements	Resistance
Land Cover	0.2737	Woodland	-	20
		Farmland	-	40
		Water	-	80
		Grass land	-	100
		Urban construction land	-	200
Elevation (m)	0.1611	0–200	0	180
		200–300	11	120
		300–500	50	10
		500–700	3	150
		>700	0	200
Slope	0.1187	0–2	43	20
		2–5	18	60
		5–10	3	100
		10–15	0	160
		>15	0	180
Vegetation coverage	0.2409	0–0.15	0	160
		0.15–0.3	1	120
		0.3–0.45	8	80
		0.45–0.6	16	60
		0.6–1	39	20
Water system distance (km)	0.0809	0–0.5	6	80
		0.5–1	16	40
		1–3	34	20
		3–5	5	60
		>5	3	120
Road distance (km)	0.0501	0–0.5	20	20
		0.5–1	17	30
		1–3	13	40
		3–5	7	60
		>5	7	80
Distance of ancient post road (km)	0.0477	0–0.5	6	100
		0.5–1	7	80
		1–3	14	40
		3–5	11	60
		>5	26	20

). Upon examining the resistance values associated with different types of land cover, it was discovered that woodlands and cultivated fields exhibit lower resistance values. This is crucial for preserving habitats in landscapes where traditional settlements are located. While human activities minimally disturb these farmland types, they are complexly connected to the cultural traditions, production methods, and basic livelihood activities of the local population [45]. Rivers play a critical role in the landscape along the Chengdu–Chongqing Ancient Post Road, significantly influencing both the economic activities and daily lives; thus, their areas are assigned lower resistance values. In contrast, urban areas receive the highest resistance values due to their disruptive impact on the continuity and dissemination of traditional culture, along with the negative effects urbanization has on the structure and appearance of traditional settlements.

The analysis of traditional settlements in various topographical gradients revealed a predominant distribution in estuarine valley regions (200–300 m) and hill zones (300–500 m), comprising 17.19% and 78.13% of the settlements, respectively, with the remainder situated in mid-mountainous areas (500~700 m). The gentler the incline, the easier and more cost-effective it becomes to develop infrastructure, which in turn better supports the inhabitants’ production and lifestyle needs, leading to a denser concentration of settlements. Generally, as the slope increases, the number of settlements tends to decrease [46], indicating a pattern where traditional settlements are primarily found in areas with slopes ranging from 0 to 5.

In addition, the coverage of vegetation has a significant effect in influencing the layout of settlements by impacting the quality of habitats and the capacity of regional resources to support populations. In the area under study, settlements tend to cluster in regions with higher vegetation coverage, plentiful water supplies, and superior ecological conditions, rendering these areas more conducive to agricultural production and living. Specifically, the data exhibit that settlements in areas with medium to high vegetation coverage (>60%) account for approximately 60.94% of the total.

In addition, the stability of the social environment is a critical factor that affects the placement of traditional settlements. The challenging terrain and sparse traffic networks along the Chengdu–Chongqing Ancient Post Road mean that this area often aligns with key migration paths and military expeditions [45]. In times of social unrest, the strategic advantages of these locations increase the vulnerability of traditional settlements to risks, impacting their formation. For instance, during the Tang and Song dynasties, the river valleys, serving as principal routes for military movements and migrations, frequently suffered from warfare, looting, and other forms of aggression. This resulted in a scarcity of villages and towns along the ancient route. Notably, traditional settlements located within 1 km of rivers and roads accounted for only 34.38% and 57.81%, respectively. However, during the Ming and Qing dynasties, as political and economic hubs shifted eastward and southward and trade prospered, numerous trading towns emerged along the Chengdu–Chongqing Ancient Post Road, including Zouma Town and Wanxingchang.

The significance of various factors in constructing the resistance factor matrix was established through a review of the literature and field surveys [3,47,48], and these factors were categorized by land cover, slope, and landform amplitude. This matrix is instrumental in calculating the significance of each resistance factor using the AHP. Building on this, the weighted sum tool in ArcGIS facilitates the overlay of resistance value distribution maps for each factor, while the cost distance tool computes the minimum cumulative resistance value, resulting in a comprehensive resistance surface (Figure 9).

