*2.3. Data*

This study uses the time-series Japan input–output tables (TJIO) consisting of the economic transaction (*Lij*) and household final demand structures ( *b fib*) for 1990, 1995, 2000, and 2005 based on the 2005 price with 397 common commodities. Hence, the data are comparable among periods. Further, we disaggregated the commodities within petroleum products into six detailed commodities including gasoline, light oil, kerosene, liquefied petroleum gas (LPG), and other petroleum products (i.e., lubricants) by using the Comprehensive Energy Statistics [39]. To identify the relationship between household CF and demographic trends, the final household demands from the TJIO were divided into consumption expenditures for six age groups of the highest income earner in the household (29≤, 30–39, 40–49, 50–59, 60–69, ≥70) for each year using the national survey of family income and expenditure (NSFIE) [40]. Then, the consumption share by attribute, summation of each final consumption type by commodity and the di fference between the producer-based price and consumer-based price were considered as detailed in a previous study [14]. *eind i* was obtained based on Equation (3). *qi* was calculated by dividing sectoral CO2 emissions obtained from the 3EID [41] by total output utilizing the TJIO. *b* denotes the age of the highest income earner (1: ≤29, 2: 30–39, 3: 40–49, 4: 50–59, 5: 60–69, 6: ≥70).


**The Spatial Analysis and Sustainability of Rural Cultural Landscapes: Linpan Settlements in China's Chengdu Plain**

#### **Qiushan Li 1 , Kabilijiang Wumaier 1,\* and Mikiko Ishikawa 2**

Received: 15 July 2019; Accepted: 12 August 2019; Published: 16 August 2019

**Abstract:** Amid rapid urbanization and globalization, rural zones in many countries have undergone dramatic shifts. Although the future development of cultural landscapes is clear, their planning and management are uncertain. The Chengdu Plain is one of the most prosperous in China, which is home to well-developed irrigation and drainage systems, with the earliest history of planting found in Sichuan Province. The Chengdu Plain's unique farming landscape is an important human resource that represents the natural integration of the material and spiritual forms in the farming era. This study takes the unique farming settlements in Dujiangyan Irrigation District as the research object and analyzes the culture, human environment, and spatial order of the Linpan settlement based on the system theory. From the hierarchical structure of each individual Linpan settlement to the spatial layout of the Linpan community, the changes in the relationship between humans and land in the farming area are explored to explain the sustainability of the rural cultural landscape. With long-term field research, the rural geographic information database is built as a basis for the identification and classification of Linpan Cultural landscape types. The results show that between 2005−2018, the Linpan of Juyuan Town illustrated a decreasing trend, and about six Linpan settlements disappeared per square kilometer. The change in the type of Linpan landscape is spatially unbalanced, which is mainly due to the difference between regional development and residents' needs. This study introduces the concept of "demand" and "restriction" in sustainable development to explore a future strategy of maintaining the cultural landscape, which is expected to provide a basis for future policy formulation to protect the traditional rural landscape.

**Keywords:** sustainability; cultural landscape; Linpan; traditional settlement; spatial analysis

### **1. Introduction**

Cultural landscapes serve as important material testimony to the interactions and sustainable development between humans and nature, as well as between history and the present; they comprise one of five major research themes in the field of cultural geography. The identification, description, and interpretation of landscapes have long been the primary work of geography [1,2]. The core concept of the cultural landscape is to emphasize the interaction between humans and nature. It considers the landscape to be a visible material phenomenon, emphasizing that the landscape styles created by different cultural groups are different [3]. In his 1927 article, "Recent Developments in Cultural Geography," the American geographer, Sauer, re-examines the research content on landscapes and the application of the morphological method. He defines cultural landscapes as "various forms of human activity attached to the natural landscape" [4]. Although it has been a well-established viewpoint that

cultural landscapes be appreciated and inherited, people only began to pay attention to the loss of their cultural value at the start of the 20th century [5]. In the past few decades, throughout rapid urbanization and globalization, the changing trends of many landscapes have been considered negative because they have broken prevailing evolutionary laws, resulting in a loss of landscape diversity, continuity, integrity, and identity; sadly, these features of ancient cultural landscapes are rapidly disappearing [6]. The influence of large-scale urban construction on rural cultural land has drawn attention in numerous countries—not only in developing ones, but also in developed nations where rural cultural landscapes face serious threats. These include (1) wastelands, intensive agriculture, and population; (2) the loss of historical culture, local knowledge and traditional features; (3) the disordered expansion of landscape spaces and the fragmentation of rural areas; (4) the depletion of natural resources with a variety of demands and uncoordinated economic growth; and (5) the disturbance of natural ecological processes and the loss of biodiversity. These problems have raised global concerns regarding the development of rural areas [7–15].

The above issues have been outstanding in most rural parts of China's Chengdu Plain since the Wenchuan earthquake struck in 2008. In particular, due to the urgent need for repairing and rebuilding, the majority of affected rural zones need to be rehabilitated in a short span of time, which undoubtedly leads to the neglect of cultural values [16]. In the process of large-scale rural reconstruction, various challenges have surfaced, which has generated research on the part of government departments and scientific scholars. As a result, policymakers have gradually become aware of the deep significance of exploiting rural resources in a prudent manner, strengthening the protection and inheritance of cultural landscapes, and balancing residents' material and spiritual wealth in relation to rural construction [17].

