1. Introduction
Urban and rural sustainable development is one of the goals of global sustainable development [
1]. However, when China’s urbanization and industrialization are rapidly advancing, the phenomenon of rural hollowing appears. Rural hollowing, which is described as “outward expansion with inside hollowing”, is a phenomenon that is harmful to sustainable rural development in the process of urbanization and industrialization. It encompasses scenarios such as one family owning more houses, building new houses without dismantling the old one, deserting new houses [
2]. To put it simply, in the process of urbanization and industrialization, the area of rural settlements has not been accompanied by a decrease in the rural population [
3]; on the contrary, the per capita residential land in rural areas continues to increase [
4]. Rural hollowing wastes precious land, causing the loss of rural talents, funds and other resources, and destroying the rural living environment [
5]. The renovation of hollow villages is an indispensable stage to realizing the strategy of rural revitalization, and it is also the premise of sustainable rural development. Additionally, rural hollowing assessment is the premise and foundation of hollow village renovation, so rural hollowing assessment is very important.
In recent years, rural hollowing has attracted attention from demography, geography, sociology and other disciplines. The study of rural hollowing generally focuses on the macro level and looks at the problem from the macro perspective. The study of rural hollowing mainly focuses on the definition, characteristics, influencing factors, response and regularity of rural hollowing [
6], and rural settlements [
7]. Meanwhile, studies also pay attention to rural hollowing degrees from population, land and economy [
7,
8,
9,
10].
The push–pull theory is an important theory to explain rural hollowing [
2]. The higher income, non-agricultural employment, etc., in cities are regarded as centrifugal forces, and the local complex, rural social relations, etc., are regarded as centripetal forces. When the centrifugal force is greater than the centripetal force, the phenomenon of rural to urban migration will occur. After China’s reform and opening up, the household registration system began to weaken, industrialization and urbanization proceeded rapidly, and farmers were given the opportunity to leave agriculture and the countryside [
11]. At this time, the strong centrifugal force formed by higher income and non-agricultural employment opportunities in the cities is far greater than the centripetal force [
2]. Therefore, China’s rural population has begun to migrate to cities on a large scale. The loss of permanent population in rural areas is serious, and rural production and economy are seriously declining [
12]. After farmers go out to work, their income also increases, their ability to improve their living conditions is significantly improved, and the area of rural homesteads continues to expand [
5]. Moreover, because of the collective ownership system of rural land, once farmers settle down in cities, it is difficult to trade rural housing, resulting in homesteads abandonment [
5].
Just like the push–pull theory, the current theoretical mechanism of rural hollowing is more concentrated in three aspects: economy, system and policy. Some scholars have also tried to incorporate resources and environment into the formation mechanism of rural hollowing, but they have emphasized the impact of natural disasters, cultivated land resources, and surrounding open space on rural hollowing [
5,
11]. In this paper, the elevation is included in the formation mechanism of rural hollowing, trying to improve the rural hollowing mechanism.
The evaluation index system of rural hollowing degree in academics is mostly measured from land, population and economic system. In terms of the land subsystem, indicators such as the extensive utilization of homesteads, the transformation degree of homestead utilization, the relative diffusion of villages and residential land area are selected more frequently [
2,
10,
13,
14]. The hollowing of the rural population is the emphasis of the current academic research, and its main measurement indicators include the proportion of the rural resident population, the effective transfer degree of the village population, the intensive degree of the rural population, and the centrality of the rural population, etc. [
8,
14,
15,
16,
17]. In the economic subsystem, scholars often use indicators such as economic development level, farmers’ income level, and regional economic structure [
8,
18]. Some scholars use electricity consumption per household to measure hollowing out [
18,
19]. The details of the indicators are shown in
Table 1.
When evaluating the degree of rural hollowing out, most of them adopt the entropy method or the analytic hierarchy process, combined with the entropy weight method to give the index weight [
8,
16,
18,
20]. Some scholars also use the BP neural network model to determine the weight [
9]. Longhualou et al. took the lead in measuring the degree of rural hollowing by using four indicators of homestead vacancy rate, abandonment rate, percentage of permanent residents, and village population density [
17]. These indicators are simple, clear and representative, but the data on the vacancy rate and abandonment rate of homesteads need to be acquired through field research, which limits the expansion of the research area and the study of long-term trends.
Yang Ren et al. used seven indicators to measure the degree of rural hollowing from the three subsystems of land, population and economy, including the transformation degree of homestead utilization, the relative diffusion of villages, the extensive utilization of homestead, the centrality of rural population, the intensive degree of rural population, effective transfer degree of the village population, the level of economic development, the regional economic structure and the income level of farmers [
9]. This evaluation index system has been widely recognized and solved the difficulty of obtaining data excluding extensive utilization of homestead, but it has also been questioned, mainly focusing on the two indicators of the centrality of the rural population and the degree of effective transfer of village population [
21].
Table 1.
Representative indicators of rural hollowing.
Table 1.
Representative indicators of rural hollowing.
