The Transformation of Rural Areas Located in China’s Agricultural Heritage Systems under the Evolution of Urban–Rural Relationships

: The sustainable logic between the Agricultural Heritage System (AHS) and environmental synergy has been signiﬁcantly changing with China’s urban–rural relationship shift from binary opposition to a stronger network exchange. During the process of transformation, China’s AHS rural areas encounter two major development trends and social realities, i


Introduction
In 2002, the Food and Agriculture Organization of the United Nations (FAO) released the project "Conservation and Adaptive Management of Globally Important Agricultural Heritage Systems (GIAHS)".This project aims to protect the unique land-use systems, agricultural landscapes, and biodiversity developed by the long-term adaptation of rural areas to their environment while facilitating regional sustainable development.China has covered 19 GIAHS and 126 China-NIAHS (China's own national-level Important Agricultural Heritage Systems selected by Ministry of Agriculture and Rural Affairs) thus far.Compared with conventional agriculture, agricultural heritage refers to a typical representative of sustainable agriculture for its nature-centered complex livelihood activities, and the conventional ecological knowledge (TEK) covered in it is capable of adaptively managing natural resources [1][2][3].The connotation of Agricultural Heritage System (AHS) villages has changed in contrast to ordinary villages (Figure 1).The rural elements of agricultural cultural heritage can be manifested as follows: agricultural industry and non-agricultural industry take agricultural cultural heritage resources as the core; crops are species with biodiversity value; communities have local ethnic minority characteristics; land management is sustainable; rural production-living-ecological spaces reveal the characteristic rural landscape [4].Rich in technology, culture and industry, AHS serves as a crucial potential development resource for rural areas.Additionally, the rational allocation of rural elements ensures the heritage system's vitality and sustainability, as well as adaptability [5].AHS space refers to a special spatial scope where agricultural cultural resources are concentrated [6].Thus, the AHS rural area acts as a single or multiple rural area where AHS resources are distributed.
agricultural landscapes, and biodiversity developed by the long-term adaptation o areas to their environment while facilitating regional sustainable development.Ch covered 19 GIAHS and 126 China-NIAHS (Chinaʹs own national-level Important A tural Heritage Systems selected by Ministry of Agriculture and Rural Affairs) th Compared with conventional agriculture, agricultural heritage refers to a typical sentative of sustainable agriculture for its nature-centered complex livelihood act and the conventional ecological knowledge (TEK) covered in it is capable of ada managing natural resources [1][2][3].The connotation of Agricultural Heritage System villages has changed in contrast to ordinary villages (Figure 1).The rural element ricultural cultural heritage can be manifested as follows: agricultural industry an agricultural industry take agricultural cultural heritage resources as the core; cro species with biodiversity value; communities have local ethnic minority characte land management is sustainable; rural production-living-ecological spaces rev characteristic rural landscape [4].Rich in technology, culture and industry, AHS se a crucial potential development resource for rural areas.Additionally, the rational tion of rural elements ensures the heritage system's vitality and sustainability, as adaptability [5].AHS space refers to a special spatial scope where agricultural c resources are concentrated [6].Thus, the AHS rural area acts as a single or multip area where AHS resources are distributed.It is very valuable to research the transformation of AHS rural areas when co ing the differences and values of AHS compared with the general countryside: core of AHS is active, organic and sustainable agriculture with characteristics inc liveliness, dynamism, adaptability, complexity, strategy, multifunctionality and su bility [7].② The transformation of AHS villages transcends the operation mode o dinary traditional village society [8].The special characteristic elements generate traditional core agriculture and local endogenous social culture can provide decisi different feedback on urban-rural relations and rural transformations, such as resi strengthening and coordination, etc.There is a higher possibility for the advant traditional agriculture to be preserved while efficient modernized modes are broug the production of AHS than in normal rural areas.③ The functions of rural agri become more diverse nowadays in China.AHS villages are important endogen sources for rural development [9].As an active heritage typology, they can enrich It is very valuable to research the transformation of AHS rural areas when considering the differences and values of AHS compared with the general countryside: 1 The core of AHS is active, organic and sustainable agriculture with characteristics including liveliness, dynamism, adaptability, complexity, strategy, multifunctionality and sustainability [7]. 2 The transformation of AHS villages transcends the operation mode of an ordinary traditional village society [8].The special characteristic elements generated from traditional core agriculture and local endogenous social culture can provide decisive and different feedback on urban-rural relations and rural transformations, such as resistance, strengthening and coordination, etc.There is a higher possibility for the advantages of traditional agriculture to be preserved while efficient modernized modes are brought into the production of AHS than in normal rural areas. 3The functions of rural agriculture become more diverse nowadays in China.AHS villages are important endogenous resources for rural development [9].As an active heritage typology, they can enrich the diversity of agricultural functions and bring more opportunities to rural development compared with normal villages.Moreover, the research is also worth attention when considering the background of the current reality.Two strengths exist in the process of urbanization and agricultural modernization nowadays in China [10].One is that the tendency for productivism, for example, the massive use of pesticides and chemical fertilizers, as well as the intensive exploitation and encroachment on agricultural land, which was originally a periodic replacement to cope with external changes [11], has already severely damaged the ecological environment, traditional landscape and traditional cultural societies, etc. [12].The other is the reverse transformation of the agricultural modernization in AHS villages.With quietly occurring consumer revolutions in China [13], residents have begun to pursue high-quality and environmentally friendly agricultural products.That is to say, there are two developing directions for the rural transformation of AHS: 1 to rely on agricultural resources and transform into industrialization and 2 to insist on the original logic of traditional agricultural development.The strong and weak relationships between these two trends determine different transformation characteristics.For example, reflected in land elements, such as maintaining the land-use form of AHS villages, the land-use structure fits more into the land-use proportion of traditional agriculture, which maintains a dispersive state with a reasonable radius [14].If local rural areas choose to develop in the mode of industrialization, there will be an intensive development trend for the land [15].Reflected in cultural and environmental elements, such as maintaining the traditional culture of agriculture, villagers shape the space needed for faith through ceremonies [16], strengthen the geo-community and protect the ecological environment through taboos and an adaptation to agricultural and forestry seasons as well as production activities [4].Otherwise, there will be a prominently negative influence.Compared with normal rural areas, AHS rural areas have a larger possibility of maintaining the advantages of traditional agriculture when completely combined with an efficient modernized production mode with a balance struck between modern and tradition because of the resistance, strengths and coordinative effect of heritage elements [8,17].This essay is focused on the transformation of traditional organic agriculture represented by AHS in the modernized transformation, aiming to reflect on the choices of China's rural agriculture in the path of modern or traditional transformation.Meanwhile, the transformation of rural agricultural development has already broken through rural boundaries and extended to the regional urban-rural perspective.Healthier urban-rural relations can be considered from the agricultural perspective.
In the context of the gradual evolution of urban-rural relations in China from duality to the multi-dimensional exchange of elements, to the direction of industrialization or the insistence on the logic of traditional agricultural development, what are the transformation characteristics of structure, identity and functions of AHS rural areas and what role do heritage elements play?These are the core research questions discussed in this paper.Given the practical situation of data and case acquisition, two main objectives are covered in this study: Firstly, the characteristics of transformation in the structure, identity and functions of AHS rural areas in the past 20 years are stated, and secondly, an explicative framework of the types of rural areas at agricultural heritage sites is established from the perspective of the urban-rural regions with the core indices representing urban-rural relations and the empirical cases of detailed field research.This study has two novel contents.Firstly, there are new data.We creatively reorganized a longitudinal dataset of the years 2000, 2010 and 2020 concerning changes in the core elements of labor, land and production in the research of the sixth batch of AHS counties (districts) in China, which has never been issued in this field.Secondly, there is new first-hand field research.We concluded five cases of agricultural heritage sites in different stages of urban-rural development, where we have carried out field research from 2019 to 2023, as fresh and brand-new materials.

