Spatiotemporal Differences and Classification Regulation of Urbanization Impact on Agricultural Development in Shrinking Areas: A Case Study of 15 Shrinking Cities in Three Provinces of Northeast China

CHEN Xiaohong ,LIU Haihan ,AN Yongle ,DAI Yue ,PAN Wei ,WANG Ying ,TANG We

(1.College of Geography Science,Harbin Normal University,Harbin 150025,China;2.Harbin Urban and Rural Planning & Design Institute,Harbin 150010,China)

Abstract: Studying the impact of urbanization on agricultural development in shrinking areas is important for maintaining food security and promoted agricultural development in China.Based on the measurement results of the shrinking cities in the three provinces of Northeast China,this paper selects 15 shrinking cities as the research object,and constructs a multi-dimensional index system to explore the impact of the urbanization level of the shrinking areas on the agricultural development in the region since 2007-2019,analyzes the influencing factors and their differences by using the geographically-weighted regression model and Geodetector,and proposes a targeted regulation strategy.The results show that: 1) overall,there is a negative correlation between the urbanization level and the agricultural development level in the contracted areas of the three northeastern provinces.The urbanization level in these areas has a certain negative impact on the overall level of agricultural development;2) regarding the time dimension,the impact of urbanization level on the agricultural development level in the contracted areas of the three northeastern provinces gradually increases over time;3) regarding the spatial pattern,the overall impact of shrinking urbanization levels in the three provinces of Northeast China on the agricultural development shows a significant distribution pattern of high in the east and low in the west;4) the total population and natural population growth rate at the end of the year were the main factors influencing a certain level of urbanization on agricultural development in the shrinking cities while population density and the urban fixed asset investment rate were the secondary factors;and 5) the main reasons why the level of agricultural development in different cities was affected by the level of urbanization were different.However,they can be categorized into areas of population loss and spatial construction,which can be further divided into area of population loss in the northeast,areas of negative population growth in the west,and areas of urban spatial change in the south.According to the causes of the impact,this paper adopted targeted regulation strategies and formulated relevant policies and solutions that cater to local conditions.

Keywords: urbanization;agricultural development;classification and regulation;shrinking cities;three provinces of Northeast China

1 Introduction

As a historical process of human social development,urbanization not only increases the number of towns and cities and expands their scale,but also reconstructs and transforms their functions (Wu and Sun,2017).From the late 19th to the early 20th century,developed countries in Europe and the United States led in urbanization and industrialization (Sun,2022).However,with the increasing level of urbanization and the influence of globalization,deindustrialization,suburbanization,and the transformation of economic institutions (Turok and Mykhnenko,2007;Kabisch et al.,2010;Batty,2016),urban shrinkage emerged in various countries,such as in the Ruhr region of Germany,the traditional industrial cities Manchester and Liverpool in England,the famous Rust Belt in the United States,and the surrounding areas of central cities and small towns in Japan (Rhodes and Russo,2013;Batty,2016;Sun and Wang,2021).Studies have shown that urban shrinkage is an inevitable side effect of urbanization.It poses a challenge to the traditional urban planning paradigm and development cognition centered around growth (Sun,2022).Therefore,the traditional path of urban development no longer involves just growth and expansion,but also urban shrinkage (Wu and Sun,2017).As a developing country in a phase of rapid economic growth,China suffers from urban shrinkage parallel to rapid urbanization (Yang et al.,2015).