The findings exhibit that the distribution of ecocultural resistance along the Chengdu–Chongqing Ancient Post Road exhibits significant differences, primarily shaped by factors such as land utilization and vegetation cover. The area identified as being a “high-resistance area” spans approximately 76.54 km², predominantly located in the urban areas of Chongqing and Chengdu.

These regions are less conducive for cultural exchanges, largely due to the uniform urban redevelopment witnessed in these areas, which obstructs the dissemination and continuity of traditional cultures. In addition, the expansion of urban areas poses a significant threat to the preservation of traditional settlements. The “moderate resistance zone”, situated near the ridge–valley configurations in the central and southeastern parts, presents significant resistance against various factors. This is attributed to the challenging natural terrain (characterized by high mountains, steep slopes, and dense forests), which complicates construction efforts. Despite these obstacles, such areas are critical ecological reservoirs and possess high ecological significance. The “low-resistance area” is primarily found near and to the northeast of the Chengdu–Chongqing Ancient Post Road. It is characterized by its relatively level landscape, high vegetation density, proximity to water bodies, outstanding habitat quality, and minimal resistance to cultural exchange.

3.3. Statistics of the Ecocultural Integrated Corridor

Here, the final traditional settlement cultural heritage corridor network is depicted (Figure 10). This illustration not only traces the original path of the Chengdu–Chongqing Ancient Post Road but also highlights potential corridors that could facilitate cultural connectivity. These pathways connect 65 traditional settlement nodes, creating a network that comprises critical cultural zones in the region. The left plot demonstrates 142 cultural heritage corridors between nodes and their corresponding lengths.

The original route of the Chengdu–Chongqing Ancient Post Road comprised 15.13% of the total corridor’s length. The Premier Corridor, being the most extensive among the three categories, connects important cultural areas in the study zone and serves as a vital conduit for devising heritage tourism strategies. The intermediate corridors, marginally less extensive than the premier ones, are critical for forging connections and fostering cohesion among cultural areas. Additionally, numerous shorter corridors in the first and second tiers necessitate integration with the corridors under planning to bolster the connectivity and cohesion of cultural spaces. The length of the potential corridor reflects that of the intermediate corridor. Despite the relatively scarce number of potential corridors, they incorporate isolated cultural areas into the network, thereby broadening the scope of cultural heritage protection and application. The total lengths of the corridors exhibit minimal variation across the three corridor types.

4. Discussion

By analyzing the influence of the natural geographic environment, rivers, and transportation on the spatial arrangement of traditional settlements along the Chengdu–Chongqing Ancient Post Road, this research devises an ecocultural corridor network. This network, grounded in the MCR model, aims to coalesce fragmented heritage components and ecological keystones, achieving a cohesive protection of both natural and cultural landscapes. The objective is to foster urban–rural integration and balance the regional economy by preserving the spatial structure, processes, and components’ integrity and continuity. This objective resolves around the protection of the comprehensive worth of the heritage corridor’s natural and cultural resource framework, thereby advancing regional sustainability. Presently, explorations into traditional settlements along the Chengdu–Chongqing Ancient Post Road predominantly adopt case study methodologies, which do not fully capture the entirety of the road and its adjacent traditional settlements. Adopting a dual lens of heritage and ecological protection, this methodology identifies ecological and cultural areas of high value warranting protection, enhances the structural cohesiveness of heritage corridors, and suggests strategies for the holistic protection and employment of cultural heritage across various regions.

We should admit that the construction of “the ecocultural network” depends on the policy support of the government. Therefore, we have sorted out the existing relevant policies in Sichuan and Chongqing (

Table 6. Policies related to the construction of ecoculture corridors in Sichuan and Chongqing region.