Linpan settlements represent a distinct lifestyle in the farming area of the Sichuan Plain, where ancestral wisdom and adaptation to nature have formed a clever human-land relationship, which has been passed down to the present. In recent years the settlements' ecological, cultural and aesthetic values have been slowly discovered and attracted the attention of the government, which has issued many protection and restoration policies. Examples include "Promoting the Protection of Western Sichuan Linpan Settlements in the City," the "Conservative Construction Plan for Western Sichuan Rural Landscapes (Linpan settlements) in the City of Chengdu" and the "Implementation Plan for the Protection and Restoration of Western Sichuan Linpan Settlements in the City of Chengdu." All these projects emphasize that the rural panoramas of western Sichuan's Linpan settlements contain not only an ancient form of rural settlements, but also a special cultural heritage with extremely high ecological, economic, and historical value. However, while China's policies focus on the importance of the Linpan settlements and culture, advocating for the protection, they fail to specify rules. In 1992, the 16th session of the World Heritage Committee decided to incorporate cultural landscape heritage into the World Heritage List. Compared with the definition of other types of patrimony, cultural landscape heritage highlights the harmony between long-term production, human life, and nature, stressing a sustainable development ideology in which people coexist with the environment [18]. The sustainability explored in this study not only refers to the continuous development and increase of the material form of the cultural landscape, but also emphasizes the development of the connotation of the landscape cultural awareness based on human needs. Cultural landscapes are a product of the interaction between people and nature. They result from an initial social, economic, administrative, and/or religious imperative and have developed to its present form by association with and in response to its natural environment. Such landscapes reflect the process of evolution in terms of their form and component features [19]. In his book Conservation and Sustainability in Historic Cities, Rodwell asserts that it is not enough to comprehend the historical environment by relying on a limited number of cultural terminologies. He believes that the understanding of regional culture should not be constrained to archaeological research, which focuses on building age and associated historical events; rather, it should also involve the connections between physical entities and intangible cultural aspects [20]. Therefore, cultural landscapes provide a new perspective for exploring social evolution and the human-land relationship, and serve as the best example for understanding the latter. This is

also why the protection of traditional Linpan settlements in the Chengdu Plain should begin with a detailed analysis.

### **2. Materials and Methods**

### *2.1. Research Area*

At more than 2300 years old, Western Sichuan's Linpan settlements date back to the ancient civilization era and took shape over a long period of immigration [21]. They are widely distributed across southwestern China, especially in the fan-shaped alluvial Chengdu Plain in western Sichuan Province. Starting from the Dujiangyan Irrigation Project, the Chengdu Plain's irrigation areas are flat, except for a northwest to southeast slope with an average gradient of 3–10%, where the relative surface relief is less than 20 m, and annual rainfall is about 900–1240 mm. The superior topography and abundant water sources form a highly networked gravity irrigation system. This study examines Juyuan Town in Dujiangyan City to scrutinize the sustainable development of cultural landscapes in rural parts of the Chengdu Plain (Figure 1). Juyuan Town covers a total area of 34 km2 and has 10 administrative villages; the land cover is mainly composed of farmland, with rice and rapeseed as the chief agricultural products. Compared to 2005, by 2018, there were approximately 515 Linpan settlements in the region under the town's jurisdiction, with a decrease of 273 in the total number and 19.87 ha in terms of area. Juyuan Town is selected for the following reasons:

### *2.2. Defining Linpan Cultural Landscape*

Based on the definition of CO Sauer, the cultural landscape has both time and space characteristics, which is the result of the continuous influence of human culture on a specific regional environment. Each traditional cultural landscape expresses a singular local spirit that helps shape its identity [22]. Historically, the Linpan settlement system in the western Sichuan Plain has changed with society's prosperity. During the pre-Qin period, the indigenous people of Laos began to establish settlements in the Chengdu Plain. The construction of the Dujiangyan Water Conservancy Project during the Qin and Han Dynasties stimulated the improvement of the agricultural and forestry management structure, and Linpan's living pattern gradually formed. During the Tang and Song Dynasties, with the prosperity of the economy, the Linpan model continued to improve and experienced large-scale expansion. In the late Ming and early Qing dynasties, due to war, natural disasters, and social and economic turmoil, the population of the western Sichuan Plain sharply reduced, and most of the Linpan settlements were damaged or uninhabited. In the late Qing Dynasty, with the gradual recovery of population and social reconstruction, the Linpan settlements cluster became more stable and has sustained itself until now through the process of constant adjustment and adaptation to the environment [21]. In terms of space, the Linpan settlement is geographically unique. The Linpan settlements are spread over

the vast plains of western Sichuan with the surname (clan) as the settlement unit. With extensive farmlands, the structure of the Linpan settlement looks like a green island. It serves as a carrier for the harmonious symbiosis of humans, plants, and animals. It is a typical natural village (Figure 2). To date, although the Linpan settlements have not been uniformly defined in the academic community, scholars with different research perspectives have described them in various ways, such as social units with cultural symbols and use value (Duan); composite, rural scattered settlements that integrate human life, production, ecology and land (Fang); and rural living units that combine agricultural production and family relations (Chen) [23–25]. These definitions all focus on social relations, landscape patterns, and ecological structures. In addition, many scholars, such as Zhang, have proposed the concept of the Linpan system, arguing that it is a complete settlement layout representing the semi-natural, semi-artificial wetlands of the Dujiangyan irrigation region [26]. Japanese expert Ishikawa asserts that the Linpan system should be regarded as a remarkable historical and cultural landscape heritage [27]. This study proposes that the Linpan system consists of scattered communities, which are composed of a number of individual (Linpan) settlements. Such settlements are independent living spaces in rural habitats, dispersed throughout the Chengdu Plain. A Linpan community refers to a whole body of spatial continuities comprising river systems, road networks, fields, and settlements of a certain size, which embody a lifestyle with local characteristics (referred to as "the Linpan mode").