Due to the early start and high level of urbanization in Europe and the United States,urban shrinkage was recorded first in the 1960s,while the research on the phenomenon had been conducted earlier.Therefore,urban shrinkage represents a relatively complete system,including the concept,an indicator system (Oswalt and Rieniets,2006;Wiechmann,2008;Hollander,2009;Martinez-Fernandez et al.,2016),the spatio-temporal evolution pattern (Couch et al.,2005;Oswalt,2005;Blanco et al.,2009;Mallach et al.,2017),and the influencing factors (Rust,1975;Blanco et al.,2009;Wiechmann and Pallagst,2012).It is generally recognized that urban shrinkage is an indispensable part of urban development and one of the development stages in urbanization.With the rise ofSmartShrinkagein cities and towns,the content of urban shrinkage gradually shifted to planning the response to urban shrinkage,which includes planning strategies,influencing factors,and response measures in cities and towns (Bontje,2004;Friedmann,2004;Hospers,2014;He et al.,2018).It can be said that the aim of research on urban shrinkage is to promote high-quality and high-level urbanization.In contrast to Europe and the United States,urbanization in China started late,but developed rapidly,thus presenting a special pattern of urbanization and urban shrinkage at the same time (Wu and Sun,2017).The characteristics of urban shrinkage in China are different from those in other developed countries.For example,the main research areas of urban shrinkage in China are old and highly urbanized industrial and resource-based cities (Hu et al.,2020),the causes of shrinkage are multileveled and complex when compared to those in Western countries (Wu and Sun,2017),and its time scale tends to be medium to short (He et al.,2017).The research on urban shrinkage in China was conducted in the following way.Firstly,it interpreted and collated foreign research results (Ma et al.,2016;Gao,2017;Wu and Sun,2017).Then,it explored the categories and distribution of shrinking cities (Long et al.,2015;Jiang et al.,2016;Hu et al.,2020) and adjusted the development model of urbanization relying on the in-depth study of empirical cases in individual shrinking regions (Wu et al.,2015;Zhao and Zhang,2018;Hu et al.,2020).Furthermore,the research constructed a system with urbanization characteristics appearing in China (Liu,2016).Later some research proposed theparadoxof urban shrinkage with Chinese characteristics (Yang et al.,2015) and conducted theSinicizationofurbanshrinkage(Wu and Sun,2017).Due to parallel urbanization and urban shrinkage,China’s pursuit of growth and spatial expansion of its cities is obviously not feasible.Therefore,attention should be diverted to the scientific understanding of urban shrinkage,the promotion of highquality and high-level urbanization,the clarification of the occurrence and transformation mechanism of urbanization and urban shrinkage,and the promotion of that transformation.

The urban system is gradually transformed from the rural one (Chen et al.,2009;Gan et al.,2015;Wang and Li,2016).Because the process of urbanization does not exist in isolation within cities,the level of urbanization will inevitably affect the level of agricultural development.Based on this,many scientists have conducted numerous studies on the impact of urbanization on agricultural development,mainly focusing on the economic development of agriculture (Song and Xiao,2005),rural employment (Sun and Ma,2017),and the development of agricultural industrialization (Wang et al.,2013).At the same time,they conducted in-depth research on the coordinated development of urban and rural areas (Ma and Luo,2017;Tang et al.,2017).On the one hand,the improvement of the level of urbanization represents the expansion of the influence of cities on the surrounding rural areas,which can absorb more rural surplus labor(Fan et al.,2015),accelerate the cities’ dissemination of advanced technology and culture in rural areas,improve agricultural productivity and production efficiency,and additionally enhance the level of agricultural development (Li et al.,2014).On the other hand,the improvement of the level of urbanization also has an inevitable negative impact on agricultural development.The process of urbanization,which blindly pursues economic growth (Lu et al.,2015) and mainly focuses on the expansion of land areas (Lu and Yao,2007),has had a great impact on the development of rural agriculture.Arable land occupation (Liu and Qiao,2014),environmental degradation,the hollowing out and aging of rural areas (Yang et al.,2012),as well as urban-rural development coordination (Wang et al.,2016) and rural ecological environment (Cui,2015),are very unfavorable for improving the level of agricultural development.

As a region with a high level of urbanization,the three provinces of Northeast China,namely Heilongjiang,Jilin,and Liaoning,have the most obvious urban shrinkage and are known astherustbeltofChina.The seventh census shows that the urbanization level reached 63.89% in China in 2021,while that in the three provinces of Northeast China reached 61.86% as early as 2010.According to previous studies,about 44% of prefectures in the three northeastern provinces are in the shrinking stage and show obvious population and economic losses,especially those affected by thesiphoneffectof big cities such as Harbin,Changchun,and Daqing (Sun and Wang,2021).TheKeyTasksofNew UrbanizationConstructionin2019(https://www.gov.cn/zhengce/zhengceku/2019-09/29/content_5435018.htm)andKeyTasksofNewUrbanizationConstructionand Urban-RuralIntegrationDevelopmentin2020(https://www.ndrc.gov.cn/xxgk/zcfb/tz/202004/t20200409_122 5431.html) clearly show that the northeastern region has the most severe net population outflow in China.However,the three provinces of Northeast China is not only important industrial bases,but also important grain bases and the largest strategic grain reserves in China,with Heilongjiang accounting for one-tenth of China’s grain production alone.The14thFive-YearPlanforthe ComprehensiveRevitalizationofNortheastChina(Communist Party Member,2021) proposes that Northeast China,as the main crop production area,should consolidate its status as a national food base and improve its ability to maintain food security.Based on the current level of urban development and the strategic position of food security,it is necessary to study the urbanization and agricultural development in the three provinces of Northeast China.

