1. Introduction
Urbanization is the process of urban spatial expansion whereby non-agricultural industries and populations gather in cities and towns [
1,
2]. With the recovery and growth of the global economy, urbanization has become the mainstream and increased steadily in both developed and developing countries. The urban population proportion rose from 39% in 1980 to 55% in 2018, and is as high as 82% in north America and as low as 43% in Africa in 2018 [
3,
4,
5]. High-speed urbanization and industrialization comes at the cost of more ecological resource consumption, ultimately resulting in resource degradation and environmental pollution, especially for agro-ecological environment, which has drawn great attention from countries around the world. Future earth, the United Nations’ 2030 Agenda for Sustainable Development, and the Agricultural Protection and Food Control Act emphasize the coupling coordinated development of agricultural ecosystem and economic system [
6,
7]. As a country with a long history of agriculture and a large-scale rural population, China has experienced a massive scale of urbanization since the reform and opening-up. The urbanization level in China has soared from 17.92% to 59.58% from 1978 to 2018, with an average annual growth rate of 3% [
8]. China’s urbanization releases the potential and accelerates to outpace the global level continuously, creating a miracle of fast urbanization development.
In spite of considerable progress in urbanization, China faces constraints and challenges in the dual choice of high-quality urbanization and ecological protection. Driven by the overexploitation of urban areas and the agglomeration of urban population [
9,
10], the improvement of urban radiation capacity exerts impacts on the surrounding cultivated land and agriculture production [
11]. To ensure food provision with shrinking cultivated land, the extensive utilization relying on agricultural material consumption has become the predominant mode of cultivated land utilization. Excessive input and inefficient use of high-carbon production materials increase evidently, such as fertilizers, pesticides, plastic film, and agricultural machinery [
12,
13,
14]. The economy-society benefits are at the cost of more carbon emissions directly or indirectly [
15,
16]. Since the developing concept of “innovative, coordinated, green, open, and shared” was put forward, green agriculture has become an inevitable trend [
17]. Thus, cultivated land low-carbon utilization (CLLCU) becomes an essential approach to achieving the goal. The core task of CLLCU is to reduce high-carbon agricultural material investment to promote ecological functions and reduce carbon emissions while ensuring benefits, which effectively drives green agriculture development in China.
There is a consensus that interactive coupling between urbanization and cultivated land utilization is an open, massive, and complex system [
18,
19]. Specifically, urbanization not only creates positive externalities through technological innovation and shared information, such as outstanding economic growth and increasing farming production, but also generates negative externalities in the quantity-quality-ecology of cultivated land [
9,
20]. In details, recent studies have found that cultivated land significantly decreased due to uneven patterns of urban sprawl in different geographical regions [
21,
22]. In addition to the reduction in quantity, the massive loss of high-quality cultivated land in peri-urban areas leads to a decline in the cultivated land quality and productivity. At the same time, the large-scale infrastructure construction in the process of urbanization easily results in ecological problems, such as soil degradation and soil erosion, which destroy the ecology of cultivated land. Although urbanization imposes pressure on cultivated land, its active role in promoting the benefits and efficiency of cultivated land utilization is gradually becoming identified. Urbanization drives the transition of cultivated land utilization through scale management and intensive development [
23,
24]. In turn, due to the efficient pattern of cultivated land utilization, agricultural development guarantees the coordination of the urban-rural relationship by the growing agriculture production, surplus labor, ecosystem services, and development space [
25,
26,
27]. Therefore, urbanization and cultivated land utilization have formed reciprocal, supportive, symbiotic relationships.
To investigate the interactions, the first step is to evaluate the level of urbanization and cultivated land utilization. In terms of the urbanization level, the measurement framework mainly contains two aspects, the single attribute and comprehensive dimensions. The single index usually refers to the degree of population urbanization and land urbanization [
28,
29,
30,
31]. Comprehensive urbanization includes multiple aspects, such as population, spatial, economy, society, ecology and so on [
32,
33,
34,
35]. In terms of cultivated land utilization level, cultivated land utilization efficiency is an important indicator that demonstrates the rationality of various input factors in cultivated land utilization and the realized value of cultivated land resources in agricultural production [
36,
37,
38]. Currently, there has not formed a unified standard to evaluate cultivated land utilization efficiency. Kendall initially measured the cultivated land utilization efficiency based on the output per unit area [
39,
40]. Since then, other common indicators for cultivated land utilization efficiency have appeared, for instance, yield ratio [
41], the land equivalent ratio [
42], and the area-time equivalent ratio [
43]. Notably, the complex process of cultivated land utilization can also include undesirable outputs. The measurement of input-output structure is supposed to be a more comprehensive method to evaluate the cultivated land utilization efficiency.