**Figure 1.** Location of the study region and an aerial view of the landscape.

**Figure 2.** Linpan landscape during the late Qing Dynasty and the Republic of China. Source: http://www.phoer.net.

#### *2.3. Methodology*

The concept of the cultural landscape is rooted in geography and was first put forth by German geographers in classifying fields, villages, towns and roads. Later, it was promoted as the focus of geography research by American geographer Sauer, who also proposed the "morphology of landscape," advocating for the use of actual observation of the surface landscape to study geographical phenomena [28]. The study of cultural landscapes initially focused on the description and observation of performance [29]. With the deepening of people's understanding of the landscape and the mutual influence of various disciplines, quantitative analysis methods such as computer technology and 3S have gradually achieved fruitful results in the study of dynamic landscape characteristics [30]. This study mainly uses the traditional geography description and classification method, combined with modern computer-aided technology, to systematically study the evolution process of Linpan culture landscape. The research methods include typology and comprehensive induction, field research, and case analysis. Based on systematology, this study draws on a large number of theories on cultural landscapes to identify and categorize the landscape features and evolution types of Linpan settlements. Finally, based on the idea of demand in defining sustainable development, the factors affecting landscape change are interpreted. Typology theory is an essential theoretical support for the study of Linpan landscape morphology, which is not just an epistemology that facilitates the understanding of the intrinsic formation mechanism and formal meaning of historical rural settlements; it is also used to guide design based on rational treatment of traditions as a prerequisite and adaptation to the requirements of new lifestyles [31]. A typological approach allows us to extract the structural components of the Linpan system, grounded in an analysis of existing settlements, and to speculate on the morphological transformation of characteristics in different contexts.

With respect to technology, this study establishes a spatial geographic information database of Juyuan Town between 2005−2018, and employs the spatial analysis module of a geographic information system (GIS) to conduct an in-depth examination of the Linpan system's spatial attributes, layout, and structural changes. Moreover, the study uses 1 km × 1 km grid cells as the unit of analysis to statistically count and summarize morphological variation features of the town. The boundaries of the Linpan system are determined by extracting historical remote sensing images from Google

Earth. Correlation analysis of spatial patterns is mainly based on 2005 data, as data after 2008 are largely subject to anthropogenic influence. The data used in the study are derived from relevant information provided by government departments (such as statistical data, planning documents, and local chronicles), as well as details obtained from field surveys (such as mapping, observation, interviews, and transcripts).

#### **3. Case Study**

#### *3.1. The Hierarchy of Linpan Settlements*

Linpan characteristics are based on two aspects: Spatial structure and human culture [32]. As the lowest level of spatial structure regarding human settlements in the Chengdu Plain, the Linpan system consists of numerous, widely distributed units, which signify the most fundamental building block of life [33]. As shown in Figure 3, each unit consists of five elements (house, courtyard, forest, farmland, and waterway) and is comprised of tens, sometimes dozens, of households. Water channels surround or pass through most Linpan units. The houses are concealed by tall trees (e.g., nanmu and cypress) and low forms (i.e., Omei Mountain and bitter) forms of bamboo, creating a tranquil scene where the inhabitants rest in the forest and work in the fields [34]. The boundaries of forests outside the Linpan settlement are often seen as criteria for defining their scale. Due to the different needs and habits of each family and the limitations of environmental conditions, Linpan settlements present a variety of features with the same hierarchy, but different shapes. For example, in the densely populated areas of the irrigation water system, there are more concentrated Linpans, and the Linpan settlements on both sides of the river are mostly long strips. As for humanistic value, the Linpan system offers a sustainable farming lifestyle that integrates humanity and nature, life and production. It relies and acts on the land, representing a local ideology of "harmony between man and nature" according to Taoist philosophy. Since antiquity, Linpan settlements have been dispersed throughout the fields, with each unit given a surname (based on patriarchal clans); the Linpan system is typical of *naturally formed villages* [35]. Over the long term, the Linpan system has been a vehicle for local farming culture and served as evidence of farming civilization. Embodying ancestral wisdom, this self-contained, composite agriculture and forestry ecosystem, founded on a small-scale peasant economy, has very high ecological, cultural and aesthetic value [36].

#### *3.2. The Spatial Structure of Linpan Settlements*

#### 3.2.1. The Distribution of Linpan Settlements

Firstly, based on the GIS database, the area of each Linpan settlement in Juyuan Town was calculated and divided all of them into five grades through natural break classification method. Then the spatial pattern of Linpan settlements in different scales were analyzed and statistics respectively, this step is mainly based on the use of the Average Nearest Neighbor tool in ArcMap software, the calculation results are shown in Figure 4: The settlements in Juyuan Town have an average area of 0.73 ha and are small and medium-sized (less than 1.26 ha), accounting for 87% of the total number of settlements. The density of settlements in the town's jurisdictional region is about 23.62 units per km2 (settlements larger than 2.16 ha in size are quite rare in most areas), and the average distance between adjacent settlements are about 134.19 m. The smaller the area, the closer the distance between adjacent Linpan settlements, and the spatial distribution is often characterized by agglomerated distribution. Conversely, the larger the area, the more scattered or random the distribution. On the whole, Linpan communities show dispersed distribution patterns in terms of spatial structure, and are characterized by dynamic evolution in the sequence of "aggregation, randomization, and dispersion" corresponding to the serial stages of their "occurrence, development, and stability."

**Figure 3.** The hierarchy structural and elements of Linpan settlements.

**Figure 4.** The spatial layout of Linpan settlements.

3.2.2. Relationship between Life and Production Space

Initially, most vernacular landscapes were created by farmers to organize their land better, and ensure their survival [37]. The Linpan system, containing typical farming settlements, provides

farmers with *an ideal environment*, wherein production takes place on cultivated land along the periphery. The relationship between living and production spaces is reflected in the tillage radius, which refers to the distance from a settlement to cultivated land. The buffer analysis method is commonly used to analyze the radius of the cultivated land. Theoretically, in a specific area, when the area of the buffer generated by a specific radius is equal to the actual cultivated area, the radius of the buffer of the settlement is equal to the farming radius. At the same time, the ratio of the buffer area to the cultivated area can indicate farming pressure [38]. In this section, the evaluation unit is first determined by the boundary of the administrative division of the village area, and then the peripheral buffer range of different scales is established based on the Linpan boundary in the database (Table 1). The buffer area in each unit is counted using layer superposition in ArcMap software. Finally, the farmland pressure coefficient is calculated using the attribute field of each unit layer to link the corresponding cultivated land area data (Table 2):

> *Ii* = *Hi*/*Gi* .