An overview of domestic and international research on the urbanization of shrinking areas reveals that most of previous studies on this type of geographical area have focused on the development of the towns themselves and their industrial development,on the impact of urbanization on the socio-economic development of shrinking areas,and have paid less attention to the level of agricultural development in the process of urbanization of shrinking areas.Based on measurement results of previous studies (Hu et al.,2020),taking population and economic contractions as the main measurement factors,this paper selects 15 prefecture-level cities (Suihua,Jiamusi,Qitaihe,Heihe,Jixi,Yichun,Shuangyashan,Hegang,Baishan,Songyuan,Siping,Liaoyuan,Fushun,Benxi,and Fuxin) as the research areas,and four years,2007,2011,2015,and 2019,as the time periods.This study combines urbanization and agricultural development in the three provinces of Northeast China,constructs an evaluation index system for the impact of urbanization level on the level of agricultural development,explores the development trend of agriculture in the process of urbanization in the three northeastern provinces,researches the impact of the level of urbanization on the level of agricultural development,analyzes the regional differences in the development of agriculture in the contracted cities,and puts forward the corresponding control strategies according to its problems.This paper provides certain theoretical guidance to promote the optimization of the spatial pattern of the national territory and guide the high-quality development of cities and towns and the modernization of agriculture in the three northeastern provinces.It provides a reference for further research on how to maintain the security of food production and promote agricultural modernization in the three provinces of Northeast China in the context of parallel urban shrinkage and urbanization.

2 Materials and Methodology

2.1 Study area

The three provinces of Northeast China including Heilongjiang,Jilin,and Liaoning are located in the northeastern plains of China.Their superior geographical position and natural conditions make them suitable for farming and large-scale mechanized production.As of 2020,the total grain output from the three northeastern provinces was 136.83 million t,accounting for 20.43%of the total grain output,making them the most important grain production base in China (http://www.stats.gov.cn/sj/zxfb/202302/t20230203_1900927.html).At the same time,the three provinces of Northeast China,have experienced population and economic loss,the spatial polarization phenomenon,and other urban issues due to the economic system,resource depletion,and poor environment (Tian et al.,2017).This affected the level of agricultural development.Based on previous studies,this paper selected 15 shrinking cities in the three provinces of Northeast China as the research areas (Hu et al.,2020) (Fig.1).These areas can more directly reflect the link between the level of urbanization and the level of agricultural development because of their high urbanization level combined with the needs of agricultural development and the phenomenon of urban shrinkage.Their high urbanization levels also help to investigate the impact of urbanization on agricultural development and address its problems.Overall,this study is more representative and in line with national security needs.

Fig.1 Location of 15 shrinking cities in the three provinces of Northeast China

2.2 Methodology

2.2.1 Data standardization

First,the entropy method is applied to standardize the data (Jiang et al.,2023).Second,a multiple linear regression model was used to test the correlation between urbanization and agricultural development in the three provinces of Northeast China.Finally,theGeographicallyWeightedRegressionModelandtheGeographical DetectorModelwere used to analyze the temporal and spatial patterns and influencing factors of urbanization on agricultural development in the three northeastern provinces.

2.2.2 Geographically weighted regression model

Geographically weighted regression is a method used to study the quantitative relationship between two or more variables with spatial distribution characteristics using the regression principle (Yin et al.,2018).The regression principle is used as the weight for local characteristics in the data processing.The geographically weighted regression model was used to investigate the spatial and temporal differentiation pattern of the impact of urbanization level on agricultural development level in the contraction areas of the three provinces of Northeast China (Eq.(1)).

whereβj(μi,θi) is thejth regression parameter at theith sample point,(μi,θi) represents the latitude and longitude of theith sample point;xijis the matrix of explanatory variables;andεiis the random error term.βis the higher value,meaning that the correlation between the urbanization and agricultural development level in the three provinces of Northeast China is higher,which means that the influence of urbanization on agricultural development is stronger.On the contrary,when the value ofβis smaller,the correlation is lower and the influence is weaker.