Subsystem | Indicators | Reference |
---|
Land | Homestead vacancy rate, homestead abandonment rate | [17] |
Land | residential land area, residential area | [2] |
Land | The transformation degree of homestead utilization, the relative diffusion of villages, the extensive utilization of homestead | [9] |
Land | Vacant residential land area, abandoned residential land area | [13] |
Land | Relative size of homestead per capita, homestead area ratio, relative rate of change in village size | [16] |
Land | The total amount of homestead, number of abandoned and vacant homesteads | [22] |
Land | Extensive utilization of homestead, hollowing trend | [20] |
Land | Per capita residential land area, the transformation degree of homestead utilization, relative size per capita, road density | [19] |
Land | Land reclamation rate, intensity of settlements, food production per unit area, marginalization rate of cultivated land, fixed asset investment, power of agricultural machinery | [8] |
Land | Rural settlement area per capita | [14] |
Land | Village relative spread, extensive utilization of homestead, the transformation degree of homestead utilization | [23] |
Population | The proportion of rural resident population, village population density | [17] |
Population | agricultural labor force structure | [15] |
Population | Rural population centrality, the intensive degree of rural population, effective transfer degree of village population | [9] |
Population | Rural land population density, rural population size, the relative proportion of non-agricultural population | [16] |
Population | Rural population centrality, Farmer’s effective transfer degree, population change rate, village population concentration | [7] |
Population | Percentage of rural permanent population, share of non-agricultural population, rural population structure | [19] |
Population | Urbanization rate, the proportion of rural employees, rural population settlement rate, population agglomeration | [8] |
Population | Effective transfer degree of village population, rural population centrality, rural population agglomeration | [23] |
Economy | The level of economic development, per capita net income of farmers | [15] |
Economy | The level of economic development, regional economic structure, farmer’s income level | [13] |
Economy | Regional economic structure, urban–rural income ratio | [20] |
Economy | Electricity consumption per household | [19] |
Economy | The level of economic development, regional economic structure, farmer’s income level | [8] |
The subsequent improvement of the rural hollowing index system is based on them. Many new indicators make the rural hollowing evaluation system more reasonable, such as the relative size of per capita homestead [
16], the ratio of urban and rural income [
20], and the electricity consumption per household [
19].
In this research, the index of electricity consumption per household is improved, hoping to improve the accuracy of the evaluation index system. Zhang Xiupeng et al. used electricity consumption per household to measure the degree of rural hollowing. They believe that the higher the per household electricity consumption of the entire county, the longer the average person spends at home, and the lower the rural hollowing [
19]. This research uses rural per capita electricity consumption instead. The higher the rural per capita electricity consumption, the longer the average person spends at home in rural areas, and the lower the degree of rural hollowing. Using rural per capita electricity consumption to measure rural hollowing is significantly more in line with the connotation and improves its accuracy.
China has launched the ‘increasing vs. decreasing balance’ land-use policy in order to optimize rural land use. In 2006, Sichuan Province was included in the pilot areas for the ‘increasing vs. decreasing balance’ land-use policy. It has achieved remarkable results in revitalizing and utilizing residential land. However, with the continuous advancement of the urbanization process, the problems of multiple houses in one family and vacant houses in rural areas are more prominent due to reasons such as migrant work, settlement, and inheritance. Residential lot area is getting larger and larger, and the per capita residential land area in the province’s rural areas far exceeds the specified area [
24]. Moreover, Sichuan Province is a large province of migrant workers [
25]. Therefore, Sichuan Province is a typical region for the study of rural hollowing. This research can provide a scientific basis for the renovation of hollow villages in the Sichuan Province.
As mentioned above, this paper explores the formation mechanism of rural hollowing, especially adding altitude to it, and hopes to improve the forming mechanism of rural hollowing. Additionally, improved the evaluation index of rural hollowing, hoping to improve the evaluation method of rural hollowing. On this basis, urbanization, industrialization, arable land area, and average elevation were selected for correlation analysis, and the impact mechanism of rural hollowing was initially discussed empirically. The specific objectives of this study are as follows:
The overall change pattern of rural hollowing in Sichuan in 2010, 2015 and 2018.
The change characteristics of rural hollowing in the study area during the same study period.
The correlation of resources and environment, urbanization and industrialization on rural hollowing.
2. Theoretical Analyses
As shown in
Figure 1, farmers have been pursuing a better life, and improving their living conditions is one of their pursuits. However, due to the low efficiency of traditional agriculture, the ability to improve housing is very poor.
The huge gap between urban and rural areas and poor natural conditions makes farmers want to leave the countryside and traditional agriculture. Industrialization and urbanization have given farmers the opportunity that they can go out to work and settle in cities.
The migration of farmers to work and settle in cities leads to population loss, which directly leads to population hollowing. In addition, the loss of population leads to the reduction of professional farmers, which in turn leads to economy hollowing.
After farmers go out to work, their income increases, their ability to improve their housing is improved, the area of rural homesteads expands, and farmers go out to work for a long time, resulting in long-term idle houses. After farmers settled in cities, due to the collective ownership of rural land, it was difficult to trade rural houses, which led to the abandonment of rural houses. These behaviors have led to land hollowing.