Date of Promulgation	Policy Name	Main Content
16 October 2020	Chengdu–Chongqing Economic Circle Construction Plan	We will make unremitting efforts to protect the ecological environment, find a new path that prioritizes ecology and green development, and promote harmonious coexistence between man and nature.
April 2022	Construction and Protection Planning of Yangtze River National Cultural Park (Sichuan Section)	Scientific plans will be made for control and protection areas, theme exhibition areas, cultural and tourism integration areas, and traditional utilization areas in the Sichuan section of the Yangtze River.
6 January 2023	Management Measures for Cultural and Ecological Protection Areas in Chongqing	To strengthen the overall regional protection of intangible cultural heritage, “Chongqing Cultural and Ecological Protection Areas” has been established. We need to protect not only the intangible cultural heritage, but also the human and natural environment that fosters its development, and uphold the comprehensive, coordinated, and sustainable development of the cultural, economic, social, and ecological environment.
January 2024	Spatial Planning of Sichuan Province (2021–2035)	We will strengthen ecological co-insurance, in accordance with the requirements of “jointly grasping great protection” and jointly build a green ecological corridor with the Yangtze River, Jialing River, Tuojiang River, Fujiang River, and the other “six rivers” as the main body. At the same time, relying on Longmen Mountain and Huaying Mountain, we will build a green ecological barrier and provide a good ecological space guaranteeing a high-quality livable place.

).

As seen from Table 6, the policy documents of Sichuan and Chongqing have gradually changed from focusing solely on the development of the economy to focusing on the coordinated development of culture and ecology. Our research is in line with the developing trend of such policies and adheres to the fundamental principle of harmonious coexistence between man and nature. These policies also provide strong policy support for our future research. The study of heritage corridors must keep pace with the needs of nation-building in the context of successive major national strategies and policies [49]. Researchers need to actively explore how to construct and manage ecological and cultural heritage corridors and carry out the establishment of corridor databases at different planning levels, based on a territorial–spatial planning perspective, with a view to corresponding domain heritage protection and management. In this way, it can not only respond to the national development strategy but also contribute to the further deepening of the heritage corridor management system.

The key point in identifying the underlying network revolves around identifying the factors that impede cultural transmission and mapping out how these resistance coefficients are distributed. Research in this area often zeroes in on natural variables such as elevation, the contours of the landscape, incline, and types of vegetation cover, among other indicators [48,50,51]. Huang et al. have expanded this scope to include societal aspects such as cultural norms, the spread of populations, and the availability of food and entertainment options, all through the lens of culture, ecotourism, and leisure [52]. However, cultural factors remain somewhat underexplored, largely due to their qualitative nature, which poses challenges for quantification. Fieldwork findings indicate that, in the Sichuan Basin, traditional settlements exhibit a stronger bond with forested areas, attributed to their unique geographical setting. This connection is further evidenced by quantifying the proportion of traditional settlements across varying levels of vegetation coverage.

Natural, cultural, and economic factors are critical in shaping the distribution and cultural continuity of traditional settlements. Thus, future research could benefit from incorporating indicators such as population density and regional GDP for a more holistic evaluation. The ecocultural network, devised using the shortest path construction tool in GIS, requires further optimization due to limitations of the current algorithm’s accuracy. Moreover, it is feasible to appraise network analysis, employing the α, β, and γ indices to optimize the structure of the ecocultural corridor network illustrated in Figure 1.