In general, most studies on cultivated land efficiency focus on the economic and social benefits, referring to economic contribution and food provision, which neglect the carbon sequestration and carbon emissions of cultivated land utilization synchronously. Cultivated land has dual attributes of carbon source and carbon sink [
44,
45,
46]. In other words, it potentially improves carbon sequestration and reduces carbon emissions. If the dual carbon effects caused by cultivated land utilization are not taken into account, the evaluation of cultivated land utilization efficiency will inevitably lead to a biased reflection of the actual situation. Therefore, this study aimed to develop an overall framework to analyze the evolution trend and coordination development of new-type urbanization and CLLCU. First, this study analyzed the theoretical mechanism of coupling coordination development between new-type urbanization and CLLCU. The comprehensive index system was constructed to evaluate the new-type urbanization and CLLCU. Second, the evolution trend of new-type urbanization and CLLCU were demonstrated. Finally, taking the Yangtze River Delta (YRD) as an example, we identified the coupling coordination relationship between new-type urbanization and CLLCU between 2000 and 2018.
Compared with the previous research, this study has two main innovations and contributions: (1) Method innovation. The study constructed an overall index system of cultivated land low-carbon utilization efficiency (CLLCUE), taking both carbon sequestration and carbon emissions into consideration. In addition, the Super-SBM model was employed to calculate utilization efficiency with undesirable outputs. The final results not only reflected the negative effect scientifically, but also distinguished multiple valid units adequately. (2) Perspective innovation. The study provided the theoretical mechanism of coupling coordination development between new-type urbanization and CLLCU. Based on the comprehensive evaluation of new-type urbanization and CLLCU, the dynamic evolution trend of new-type urbanization and CLLCU was described. And the coupling coordination development and relative development of new-type urbanization and CLLCU were analyzed.
The paper is structured as follows.
Section 2 constructs the theoretical mechanism of coupling coordination development between new-type urbanization and CLLCU.
Section 3 introduces the methodology and the data source.
Section 4 describes the spatio-temporal evolution trend of new-type urbanization and CLLCUE, which analyzes the coupling coordination degree and relative development degree of new-type urbanization and CLLCUE.
Section 5 includes a discussion of the relationship between new-type urbanization and CLLCU, similarities and differences compared with previous studies, and limitations of this paper.
Section 6 draws main conclusions and provides policy implications.
5. Discussion
New-type urbanization and CLLCU are important practices to achieve high-quality economy-society-ecology development. In support of coordinated and sustainable development, it’s meaningful to explore the relationship between new-type urbanization and CLLCU. The findings of this study showed that the relationship between new-type urbanization and CLLCU follows a dynamic process, rather than being static. The coupling coordinated degree of new-type urbanization and CLLCU evolved towards higher levels in the YRD. The results of the present study are in line with the findings of previous studies [
5,
82]. This paper constructed the comprehensive evaluation systems of the new-type urbanization and CLLCU according to the principles of comprehensiveness, scientificity, and typicality. The new-type urbanization was evaluated from the perspective of demographic urbanization, spatial urbanization, economic urbanization, social urbanization, and ecological urbanization. Different from traditional urbanization measurement in the previous study, this paper took the economy-society-ecology effect of urbanization into consideration, reflecting the connotation of new-type urbanization. Additionally, CLLCU was evaluated exhaustively by taking carbon sequestration and carbon emission as a desirable output and undesirable output of cultivated land utilization, respectively. The objective evaluation of the new-type urbanization and CLLCU provides the scientific basis for the coupling coordination analysis of new-type urbanization and CLLCU.