2.2.3 Geographical detector model

The geographical detector model is an effective tool for studying the mechanism behind spatial differentiation.It is widely used in studying the influencing socioeconomic and physical geographic factors (Wang and Xu,2017).The influence of the urbanization level on the agricultural development level in shrinking areas of the three northeastern provinces was analyzed using the geographic probe model in Eq.(2):

whereh=1,2,...L,Ldenotes the number of variablesY;q(Y/h) is the detection indicator of the influencing factors of urbanization in the three provinces of Northeast China;Nhis the number of detection indicators andNis the number of evaluation units;andσh2andσ2are the variance of the indicator layerhand the area-wideYvalue,respectively.Assuming the model holds,q(Y/h)takes values in the interval [0,1].q(Y/h)=0indicates that the spatial and temporal differences of the influence of urbanization on agricultural development in the three northeastern provinces are not driven by the influencing factors,while larger values ofq(Y/h) indicate that they are strongly driven by the influencing factors.

2.2.4 Data sources

This paper focuses on the spatial and temporal differences in the impact of urbanization on agricultural development in shrinking areas and their influencing factors and proposes corresponding regulation strategies for their geographical differences.At the temporal level,2007,2011,2015,and 2019 were selected as the time periods,where 2007 represents the starting year and 2019 is the target year.The research data were mainly obtained fromtheChinaStatisticalYearbook,China UrbanStatisticalYearbook,ChinaRuralStatistical Yearbook,HeilongjiangProvincialBureauofStatistics(http://tjj.hlj.gov.cn/),Jilin Provincial Bureau of Statistics (http://tjj.jl.gov.cn/),Liaoning Provincial Bureau of Statistics (http://tjj.ln.gov.cn/) for 2008,2012,2016,and 2020,and provincial and municipal statistical yearbooks and bulletins.The interpolation method of adjacent years was used to complete the individual missing data.

2.2.5 The construction of an indicator system

Combined with relevant research and existing index system,a comprehensive index system was constructed to evaluate the urbanization level in shrinking urban areas(Table 1).The urbanization level of shrinking areas in Northeast China was mainly evaluated through four as-pects,including population urbanization,economic urbanization,social urbanization,and spatial urbanization.The total population at the end of the year,the natural population growth rate,the number of college students per 10 000 people,and the proportion of employees in the secondary industry,were selected to reflect the change in the urban population structure and visually show the level of urbanization.In this paper,economic urbanization consisted of the regional GDP per capita,the proportion of the secondary industry,and public budget income,which reflect the economic level and living standards of the residents.Social urbanization: included water supply per capita,the proportion of registered unemployed in urban areas,and the number of beds in medical and health institutions per 10 000 people.These indicators reflect the level of urban infrastructure,generally regarded as one of the most important manifestations of urbanization.Lastly,spatial urbanization consisted of the proportion of the built-up area,population density,and the growth value of the urban fixed asset investment which reflect the development and utilization of urban space and evaluate the urbanization level of shrinking areas in the three northeastern provinces.

Table 1 The index system for evaluating the urbanization level

Based on the collation of relevant studies (Zhao et al.,2018),the index system for evaluating the level of agricultural development was constructed to evaluate the agricultural development level in shrinking areas of the three provinces of Northeast China (Table 2).The proportion of population in the primary industry was selected to indicate the level of agricultural employment and reflect the change in agricultural population and its proportion,which generally has a more significant impact on agriculture.The level of agricultural production is expressed through primary industry,grain output per capita and proportion of grain output per unit area.Among them,the level of agricultural development is used to indicate changes in agricultural productivity.Moreover,the total power of agricultural machinery was selected to represent the level of agricultural technology.To a certain extent,the change in the total power of agricultural machinery can present the level of mechanization in agriculture,which laterally reflects the level of the agricultural technology and the quality of the agricultural workforce.