Literature Review
From 1978 to 2020, China has completed industrialization and social and institutional modernization rapidly [18], such that changes in the labor-land-industry texture in AHS rural areas have been stimulated.The changing processes of the above-described elements in the broader urban-rural relationship should be examined [19,20].The theoretical research on urban-rural relationships in the West displays a significant process from urban-rural connection [21], urban-rural binary opposition [22], to close urban-rural connection [23][24][25], whereas most Chinese urban and rural areas still exhibit typical dualistic characteristics currently [26,27].The existence of urban-rural differences is recognized as an objective fact (e.g., in socio-ecological systems [28], road accessibility, the average age of the population, population growth rate [29], access to ecosystem services [30], income [31] and quality of life [32]).Du and Liu point out that the energy differences and functional complementarities between villages and urban areas shape the changing urban-rural relationships [33], and we agree with this view.After the literature review, the current descriptive research on urban-rural relationships covers two categories, i.e., a horizontal comparison of comprehensive indexes [26,34] and a longitudinal analysis of vital factors [33,35].Comprehensive indexes are capable of clearly expressing urban-rural relationships in different regions, while the vital factors can reveal the essence of urban-rural relationships.For instance, Yu and Zhou have paid attention to the elements of "labor and means of production" [36], while Fan has studied "urban construction land and cultivated land" [35].Ma et al. and Li et al. believe that, in essence, labor-land-industries are important dimensions that drive the evolution of urban-rural relationships [37,38], and we strongly endorse this view.
Furthermore, the change of the above three elements drives the transformation of AHS rural areas.To some, transformation is "deep social change" in a resilient system [39].A concept of transformation is adopted in this study, consistent with Wilson et al., that SES transformation refers to the process of a deep change of identity, feedback processes, structure and functions [40].A total of two trends are revealed in rural transformations relying on AHS resources, i.e., to rely on and detach from agricultural resources to transform in the direction of industrialization, as well as to comply with the conventional agricultural development logic.The strong and weak relationship between the above-mentioned two trends will contribute to the transformation of rural areas.This study places a focus on the transformation of the structure, identity and function of China's AHS rural areas.In 2017, China started to push forward with all-round rural vitalization, such that AHS has been promoted to serve as a crucial endogenous development resource for rural development.As indicated by the view of Lendvay, the agricultural system sometimes refers to a more-thanhuman entity that triggers changes in the community (e.g., watermelon production driving rural transformation), rather than simply a non-human object passively accepting human interventions [41].Moreover, Liu and Peng provide evidence for thousand-year-old tea plants driving the local nesting markets and improving the rural economic status through the "Matthew effect" [17].Therefore, this study will also focus on the counter-effect of characteristic elements of AHS on urban-rural relationships.

Study Area
Under national conditions, the Ministry of Agriculture and Rural Affairs of China proposed the China-NIAHS program in 2012 [42].After a decade of development, a total of 126 programs have been identified until 2021, covering various types including conventional farming, cash crop cultivation, livestock and poultry raising, nomadic grazing, agricultural landscape, irrigation engineering and complex symbiotic systems, and so forth.We selected 109 of these items for our quantitative analysis.The rural areas where the China-NIAHS programs are located are subjected to different stages of urban-rural relationships.To be specific, five programs exhibiting differences in their urban-rural relationship and representativeness in regional development serve as the specific analysis objects (Figure 2): (1) Congjiang Rice-Fish-Duck System, located in Congjiang County, Guizhou Province, where rice, fish and ducks coexist and are harvested together in paddies; (2) Puer Con-ventional Tea Garden and Cultural System, located in Yun County, Yunnan Province, and includes ancient tea trees, a tea plantation, related conventional knowledge and culture; (3) Huangyan Citrus Pier-Cultivation System, located on both sides of Chengjiang River in Huangyan District, Zhejiang Province, and characterized using pier building techniques for citrus cultivation; (4) Qingyuan Forest-Mushroom Co-Cultivation System, located in Qingyuan County, Zhejiang Province, including sustainable forest management, mushroom cultivation and processing and local culture and customs; (5) Foshan Dike-Pond Agricultural System, located in Nanhai District, Guangdong Province, which is a complex irrigation and drainage system comprising mulberry-dyke trees, silk rearing, as well as fish cultivation.
Sustainability 2023, 15, x FOR PEER REVIEW 5 of 25 tionships.To be specific, five programs exhibiting differences in their urban-rural relationship and representativeness in regional development serve as the specific analysis objects (Figure 2): (1) Congjiang Rice-Fish-Duck System, located in Congjiang County, Guizhou Province, where rice, fish and ducks coexist and are harvested together in paddies; (2) Puer Conventional Tea Garden and Cultural System, located in Yun County, Yunnan Province, and includes ancient tea trees, a tea plantation, related conventional knowledge and culture; (3) Huangyan Citrus Pier-Cultivation System, located on both sides of Chengjiang River in Huangyan District, Zhejiang Province, and characterized using pier building techniques for citrus cultivation; (4) Qingyuan Forest-Mushroom Co-Cultivation System, located in Qingyuan County, Zhejiang Province, including sustainable forest management, mushroom cultivation and processing and local culture and customs; (5) Foshan Dike-Pond Agricultural System, located in Nanhai District, Guangdong Province, which is a complex irrigation and drainage system comprising mulberry-dyke trees, silk rearing, as well as fish cultivation.

Research Framework
It is imperative to classify the stages of the urban-rural relationship, so as to gain insights into the patterns of changes in labor, land resources and industries at different urbanization stages (Figure 3).The empirical values of "stage theory" originating from much research in China, i.e., urbanization rates of 30%, 50% and 70% [21,30], were adopted in this paper, which separately complied with the stages of urban areas, namely, the beginning to take off, urban-rural uneven development, coordinated urban-rural development and integrated urban-rural development, suggesting the general urban-rural relationship under industrialization in China.Then, quantitative and qualitative analyses were combined in this paper to analyze the transformation of AHS rural areas from two aspects.On the one hand, as for changes in single development elements, descriptive statistics were carried out based on the data panel, and field surveys were conducted on five AHS rural areas at different stages of the urban-rural relationship.The transformation characteristics of AHS rural areas in the past 20 years were analyzed based on three development elements from corresponding transformation dimensions: land structure, population identity and industry function.On the other hand, as for relations among development elements, based on the data panel, a regression analysis among development elements was carried out, which was combined with the characteristic elements extracted from the connotation of AHS rural areas.The analysis was carried out to determine how the development elements and characteristic elements influenced each other and worked together on the transformation of AHS rural areas.

Research Framework
It is imperative to classify the stages of the urban-rural relationship, so as to gain insights into the patterns of changes in labor, land resources and industries at different urbanization stages (Figure 3).The empirical values of "stage theory" originating from much research in China, i.e., urbanization rates of 30%, 50% and 70% [21,30], were adopted in this paper, which separately complied with the stages of urban areas, namely, the beginning to take off, urban-rural uneven development, coordinated urban-rural development and integrated urban-rural development, suggesting the general urban-rural relationship under industrialization in China.Then, quantitative and qualitative analyses were combined in this paper to analyze the transformation of AHS rural areas from two aspects.On the one hand, as for changes in single development elements, descriptive statistics were carried out based on the data panel, and field surveys were conducted on five AHS rural areas at different stages of the urban-rural relationship.The transformation characteristics of AHS rural areas in the past 20 years were analyzed based on three development elements from corresponding transformation dimensions: land structure, population identity and industry function.On the other hand, as for relations among development elements, based on the data panel, a regression analysis among development elements was carried out, which was combined with the characteristic elements extracted from the connotation of AHS rural areas.The analysis was carried out to determine how the development elements and characteristic elements influenced each other and worked together on the transformation of AHS rural areas.

Analysis Method
A total of two parts were involved, i.e., quantitative and qualitative analyses.Methods (1) to (3) referred to quantitative analyses and method (4) was a qualitative analysis.1.To build indexes of core elements in the transformation of urban-rural relationships.
Four indexes, i.e., population urbanization rate, land urbanization rate, the proportion of non-agricultural output value, and urban-rural income ratio, were selected to measure the development of counties where China-NIAHS programs are located.The four indexes were defined in the following equations.
PU denotes the population urbanization rate of county i. UP represents the urban population size of county i. TP expresses the permanent population size of county i. LU is the land urbanization rate of county i. UL , RL , IL are the area of urban construction land, the area of rural construction land and other construction land (independent industrial and mining land, etc.), respectively, jointly constituting the total area of construction land in rural and urban areas of county i. TL is the gross area of the administrative division of county i. IU denotes the proportion of non-agricultural output value of county i. GDP represents gross domestic product of county i. PGDP is the value added of primary industry of county i. EU is urban-rural income ratio of county i. UE is the disposable income of urban households per capita of county i. VE expresses the disposable income of rural households per capita of county i.

