Study on Land Use Changes in Changsha–Zhuzhou–Xiangtan under the Background of Cultivated Land Protection Policy

Abstract

The Changsha–Zhuzhou–Xiangtan region has experienced rapid social and economic development over the past 40 years, and cultivated land has changed dramatically. The contradiction between built and cultivated land has intensified, for which the local government has implemented a series of policies related to cultivated land protection. However, thus far, it is not clear what the substantial effects of the cultivated land protection policies are. To this end, this paper quantitatively characterizes the changes in the Changsha–Zhuzhou–Xiangtan region during the 20 years before and after the implementation of the cultivated land occupation balance policy, based on land use data from 1980, 2000, and 2020 using intensity analysis. In this paper, we examine the types of spatial land use patterns occurring in Changsha–Zhuzhou–Xiangtan since 1980 and explore the transition path of land use types in urban–rural integration. After the cultivated land protection policy, the transformation relationship between land use types and the changing trend of the cultivated land area was analyzed from the landscape scale. The influence of policy factors on the transformation of land use types was revealed. The results show that, from 1980 to 2020, the changing intensity of construction land and unused land was relatively large and was in an active state; the amount of built land in the Changsha–Zhuzhou–Xiangtan region has been growing, with a net increase of 1101 km², while the amount of cultivated land has been showing a net decrease, with a net reduction of 677 km². Moreover, the cultivated land has mainly been converted into built land, and the lost cultivated land area in Changsha–Zhuzhou–Xiangtan has not been fully compensated elsewhere in the region, indicating that the cultivated land protection policy has not been able to maintain the cultivated land area in Changsha–Zhuzhou–Xiangtan. From 2000 to 2020, cultivated land change was mainly due to exchange, which indicates that the policy has had a particular effect on the protection of cultivated land. Still, if the government wants to achieve the “balance of cultivated land occupation and compensation” goal, it must establish a complete system for the allocation of cultivated land resources. This study can provide a scientific reference for further implementing the cultivated land protection policy, which is thus of great significance for promoting the construction of the Changsha–Zhuzhou–Xiangtan region and its high-quality economic and social development.

1. Introduction

Land use and land cover, as the most prominent landscape markers of the Earth’s surface system [1], are critical vectors of the action of human activities on the Earth’s surface system, thus becoming the basis for studying global change issues, such as climate fluctuations [2], carbon cycle [3], global warming [4], climate comfort of urban human settlement environments, and soil erosion in the Earth’s surface system [5,6]. In the course of in-depth research on global change, scholars have found that land use and cover changes caused by human production and living processes are vital human factors that cause global change [7].

Scholars researching land use include simulations of land use dynamics under multiple scenarios [8], spatial and temporal heterogeneity of urban land area and PM_2.5 concentrations [9], the impacts of land use change on flood protection services among multiple beneficiaries [10], and land use change and collaborative manure shed management [11]. Since the degree and complexity of land use change in different cases are different and are affected by various factors, a meaningful way to deeply understand the state of land use and cover change is the land use change model. It can quantify the impact of land use and cover change on surface runoff and sand content [12], analyze the evolutionary patterns and driving mechanisms of the relationship between urban and rural construction land and the resident population [13], simulate land use change from 2008 to 2018, predict deforestation until 2028 [14], and participate in the development of river-water-quality management policies [15]. Scholars have explored and evaluated the impact of human activities on land use change based on qualitative and quantitative approaches, for example, the identification of priority areas for the conservation of native vegetation in the Cerrado (Brazil) under different land use change scenarios [16], trade-offs in land use functions in urban fringe areas [17], and multifunctional green spaces in areas where urbanization and horticultural landscapes conflict [18]. These studies can provide a reference for the sustainable development of land resources in integrated urban–rural development. Implementing the dynamic monitoring of land use is a prerequisite for analyzing and evaluating land use change [19]. The transfer matrix can comprehensively reflect each category’s quantitative and exchange changes. Still, most previous studies have analyzed and studied the area changes of a single period in a region. The information on land use change contained in the transfer matrix has not been studied thoroughly or sufficiently [20].