Table 2 The index system for evaluating the agricultural development level

3 Spatial and Temporal Differences of the Impact of Urbanization on Agricultural Development in the three provinces of Northeast China

The multiple linear regression model was used to diagnose multiple cointegration of the data in the SPSS software.The test concluded that the VIF value was <10.In other words,there was no cointegration relationship between the characteristic variables.The results showed that there was a negative relationship between the level of urbanization and the level of agricultural development in the shrinking areas of the three provinces of Northeast China.To clarify the relationship and to elaborate on the influence of one on the other,this paper selected the geographically weighted regression model in the ArcGIS software.To carry out the calculation,the index of the level of agricultural development was chosen as the dependent variable,while the index of the level of urbanization was the independent variable.After testing the significance (P<0.05) of the calculation results,the results are highly significant,which has a certain value for further research.The distribution of the spatial coefficients of the geographically weighted regression of the impact of the urbanization level on the level of agricultural development in 15 shrinking cities in the three provinces of Northeast China was graded using the natural breakpoints method,which includes lower level,low level,moderate level,high level,and higher level categories (Fig.2).

Fig.2 The spatial coefficient distribution of the geographically weighted regression for the impact of urbanization on agricultural development in the three provinces of Northeast China

In terms of the temporal dimension,the influence of urbanization on agricultural development gradually increased and spread.The level of the influence of urbanization on agricultural development in the three provinces of Northeast China was low in 2007.During that time about half of the shrinking cities were at low or lower levels.In 2011,the level of the influence of urbanization on agricultural development grew.Similarly,the overall influence increased in 2015.Compared to 2011,there was no significant change in the highlevel and low-level cities.The number of higher-level cities increased significantly,reaching half of the number of the cities in the study area.However,the number of lower-level cities decreased to three,while only one city was found at the medium level.The growing influence was most significant in 2019.The number of highlevel cities occupied one-third of the number of cities in the study area.The number of higher-level cities decreased from seven to two,while that of lower-level ones increased from one to four.Only one city was at the medium level.Likewise,no significant change was found in the low-level cities.

From a spatial perspective,the impact of urbanization on agricultural development in the three provinces of Northeast China decreases from east to west,and the impact in the west is significantly higher than that in the east.The influence of urbanization on agricultural development was the most significant in Heilongjiang Province,while that in Liaoning and Jilin provinces was weaker.The influence of urbanization on agricultural development in Heilongjiang was weakening from east to west in 2007.Heihe and Suihua were most strongly influenced by the level of urbanization,and Yichun and Hegang were also strongly influenced by it.However,the level of urbanization had a medium level of influence on agricultural development in Jiamusi,Shuangyashan,Qitaihe,and Jixi.In Jilin and Liaoning,the influence of urbanization on agricultural development was the weakest,except for Songyuan City,although it was still weakly influenced.Although urbanization affected agricultural development in Heilongjiang Province in 2011,it showed signs of weakening from east to west.Yichun,Hegang,Jiamusi,and Shuangyashan were strongly influenced by urbanization,so much so that the influence of urbanization on agricultural development increased in Jiamusi and Shuangyashan.Suihua,Qitaihe,and Jixi were moderately influenced.In particular,Suihua was the least influenced by urbanization.In contrast,Heihe continued to be the most affected city.Growing urbanization in Jilin and Liaoning provinces did not affect agricultural development as much.Liaoyuan,Baishan,Fushun,and Benxi were weakly affected,while Songyuan,Siping,and Fuxin were affected even less than the former.In 2015,the level of urbanization in Heilongjiang had a strong influence on its seven cities,except for Heihe,which was affected by urbanization the most.In contrast,urbanization in Jilin and Liaoning affected agricultural development,except for Baishan,which rose to a medium level,while the other cities did not change significantly.In 2019,more than half of the cities in Heilongjiang were strongly affected by the level of urbanization.Suihua fell to a medium level,while Qitaihe and Jixi did not change.The cities in Jilin and Liaoning did not change,except for Baishan,which fell to a lower level.

4 Influencing Factors and Categorization Regulation

4.1 Impact factors of urbanization level on agricultural development

The influence of urbanization on agricultural development is affected by many factors.To accurately identify the main influencing factors of urbanization on agricultural development in the proposed time periods,the indicators of the urbanization level in the index system were seen as factors that can identify the main factors influencing agricultural development.These are population urbanization,economic urbanization,social urbanization,and spatial urbanization.Using the geographical detector model,this paper conducted an empirical study on the influencing factors.Furthermore,it calculated the influence levels of each factor in the index system for evaluating the impact of urbanization on agricultural development in the three provinces of Northeast China (Table 3).