2.
The processing and extraction of land use raster data.The national-scale land use non-integrable raster dataset, China Land Use and Land Cover Remote Sensing Monitoring Data Collection (CNLUCC) [43], was employed in this study by the Resource

Analysis Method
A total of two parts were involved, i.e., quantitative and qualitative analyses.Methods (1) to (3) referred to quantitative analyses and method (4) was a qualitative analysis.

1.
To build indexes of core elements in the transformation of urban-rural relationships.Four indexes, i.e., population urbanization rate, land urbanization rate, the proportion of non-agricultural output value, and urban-rural income ratio, were selected to measure the development of counties where China-NIAHS programs are located.The four indexes were defined in the following equations.
PU i denotes the population urbanization rate of county i. UP i represents the urban population size of county i. TP i expresses the permanent population size of county i. LU i is the land urbanization rate of county i. UL i , RL i , IL i are the area of urban construction land, the area of rural construction land and other construction land (independent industrial and mining land, etc.), respectively, jointly constituting the total area of construction land in rural and urban areas of county i. TL i is the gross area of the administrative division of county i. IU i denotes the proportion of non-agricultural output value of county i. GDP i represents gross domestic product of county i. PGDP i is the value added of primary industry of county i. EU i is urban-rural income ratio of county i. UE i is the disposable income of urban households per capita of county i. VE i expresses the disposable income of rural households per capita of county i.

2.
The processing and extraction of land use raster data.The national-scale land use nonintegrable raster dataset, China Land Use and Land Cover Remote Sensing Monitoring Data Collection (CNLUCC) [43], was employed in this study by the Resource and Environment Science and Data Centre of Chinese Academy of Sciences, with the aim of calculating the land urbanization rate.The land use raster data of the respective county was extracted using Extract by Mask from the Spatial Analyst toolset in ArcGIS.Subsequently, attribute tables for the non-integrable raster data were constructed, and the land use of the respective county was counted by category in accordance with the original data classification system.The category included nine types of land use, i.e., urban land, rural settlement, other construction land, arable land, forest land, grassland, waters, unused land and marine.

3.
Ordinary Least Squares regression (OLS).From a macro perspective, it is supposed to analyze the transformational logic of development in China's AHS rural areas in the process of rapid urbanization in this paper by building a theoretical analytical framework.That is, how the three types of development factors (land, population and industries) affect the transformational development of China's AHS rural areas from 2000 to 2020.The data available were not suitable for very rigorous cause-and-effect analyses [44][45][46], so we chose OLS.In statistics, OLS is a common method used to select unknown parameters through a linear regression model.So, in the study, the statistical indicators of three time periods (2000, 2010 and 2020 year) were brought into an explanatory model, and the OLS method was used to analyze and verify that there was an influential relationship between changes in the development factors and the transformational development of China's AHS rural areas in the evolution of urban-rural relationships.

4.
The transformation analysis of structure, identity and function.Structure is the pattern of relationships between system parts or elements.In this study, the structure is the spatial structure of AHS rural areas.Identity is "what is it about?"and "what does it do?".The above-described questions clarify the boundaries, goals, directions or focal points of a system, which are the roles and distinctive signs of core subjects in AHS rural areas in this study.The function is the outcome of a system (e.g., goods, services and choices) [40].The function is about industrial functions of which agriculture is the core in AHS rural areas in this study.To understand the transformation of the above three dimensions, the writers and the project team conducted field research in five AHS rural areas between 2019 and 2023.We conducted in-depth interviews with key stakeholders, including farmers, marketers and public administration managers, and so on, and sorted out the depth of and reasons for the transformation of AHS rural areas based on interview materials.

Data Collection and Processing
For quantitative data, a total of 109 programs and their corresponding county-level administrative units (i.e., districts, counties or banners) were selected by excluding programs with too many scattered territories and serious data deficiencies after 126 China-NIAHS programs were matched with their administrative territories [47].Indexes of the population and land urbanization rates, proportion of non-agricultural output value and the urbanrural disposable income ratio of the respective unit in 2000, 2010 and 2020 were collected and processed to form high-quality panel datasets (Table 1) by referring to local Statistical Yearbooks, Statistical Bulletin of National Economic and Social Development, China Land Use and Land Cover Remote Sensing Monitoring Data Collection (CNLUCC) [43].For qualitative data, first-hand cognitive information from five typical programs has been acquired through fieldwork methods such as participatory observation, interviews and photographic records.Structure refers to the pattern of relationships between system parts or elements and the structural transformation process of AHS rural areas is reflected in the change in the relationship between a wide variety of development elements (e.g., nature, agriculture, land, construction and labor) under a spatial or production structure.AHS rural areas at the stage of coordinated and integrated urban-rural development often show concomitant changes in spatial and production structures.In Qingyuan, the vertical spatial structure of "river-village-terrace-forest" was formed with the outer villages in remote mountains, as the mushroom cultivation base was in the past [48] (Figure 5).Afterwards, the production mode of mushrooms shifted towards the factory and base, with individual family farms and industrial parks migrating and gathering close to the county town, such that a flattened spatial structure is generated.In Huangyan District, the conventional production area located on both sides of the Chengjiang River moved to the underdeveloped mountainous area due to the expropriation of citrus planting land for urban and industrial construction.The quality of citrus was affected by the loss of seawater backflow of the original river embankment system, which was transformed into a reservoir.Meanwhile, the external market impact of the rise of Wenzhou citrus led to the loss of advantages in the variety structure of Huangyan citrus.In Foshan, the efficient dike-pond system originally occupied the highest proportion of the land use of heritage sites, but it was greatly reconstructed due to urban expansion.Moreover, to increase the efficiency of modern freshwater aquaculture, most farmers dug the dike to expand the pond spontaneously, such that the system is subjected to structural damage [49], and the river corridor and the ecological dike are no longer effective in regulating floods and droughts.However, in AHS rural areas at the take-off stage, the production structure was partially changed while the spatial structure remained unchanged.In CongJiang County, the habitats and terraces were still well preserved when the planting type changed from glutinous rice to indica rice, but local elders resisted planting indica rice because it would not be conducive to the local material cycle or ecological environmental protection.In Yun County, on the premise of keeping the overall village spatial structure basically unchanged, tea farmers built roofs for their houses to form small manual workshops and transformed some idle buildings into professional tea preliminary factories [17].Structure refers to the pattern of relationships between system parts or elements and the structural transformation process of AHS rural areas is reflected in the change in the relationship between a wide variety of development elements (e.g., nature, agriculture, land, construction and labor) under a spatial or production structure.AHS rural areas at the stage of coordinated and integrated urban-rural development often show concomitant changes in spatial and production structures.In Qingyuan, the vertical spatial structure of "river-village-terrace-forest" was formed with the outer villages in remote mountains, as the mushroom cultivation base was in the past [48] (Figure 5).Afterwards, the production mode of mushrooms shifted towards the factory and base, with individual family farms and industrial parks migrating and gathering close to the county town, such that a flattened spatial structure is generated.In Huangyan District, the conventional production area located on both sides of the Chengjiang River moved to the underdeveloped mountainous area due to the expropriation of citrus planting land for urban and industrial construction.The quality of citrus was affected by the loss of seawater backflow of the original river embankment system, which was transformed into a reservoir.Meanwhile, the external market impact of the rise of Wenzhou citrus led to the loss of advantages in the variety structure of Huangyan citrus.In Foshan, the efficient dike-pond system originally occupied the highest proportion of the land use of heritage sites, but it was greatly reconstructed due to urban expansion.Moreover, to increase the efficiency of modern freshwater aquaculture, most farmers dug the dike to expand the pond spontaneously, such that the system is subjected to structural damage [49], and the river corridor and the ecological dike are no longer effective in regulating floods and droughts.However, in AHS rural areas at the take-off stage, the production structure was partially changed while the spatial structure remained unchanged.In CongJiang County, the habitats and terraces were still well preserved when the planting type changed from glutinous rice to indica rice, but local elders resisted planting indica rice because it would not be conducive to the local material cycle or ecological environmental protection.In Yun County, on the premise of keeping the overall village spatial structure basically unchanged, tea farmers built roofs for their houses to form small manual workshops and transformed some idle buildings into professional tea preliminary factories [17].In terms of the difference in permanent resident population in China's AHS over different periods, generally, the population urbanization rate follows a smiling relationship, which shows that the characteristic of population changes is "stable a end, shrinking in the middle, and growing at the other end" (Figure 6).For China's areas with a population urbanization rate of more than 70% in 2020, the difference i manent resident population between 2010 and 2020 is significantly larger than the sponding value between 2000 and 2010.It is known that China's AHS areas with a h level of urbanization are becoming more attractive to people for living and working Regarding changes of rural population in China's AHS areas, only 6.42% of C AHS rural areas (7 out of 109 projects) have an influx of permanent population ov two-decade period, while the majority of AHS rural areas suffer from a shrinkage permanent rural population.Combined with the statistical indicators of China's AH eas based on different stages of urban-rural development, the average value of ch in the rural population in the four stages of urban-rural development was 3.69%, −15 −18.70% and −30.08% from 2000 to 2010, and −14.65%, −21.65%, −24.32% and −18.44% 2010 to 2020, respectively (Table 2).It is worth noting that for those AHS areas w population urbanization rate of more than 70% in 2020, the magnitude of the rural p lation outflow between 2010 and 2020 was decreasing compared with that between and 2010.By contrast, the magnitude of rural population outflow was expanding in areas with a population urbanization rate of less than 70%.To a certain extent, it ind that AHS areas with a higher urbanization rate are likely to experience a more sever of the rural population, which will gradually ease thereafter.The structural transformation process in the above typical cases also verifies that AHS rural areas have experienced a serious loss of the land elements required for special agricultural heritage, especially in those at the stage of coordinated and integrated urban-rural development, such as AHS rural areas in Qingyuan County, Huangyan District and Nanhai District.Traditional methods to produce mushrooms in the Qingyuan area rely on forest land resources, which are a kind of mountainous agroforestry production system.The locals propose two strategies for coping with land loss.Firstly, the iteration of mushroom cultivation technologies can respond effectively to the challenge brought by shrinking forest land resources.From the "Duohua" cultivation method to "Wood logging" and the "Material substitution" cultivation method ("Duohua" and "logging" are traditional Chinese techniques for cultivating edible mushrooms, and "Material substitution" is a modern cultivation technique, with lower requirements on environment and labors), mushroom farmers are able to get out of the forest land in mountains and cultivate mushrooms at large-scale, standardized and modernized sites.In addition, the local government has issued policies and regulations to increase the level of forest coverage in forest-mushroom co-cultivation areas year by year.With the protection policy of the Ecological Red Line, the areas, time and quantity of timber cutting have been strictly regulated, which has not only preserved the land space required by a certain scale of mushroom production using the traditional "Duohua" cultivation method, but also provided sufficient raw materials like timbers or woodchips for new mushroom cultivation modes, so as to effectively deal with the contradictions between the great expansion of edible mushroom production scale and the protection of forest land resources.As for AHS rural areas in the Huangyan and Nanhai District, it is difficult to effectively cope with the large-scale demand for land space for citrus production, mulberry cultivation and fish farming by upgrading agricultural production techniques.The government of the Huangyan and Nanhai District has introduced the regulation, protection and development planning for land resources and space, which are needed for local characteristic agricultural production.On the one hand, a core protection zone has been designated to stabilize the planting and breeding areas, where the local government takes the lead in transforming and upgrading the agricultural production space in accordance with the requirements of mechanization, informatization and standardization.On the other hand, great attention has been paid to the property rights of agricultural land.The goal of intensifying production and operation in the core protection zone has been achieved through land circulation.In Huangyan, the local government has implemented land circulation incentives, encouraging collective economic organizations in villages to develop characteristic agriculture through the following process: leasing agricultural land contracted by families, making unified planning of the leased land, such as building farmland infrastructures, and then contracting the above land to farmers block by block.In Foshan, the local government has adopted a model of unified development by leasing land to implement the traditional mulberry-based dike-pond agricultural system.Furthermore, the area of land used for characteristic agricultural production has increased year by year, and the output of characteristic agriculture has been expanded continuously.Lastly, to enhance the land value of characteristic agriculture, the local people have explored the cultural tourism value of agricultural heritage and created a unique regional cultural brand based on eco-cultural agricultural industry parks.