For this reason, Aldwaik et al. pioneered an analytical study through transfer matrices using a bottom-up approach at three levels: time interval, land class, and land class transition level [21]. Still, it did not explain the amount of error assumed for the non-uniform variation in intensity analysis at each level. At present, many scholars at home and abroad have used land use change intensity analysis models to quantify the process and pattern of land change over multiple time intervals within a watershed [22] to further explain and clarify the concepts in the model [23], to innovate and optimize model formulas [24], to compare the intensity of land use change at the same time interval [25,26,27], to describe the contingency tables in the intensity analysis method [28], and to evaluate the spatial and temporal distribution characteristics of ecological land [29]. The intensity of land was compared and studied from the perspective of the terrain slope [30]; all focus was on the quantitative analysis of land use change intensity. There are few studies that have combined China’s primary national conditions and its cultivated land protection policies.

Land use change is a complex process influenced by natural factors and human activities. However, land use policy is an important driver of land use change [31]. It has drawn more attention from researchers who want to understand how land policy affects how land resources are used sustainably during integrated urban–rural development. The amount and quality of cultivated land, a significant component of land resources, directly affects the populace’s life. Since the reform and opening up, people’s vastly increased desire for a better life has fueled rapid socioeconomic development, which has brought with it a number of issues, such as a decline in the quantity and quality of cultivated land, the conversion of cultivated land to “non-food” land, and the ecological degradation of cultivated land [32,33,34]. Measures to safeguard the sustainable development of Turkey’s land resources include the dynamic management of special environmental protection zones established through the national geographic information system (GIS) and the prevention of agricultural land conversion through cadastral registration [35,36]. The Communist Party of China (CPC) Central Committee has attached great importance to the protection of cultivated land and has launched a series of policies and guidelines to guide the work of cultivated land protection. For example, land use changes within nature reserves and national forest parks are strictly restricted [37,38], the amount of arable land is guaranteed by establishing a red line of 120,000 km² (1.8 billion mu) of cultivated land [39], and a basic system of farmland protection has been implemented [40]. Since the “balance of occupation and compensation” policy for cultivated land was first implemented in 1997, it has been more than 20 years. As a result, it is crucial to look into the consequences of cultivated land conservation policies before and after they were implemented.

The “Guiding Opinions on Promoting the High-Quality Development of the Central Region in the New Era” were taken into consideration at the meeting held by the Political Bureau of the CPC Central Committee on 30 March 2021. It was noted that the development of the middle reaches of the Yangtze River should be promoted, and the revitalization of the countryside should be broadly promoted. General Secretary Xi Jinping has repeatedly pointed out that it is necessary to “see the mountains, see the water, and remember nostalgia,” reflecting the great importance of rural revitalization and cultural preservation. In the context of accelerated urbanization around the world, the current urbanization rate in China has exceeded 60% [41]. Rapid urbanization has promoted economic development while threatening regional food security, ecological construction, and sustainable urban development, including the loss of bare agricultural land and the environment, the generation of housing bubbles, and the reduction in biodiversity [42,43,44]. With the continuous progress of reform and opening-up processes, the rapid and continuous socioeconomic development, and the large-scale disturbance of human activities, the impact on the surface morphology has been increasing. Changsha–Zhuzhou–Xiangtan (CZT) has undergone radical changes in its land use structure since the reform and opening up due to the influence of social and economic development and human activities, and the quantity of cultivated land has been decreasing. To ensure food security, it is necessary to maintain a certain amount of cultivated land. The intensity analysis model has yet to be used in the CZT region in the middle reaches of the Yangtze River to quantitatively analyze the implementation effect of cultivated land occupation and replenishment policies. This paper tries to reveal the change path and characteristics of cultivated land in CZT in the context of the cultivated land protection policy.