Table 3 The influence of the level of urbanization on the agricultural development factors in the three provinces of Northeast China

As shown in Table 3,the total population and the natural population growth rate at the end of the year were the primary factors affecting the level of urbanization on the level of agricultural development in the three northeastern provinces.According to the data of the seventh census,the three provinces of Northeast China is the region with the most serious net outflow of population in the entire country.The population size of the three northeastern provinces is 98.51 million,about 11 million less than ten years ago (Qiao,2021).Heilongjiang Province is a large agricultural area whose agricultural development was most affected by urbanization.It suffered the most severe population loss,with a decrease of about 6.46 million people,accounting for half of the total population loss.Many farmworkers either moved to other regions or to other industries,resulting in their shortage.On top of the fact that agriculture is not fully mechanized in the three provinces of Northeast China,the shortage had a further negative impact on agricultural development.At the same time,the large outflow of young workers led to a decrease in the young population.Consequently,the mortality rate increased due to the remaining aging population.This further affected the birth rate in the three northeastern provinces.In particular,a high mortality and low birth rate eventually caused a low natural population growth rate at the end of the year.Thus,the three provinces of Northeast China had a negative growth rate,which hinders the future development of their agriculture and the workforce needed for it.

Population density and the urban fixed asset investment rate were also important influencing factors.Although population loss was severe in the three provinces of Northeast China,urban construction did not slow down.While the urban population kept decreasing,the urban fixed asset investment rate increased.It can be seen that while the population in the shrinking areas continued to decline,the local urban construction area grew,resulting in low urban population density in the three northeastern provinces.On one hand,the declinein population density reduced excessive use of urban space and led to its partial abandonment,thus affecting the level and quality of urbanization.This decline also had an impact on the flow of rural population.The movement of people from rural to urban areas is more frequent,which ultimately improves the agricultural development.On the other hand,the increase in the urban fixed asset ratio reflects a certain extent the increase in urban construction area and is accompanied by encroachment on agricultural land.The conversion of agricultural land into urban land is an inevitable process in urbanization which reduces the space for agricultural development.Constructing urban spaces on agricultural land greatly hinders the development of agriculture.

4.2 Regional differences in the main factors affecting agricultural development of urbanization level

As can be seen from Fig.3,the total population at the end of the year had a more significant impact on the level of agricultural development in the shrinking cities,mainly in Shuangyashan,Jiamusi,Qitaihe,and Jixi in Heilongjiang Province.These four cities were found to be more dependent on agriculture than other cities,with the highest proportion of the output value of the primary industry reaching 46.95% in Jiamusi,far exceeding the output value of its secondary industry,which is its major industry.Therefore,its agricultural development level was more sensitive to population loss.The natural population growth rate has a more significant impact on the shrinking cities in Jilin and Liaoning provinces,especially in Baishan,Fushun,and Benxi.The natural population growth rate of these three cities was negative and their population growth rates ranked the lowest of the 15 study areas.Due to the natural conditions of the three northeastern provinces,their agricultural production cycles were long and inefficient,while their workforce consisted mainly of middle-aged and elderly people.Their elderly workforce was decreasing due to high mortality,which was above 8‰ in the three cities.At the same time,their natality of less than 8‰ also affected the subsequent modernization of agriculture and created a wider gap in the workforce.

Fig.3 Spatial distribution of the geographical weighted regression coefficients of the total population,natural population growth rate on agricultural development level at the end of 2007,2011,2015,and 2019 in the three provinces of Northeast China

It can be seen from Fig.4 that population density and the urban fixed asset investment rate had a significant impact on the level of agricultural development in the shrinking cities in a relatively similar geographical area,with a more significant impact on Heilongjiang Province in earlier years and on Jilin Province and Liaoning Province in recent years.The population density of Heilongjiang was smaller,and more attention was paid to agricultural development.Likewise,national plans,such as the Harbin-Changchun urban agglomeration,were developed earlier with the positive impact on geographical location.In contrast,Liaoning and Jilin are closer to the economic center,so urbanization was more rapid there than in Heilongjiang.Therefore,the decline in population density and the urban fixed investment rate was more significant in Heilongjiang Province in the early stages of urbanization.Due to rapid urbanization in the three provinces of Northeast China in recent years,Liaoning and Jilin were more severely affected,mainly due to low population density and encroachment on agricultural land.More emphasis was put on industrial construction and less attention was given to agricultural development,resulting in a greater impact of urbanization on agriculture.