Population Identity: Increase in Total Population Accompanied by Sharply Shrinking Rural Population and Combination or Separation of Farmers with Conventional Agriculture
In terms of the difference in permanent resident population in China's AHS areas over different periods, generally, the population urbanization rate follows a smiling curve relationship, which shows that the characteristic of population changes is "stable at one end, shrinking in the middle, and growing at the other end" (Figure 6).For China's AHS areas with a population urbanization rate of more than 70% in 2020, the difference in permanent resident population between 2010 and 2020 is significantly larger than the corresponding value between 2000 and 2010.It is known that China's AHS areas with a higher level of urbanization are becoming more attractive to people for living and working.In conclusion, when an AHS area is of a higher urbanization rate, the more attractive the migrant residents in AHS rural areas are, the stronger the economic vitality is in those AHS rural areas; however, normally, there tends to be a greater loss of the rural permanent population in such AHS rural areas.Through changing the structure of the rural labor force, the above-mentioned demographic characteristics in the evolution of the urbanrural relationship will have a great impact and influence on AHS rural areas, which are characterized by the development of conventional characteristic agriculture by means of the small-scale peasant economy and individual operation mode.Regarding changes of rural population in China's AHS areas, only 6.42% of China's AHS rural areas (7 out of 109 projects) have an influx of permanent population over the two-decade period, while the majority of AHS rural areas suffer from a shrinkage in the permanent rural population.Combined with the statistical indicators of China's AHS areas based on different stages of urban-rural development, the average value of changes in the rural population in the four stages of urban-rural development was 3.69%, −15.90%, −18.70% and −30.08% from 2000 to 2010, and −14.65%, −21.65%, −24.32% and −18.44% from 2010 to 2020, respectively (Table 2).It is worth noting that for those AHS areas with a population urbanization rate of more than 70% in 2020, the magnitude of the rural population outflow between 2010 and 2020 was decreasing compared with that between 2000 and 2010.By contrast, the magnitude of rural population outflow was expanding in AHS areas with a population urbanization rate of less than 70%.To a certain extent, it indicates that AHS areas with a higher urbanization rate are likely to experience a more severe loss of the rural population, which will gradually ease thereafter.In conclusion, when an AHS area is of a higher urbanization rate, the more attractive the migrant residents in AHS rural areas are, the stronger the economic vitality is in those AHS rural areas; however, normally, there tends to be a greater loss of the rural permanent population in such AHS rural areas.Through changing the structure of the rural labor force, the above-mentioned demographic characteristics in the evolution of the urban-rural relationship will have a great impact and influence on AHS rural areas, which are characterized by the development of conventional characteristic agriculture by means of the small-scale peasant economy and individual operation mode.
Identity is the socio-economic roles and rights of system subjects and the specific social structure they form.The identity transformation process of AHS rural areas is reflected in the changes in farmers' livelihoods and social structure.AHS rural areas at the stage of uneven development among rural and urban areas have strong social autonomy.In Yun County, villages and towns spontaneously established the Protection Convention and Processors Association to improve the quality of tea trees (Figure 7).Moreover, Baiyingshan Village established links with external social networks to attract domestic and foreign journalists, scholars, tea merchants and civil servants to visit for investigation and trade.The tea planting mode changed from individual small households to village collectives and groups for better resource integration and co-cultivation.The aging of conventional farmers and the emergence of new agricultural management subjects occurred simultaneously in AHS rural areas at the stage of coordinated urban-rural development.In Qingyuan, the agricultural business entities changed from individual households to professional large households, family farms, farmers' cooperatives and leading enterprises, and the mobile individual mushroom livelihoods were included in the government's planning and regional integrated development.In the Huangyan District, conventional citrus farmers have shown a decreasing and aging trend.Under policy guidance, a large amount of external capital entered the citrus industry and was deeply embedded in the agricultural materials market.There have been some cases where citrus farmers were entrusted with modern citrus orchards by enterprises, and agricultural data companies were entrusted by the government to provide technical guidance on citrus planting.Farmers in AHS rural areas at the stage of integrated urban-rural development have a higher degree of separation from conventional characteristic agriculture.In Foshan, due to the impact of precision feeding aquaculture on the income of conventional dike planting, a large number of dikepond farmers transformed into specialized fishery farmers.Moreover, the ownership of dike ponds was transferred to the local government, therefore farmers needed to rent ponds from the government, which further led to a decrease in farmers' enthusiasm for production and a shift to the fishery processing industry and other production departments.
citrus farmers have shown a decreasing and aging trend.Under policy guidance, a amount of external capital entered the citrus industry and was deeply embedded in agricultural materials market.There have been some cases where citrus farmers wer trusted with modern citrus orchards by enterprises, and agricultural data companies entrusted by the government to provide technical guidance on citrus planting.Farme AHS rural areas at the stage of integrated urban-rural development have a higher de of separation from conventional characteristic agriculture.In Foshan, due to the impa precision feeding aquaculture on the income of conventional dike planting, a large n ber of dike-pond farmers transformed into specialized fishery farmers.Moreover ownership of dike ponds was transferred to the local government, therefore far needed to rent ponds from the government, which further led to a decrease in farm enthusiasm for production and a shift to the fishery processing industry and other duction departments.After two decades of development, different AHS rural areas exhibit an uneven nomic aggregate and a growing disparity in GDP between them (Figure 8).For indu After two decades of development, different AHS rural areas exhibit an uneven economic aggregate and a growing disparity in GDP between them (Figure 8).For industrial structure, there is a clear trend towards non-agricultural development in the economy, with the proportion of the agricultural output value continuing to decline (Figure 9).Specific to the different stages of urban-rural relationship, there are some differences in changes in the industrial structure between different AHS rural areas.For the agricultural heritage with an urbanization rate below 50%, the proportion of the agricultural output value is high.Agriculture has a great influence on the local economy.For instance, the proportion of the agricultural output value in some areas reached over 50% in 2000, thus taking on critical significance in the development of the local economy.Despite the notable trend of non-agricultural development, the proportion of agricultural output value in many areas was 20-30% in 2020, which is still a high proportion.A small number of AHS areas with a 50-70% urbanization rate experience an increase in the proportion of the agricultural output value, such as the Xiangshui Rice Cultivation Culture System and Fuyuan Fish Farming System in Heilongjiang province and the Xinglong Hawthorn Cultivation System in Hebei province.It reflects that there is a strong vitality of conventional agricultural activities in the above-described AHS areas.Under the rapid increase in urbanization in China, the transformation in the above-described AHS rural areas, where the proportion of the agricultural output value increase, is worthy of our attention, while in AHS rural areas with an urbanization rate over 70%, the proportion of agricultural output value is at a very low level and continues to decline, reflecting a huge impact on local conventional agricultural activities.In the above-mentioned AHS rural areas, the conventional agricultural production activities have shrunk or declined or even migrated to other surrounding counties and regions for development.
ble trend of non-agricultural development, the proportion of agricultural output value in many areas was 20-30% in 2020, which is still a high proportion.A small number of AHS areas with a 50-70% urbanization rate experience an increase in the proportion of the agricultural output value, such as the Xiangshui Rice Cultivation Culture System and Fuyuan Fish Farming System in Heilongjiang province and the Xinglong Hawthorn Cultivation System in Hebei province.It reflects that there is a strong vitality of conventional agricultural activities in the above-described AHS areas.Under the rapid increase in urbanization in China, the transformation in the above-described AHS rural areas, where the proportion of the agricultural output value increase, is worthy of our attention, while in AHS rural areas with an urbanization rate over 70%, the proportion of agricultural output value is at a very low level and continues to decline, reflecting a huge impact on local conventional agricultural activities.In the above-mentioned AHS rural areas, the conventional agricultural production activities have shrunk or declined or even migrated to other surrounding counties and regions for development.In addition, changes in the per capital disposable income can demonstrate the ch acteristics of industrial development changes in AHS rural areas.As the urbanization r increases, the urban-rural income ratio of the permanent population declines, and the u ban-rural income gap reduces (Table 3).In 2020, the disposable income of rural residen In addition, changes in the per capital disposable income can demonstrate the characteristics of industrial development changes in AHS rural areas.As the urbanization rate increases, the urban-rural income ratio of the permanent population declines, and the urban-rural income gap reduces (Table 3).In 2020, the disposable income of rural residents increased with an upgrade in stages of the urban-rural relationship, suggesting that the disposable income of residents in AHS rural areas increases significantly in line with urbanization.Combined with the features mentioned above, such as the trend of non-agricultural development, the serious loss of the rural permanent population in AHS rural areas with a high urbanization rate and low-level proportion of the agricultural output value, accompanied by continuous a decline in the proportion of the agricultural output value, it can be assumed that the income of rural residents comes more from non-agricultural industries, and the proportion of this kind of income increases.The residents or households in AHS rural areas engage in non-agricultural work, take concurrent employment in agricultural and non-agricultural industries or engage in high-value-added modern agricultural activities.Function refers to the products, services and choices produced by system operations.The functional transformation process of AHS rural areas is reflected in the combination structure and input-output status of their main industries.In the AHS rural areas at the stage where the development in urban areas is beginning to take off, the characteristic agricultural production function basically continues its conventional logic.In Congjiang County, after a series of cultural heritage certifications, conventional villages underwent a non-subversive transformation and slow evolution of rice, fish and duck agriculture under the activation of funds and exposure (Figure 10).New combinations of local industries emerged in AHS rural areas at the stage of uneven development among rural and urban areas.In Yun County, Baiyingshan Village created a natural museum, tourist walkway and home-stay inn in addition to tea processing.In the AHS rural areas at the stage of coordinated urban-rural development, the industrial chain of characteristic agriculture has been extended and improved.In Qingyuan County, the mushroom industry has gradually developed from production and rough processing to high value-added directions such as leisure and health care and biotechnology, forming a whole industry chain integrating cultivation and production, deep processing, trade and logistics and raw and auxiliary materials, while this characteristic agriculture effectively supported the tourism and exhibition industries.Another case was the establishment of the Citrus Source Museum and Seed Research Center based in Huangyan District.AHS rural areas at the stage of integrated urban-rural development may experience disruptive changes and chain reactions in their conventional agricultural functions.In Foshan, sericulture and sugar production shifted to other areas due to the decline of dike agricultural cultivation such as mulberry and sugarcane [49], while the government built the Cultural Park to promote research, exhibition and tourism of the dike-pond agricultural system.exhibition industries.Another case was the establishment of the Citrus Source Mu and Seed Research Center based in Huangyan District.AHS rural areas at the sta integrated urban-rural development may experience disruptive changes and chain tions in their conventional agricultural functions.In Foshan, sericulture and sugar duction shifted to other areas due to the decline of dike agricultural cultivation su mulberry and sugarcane [49], while the government built the Cultural Park to pro research, exhibition and tourism of the dike-pond agricultural system.