Due to the Beijing-Guangzhou railway line in the north–south direction and the Shanghai–Kunming railway line in the east–west direction meeting in the CZT, this region is an important hub connecting the west and the eastern coastal regions of China and bridging the north and south of China. It is the forerunner of constructing the national urban agglomeration among the six major provincial capitals. It is crucial to actively investigate the land use changes in urban–rural integration and development as a pilot zone for a “resource-saving and environment-friendly” society, to reference Hunan and even the national product, which is a study topic for many academics. The existing studies on land use change in the region have focused on the characteristics of regional urban expansion [45], variations in built land throughout time and space [46], analog simulations of land availability and demand for urban building [47], carbon conduction effects and temporal-spatial differences caused by land type transfer [48], the impact of urban development on ecological processes [35], and exploring spatial-temporal changes and gravity center movement of construction land [49]. However, not many studies have looked at the impact of land policy on local implementation in the development of urban–rural integration, and even fewer have looked at the intensity of land use change based on the policy of “balancing of cultivated land.” This research sought to:

(1)

Study the path of land use change in the CZT region.

(2)

Study the quantity change, exchange change, and shift change in land use types.

(3)

Explore the intensity and area of land use change.

(4)

Investigate whether arable land tends to shift to (or avoid) this land use type.

(5)

Explain whether the goal of the “balance of occupation and compensation” policy for cultivated land has been achieved.

In light of this, it is vital to discuss the pattern, course, and process of land use change before and after the adoption of the policy of “balance of cultivated land occupation”, using the temporal layer, land category layer, conversion layer, and component analysis of land change. It contributes to developing a new model for the coordinated development of cultivated land protection and regional economic growth. It also serves as a valuable reference for the continued implementation of the national policy of “balance of cultivated land occupation and compensation” in the integrated urban–rural development. Moreover, it is of great practical significance in promoting the coordinated development of urban–rural society, economy, and ecological environment, optimizing the layout of regional land use and fostering urban–rural integration, and even promoting the overall sustainable development of the region.

2. Study Area and Methodologies

2.1. Study Area

Located in the southeastern part of China, it is one of the five national metropolitan areas in China. In the central-eastern region of Hunan Province, the CZT region comprises 23 county-level administrative entities, 11 municipal districts, 4 county-level cities, and 8 counties inside Changsha, Zhuzhou, and Xiangtan. A total of 23 county-level administrative units are distributed in a zigzag pattern in the central-eastern part of Hunan Province [50], located between 112°57′30″~114°07′15″ E and 26°36′05″~28°01′07″ N [51], with a land area of 28,069 square kilometers. At the national development and reform conference on 7 December 2007, the CZT region was recognized as a national pilot region for comprehensive supporting reform to establish a resource-saving and environmentally friendly society [52]. It is the most economically developed area in Hunan Province and the “first instance of a purposeful regional economic integration experiment in China.” It is located in the lower reaches of the Xiangjiang River, with less undulating terrain and uncomplicated elevational topography. It is dominated by low hills, a plain-hilly interlaced area, and a typical subtropical monsoon climate. The population at the end of 2020 was 7.47 million [50], the share of the regional GDP of CZT cities in the province was 41.7% [53], and the land area of the study area accounted for 13.25% of the total land area of Hunan Province From Figure 1, we can see the geographical location and altitude of the study area in Hunan Province.

2.2. Data Source and Processing

The vector boundary data of Hunan and CZT come from the 1:1 million public versions of primary geographic information data of the National Basic Geographic Information Center (https://www.webmap.cn/commres.do?method=result100W (accessed on 10 August 2022)) [54]. The Landsat TM/ETM remote-sensing images of each period were used as the primary data source to produce the 1980, 2000, and 2020 land use data from the Chinese Academy of Sciences Resource and Environment Science Data Center (http://www.resdc.cn/Datalist1.aspx?FieldTyepID=1,3 (accessed on 10 August 2022)) [55]. These data were generated through human–computer interactive interpretation, and the interpretation accuracy was above 85% in all cases [56]. The classification of land use types refers to the land use classification system in the “National Land Use/Cover Data Construction Technical Program” of the Chinese Academy of Sciences. The actual situation of land types in the CZT area was combined. The land types were re-divided as shown in

Table 1. The classification system of land use in CZT [55,58].