The continuous improvement of the coordinated development level of new-type urbanization and CLLCU indicates that new-type urbanization and CLLCU form positive interactions. With the development of new-type urbanization, agricultural scale management and intensive utilization can be promoted by large capital investment, complete infrastructure, and advanced technology, which contributes to the improvement of CLLCUE [
57,
58]. Taking Jiangsu Province as an example, new-type urbanization not only promotes the rapid flow of important production factors such as capital and technology, but also promotes the application of green production methods, which have a positive effect on the transition and upgrade of cultivated land utilization. Under the premise of ensuring a stable food supply, most cities attach importance to the protection of cultivated land and their ecosystems, and advocate the coordination of economy-society-ecology benefits, thereby enhancing the development of sustainable agriculture to a great extent. Meanwhile, the transfer of rural surplus labor drives urban-rural land use transition and the improvement of urban public infrastructure, which has a feedback effect on the new-type urbanization [
83]. For example, the cultivated land utilization has gradually shifted towards a green and low-carbon mode in cities with a high new-type urbanization level, such as Shanghai, Nanjing, and Hangzhou. Cultivated land with economy-society-ecology functions ensures the development of new-type urbanization, thereby promoting the co-evolution of new-type urbanization and CLLCU.
Although most cities have been in a state of high coordination between new-type urbanization and CLLCU, the CLLCU of each city lags behind new-type urbanization. The rapid advancement of new-type urbanization and the andante promotion of CLLCU make it difficult to develop simultaneously. Though the new-type urbanization emphasizes green and low-carbon development, it is still an important carrier of industrialization and population migration. The unavoidable negative problems such as land resource waste and “out-of-control” urban sprawl will exert pressure on cultivated land utilization. The urban expansion occupies a large amount of high-quality cultivated land in the suburbs, resulting in a decline in the quality and productivity of cultivated land resources [
84]. Cultivated land loss induces excessive and inefficient utilization of high-carbon production materials, which leads to massive carbon emissions. Moreover, although the cultivated land protection policy is a strict and powerful institutional guarantee system composed of specific laws and regulations, it’s unable to solve a series of problems in cultivated land utilization [
20]. The phenomenon, for instance, occupying the superior to make up for the inferior and occupying paddy fields to make up for the dryland not only leads to the decline in the quality and the increase in utilization intensity of cultivated land but also results in the damage to the cultivated land ecosystem and its carbon sequestration capacity. In conclusion, since the rapid development of new-type urbanization exerts the pressure on the cultivated land resources, the cultivated land utilization still relies on high-intensity agricultural material inputs to ensure its productivity so that the spread of CLLCU lags. Therefore, in the process of social and economic transition, the new-type urbanization should not only maintain the speed of development but also focus on improving the quality and efficiency of development. In particular, it is necessary to further alleviate conflicts among important subsystems such as construction land and cultivated land, urban and rural areas, and prevent the continuous escalation of unbalanced and uncoordinated problems accumulated in the development. The cultivated land utilization also needs to be actively combined with the concept of green and low-carbon. Based on cultivated land protection, the balance between improving cultivated land productivity and reducing carbon emissions could strengthen the promotion of sustainable cultivated land utilization.
This study sheds light on the relationship between new-type urbanization and cultivated land utilization, and provides a scientific basis for promoting the high-quality development of new-type urbanization and sustainable utilization of cultivated land. However, there are certain inadequacies. Firstly, due to the availability of data, our research area is from the perspective of cities, which leads to a relatively rough estimation of regional heterogeneity of the coupling coordinated development. Secondly, the driving factors of the coupling coordinated relationship between new-type urbanization and CLLCU were not addressed in the present study. However, the interaction between new-type urbanization and CLLCUE has heterogeneous features and is droved by multiple factors. Thus, in order to provide the scientific reference for differentiated policy-making, it’s necessary to conduct an in-depth exploration of the relationship between new-type urbanization and CLLCUE from a more detailed spatial scale and detect its driving factors comprehensively in future study.
6. Conclusions and Policy Implications
6.1. Conclusions
This paper constructed systematic evaluation models for new-type urbanization and CLLCU based on the concept of new-type urbanization and CLLCU. Taking the YRD as the typical research area, the evolution of new-type urbanization and CLLCU was analyzed from the spatial and temporal scales. Furthermore, the CCDM and RDDM were applied to reflect the coordinated and relative development of new-type urbanization and CLLCU, which has strong theoretical guiding significance for the realization of high-quality economy-society development and sustainable agricultural development.