In the formula, *Ii* is defined as the cultivated pressure coefficient of the evaluation, which represents the rural labor carried out on the cultivated land in the evaluation unit (village); *Hi* is defined as the buffer area of the Linpan settlement in the evaluation unit; and *Gi* refers to the cultivated land within the unit. Tillage radius affects the residential layout in rural zones, serving as an important reference for exploring the human-land connection in farming areas and assessing the layout rationality of future protection planning [39].

The findings demonstrate that 50–60 m is the optimal tillage radius of a Linpan settlement in Juyuan Town (Table 1). Within this range, the tillage pressure coefficient of each village is close to 1, suggesting that this is the best spatial distribution for rural settlements and cultivated land in the process of natural adaptation (Table 2). That is, there is neither excessive labor nor a large amount of wasted arable land, which reflects the environmental adaptation of the Linpan-based residential mode according to different scales of land use.

#### *3.3. Type Conversion*

By constructing a spatial geographic information database in rural areas, it is possible to quickly identify changes in the spatial patterns of a given area over a period of time. Cultural landscapes are complex cultural phenomena that generally result from human activities acting on the earth's surface; they are composed of the natural environment, residential architecture, transportation, art, and people. Meanwhile, shifts in spatial patterns reflect long-term interactions between the landscape and the natural environment, the social economy, and historical development [40]. The basis for the classification of Linpan dynamic evolution is the morphological identification and field research (including questionnaires, interview minutes, phenomenon descriptions, etc.) of geospatial databases at two different time points. According to the overall system-to-local rules of the system theory, the dynamic changes of the Linpan settlement are summarized into three first-class categories of internal change, morphological change, and external landscape change, as well as the original site renewal, relocation, primary forest expansion, economic forest planting, municipal infrastructure, and social foundation. The facility has six sub-categories, and the different spatial representations of each sub-category are illustrated based on the typology performance method. The selection of typical samples is shown in Figure 5. In addition, based on interviews with 114 households in Juyuan Town and the results of several rounds of expert consultation, this paper used the demand hierarchy theory to mark the spatial shape change of Juyuan Town. For example, the demand for basic life, agricultural production, or non-agricultural supply is marked as survival demand; the outstanding desire for the development of individuals or local economic development and social development is marked as development demand; and people's spiritual needs, such as cultural heritage, and environmental protection, indicate quality demand. The classification description is shown in Table 3.

**Table 1.**Statistical table of buffer zones and actual farmland area in each village.

**Table 2.**Statistical table of the farming pressure coefficient of each village.

Note: I = 1 indicates the optimal spatial distribution state; I > 1 refers to a surplus labor force and high tillage pressure; I < 1 denotes excess arable lands, a labor force deficiency, and wasted resources

**Figure 5.** A classification sample of changes in a Linpan community.

#### 3.3.1. Type I: Internal Changes

Internal changes refer to alterations of the residential environment, as well as the structure and function of each individual Linpan settlement over time. Two modes are involved: On-site updates and off-site migration:

gauze, demonstrating improvement in residents' security awareness, promotion of land tenure awareness (i.e., boundaries), and greater concern about personal privacy [41].

#### 3.3.2. Type II: Morphological Changes

As presented in Figure 7a–c, morphological changes consist of three modes: Unconstrained expansion, joint expansion, and constrained expansion:

Furthermore, the transformation of land-use types is a direct factor affecting changes in rural landscapes and has clearly identifiable spatial traits. As exhibited in Figure 7d,e, the market economy has triggered industrial structural adjustments, while the planting industry (of economic forests) has brought high economic benefits to farmers, with such market-driven trends becoming increasingly popular [42]. In Juyuan Town, economic forestry planting covers almost every village and can be divided into two types: Large-scale and non-scale. Large-scale planting is primarily carried out by several adjacent Linpan settlements to jointly manage an area and undertake forest planting. Large-scale planting is the uniform planting type, marked by regular borders in the planting area. In contrast, non-scale planting in economic forests mostly indicates spontaneous planting by some Linpan owners in the open space surrounding their own settlements. The forest types are not uniform, with the entire planting area showing a broken, patch-like pattern in the absence of an obvious spatial order.

**Figure 6.** Schematic diagram of Type I changes. (**a**) Spatial replacement; (**b**) Functional replacement; (**c**) Old-for-new replacement; (**d**) New rural communities; (**e**) Off-site construction.

**Figure 7.** Schematic diagram of Type II changes. (**a**) Unconstrained expansion; (**b**) Joint expansion; (**c**) Constrained expansion; (**d**) Non-scale planting; (**e**) Large-scale planting.

3.3.3. Type III: External Landscape Changes

With the development of Juyuan Town and the surrounding municipalities, residents' demands for resources have become more diverse. The construction of supportive facilities necessary to meet daily needs has broken the spatial integrity and continuity of the original rural landscape. In particular, the layout of the transportation network has divided the continuous landscape matrix, and different kinds of land have been assigned different functions. External landscape changes are mainly reflected in

the impact of urbanization-related construction on the landscape matrix, with roads and other facilities being built. There are roads with three purposes (Figure 8): New forms of transportation facilities (for example, two additional highways and one railway have been built in the past decade, as shown in Figure 8a); to enhance internal connections (Figure 8b) (i.e., the accessibility of Linpan settlements); and new village- and town-level roads, as well as upgrades made to them (Figure 8c). The construction of new facilities implies social infrastructure besides the addition and improvement of municipal infrastructure, such as cultural and leisure facilities (e.g., Western-style concert venues, cultural squares, activity centers, and resort hotels), and educational and medical facilities (e.g., Bayi High School, Qiyi Middle School, Sichuan Business and Technology Vocational College, general hospitals). In addition, some commercial organizations (e.g., automotive service companies, horticultural fields, and machine manufacturing companies) are slowly being introduced as the supporting infrastructure continues to be improved.

**Figure 8.** Schematic diagram of Type III changes. (**a**) Enhancement and new construction of roads; (**b**) Enhancement and new construction of roads; (**c**) Construction of public facilities and business organizations.