Therefore, this paper selects four indicators of average elevation, per capita arable land, urbanization rate and industrial output value, and uses the Pearson correlation test to preliminarily explore the relevant factors of rural hollowing from three aspects: resource and environmental endowment, urbanization and industrialization.
5. Discussion
Carrying out the renovation of hollow villages is an important process to realize rural revitalization, and the calculation and evaluation of the degree of rural hollowing is the basis and premise of the renovation of hollow villages. The results of this research can provide a scientific basis for the renovation of hollow villages and rural revitalization planning in Sichuan Province. We believe that the current high level of rural hollowing is mainly concentrated in the Chengdu Plain and its surrounding areas, so the improvement of rural hollowing should focus on these areas; in the northwestern Sichuan region, we should pay attention to the improvement of land hollowing, and continue to promote rural land improvement work; in the eastern Sichuan area, we should focus on economy hollowing and population hollowing, promote the development of rural industries, and prevent the loss of rural population.
Compared with a previous study [
14], the distribution trend of rural hollowing degree in Sichuan Province is consistent, which is high in the east and low in the west. However, the higher degree of rural hollowing in this paper is more concentrated in the Chengdu Plain Economic Zone. In their study, the higher rural hollowing is more concentrated in the eastern Sichuan area. From the theoretical analysis, under the condition of similar resource and environmental endowments, the urbanization and industrialization of the Chengdu Plain Economic Zone should be higher, and the rural hollowing should also be higher. The rural hollowing calculation in this paper should be more accurate. Due to the differences in the multiple indicators involved and the study sites, it is difficult to compare with the results of Zhang Xiupeng et al. [
19] to explain the increased accuracy after the improved indicators, but from a theoretical perspective, this research uses rural electricity consumption per capita instead of electricity consumption per household which improved accuracy of the assessment. For example, in 2018, the per capita living electricity consumption in Sichuan Province was 489.37 kilowatts (county-level per capita living electricity consumption data are not available); the per capita electricity consumption in Sichuan Province is 2696.23 kilowatts, which is about 5.5 times that of the per capita living electricity consumption; rural electricity consumption per capita in Sichuan Province is 339.52 kilowatts, which is about 0.7 times that of the per capita living electricity consumption (Source: Sichuan Statistical Yearbook in 2019). Whether it is judged from the value or the proportion, it is more reasonable and accurate to use rural electricity consumption per capita to measure the rural per capita home time.
In terms of relevant factors, rural hollowing is positively correlated with urbanization and negatively correlated with per capita arable land, which is consistent with previous research results [
8,
13,
14]. Urbanization in this paper refers to population urbanization. The higher the degree of urbanization, the more rural residents settle in cities, the greater the loss of rural population, and the more serious the rural population hollowing. In addition, because of the collective property rights system of rural land, the more rural population is lost, the more rural homesteads are abandoned, and the more serious the rural land hollowing. Therefore, the higher the degree of urbanization, the higher the degree of rural hollowing.
The per capita arable land resources are abundant, and the rural residents can get more remuneration from the arable land; the better the development of the primary industry, the lower the degree of the rural economy hollowing. Moreover, rural residents can get more remuneration from arable land, and the lower the willingness of rural residents to go out to work, the less rural population flows, and the lower the degree of rural population hollowing. Therefore, the richer the per capita arable land resources, the lower the degree of rural hollowing.
Rural hollowing is positively correlated with industrialization. The industrialization used in this paper is the industrialized output value. The higher the degree of industrialization, the stronger the pull of industrialization for rural residents, the more likely they are to go out to work, the more serious the loss of rural population, the fewer professional farmers, and the higher the degree of the rural population and economy hollowing. Moreover, after going out to work, the income increases, the expansion capacity of the homestead is enhanced, and the rural land hollowing is more serious. Therefore, the higher the degree of industrialization, the higher the degree of rural hollowing.
On the whole, the altitude is negatively correlated with the rural hollowing, but in the sub-regional test, it is found that the rural hollowing degree is positively correlated with the altitude in the Panxi area. We believe that transportation infrastructure and communication conditions have caused such different results. Panxi is a typical resource-based city with good local transportation and communication conditions, while other high-altitude areas in Sichuan Province have poor transportation infrastructure and communication conditions. When the altitude is higher, the transportation infrastructure and communication conditions are generally worse, the rural areas are more closed, the ability of rural residents to obtain external information and the ability to go out to work are lower, and the loss of rural population is lower; there are more professional farmers, and the lower the degree of the rural population and economy hollowing. Therefore, we believe that when the transportation infrastructure and communication conditions are poor, rural hollowing will be negatively correlated with the altitude; when the transportation infrastructure and communication conditions are good, the opposite is true.
The contribution of this paper is to improve the rural hollowing measurement index and enrich the research on the correlation between altitude and industrialization in rural hollowing. The deficiency of this paper is the evolution of rural hollowing has gone through different stages and changes in time and space, thus requiring a longer evaluation period than the one done by this paper. Due to data availability, this paper only calculated the degree of rural hollowing in 2010, 2015 and 2018. Therefore, continuous time series are needed to evaluate rural hollowing in future studies.