Firstly, the new-type urbanization level of cities in the YRD increased, showing a spatial pattern of “single-core, north-south symmetry”. The YRD formed a radiate development model of “growth pole-advantage area-overall region”, and took full advantage of the scale effect. Due to differences in the geographical location conditions, and economic growth patterns, the new-type urbanization level continued to be polarized in the YRD.
Secondly, the CLLCUE of cities in the YRD increased but polarized obviously, showing a spatial pattern of “high in the north and low in the south, high in the east and low in the west”. Under the guidance of sustainable development, cultivated land utilization transformed from extensive and inefficient mode to a low-carbon and efficient state, although there were still significant differences in the CLLCUE of cities due to natural endowments, agricultural mode, development intensity, etc.
Thirdly, the coupling coordination development of cities in the YRD showed the trend of “rapid increase-stable development”. Most cities shifted from uncoordinated development to coordinated development, and the spatial pattern shifted from “high in the north and low in the south” to the regional equilibrium. It proved that the new-type urbanization drove the development of CLLCU and the CLLCU fed back to the new-type urbanization positively.
Fourthly, the relative development of new-type urbanization and CLLCU of cities in the YRD showed a “reversal” trend. In other words, the relative development state transformed from the new-type urbanization lagging behind the CLLCU to the new-type urbanization ahead of the CLLCU. None of the cities were in simultaneous development and the spatial pattern has shifted from “north-south symmetry” to regional equilibrium.
Although the new-type urbanization and CLLCU have reached a state of coordinated development, the rapid advancement of new-type urbanization and the slow development of CLLCU might hinder the sustainable utilization of cultivated land. It is necessary to further emphasize the high-quality development of new-type urbanization and the low-carbon development of cultivated land utilization.
6.2. Policy Implications
Firstly, the differentiated modes of CLLCU should be explored to realize the dual goals of efficient utilization and low-carbon emission. Under the premise of reasonable evaluation of natural endowment and development period, cities in the phase of low CLLCUE should strengthen the optimization of cultivated land to avoid the loss of cultivated land and improve the CLLCUE. Cities in a period of high CLLCUE should improve the intensity of agricultural carbon emissions reduction with multiple approaches such as scientific fertilization, innovative techniques, moderate scale management, and pollution detection. At the same time, it is necessary to establish relevant laws and regulations to improve the supportive system and compensation mechanism to ensure the promotion of CLLCU successfully.
Secondly, the quality and efficiency of new-type urbanization need to be promoted in the YRD. On one hand, cities with a higher new-type urbanization level such as Shanghai, Nanjing, and Hangzhou should continue to promote new-type urbanization steadily. These cities should focus on strictly delimiting growth boundaries, exploring the potential within the city, optimizing the urban spatial layout, and promoting the circulation of resources. As the stable growth pole of the YRD, these cities should not only improve their comprehensive competitiveness and form the low-carbon development mode but also drive the development of surrounding cities. On the other hand, cities with a lower new-type urbanization level, for example Taizhou, Huzhou, and Zhoushan, should learn from the experience of cities with high-levels of new-type urbanization to make up for shortcomings of urbanization construction. These cities must solve the basic problems of new-type urbanization such as spatial layout, public service, and environmental governance. Specifically, these cities should effectively control the city scale and promote intensive space utilization. At the same time, they should actively expand the sharing scope of public services and strictly control production-living pollution to improve residents’ well-being.
Finally, the coordinated development of new-type urbanization and CLLCU should be promoted comprehensively to reduce the region gap through the linkage effect. Shanghai and Jiangsu should further play a leading role in the radiating development. It’s essential to build an open and sharing development community in the YRD by promoting the integration and coordination of natural resources and social resources, especially innovative technology and information. Various resources should be allocated out of the balance between equity and efficiency, and administrative barriers should be broken down to avoid the formation of a polarized pattern due to the strengthening of the “Matthew effect”. In other words, cities with a high development level and strong radiation ability continue to use advantageous conditions to promote the new-type urbanization and CLLCU, while cities with lagging development levels are difficult to change the passive roles, and continue to lag. Therefore, cities in Zhejiang Province should actively promote the interconnection of various production factors to promote the positive interaction and coordinated development of new-type urbanization and CLLCU, especially marginal cities.