#### **4. Results and Findings**

#### *4.1. Change Statistics*

From 2005 to 2018, the total number of Linpan settlements in Juyuan Town decreased by 273, amounting to an average loss of six settlements per square kilometer. As shown in Figure 9, correlation analysis of the various types of Linpan settlements and their reduced areas, with respect to the spatial locations where the reduction occurs, reveals seven statistical grid cells each that have experienced a change in the quantity of Linpan settlements by one or less than one, largely in the border zone within the central urban area, with the city's surrounding green belt designed to control disorderly expansion and to protect the rural cultural landscape in the restoration and reconstruction process following an earthquake [43]. By contrast, areas—where the number of Linpan settlements has decreased by more than ten—are chiefly concentrated in the south of the built-up zone, indicating

that the urban construction of Juyuan Town tends to extend southward. In most areas, the number of Linpan settlements was approximately ten, which also reflected the fact that the broad area of Linpan's traditional settlements was reduced. In other areas, the number of Linpan settlements was within ten. According to the change test, the main external material conditions that lead to a decrease in the number of Linpan settlements are the construction of roads (e.g., public roads, highways, and railways), the development of towns and new rural communities, and improvements in living service facilities (e.g., hospitals, schools, factories, and power stations). This new construction requires more land. The expansion of land for such purposes in the town is the most direct cause of the decline in the number of Linpan settlements.

**Figure 9.** Schematic diagram of changes.

The grid statistics reveal that type IIIA (municipal infrastructure construction) and type IA (on-site renewal) are the most frequent landscape changes in the study region. Second, type IIB (economic forest planting) is a factor causing apparent visual shifts in the overall landscape pattern. A large number of trees planted for their economic value has destroyed the original landscape matrix, making the landscape discontinuous. Such fragmentation leads to a decrease in regional identity and sense of belonging [44]. Changes in settlement morphology resulting from the growth of the Linpan settlements' native and secondary forests (type IIA) are also common. Moreover, with respect to the geographical positions of these transformations (Figure 9), the construction of new rural communities (type IB) is largely concentrated in the center of town, where there are well-developed transportation facilities with convenient living conditions. Farmers' self-built homes are mostly distributed along both sides of the roads not far from the above-mentioned, large Linpan settlements. The survey and interviews reveal that when the number of people living in a Linpan settlement increases, people will build new houses in the adjacent open space (while in the past, a new Linpan settlement would be erected, rather than a new, single-family home). This embodies a randomized, jump-like expansion mode. Moreover, the construction of new and modern homes is preferentially conducted close to roads rather than river systems. This reveals that the traditional functions of the Linpan settlement have changed, and their farming culture is also disintegrating.

#### *4.2. Discussion on Demand and Sustainability*

The World Commission on Environment and Development defines sustainable development in the book Our Common Future (Brundtland Commission) as "development that meets the needs of today's people without compromising the ability of future generations to meet their needs." Moreover, it points out that sustainability includes the two concepts of "needs" and "restriction" [45]. The results of this study indicate that the needs of Juyuan Town's residents are transitioning from those of survival to those of development. Such growth, alongside the hierarchy of needs, is engendering changes in the cultural landscape of Juyuan Town's Linpan community. For example, types I (IA,IB-b) and II (IIA) tend to meet survival needs. The residents' new housing locations also indicate that the prerequisites for choosing a home have shifted from the convenience of production to the convenience of living. Meanwhile, types II (IIB-a) and III (IIIA) meet development needs. The layout of a large number of transportation networks and the construction of new rural communities represent a trend toward urbanization. Type III (IIIB) shows that people are striving to obtain more education and entertainment resources, improve living standards, and pursue a higher quality of life.

The differences in the categories of need have led to the spatial differentiation of rural landscape patterns. The more categories of need there are, the higher the requirements for landscape diversity. Meanwhile, the changes in the level of demands have caused the time differentiation of landscape patterns. For instance, the closer to the built-up area of the town center, the richer the various types of land, and the more quickly residents' needs can be met, which leads to a desire for another level of resources. The expansion of residents' needs, along with the hierarchy of needs, is the intrinsic driving force that affects the sustainability of the Linpan cultural landscape. Interviews reveal that population in the settlements is dominated by the elderly, as most young people leave to seek work: This means that the main human resources for protecting Linpan culture are constantly being lost. Although the basic structure of the Linpan settlements under investigation has remained intact, some are gradually showing signs of "empty nests", due to the neglect of management. In addition, changes in transportation patterns have a large impact on the land of the studied region. The arrangement of transportation networks accelerates the connections and energy exchanges between the interior and the outside world, while the modernization process of rural cultural landscapes has a high degree of synergy with the construction of transportation infrastructure.

According to this study, the sustainable development of traditional cultural landscape should have traceable spatial continuity, regional uniqueness, cultural accumulation, and landscape inheritance. The discussion of the sustainability of cultural landscape mainly refers to the quality requirements in the future development process, rather than the pursuit of the maximum number of regional resources or similar landscapes. The cultural landscape is a real reflection of personal lifestyle and an expression of how people meet their own needs at all levels. The cultural value of the traditional cultural landscape lies in the fact that the environment records and reproduces the methods of people's survival under

previous material technology and thinking in the form of carriers. Then, with the progress of society, economic development, and the change of value system, traditional culture and lifestyle are gradually detached from modern society. Therefore, to achieve sustainability, traditional cultural landscapes must continue to meet the expectations of people's needs according to different levels of survival, development, and quality of life. For example, according to the case study, at the level of basic survival needs, the impact of people on the landscape is mainly due to the creating of residences, using the most inexpensive choice. In this respect, the maintenance of cultural landscape depends chiefly on the realization of science, that is, rapid advances in technology. From the perspective of development needs, once basic needs are guaranteed, people begin to consider physical renewal and optimization. At this stage, the impact of human activities on the environment essentially comes from the social environment and personal feelings. Here, the cultural landscape can sustain itself if the traditional functions of the landscape are balanced with contemporary needs. Finally, the relationship between the demand for quality of life and cultural landscape sustainability lies in the use of traditional values and aesthetic concepts to combine the material, technology, and culture of the time to establish a new cultural philosophy. To sum up, the sustainability of cultural landscapes does not mean that the traditional landscape is preserved and continued in its entirety; rather, it is adapted to social life, is people-centered, and can be organically inclusive and continuously updated in future development.