First-Class Land Name	Figure	ID	Second-Class Land Name	ID
Cultivated		1	Paddy field	11
			Dryland	12
Forest		2	Forest land	21
			Shrubland	22
			Open forest land	23
			Another forest land	24
Grass		3	High-coverage grass	31
			Medium-coverage grassland	32
			Low-coverage grassland	33
Water		4	River and canal	41
			Lakes	42
			Reservoirs or Ponds	43
			Bottomland	46
Built		5	Urban and Townland	51
			Rural Settlements	52
			Another construction land	53
Unused		6	Marshland	64
			Bare land	65
			Bare rock	66

. Land use transfer matrices were created using ArcGIS software for two periods, 1980–2000 and 2000–2020 [57].

2.3. Research Methods

2.3.1. Components of Difference

Each period’s difference was divided into three parts, referred to as “quantity,” “exchange,” and “shift.” Seven examples are shown in Figure 2 to show the differences between a map at time t and a map at time t + 1. The map at time t is the comparison map, and the map at time t + 1 is the reference map if the application involves error assessment. Six pixels make up each map, and each of those pixels falls into one of the three categories (A, B, or C) [59].

The square contingency table for each example is shown in Figure 2, together with marginal totals. If and only if the bottom row of the marginal totals at time t + 1 equals the right column of the marginal totals at time t, the quantity difference is zero. Each case’s title indicates the quantity, exchange, and shift pixels. The first example at the top provides a comprehensive quantity difference example. The second scenario exhibits a full exchange difference when three pixels are A at t and B at t + 1 and three additional pixels are B at t and A at t + 1. The final example illustrates a complete shift difference and indicates that a shift can only occur when at least three categories are present. Because just two pixels in this third scenario are A at t and C at t + 1 and no additional pixels are C at t and A at t + 1, there is no interchange between these two categories in this situation. The remaining instances in Figure 2 display the different combinations of quantity, exchange, and shift components [59].

Quantitative difference refers to the change in land use composition caused by the different land use types in different periods, influenced by the different number of classes in each place. The period from Y_t to Y_t+1 is referred to as t, and the number of elements transferred from land class i to land class j in period t, i.e., the increase in land class j, is referred to as C_tij. The number of elements transferred from land class j to land class i in period t, i.e., the decrease in land class j, is called C_tji. The quantity difference of a particular land class i in period t is referred to as q_tj, as shown in Equation (1). The quantity difference in the study area in period t, referred to as Q_t [59], is shown in Equation (2).

$${{\displaystyle q}}_{tj}=\frac{\left|{\sum }_{i=1}^J({{\displaystyle C}}_{tj}-{{\displaystyle C}}_{tij})\right|\times 100\%}{{\sum }_{i=1}^J{\sum }_{j=1}^J{{\displaystyle C}}_{tij}}$$

(1)

$${{\displaystyle Q}}_t=\frac{{\sum }_{j=1}^J{{\displaystyle q}}_{tj}}{2}$$

(2)

Exchange difference refers to the change in land use composition caused by the uneven spatial distribution of land types in different periods. Equation (3) uses multiplication by two because the exchange in the column table is a pair of appearances, while each team in the exchange process is multiplied by the smaller value of C_tij and C_tji in the constraint, thus the need to use the minimum value function. The exchange component of category j is given in Equation (3), which is the sum of all exchanges involving category j. C_tjj is subtracted from Equation (3) because the sum of the molecules contains C_tjj. The allocation difference of a particular land class j in the time period t, referred to as a_tj, is shown by Equation (3); the allocation difference of the study area in the time period [Y_t, Y_t+1], referred to as A_t, is shown by Equation (4) [59].

$${{\displaystyle a}}_{tj}=\frac{2\min [({\sum }_{i=1}^J{{\displaystyle C}}_{tij})-{{\displaystyle C}}_{tii}, ({\sum }_{i=1}^J{{\displaystyle C}}_{tij})-{{\displaystyle C}}_{tij})]\times 100\%}{{\sum }_{i=1}^J{\sum }_{j=1}^J{{\displaystyle C}}_{tij}}$$