Fig.4 Spatial distribution of the geographical weighted regression coefficients of the population density,urban fixed asset investment rate on agricultural development level in 2007,2011,2015 and 2019 in the three provinces of Northeast China

4.3 Disaggregated strategies for regulating the impact of urbanization levels on agricultural development

The three provinces of Northeast China is the backbone of food security in China.Maintaining food security is an important mission of agricultural development in the three northeastern provinces.According to the geographical differences of the impact of urbanization on agricultural development,the cities in the shrinking areas were categorized based on the most important factors influencing the level of agricultural development in each area,i.e.,they were categorized into an area of population loss in the northeast,area of negative population growth in the south,and area of spatial change response of the cities in the west (Fig.5).

Fig.5 Urban type zoning of the shrinking areas of the three provinces of Northeast China

According to the analysis of the main influencing factors,this paper proposed the following regulation strategies (Table 4).

5 Discussion and Conclusions

5.1 Discussion

This paper studies the comprehensive impact of urbanization on agricultural development in the three provinces of Northeast China and investigates the spatial and temporal variation of the influence of urbanization on agricultural development and its influencing factors in shrinking areas of the three northeastern provinces.It has been found that improving the urbanization level can improve agricultural production,technology and employment levels,and then promote the development of agriculture.However,at the same time,the urbanization level may be affected by the phenomena of urban shrinkage,such as the reduction of population density in the context of improving the level of agricultural development (Fig.6).The main aim of the paper was to provide a theoretical basis for improving agricultural development and modernization and to enrich research on urbanization.The existing research results usually discuss the level of urbanization or agricultural development separately,and there are few studies on the mechanism of their interaction.

Fig.6 The impact mechanism of urbanization level on agricultural development level in shrinking areas of the three provinces of Northeast China

It found that the influence of urbanization on agricultural development gradually increased and had a negative correlation,which reflects the relationship between urbanization and agricultural development in shrinking areas to some extent.The influencing factors mainly include aspects of population and spatial urbanization.In particular,the northeastern cities were affected by labor shortage brought by population loss and low mechanization,while the southern ones were affected by negative population growth which led to an insufficient number of people in the agricultural workforce reserve.Although the western cities had a relatively high economic development level,experienced rapid urban expansion,and put more emphasis on industrial construction,they did not devote attention to developing agriculture,which led to encroaching on agricultural space.

Previous studies on urbanization in shrinking areas have focused on urban areas and the mechanism behind urban shrinkage,ignoring the impact of urbanization on agricultural development in the context of urban shrinkage.The research on the level of agricultural development is limited to the development of agriculture itself.Thus,there is a lack of research that links the level of agricultural development to urbanization under the background of urban shrinkage.The study area in this paper only includes prefecture-level cities,not ones on the county or even the township level.To highlight the importance of food production bases in the three provinces of Northeast China,the agricultural production indicators were mainly focused on food production,with more emphasis on food crops,but neglected other agriculturerelated industries.Therefore,the limitation of this paper lies in the lack of evaluation indicators for agricultural ecology and output,i.e.,it fails to evaluate the level of agricultural development in all aspects.This study mainly chooses the issuance of relevant policies as a time node for phased research,which should further improve the universality of the index system and research methods compared to a large sample size of panel data.In the future,a more refined definition and division of shrinking areas,a comprehensive and multi-level evaluation of agricultural development,and a more in-depth investigation of the relationship between urbanization and agricultural development can assist the research on agricultural development in the urbanization process in the three northeastern provinces and in shrinking cities across China.