The Core Logic of Establishing the Analytical Model of Regression
When establishing the relations of a population-land-industry model, it is cruc put emphasis on the industrial transformation situations in rural areas relying on th ments of AHS.After our field research, we find that, on the one hand, the industrial formation at heritage sites depends on the transformation of urban-rural relations, as the binary state of the elements of the population, land and industry in cities an lages.On the other hand, the transformation is influenced by the special attributes ricultural heritage (Figure 11).For example, whether the heritage types can be large

Relations of Development Elements 6.2.1. The Core Logic of Establishing the Analytical Model of Regression
When establishing the relations of a population-land-industry model, it is crucial to put emphasis on the industrial transformation situations in rural areas relying on the elements of AHS.After our field research, we find that, on the one hand, the industrial transformation at heritage sites depends on the transformation of urban-rural relations, such as the binary state of the elements of the population, land and industry in cities and villages.On the other hand, the transformation is influenced by the special attributes of agricultural heritage (Figure 11).For example, whether the heritage types can be largescale or scarce, or whether or not they determine different development forms of heritage elements in the modern industrial system.The core logic could be listed as follows.or scarce, or whether or not they determine different development forms of heritage elements in the modern industrial system.The core logic could be listed as follows.A regression model was determined according to the core logic (Figure 12).The industrial transformation situation of rural areas with agricultural heritage was reflected by the non-agricultural proportion of agricultural sites.The general situation of regional urban-rural relations was reflected by the population urbanization rate, the land urbanization rate and the urban-rural income ratio, as well as the locations of provincial capitals of eastern, central and western China.An OSL regression analysis was performed on the above data using the R language, while the special attributes of heritage were analyzed through case studies, which were not reflected in the regression model.A regression model was determined according to the core logic (Figure 12).The industrial transformation situation of rural areas with agricultural heritage was reflected by the non-agricultural proportion of agricultural sites.The general situation of regional urbanrural relations was reflected by the population urbanization rate, the land urbanization rate and the urban-rural income ratio, as well as the locations of provincial capitals of eastern, central and western China.An OSL regression analysis was performed on the above data using the R language, while the special attributes of heritage were analyzed through case studies, which were not reflected in the regression model.
dustrial transformation situation of rural areas with agricultural heritage was reflected by the non-agricultural proportion of agricultural sites.The general situation of regional urban-rural relations was reflected by the population urbanization rate, the land urbanization rate and the urban-rural income ratio, as well as the locations of provincial capitals of eastern, central and western China.An OSL regression analysis was performed on the above data using the R language, while the special attributes of heritage were analyzed through case studies, which were not reflected in the regression model.
The result revealed that the non-agricultural industrial ratio was the only significant statistical variable of the regression model (Table 4), which pointed out that, from 2000 to 2020, the original non-agricultural industrial ratio of the counties where agricultural heritage was located had a direct influence on the successive non-agricultural industrial transformation.The conditions of the initial industrial structure are very important.The OSL regression model was established based on an analysis of the influence of population urbanization rate, non-agricultural industrial ratio, land urbanization rate and areas in 2010 on the proportion of non-agricultural industries in 2020: The result revealed that the non-agricultural industrial ratio was the only significant statistical variable of the regression model (Table 4), which pointed out that, from 2000 to 2020, the original non-agricultural industrial ratio of the counties where agricultural heritage was located had a direct influence on the successive non-agricultural industrial transformation.The conditions of the initial industrial structure are very important.The OSL regression model was established based on an analysis of the influence of population urbanization rate, non-agricultural industrial ratio, land urbanization rate and areas in 2010 on the proportion of non-agricultural industries in 2020: industry2020 = urbanrate2010 + indusry2010 + land2010 + income2010 + factor(region) The result revealed that the non-agricultural industrial ratio, land urbanization ratio, urban-rural income ratio and locations of western China were statistically significant for the regression model (Table 5), which pointed out that the comprehensive strengths at the county level influenced the non-agricultural industrial transformation from 2010 to 2020, and that the difference was significant in western areas since the ratio of non-agricultural industrial transformation there was 0.04 percent (p < 0.05) lower than that in eastern areas on average.We proposed a simple visual model for the potential drivers of population growth rate based on the empirical correlation results presented (Figure 13).Neither a correlation nor a regression analysis could prove causation, while statistics could only provide strong evidence in favor of or against potential drivers [29].Based on a quantitative analysis of human, land and industrial factors, it can be concluded that there is a path dependence in the industrial structure of the industrial transformation in agricultural heritage villages, because areas with a high proportion of non-agricultural industries 20 years ago had a higher ratio of non-agricultural industrial transformation, and such an effect was especially significant from 2010 to 2020.In addition, the urban-rural income ratio, locations and land urbanization rate all positively stimulated the transformation of agriculture into nonagricultural industries at agricultural heritage sites from 2010 to 2020.A supplementary analysis indicates that, in the same time section, the population urbanization rate is a direct index reflecting the transformation process of non-agricultural industries.We proposed a simple visual model for the potential drivers of population growth rate based on the empirical correlation results presented (Figure 13).Neither a correlation nor a regression analysis could prove causation, while statistics could only provide strong evidence in favor of or against potential drivers [29].Based on a quantitative analysis of human, land and industrial factors, it can be concluded that there is a path dependence in the industrial structure of the industrial transformation in agricultural heritage villages, because areas with a high proportion of non-agricultural industries 20 years ago had a higher ratio of non-agricultural industrial transformation, and such an effect was especially significant from 2010 to 2020.In addition, the urban-rural income ratio, locations and land urbanization rate all positively stimulated the transformation of agriculture into non-agricultural industries at agricultural heritage sites from 2010 to 2020.A supplementary analysis indicates that, in the same time section, the population urbanization rate is a direct index reflecting the transformation process of non-agricultural industries.
Of course, the attributes of heritage sites would be neglected if the framework of heritage transformation was established merely based on a quantitative analysis of data and elements of heritage, such as the culture, community and agricultural heritage crops, etc., which cannot be observed.So, the framework was supplemented and improved by some empirical cases based on this visualized frame.Of course, the attributes of heritage sites would be neglected if the framework of heritage transformation was established merely based on a quantitative analysis of data and elements of heritage, such as the culture, community and agricultural heritage crops, etc., which cannot be observed.So, the framework was supplemented and improved by some empirical cases based on this visualized frame.