(3)

$${{\displaystyle A}}_t=\frac{{\sum }_{j=1}^J{{\displaystyle a}}_{tj}}{2}$$

(4)

Shift difference refers to the land use change caused by the shift of land use types from one place to another within a certain vector boundary in different time periods. Equation (5) refers the difference of the ground class j in time period from t to d_tj, showing that the shift component of class j is equal to d_tj minus the difference between the quantity component q_tj and the exchange component a_tj [42].

$${{\displaystyle S}}_{tj}={{\displaystyle d}}_{tj}-{{\displaystyle q}}_{tj}-{{\displaystyle a}}_{tj}$$

(5)

2.3.2. Land Use Intensity Analysis Model

The intensity analysis model can quantitatively represent the intensity of the transfer in and out of a land class over a certain period. The time-level changes in intensity analysis are annual average change intensity and equilibrium change intensity.

The mean annual intensity of change refers to the percentage of the area of change in the class in the study time period over the total area of the study area during the time interval [Y_t, Y_t+1] divided by the number of time intervals, referred to as S_t [60], as shown in Equation (6).

The intensity of equilibrium land use change is defined as the percentage of the area of change over the total area of the study area over all study periods divided by the entire study time interval, referred to as U [60], as shown in Equation (7).

$$St=\frac{\{{\sum }_{j=1}^J[({\sum }_{j=1}^J{{\displaystyle C}}_{tij})-{{\displaystyle C}}_{tii}]\}/\{{\sum }_{j=1}^J[({\sum }_{i=1}^J{{\displaystyle C}}_{tij})]\}}{{{\displaystyle Y}}_{t+1}-{{\displaystyle Y}}_t}\times 100\%$$

(6)

$$U=\frac{{\sum }_{t=1}^{T-1}\{{\sum }_{j=1}^J{{\displaystyle [{\sum }_{i=1}^{J}C}}_{tij}]\}/{\sum }_{j=1}^J[({\sum }_{i=1}^J{{\displaystyle C}}_{tij})]}{{{\displaystyle Y}}_T-{{\displaystyle Y}}_1}\times 100\%$$

(7)

The changes in the land class level in the intensity analysis are the average annual loss intensity and the average annual increase intensity. The annual average intensity of loss of land class i in time interval [Y_t, Y_t+1] relative to time t is the percentage of the area of land class i reduced in the period from the specific year from Y_t to Y_t+1 as a percentage of the area of land class i at the time point Y_t divided by the time interval, referred to as L_ti [60], as shown in Equation (8).

The annual average increasing intensity of land class j in the time interval [Y_t, Y_t+1] relative to time t + 1 refers to the reduction in the area of land class j during the period from the specific year from Y_t to Y_t+1 as a percentage of the area of land class I at the point in time Y_t divided by the time interval, referred to as G_tj [60], as shown in Equation (9).

$${{\displaystyle L}}_{t\mathrm{i}}=\frac{[({\sum }_{j=1}^J{{\displaystyle C}}_{tij})-{{\displaystyle C}}_{tii}]/({{\displaystyle Y}}_{t+1}-{{\displaystyle Y}}_t)}{{\sum }_{j=1}^J{{\displaystyle C}}_{tij}}\times 100\%$$

(8)

$${{\displaystyle G}}_{tj}=\frac{[({\sum }_{j=1}^J{{\displaystyle C}}_{tij})-{{\displaystyle C}}_{tjj}]/({{\displaystyle Y}}_{t+1}-{{\displaystyle Y}}_t)}{{\sum }_{i=1}^J{{\displaystyle C}}_{tij}}\times 100\%$$

(9)

There are also variations of transfer levels in the intensity analysis of transfer levels. The annual average transfer intensity of transfer i land classes to land class n in time interval [Y_t, Y_t+1] relative to time t refers to the area of land class i transferred to land class n in the period from the specific year from Y_t to Y_t+1 as a percentage of the area of land class i at the time point Y_t divided by the time interval, referred to as R_tin [60], as shown in Equation (10).