In future research on the development and utilization of resources, there appears to be potential in merging traditional settlements with nearby tourism offerings to establish varied zones dedicated to heritage tourism. This approach shifts the focus from individual tourist attractions to a holistic enhancement and integration of cultural heritage resources. This strategy allows for the preservation of traditional settlements and their associated cultural heritage while fostering development [17]. Future efforts should appraise finding modes to connect different cultural factors in expansive cultural territories, particularly those rich in diverse cultural heritage. A key consideration is tailoring solutions to specific needs, such as implementing slow transportation options such as bike paths and walking trails. This initiative aims to forge a sustainable, low-emission, and eco-friendly network that encourages meaningful interactions between visitors and cultural heritage landscapes [3,42]. In addition, it is crucial to address the categorization and hierarchical protection approaches for traditional settlements across different scales [53,54]. By employing a landscape zoning method adapted to different scales, the protective measures for cultural spaces in traditional settlements can be further analyzed. This optimization is built based on the partitioned protection of traditional settlement environments at the territorial scale and the classification and graded protection of traditional settlements at the corridor scale. Special attention is necessary for certain unique settlements that might be neglected in the standard protection framework for historical settlements. These settlements are particularly vulnerable as they often lie on the periphery of corridors, are dispersed, are limited in quantity, and are situated far from other traditional settlements [3,55,56]. In future research, emerging technologies such as remote sensing [57] and artificial intelligence [58] can be used to support the establishment of cultural corridors, while cultural corridors can also be further developed, such as by enhancing the promotion of cultural corridors, promoting their unique values and thus building cultural confidence [59]. At the same time, a comprehensive and systematic plan based on AI can be developed, and the important role of digital technology in promoting the development of cultural corridors can be clarified. Combining emerging technologies, communication channels, and consumption formats, we will explore the potential value of cultural heritage corridors in contemporary communication, especially digital communication, and pay more attention to the “video and experience”, “open source and digital potential of elements”, and “digital survival and virtual community inheritance” presented by the digital communication of cultural heritage [60,61].

5. Conclusions

This study constructs a well-integrated ecocultural corridor network that bridges various regions by carefully examining crucial traditional settlement locations, identifying areas of cultural and ecological significance. By combining the dual strands of nature and culture, this approach fosters the creation of heritage corridors, which play a critical role in devising a sustainable strategy for ecological preservation, heritage protection, and recreational use. The results show the following: (1) The spatial distribution of traditional settlements in Chengdu–Chongqing area shows obvious clustering characteristics: the nearest neighbor ratio is below 1. The core ecological space in this study is mainly located in the Longquan Mountains in the north and the Jinyun Mountains in the southwest, representing 10.82 percent of the overall study area. The cultural spaces are predominantly located along the central and southwestern sections of the ancient road, creating a linear distribution pattern, and include 32 traditional settlements and 171 cultural heritage conservation units. (2) The findings exhibit that the distribution of ecocultural resistance along the Chengdu–Chongqing Ancient Post Road exhibits significant differences, primarily shaped by factors such as land utilization and vegetation cover. Among them, areas identified as being “high-resistance areas” span approximately 76.54 km², predominantly located in the urban areas of Chongqing and Chengdu. These areas are less conducive to cultural exchange, in large part because uniform urban redevelopment has caused devastating damage to traditional settlements in these areas, which has hindered the spread and continuity of traditional culture. (3) In the ecological culture corridor network we constructed, the original route of the Chengdu–Chongqing Ancient Post Road accounted for 15.13 percent of the total length of the corridor. The Premier Corridor, the most extensive of the three categories, connects important cultural areas within the learning area and serves as a vital conduit for developing heritage tourism strategies.

The primary objective of this study is to advocate for the overall protection of traditional settlements along the Chengdu–Chongqing Ancient Post Road, facilitating the integration of urban and rural domains in Chengdu and Chongqing. In this study, a quantitative and objective approach to the construction of ecocultural heritage corridors was explored. The logic of the research method is also applicable to other areas with rich heritage resources and a roughly linear distribution pattern. The research results have reference value for the local economy, cultural tourism industry development, and overall heritage planning.

The limitation of this study is that the value of the resistance factor is subjective and determined by expert opinion and literature studies combined with the state of the study region. Therefore, we should strengthen the collection of field data and information and choose more objective methods to determine resistance values in follow-up studies. Combined with the current planning policies for the Sichuan–Chongqing region, our research framework can contribute to a broader conservation agenda, enhancing the cultural, ecological, tourist, and educational merits of these traditional settlements and championing the sustainable protection and development of traditional settlement landscapes and cultures along the Chengdu–Chongqing Ancient Post Road. Therefore, our future research can be more in-depth on the overall protection of traditional settlements and the surrounding environment by selecting appropriate cases at different planning scales. We can also expand the role of digital technology in the data management and visualization of ecocultural corridors to enhance the public’s sense of identity with local culture and encourage conscious participation in conservation actions.