Discussion
Agricultural cultural heritage is a living heritage, which is part of the local social and economic life that constantly changes with the development of a region.Different from ordinary villages, while being affected by the general structural factors such as population, land and industries generated through state intervention and market operation, AHS villages transcend the operation mode of traditional village societies [8].The special characteristic elements generated from traditional core agriculture and local endogenous social culture can provide decisive and different feedback on urban-rural relations and rural transformation, such as resistance, strengthening and coordination, etc.These special factors are usually characterized by food and livelihood security, agro-biodiversity, local and traditional knowledge systems, cultures, values, social organizations and landscapes, as well as seascape features, etc., which drive the rural transformation process in terms of population patterns, capital allocation, benefit distribution and village organization, etc., leading rural areas towards different paths such as traditional sustainable agriculture, organic agricultural production, modern industries and sustainable tourism development (Figure 14).land protection plan.After ecological restoration, these lands were leased to local farmers willing to be under contract management.Meanwhile, for other lands outside of the core protected areas, after land reclamation, the government introduced research institutes and village sages to develop organic farming and breeding technology, which will promote the transformation of such agricultural cultural heritage systems into organic agriculture as an embodiment of its ecological agricultural value attached to agricultural products [51].Various elements and their laws related to AHS rural areas all act on space, with land being the most fundamental and important spatial carrier.The stability and protection of property relations and livelihood attached to the land are at the forefront of the subject [52].Laws, regulations, policies and other measures related to land are fundamental means of maintaining the internal development mechanisms of AHS.For example, the Slovak Republic arranges the land ownership of all agricultural and forest land, as well as the related immovable properties using land consolidation [52].In Romanian laws, the legal preemption of the state to public forests and that of co-owners or neighbors of private forests aims to ensure the compaction of forests as well as their efficient exploitation, taking into account the preservation of biodiversity [53].In addition, land has also been one of the ways to receive profits.In Ukraine, the fertile black soil is one of the most attractive objects to be invested in.A restriction on the possibility for foreigners to acquire property rights of agricultural land is carried out for the specific purpose of protecting national interests and public orders [54].In this paper, the land-related issues, on the one hand, are reflected in the great loss of agricultural land to construction land, which ruin the performance of AHS rural areas.On the whole, the current government has tried to curb this negative impact by means of technological improvement, land property right transfer and the protection policy of the Ecological Red Line, etc., which have been analyzed in detail in Section 6.1.1Land structure, so it will not be repeated here.On the other hand, the contradictions between the rigid land control rules and the dynamic, multi-compound characteristics of AHS land are also core issues that need additional attention.The spatial Firstly, host communities play a key role in the protection of agricultural systems due to their rich knowledge of the local ecological environment, agricultural labor and traditional culture, which often have the experience and capacity to address local significance issues [50].In Yun County, producers and consumers formed a joint social network beyond the village based on the scarce thousand-year-old ancient tea trees and characteristic tea culture.With the value certification and brand promotion of the government and research institutions, global tea distributors come to Baiyingshan Village every spring to appreciate and purchase the well-known puer tea.Such face-to-face trades with local tea farmers promote the emergence of local nested markets and tourism.The purchased fresh leaves need to be roasted, dried or flattened in a local primary processing factory before being transported, which encourages tea farmers to transform their houses into small handmaking workshops.A spontaneous local processors' association, jointly established by the local government, formulates industrial rules to ensure the quality and income of tea and operates tea cultural tourism with government and village collectives [17].These efforts have led to a return of labor to continue the development trend of traditional tea cultivation in the village.Secondly, the attributes of agricultural species are also crucial.In Qingyuan County, mushrooms, the local core agricultural species, in contrast to tea trees, are more scalable and mobile.Based on these characteristics, the production and life related to mushroom planting can be liberated from deep mountains or forests and reorganized according to the trend of urban-rural integration.Mushroom cultivation is relocated near counties with abundant land, convenient transportation and a dense population in the form of family farms and industrial parks, which strongly promotes the modern industrialization transformation of this agricultural heritage system and significantly increases the proportion of the non-agricultural output value.The product transformation supported by special characteristics also drives the livelihood of local farmers to solidify from the mobile individual livelihood mode of building mushroom sheds in mountains to a new agricultural operation mode with stable markets and employment in cities and towns, resulting in an improved population urbanization rate.Last but not least, unique land use systems also need to be considered.In Foshan, the unique land use system formed by the combination of pond aquaculture and dike planting was originally an efficient land production and utilization mode with the highest proportion of heritage sites.However, due to its lack of scarcity, sociality (such as tea trees), mobility and scalable potential (such as mushrooms), when facing the high productivity and profit impact of the modern freshwater aquaculture industry, the dike-pond system struggled with the problem of the separation of planting from aquaculture and an imbalance of spatial structure caused by the farmers' spontaneous behavior of digging dikes and expanding ponds.The sericulture and sugar industries, which are dependent on dikes, have migrated to other places, and some abandoned ponds have been replaced by urban construction land with the trend of urban sprawl.Correspondingly, farmers' land ownership has been transferred to the government.Subsequently, the proportion of the non-agricultural output value, land urbanization rate and non-agricultural as well as part-time employment rate of farmers has rapidly increased.In recent years, the government has incorporated some well-maintained dike-pond systems with traditional features into a permanent basic farmland protection plan.After ecological restoration, these lands were leased to local farmers willing to be under contract management.Meanwhile, for other lands outside of the core protected areas, after land reclamation, the government introduced research institutes and village sages to develop organic farming and breeding technology, which will promote the transformation of such agricultural cultural heritage systems into organic agriculture as an embodiment of its ecological agricultural value attached to agricultural products [51].
Various elements and their laws related to AHS rural areas all act on space, with land being the most fundamental and important spatial carrier.The stability and protection of property relations and livelihood attached to the land are at the forefront of the subject [52].Laws, regulations, policies and other measures related to land are fundamental means of maintaining the internal development mechanisms of AHS.For example, the Slovak Republic arranges the land ownership of all agricultural and forest land, as well as the related immovable properties using land consolidation [52].In Romanian laws, the legal preemption of the state to public forests and that of co-owners or neighbors of private forests aims to ensure the compaction of forests as well as their efficient exploitation, taking into account the preservation of biodiversity [53].In addition, land has also been one of the ways to receive profits.In Ukraine, the fertile black soil is one of the most attractive objects to be invested in.A restriction on the possibility for foreigners to acquire property rights of agricultural land is carried out for the specific purpose of protecting national interests and public orders [54].In this paper, the land-related issues, on the one hand, are reflected in the great loss of agricultural land to construction land, which ruin the performance of AHS rural areas.On the whole, the current government has tried to curb this negative impact by means of technological improvement, land property right transfer and the protection policy of the Ecological Red Line, etc., which have been analyzed in detail in Section 6.1.1Land structure, so