China’s agricultural development is different from other countries.Agriculture has always been a top priority in the Chinese national development strategy,especially in the three provinces of Northeast China,which are important food production bases and are responsible for maintaining food security.How to improve agricultural development and modernize agriculture in the context of parallel urban shrinkage and urbanization is an important issue in urban construction,agricultural development,urban-rural integration,and overall revitalization of the countryside,not just in the northeastern provinces,but the whole country.Urban shrinkage is a phenomenon that should not be avoided in the future Urban population loss and economic decline should be addressed so that urban shrinkage creates an opportunity for agricultural mechanization and modernization in the process of agricultural development.The rise of modernized agriculture represents a new wave of industrial revitalization.This revitalization can become an important factor in the implementation of revitalization strategies in the three northeastern provinces and a new means of urban development and construction of cities in shrinking areas in the entire country.However,a question worthy of consideration is whether urban contraction slows down the urbanization process and negatively affects the comprehensive revitalization of the countryside,which can in turn affect the implementation of major strategies such as urban-rural integration,and whether it affects the security of food production and hinders agricultural development.Therefore,more attention should be devoted to the relationship between urbanization and agricultural development in shrinking areas.Likewise,a better feedback mechanism should be established between the urbanization process and agricultural development.In the context of urban shrinkage and urbanization in China,it is imperative to find a way to deal with the agricultural development of shrinking areas in the process of urbanization.

5.2 Conclusions

The three provinces of Northeast China is major grainproducing regions with high levels of urbanization and a good base for agricultural development.However,due to a southward economic shift,institutional reform,and unfavorable climate conditions,urbanized cities in the three northeastern provinces have experienced urban shrinkage,which is evident in their population and economic losses that had an impact on agricultural development.This paper found a significant negative correlation between the level of urbanization and the level of agricultural development in the shrinking areas of the three northeastern provinces.The overall impact of urbanization on the level of agricultural development is negative,and the level of agricultural development decreases with increasing urbanization.

(1) The impact of the level of urbanization on agricultural development level in the shrinking areas of the three provinces of Northeast China gradually increased over time.Urbanization in the three northeastern provinces started earlier and developed rapidly because of which some cities experienced the joint influence of urbanization and urban shrinkage.Likewise,urbanization had a certain impact on agricultural development.Population loss,a high unemployment rate,and economic recession aggravated the agricultural workforce,which is the reason they transitioned to urban areas.Thus,agricultural development was negatively affected.This phenomenon is consistent with the temporal characteristics of urbanization in the three provinces of Northeast China and reflects the development of agriculture to a certain extent.

(2) Spatially,the influence of urbanization on agricultural development gradually decreases from east to west.On one hand,urbanization in the three provinces of Northeast China was different in one and the same area,while urban shrinkage was more severe in other areas due to uneven economic development.This resulted in a stronger impact of urbanization on their agricultural development.On the other,the provinces belong to different administrative divisions,even though their natural conditions are similar.Due to their geographical location,national strategies and government policies,each province chose a development focus different from the other and paid attention to agricultural development in different ways.As a large agricultural province in a remote area,Heilongjiang’s agricultural development was more affected by urbanization.In contrast,Liaoning and Jilin are closer to the economic centers and have a higher level of economic development,so their agricultural development was less affected by urbanization.

(3) The main factors influencing the level of urbanization on the level of agricultural development include population and spatial urbanization.Population decline was the primary influencing factor.It was caused by negative population growth in the shrinking areas,which hindered agricultural development.Moreover,the quality of the urban space was also an important influencing factor.The expansion of shrinking areas and low population density prompted the decline of urban spatial quality.Consequently,this negatively affected the spatial quality of agricultural production and ultimately hindered agricultural development.

(4) The main reasons why agricultural development in different cities was affected by urbanization were different.However,they can be categorized into two major groups of population loss and the construction of urban space which can further be divided into: area of population loss in the northeast,area of negative population growth in the west,and area of change in urban space in the south.According to the causes of the impact this paper adopted different targeted control strategies and formulated relevant policies and solutions.As an important base of national food production and security,the three provinces of Northeast China need to implement better food security,adhere to smart shrinkage,improve the quality of urban space,and secure space for agricultural development.While promoting economic development and urban construction,agricultural modernization can benefit the further development of cities in other shrinking areas of the country.

Conflict of Interest

All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest or non-financial interest in the subject matter or materials discussed in this manuscript.

Author Contributions

CHEN Xiaohong: conceptualization,writing-review and editing;DAI Yue: writing-original draft preparation;WANG Ying: formal analysis and investigation;LIU Haihan: methodology;TANG Wei: figure editing;AN Yongle: supervision;PAN Wei: typography design.