#### **5. Conclusions**

Linpan settlements are distributed as independent living units in the vast rural area of the Chengdu Plain. During conventional planning, the integrity and continuity of the Linpan community often become fragmented. As a result, traditional Linpan farming settlements have failed to receive effective protection and attention in the planning preparation process. This study establishes a spatial geographic information database of Juyuan Town. Through the application of the hierarchy description of the settlement system and the description of spatial features, the internal logic of the spatial layout of the traditional settlement culture landscape is expounded from three aspects: Hierarchy, geographical layout, and type conversion. Using the typology theory, the Linpan settlement group of Juyuan Town was used as a case study to demonstrate the dynamic evolution process of agricultural settlements in the western Sichuan Plain. Otherwise, the Linpan settlement landscape type conversion process was described in stages based on the demand hierarchy theory in sustainable development. The findings were as follows.

The Linpan settlement in Juyuan Town has a decreasing trend as a whole. Approximately six traditional Linpans per square kilometer have been demolished in the past decade. The new rural settlements in the region do not substantially retain the typical characteristics of the traditional settlements. The degradation of the Linpans' traditional functions and the changes in people's contemporary life concepts are the root causes of the abandonment of Linpan settlements. Historically, although these settlements have been highly self-sustainable and capable of organic self-replication and renewal, in the process of transformation and evolution, residents and settlements often have a unique symbiotic relationship of separation and integration. The differences in the level and type of need affect the changing trends of the landscape, and growth in terms of the hierarchy of needs influences the speed and magnitude of landscape transformations, thus resulting in the continuous reduction of the integrity, continuity, and recognizability of the landscape. Additionally, the development of the social economy will inevitably introduce higher requirements for the construction of rural areas. The construction of rural infrastructure not only promotes internal convenience, but also strengthens energy exchange with surrounding areas; however, it is also a double-edged sword. Due to the lack of awareness of traditional culture in the early stage, and the lack of inheritance, regional culture cannot resist the erosion from a foreign culture. Coupled with the dilemma of the younger generation migrating to urban environments and the aging of the local population, the leading human resources that protect and inherit the Linpan culture are continually being lost with the laying of the transportation network.

Landscapes have always been subject to alterations in order to better adapt to evolving social needs. It is necessary to correctly grasp the harmonious human-nature relationship in the Linpan farming settlements of western Sichuan plain, to explore the potential for the sustainable development of cultural landscapes, and to strengthen the understanding of rural cultural landscapes, which is an inevitable requirement to transform natural environment. The sustainable development of western Sichuan's Linpan communities depends on the strategic measures of spatial planning. According to this study, sustainable development of cultural landscape is an original implementation path that takes protection as the main factor and development as a supplement to maintain the identities, continuity, authenticity, and outstanding cultural value of the cultural landscape. House, courtyard, forest, field, and waterway are the five critical elements of the Linpan settlement hierarchy, which are the essential factors to ensure the sustainability of cultural landscape construction and landscape culture communication. In addition, the Linpan community appears to be in a random, but orderly spatial order, and these universal commonalities within the Linpan settlement are sustainable landscape inheritance characteristics. The hierarchy of needs to examine the spatial evolution of Linpan settlements' landscapes is adopted as a result of an inspiration during the field survey: It is hoped that the ultimate beneficiaries of the sustainable development of cultural landscapes are human beings, particularly the original residents, and that this will be not only the fundamental starting point of scientific development, but also a basic requirement for sustainable growth.

**Author Contributions:** Conceptualization, Q.L. and M.I.; methodology, Q.L. and M.I.; software, Q.L.; validation, Q.L., K.W. and M.I.; formal analysis, Q.L., K.W. and M.I.; investigation, Q.L., K.W. and M.I.; resources, Q.L., K.W. and M.I.; data curation, Q.L.; writing—original draft preparation, Q.L.; writing—review and editing, Q.L., K.W. and M.I.; visualization, Q.L.; supervision, K.W., M.I.

**Funding:** This research was funded by Sichuan University, Fundamental Research Funds for the Central Universities, grant number 2018skzx-pt243.

**Acknowledgments:** We gratefully acknowledge the support provided by the Dujiangyan government and villagers live in Juyuan Town. Thanks for the data and relative sources offered by the government.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**

© 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

MDPI St. Alban-Anlage 66 4052 Basel Switzerland Tel. +41 61 683 77 34 Fax +41 61 302 89 18 www.mdpi.com

*Sustainability* Editorial Office E-mail<EMAIL_ADDRESS>www.mdpi.com/journal/sustainability

MDPI St. Alban-Anlage 66 4052 Basel Switzerland

Tel: +41 61 683 77 34 Fax: +41 61 302 89 18

www.mdpi.com ISBN 978-3-0365-2570-9


**2.2 Cardiovascular changes**

*Special Considerations in Human Airway Management*

techniques during air transport and aviation conditions.

**2. Physiological changes in microgravity**

junction changes.