it will not be repeated here.On the other hand, the contradictions between the rigid land control rules and the dynamic, multi-compound characteristics of AHS land are also core issues that need additional attention.The spatial attribute is an important prerequisite for the management and control of AHS land.The currently implemented territorial spatial planning system is the most important legal planning and control rule for territorial space.However, due to its rigid and inflexible management and control framework, conflicts with the rural production and livelihoods of AHS rural areas are easily triggered.First of all, the use of land is dynamic, which is reflected in the bidirectional and cyclic alternation of natural elements to cope with external changes [55].In Foshan, farmers periodically adjust the dike-pond area ratio and the types of crops planted on dikes (mulberries, fruit trees, sugarcane, flowers and vegetables, etc.) according to climate changes and market demands.The territorial spatial planning stipulates that the overall dike-pond ratio be kept at about 6:4, which obviously hinders the circulation among different agricultural lands within an acceptable range and the improvement of farmers' livelihood incomes.Secondly, the use of land has a mixed Mosaic feature, with biodiversity and livelihood reflected in both the horizontal and vertical spaces [55].In Yun County, a mountainous county with multi-ethnic groups living in the mid-levels, the local cultivated land can only survive on the gentle-slope land, while tea gardens can adapt to a variety of terrains such as flat land, terraces and slope land, which can conserve water and soil while generating incomes for rural communities in mountainous areas.There is a spatial overlap between the protection areas of ancient tea gardens and permanent basic farmland, but there is a lack of relevant rules to coordinate the priority order of the protection and development of these two subjects.For ancient tea gardens located on slopes, there will be no spatial conflict with the permanent basic farmland, which can achieve simultaneous protection; for gardens located on flat or terraced land and contiguous permanent basic farmland, simultaneous protection rules can be implemented, but it is necessary to prohibit the spraying of pesticides within the gardens; for gardens located on non-contiguous permanent basic farmland, farmland patches should be ecologically restored to tea gardens.For AHS land management and control, it is necessary to make standards match the diversified AHS land types to enhance their promoting role in rural revitalization.
However, there are also some issues worth further discussion due to the existing limitations.Firstly, in addition to identities, structures and functions, there would be another dimension of transformation referring to feedback.Due to limited research, it was difficult to obtain all the information on social relationships among the key players through a field trip, thus, this part was not carried out.Secondly, before the concept of transformation, there were still some signs of coping and adaptation in some rural areas, which did not reach the state of deep transformation.Through actual operation, research on the adaptation and coping would require a more microscopic research perspective, which was not discussed in this study.In addition, the study also had a methodological research limitation, as it was limited by the difficulties in data acquisition and the length of the study.A correlation analysis was used in the research rather than a causal analysis in the establishment of the basic interpretation framework, resulting in a slightly worse rigor of the interpretation, yet the overall conclusion of the study was not affected.Of course, the relationship among the factors was also a problem worth studying, which would be a very heavy task.In the future, we will make use of a causality analysis alone to distinguish and analyze studies.

Conclusions
Combined with quantitative and qualitative analyses, the transformation characteristics of AHS rural areas in the past 20 years are explained in this paper based on three development elements from corresponding transformation dimensions.From the land structure perspective, the higher the level of population urbanization rate is, the larger the proportion of the land use scale that will be shifted from a rural system to an urban system.Especially, AHS rural areas at the stage of coordinated and integrated urban-rural development have inevitably experienced a loss of land elements, showing a concomitant relationship with changes in spatial and production structures.By contrast, AHS rural areas at the development stage in urban areas begin to take off and maintain their unchanged spatial structures relatively when production structures have changed.From the population identity perspective, AHS rural areas are more attractive to migrant residents and have a stronger economic vitality at a higher urbanization rate, which, however, are normally with a greater loss of the rural permanent population.Rural areas at the stage of uneven development in rural and urban areas have a greater increase in social autonomy.The ageing of farmers working on traditional agriculture and the transformation of business entities in which new farmers are engaged occur in rural areas at the stage of coordinated urban-rural development, and farmers are more likely to divest the traditional characteristic agriculture in rural areas at the stage of integrated urban-rural development.From the industry function perspective, there is a clear trend towards non-agricultural development in the economy, with the proportion of the agricultural output value continuing to decline.As for rural areas at the stage where development is beginning to take off in urban areas, the proportion of the agricultural output value is high, and the production function of characteristic agriculture can follow the routes of traditional agriculture development.New combinations of local industries have begun to emerge in rural areas at the stage of uneven development.At the same time, a greater extension and improvement happen in the upstream and downstream characteristic agriculture industry chain in rural areas at the stage of coordinated urban-rural development.Meanwhile, in AHS rural areas with an urbanization rate of over 70%, the proportion of agricultural output value is at a very low level and continues declining, so the production function of characteristic agriculture in rural areas at the stage of integrated urban-rural development may undergo disruptive changes and chain reactions.
In the regression analysis, the initial proportion of non-agricultural industries in AHS rural areas has the most direct influence on the subsequent non-agricultural industrial transformation process, which means that the original conditions of an industry are very important and that the transformation depends on the path of an industrial structure.Meanwhile, the urban-rural income ratio, regional distribution and land urbanization rate all positively stimulate the transformation from agricultural to non-agricultural industries.Moreover, the transformation of AHS rural areas is also affected by the characteristic elements of their special agricultural heritage, such as host communities, unique attributes of agricultural species and land use systems.Specifically, whether their agricultural heritage is scalable, scarce or socialized, etc., these special attributes can determine the different development forms of heritage elements in modern agricultural industrial systems.
During the transformation process of AHS rural areas, China's AHS areas encounter two major development trends and social realities, i.e., whether to continue with conventional characteristic agricultural development or to achieve an industrial transformation by detaching from conventional characteristic agricultural resources.When the dividend relying on the non-agriculturalization of land and population that drives local economic development progressively disappears, the transformation of AHS rural areas should fully exploit the role of supporting agriculture with industries and supporting rural areas with urban development.At the stage of a high-level urban-rural relationship, the conventional characteristic agricultural system of AHS rural areas is coped with through two development paths, i.e., a persistent decline or transformation with the reconstruction of an agricultural system.Well-preserved characteristic agricultural systems are more likely to receive development support from non-agricultural sectors, which can extend to secondary and tertiary industries based on conventional characteristic agriculture, achieving agricultural modernization while supporting high-quality urban and rural development.It is imperative for the conventional characteristic agricultural system, which has been subjected to significant disruptions and effects, or even serious damage, to restore local characteristic agricultural development with the support of development element inputs and government policies.In areas at the stage of uneven development among rural and urban areas, where the conventional characteristic agricultural system is disturbed and affected, the local government should protect elements and space for characteristic agricultural systems and further enhance the resilience of characteristic agricultural systems, so that these areas can be prevented from being severely damaged or falling under the threshold of non-recoverability.