**2.1 Pressure related effects**

underlying medical conditions. Although medical services in aviation has evolved over years based on our understanding of physiology, advancement in monitoring technology but airway management was only recently studied with a focus on space environment. Airway management and other hemodynamic goals parameters, especially during medical air transport and aviation put the patient and medical team under unfamiliar and extreme physiological conditions, with detrimental clinical sequalae. In this chapter will cover the airway management in aviation with high emphasis on physiological changes and he preferred airway management

The changes occur to human body during aviation can affect the anesthesia delivery if surgery is needed. Almost all the body organs will be affected, but what is more relevant to anesthesia administration is: cardiac systolic and diastolic changes, gastric motility, reduction in blood volume as well as neuromuscular

At sea level, barometric pressure is 760 mmHg with a partial pressure of oxygen of 160 mmHg. The barometric pressure of ambient air declines as altitude increases, while the volume of air in a confined space will increase according to Boyle law, and this is why oxygen concentration remains at a constant 21% [1]. The intracranial air volume could be increased by 30% at the usual maximum cabin altitude of 8000 feet. These volume and pressure effects are sometimes associated with hemodynamic compromise (tension pneumothorax), barotrauma (sinuses), equipment malfunction (blood pressure cuffs), and possible injury or compromised monitoring as inflated gas bubble in the arterial line. Certain conditions such as pneumopericardium, subcutaneous emphysema, gas gangrene, systemic air emboli, decompression sickness, and gastric distension may be worsened at altitude [2]. Altitude sensitive equipment includes endotracheal and tracheostomy cuffs, pneumatic antishock garments (eg, medical antishock trousers), air splints, colostomy bags, foley catheters, orogastric and nasogastric tubes, ventilators, invasive monitors, and intra-aortic balloon pumps. Most aircraft cabins are usually pressurized to a pressure equivalent to 5000 to 8000 feet, giving an atmospheric partial pressure of oxygen of 118 mm Hg [3]. Thus, the oxygen requirement (Fio2) of a patient on mechanical ventilation may increase at altitude. ARDS in animal models were more

responsive to increased PEEP, yet resistant to increases of (Fio2) [4].

tion injury, anxiety and prolonged access to healthcare.

Hypoxemia, even at low altitudes (3281–9843 feet), which is the usual flight range for the medical helicopter transport, could lead to global hypoxic pulmonary vasoconstriction and pulmonary edema. Hypoxemia is detrimental to patients with coronary ischemia, pulmonary compromise acute respiratory distress syndrome [ARDS], or neurologic injury. Besides, the hypoxia associated-tachycardia and hypertension increases the cardiac mechanical load and myocardial oxygen

Flying at low altitude is commonly known as "Altitude restrictions" which mainly for pressure sensitive conditions as in eye trauma, pneumothorax, intracerebral air, and sinusitis [5]. Those low altitude flying restrictions come with the cost of more turbulence and longer transport times, another risk factor for more vibra-

**218**

consumption.

The loss of gravity effect of the distribution of blood volume in different body compartments is notable in a microgravity environment. In normal environment at the earth surface there is a pressure gradient created by the gravity and the loss of this gradient during aviation result in more diuresis and by so reduction in blood volume [6–8]. The blood volume is one of the determinants of cardiac output, the reduction in the blood volume in microgravity will result in a 20% reduction in COP [6]. The reduction in these parameters will definitely reduce the body compensation capacity for hemorrhage, while the redistribution of the blood can affect intubation by causing facial edema [6, 9–11].

#### **2.3 Musculoskeletal changes**

Two main issues regarding musculoskeletal system changes in microgravity are the reduced bone mass [12] and the muscle atrophy which may lead to increase expression of extra junctional acetylcholine receptors [13, 14]. The abnormally expressed receptors can explain the risk of severe hyperkalemia after succinylcholine in space men [6, 10, 11].

Along with muscle atrophy changes in fat distribution affect the pharmacokinetics of anesthetic medications.

#### **2.4 Gastrointestinal changes**

Some studies suggest that there is a decrease gastric emptying during aviation in the first three days [6, 15, 16]. Some studies used paracetamol absorption as an indicator of gastric emptying [17, 18]. In anesthesia, gastric emptying time is very important factor in the assessment of aspiration risk following anesthesia induction.


*Polyimide Films for Digital Isolators DOI: http://dx.doi.org/10.5772/intechopen.93343*

20% voltage derating). Based on wafer-level analysis comparison, it is reasonable to attribute the lifetime and working voltage improvements to the SiN injection barriers between polyimide and metallic coils. These SiN thin layers, by mitigating bipolar charge injection at the onset of space charge formation, reduce the electrical current, the related thermal effects, and, very likely, extend the lifetime for a given voltage.


**3. Limitations of single APD-APIs and shift to multiple first-line therapies in the treatment of malaria**

#### **3.1 Limitations of single APD-APIs in malaria treatment**

The treatment of malaria is basically based on natural products, for example, APD-APIs, semisynthetic and synthetic compounds. Effective and safe antimalarial drugs are broadly classified into three main categories: (1) quinoline derivatives, (2) antifolates, and (3) artemisinin derivatives [64]. The first identified and widely used APD-APIs was quinine, an alkaloid. Notably, quinine was extracted from the *Cinchona calisaya* bark [65] and was used as first-line monotherapy. However, this antimalarial drug was exploited in the synthesis of a number of derivatives including 8-aminoquinoline (primaquine) and 4-aminoquinoline (chloroquine) [65, 66]. These derivatives of quinine were shown to eliminate malaria parasites through preventing biotransformation of heme, into nontoxic pigment granules, and therefore allowing heme to accumulate and promote cell lysis as well as Plasmodia auto-digestion [66]. Though quinine was an effective APD-API, development of resistance among *P. falciparum* strains and high toxicity has significantly contributed to its limited use. Additionally, this alkaloid (quinine) has a fairly short pharmacological half-life [66, 67]. However, use of quinine combined with other antimalarial drugs (in order to improve therapeutic efficacy) against malaria has been reported [12, 64].

The derivative of quinine, 8-aminoquinoline (primaquine), was utilized as a monotherapy against malaria during the first part of the twentieth century. However, it was disregarded due to abnormally elevated toxicity associated with highly reduced activity [64]. The other antimalarial drugs, which were widely exploited as

#### *Co-Crystallization of Plant-Derived Antimalarial Drugs: An Alternate Technique for Improved… DOI: http://dx.doi.org/10.5772/intechopen.106200*

first-monotherapy after abandonment of primaquine, include quinacrine, a derivative of acridine. Another derivative of quinine, a 4-aminoquinoline, chloroquine was later used as a first-line monotherapy against malaria for several years due to its efficacy, low as well as manageable side effects, and low cost [68]. Being the first-line monotherapy for a long period of time, chloroquine has led to *P. falciparum* strains, which are chloroquine-resistant [36]. Other quinine derivatives used as first-line monotherapies and are linked to several adverse effects and emergence of resistance include pyronaridine and mefloquine [69]. Although chloroquine significantly reduced malaria-related mortality and morbidity, its prolonged use has resulted in spread of resistance. For instance, cases of chloroquine resistance were reported in countries including Brazil, Thailand, and Vietnam by 1964 [70, 71]. Furthermore, according WHO reports of 1979 and 1981, chloroquine resistance was reported to have covered most parts of North-East India, South America, and Southeast Asia by 1980 [71].

Though not plant-derived, pyrimethamine was widely utilized as an antimalarial monotherapy in early 1950 and late 1960 as a prophylactic and treatment drug. Due to resistance of malarial parasite against pyrimethamine, pyrimethamine was combined with sulfadoxine to produce a more efficient antimalarial drug, sulfadoxine-pyrimethamine (SP) [71]. This antimalarial drug was recommended as a first-line drug in many countries associated with chloroquine inactivity [72, 73]. Although for some time, resistance to pyrimethamine was inhibited by sulfadoxine, inactivity of sulfadoxine to malaria parasites was finally reported in African and Asian countries [71–73]. This prompted the use of artemisinin, an antimalarial drug, which was discovered from an important plant, *Artemisia annua* in the year 1972 [74]. Artemisinin is an APD-API classified under terpenoids and is specifically a sesquiterpene lactone [75]. This APD-API has been identified to be effective against blood as well as *P. falciparum* gametocyte stages [76].

The use of artemisinin as monotherapy has been noted in many regions including western part of Cambodia, and clinical studies in these regions have shown emerging *P. falciparum* strains, which are resistant to artemisinin [77]. Apart from reports of resistance of *P. falciparum* strains to artemisinin, artemisinin is inherently linked to solubility and bioavailability challenges [78, 79]. This, therefore, has resulted in the synthesis of quite a number of artemisinin derivatives with varying degrees of solubilities in oil and water [78–80]. The most common synthetic artemisinin derivatives include artemether, dihydroartemisinin, artesunate, and arteether. Based on their solubilities in water and oil, they are administered into the patient using different routes, for instance, artemether and dihydroartemisinin, which are oil- and water-soluble, are intramuscularly and administered orally administered, respectively [78]. In the face of this improvement, artemisinin derivatives are quickly absorbed, distributed, and metabolized.

Artemisinin and its derivatives including artesunate are characterized by being quick-acting and rapid blood parasite reduction. However, this effectiveness is hampered by a rise of artemisinin-resistant *P. falciparum* as described in nations including western Cambodia, Myanmar, Viet Nam, and Thailand [5, 78, 81]. Additionally, reports of decreased sensitivity to artemisinin of *P. falciparum* isolates have been made in Nigeria and Madagascar [82]. A number of malaria patients from countries such as Sierra Leone, India, and western Thailand took time to respond to artemisinin derivatives including artesunate and artemether [78, 83, 84]. Furthermore, the use of these antimalarial drugs as first-line monotherapy is associated with maintenance of an effective drug concentration for a short period after drug administration. In addition to this, short oral treatment courses have contributed to increased rates of

recrudescence [66, 71, 85]. An increase in the number days of days of treatment to 7 has significantly reduced recurrent parasitemia, when artemisinin or its derivatives are utilized as monotherapy [74, 77, 85]. Generally, insensitivity to conventional antimalarial monotherapy including artemisinin as well as artemisinin-derived drugs has contributed significantly to antimalarial monotherapies being overlooked and disregarded [86]. Thus, a number of techniques are being explored globally to enhance potency of antimalarial drugs especially plant-derived ones and significantly interrupt parasite resistance to these drugs.


**Meet the editor**

Editor, Prof. Yusuf Bozkurt holds an Agronomy Engineer degree and also MSc and PhD degrees from Ankara University. He is currently working as a professor of Biotechnology of Reproduction in the field of Aquaculture at the Iskenderun Technical University. His research interests are mainly related to reproductive biotechnology especially in cryopreservation of gamete in aquatic species.

Contents

**Preface VII**

**Zebrafish 45**

James E. Turner

**Screening 83**

**Section 1 Using of Zebrafish in Medical Researches 1**

Kafaligonul and Michelle Adams

Chapter 2 **Zebrafish Model of Cognitive Dysfunction 27**

Carvalho, Priscila Silva and Ana Luchiari

**Zebrafish (Danio rerio) 63**

Chapter 1 **Zebrafish Aging Models and Possible Interventions 3**

Brandon Kar Meng Choo and Mohd. Farooq Shaikh

Chapter 3 **Zebra Fitness: Learning and Anxiety After Physical Exercise in**

Chapter 4 **The Roles of Estrogen, Nitric Oxide, and Dopamine in the**

Mayara Silveira, Jonatas Silveira, Thais Agues-Barbosa, Miguel

**Generation of Hyperkinetic Motor Behaviors in Embryonic**

Conor Snyder, Reid Wilkinson, Amber Woodard, Andrew Lewis, Dallas Wood, Easton Haslam, Tyler Hogge, Nicolette Huntley, Jackson Pierce, Kayla Ranger, Luca Melendez, Townsend Wilburn, Brian Kiel, Ty Krug, Kaitlin Morrison, Aaliayh Lyttle, Wade E. Bell and

Chapter 5 **Excitation and Excitation-Contraction Coupling of the Zebrafish Heart: Implications for the Zebrafish Model in Drug**

Matti Vornanen, Jaakko Haverinen and Minna Hassinen

Dilan Celebi-Birand, Begun Erbaba, Ahmet Tugrul Ozdemir, Hulusi