Figure 1 .
Figure 1.The connotation of AHS rural area.

Figure 1 .
Figure 1.The connotation of AHS rural area.

Figure 2 .
Figure 2. Distribution of NIAHS programs under different population urbanization rates in 2020.

Figure 2 .
Figure 2. Distribution of NIAHS programs under different population urbanization rates in 2020.

Figure 4 .
Figure 4. Changes in difference in land urbanization rate in China's AHS rural areas, 2000-2020.

Figure 4 .
Figure 4. Changes in difference in land urbanization rate in China's AHS rural areas, 2000-2020.

Figure 5 .
Figure 5.The structural transformation process of AHS rural areas: (a) Qingyuan County: the cal spatial structure of "river-village-terrace-forest"; (b) Qingyuan County: mushrooms in farms; (c) Huangyan District: citrus groves that no longer use pier cultivation techniques; (d) F dike-pond landscape between villages; (e) Foshan: mulberry trees on the dike are replaced b etables; (f) Yun County: houses and tea preliminary processing factories in the mountains; (g County: tea preliminary processing factories; (h) Yun County: tea farmers transform their hou small manual workshops.6.1.2.Population Identity: Increase in Total Population Accompanied by Sharply Shrinking Rural Population and Combination or Separation of Farmers wit Conventional Agriculture

Figure 5 .
Figure 5.The structural transformation process of AHS rural areas: (a) Qingyuan County: the vertical spatial structure of "river-village-terrace-forest"; (b) Qingyuan County: mushrooms in family farms; (c) Huangyan District: citrus groves that no longer use pier cultivation techniques; (d) Foshan: dikepond landscape between villages; (e) Foshan: mulberry trees on the dike are replaced by vegetables; (f) Yun County: houses and tea preliminary processing factories in the mountains; (g) Yun County: tea preliminary processing factories; (h) Yun County: tea farmers transform their houses to small manual workshops.

Figure 6 .Table 2 .
Figure 6.Changes in difference in permanent residents' population in China's AHS areas, 2000-2020.Table 2.The growth rate of the rural population in China's AHS areas at different stages of the urban-rural relationship, 2000-2020.Urbanization Rate 2000-2010 Year 2010-2020 Year Mean Median S.D. Mean Median S.D.

Figure 7 .
Figure 7.The identity transformation process of AHS rural areas: (a) Yun County: tea festiv Baiyingshan village; (b) Yun County: tea distributor from Hong Kong and local mayor; (c) Qing County: mushroom industrial park and the younger generation of farmers; (d) Qingyuan Co master plan of mushroom town; (e) Qingyuan County: mushroom town under constructio Huangyan District: most citrus farmers are middle-aged and elderly; (g) Foshan: farmers who to work for the dike-pond system transform into specialized fishery farmers; (h) Foshan: proce in-dustry spring up in the village.6.1.3.Industry Function: Improvement in Overall Economy under the Trend of Non-Agricultural Development and Continuation or Deep Transformation of Conventional Agricultural Functions

Figure 7 .
Figure 7.The identity transformation process of AHS rural areas: (a) Yun County: tea festival in Baiyingshan village; (b) Yun County: tea distributor from Hong Kong and local mayor; (c) Qingyuan County: mushroom industrial park and the younger generation of farmers; (d) Qingyuan County: master plan of mushroom town; (e) Qingyuan County: mushroom town under construction; (f) Huangyan District: most citrus farmers are middle-aged and elderly; (g) Foshan: farmers who used to work for the dike-pond system transform into specialized fishery farmers; (h) Foshan: processing in-dustry spring up in the village.6.1.3.Industry Function: Improvement in Overall Economy under the Trend of Non-Agricultural Development and Continuation or Deep Transformation of Conventional Agricultural Functions

Figure 9 .
Figure 9. Change in the proportion of agricultural output value in AHS rural areas, 2000-2020.

Figure 10 .
Figure 10.The functional transformation process of AHS rural areas.(a) Congjiang County fish and ducks grow together in the terraces; (b) Yun County: natural museum of the evolut tea tree; (c) Qingyuan County: area for mushroom trading in the mushroom market; (d) Qin County: a road used to transport mushrooms; (e) Huangyan District: museum of the source of (f) Huangyan District: Research Center of the seed of citrus; (g) Foshan: cultural park of Dike system; (h) Foshan: amusement facilities in the cultural park of Dike-Pond system.

Figure 10 .
Figure 10.The functional transformation process of AHS rural areas.(a) Congjiang County: Rice, fish and ducks grow together in the terraces; (b) Yun County: natural museum of the evolution of tea tree; (c) Qingyuan County: area for mushroom trading in the mushroom market; (d) Qingyuan County: a road used to transport mushrooms; (e) Huangyan District: museum of the source of citrus; (f) Huangyan District: Research Center of the seed of citrus; (g) Foshan: cultural park of Dike-Pond system; (h) Foshan: amusement facilities in the cultural park of Dike-Pond system.

Figure 11 .
Figure 11.The core logic of establishing the analytical model of regression.

Figure 11 .
Figure 11.The core logic of establishing the analytical model of regression.

Figure 12 .
Figure 12.Decompose the core logic of the analytical model of regression into variables.6.2.2.The Influence of Urban-Rural Relations of Population-Land-Industry in Different Areas during the Non-Agricultural Transformation from 2000 to 2020The longitudinal data waves of 2000, 2010 and 2020 were established in the research focusing on characteristic objects such as agricultural heritage sites, so a longitudinal analysis of time would be very important.An OSL regression model was established based on an analysis of the influence of the population urbanization rate, non-agricultural industrial ratio, land urbanization rate and areas in 2000 on the proportion of non-agricultural industries in 2020: industry2020 = urbanrate2000 + indusry2000 + land2000 + factor(region)(5)

Figure 12 .
Figure 12.Decompose the core logic of the analytical model of regression into variables.6.2.2.The Influence of Urban-Rural Relations of Population-Land-Industry in Different Areas during the Non-Agricultural Transformation from 2000 to 2020The longitudinal data waves of 2000, 2010 and 2020 were established in the research focusing on characteristic objects such as agricultural heritage sites, so a longitudinal analysis of time would be very important.An OSL regression model was established based on an analysis of the influence of the population urbanization rate, non-agricultural industrial ratio, land urbanization rate and areas in 2000 on the proportion of non-agricultural industries in 2020: industry2020 = urbanrate2000 + indusry2000 + land2000 + factor(region)(5)

Figure 13 .
Figure 13.The visual model of drivers of the proportion of non-agricultural in AHS rural areas.Figure 13.The visual model of drivers of the proportion of non-agricultural in AHS rural areas.

Figure 13 .
Figure 13.The visual model of drivers of the proportion of non-agricultural in AHS rural areas.Figure 13.The visual model of drivers of the proportion of non-agricultural in AHS rural areas.

Figure 14 .
Figure 14.Transformation mechanism of AHS rural areas for 20 years.

Figure 14 .
Figure 14.Transformation mechanism of AHS rural areas for 20 years.

Table 1 .
Data collection and processing.
6. Results 6.1.Changes in Development Elements and Corresponding Dimensions of Transformation of AHS Rural Areas 6.1.1.Land Structure: Loss of Land Elements in Agricultural Systems of Rural Areas and Concomitant Changes in the Spatial and Production Structure

Table 2 .
The growth rate of the rural population in China's AHS areas at different stages of the urban-rural relationship, 2000-2020.
Note: The standard deviation is abbreviated as S.D.

Table 3 .
Indexes of disposable income in China's AHS areas at different stages of urban-rural relationship in 2020.