The annual average transfer intensity of all non-n land classes in time interval [Y_t, Y_t+1] for land class n transferred at time t refers to the total increase in the area of land class n in the period from the specific year from Y_t to Y_t+1 as a percentage of the sum of the area of land classes that are not land class n at the time point Y_t divided by the time interval, referred to as W_tn [60], as shown in Equation (11).

$${{\displaystyle R}}_{tin}=\frac{{{\displaystyle C}}_{tin}/({{\displaystyle Y}}_{t+1}-{{\displaystyle Y}}_t)}{{\sum }_{i=1}^J{{\displaystyle C}}_{tij}}\times 100\%$$

(10)

$${{\displaystyle W}}_{tn}=\frac{[({\sum }_{j=1}^J{{\displaystyle C}}_{tin})-{{\displaystyle C}}_{tnn}]/({{\displaystyle Y}}_{t+1}-{{\displaystyle Y}}_t)}{{\sum }_{i=1}^J{{\displaystyle [({\sum }_{i=1}^{J}C}}_{tij})-{{\displaystyle C}}_{tnj}}\times 100\%$$

(11)

3. Results

3.1. Spatial Distribution Characteristics

This can be seen in Figure 3. The built land is primarily distributed in the northern part of the CZT region, exhibiting spatial distribution characteristics with more in the north and less in the south. The arable land in the CZT region is mainly planted with rice, which needs flat terrain and abundant irrigation water to grow. The cultivated land in the CZT is not evenly distributed, mainly in flat plains, basins, and near rivers [61]. From 1980 to 2020, the expansion direction of built land in the CZT region has been gradually affected by the integration construction of CZT urban agglomeration; there has been a trend of agglomeration in the intersection area of the three cities, and the integrity has improved. The amount of cultivated land in flat areas is becoming smaller, resulting in a more fragmented distribution of cultivated land.

3.2. Analysis of the Components of Land

The change information of each category in CZT in two time periods is shown in Figure 4. The horizontal coordinate indicates the annual average percentage of different components of change in land use to the total area of the CZT area [29], and the vertical coordinate indicates different land use types. The “+” in the graph indicates a net increase in the quantity change component for that land use type, and the “−” in the graph indicates a net decrease in the quantity change component for that land use type. Figure 4a shows the change information of each category in CZT from 1980 to 2000 [23], and Figure 4b shows the period from 2000 to 2020.

The 20 years between 1980 and 2000 are the 20 years during which the “balancing of cultivated land” policy was not in place, while the 20 years between 2000 and 2020 are the 20 years following its adoption. The area of built land had a net increased of 119 km² during the 20 years before the “balancing of cultivated land” policy was put into practice. The amount of cultivated land had a greatest net decrease of up to 88 km². The area of built land had a net increase of 982 km² in the 20 years from the establishment of the policy of “balanced occupancy” of cultivated land. The amount of farmed land decreased by up to 589 km², which was the most. The resident population in the CZT region increased from 4.7 million in 1980 to 7.47 million in 2020 [23]. Humans rely on the land for their food, clothes, shelter, and transportation, and as populations have grown, so has the need for land that can be farmed. With the development of the social economy, the industrial structure changes, and the cultivated land formerly used for agricultural production is transferred to construction land. Although the increase in investment in land has improved land use intensification, and the yield per unit area of cultivated land is steadily increasing with the improvement of science and technology, the contradiction between man and land still exists, and the quality and quantity of cultivated land cannot fully meet the demand of the population growth.

As shown in Figure 4, in the land use change from 1980 to 2020, arable land and construction land experienced the largest change. From 1980 to 2020, the quantity of cultivated land consistently changed the most; from 1980 to 2000, the quantity of cultivated land changed the most; and from 2000 to 2020, the largest change in cultivated land was the exchange change. The increase in the change in cultivated land exchange reflects that the cultivated land lost from 2000 to 2020 has been supplemented in other places in the region, indicating that the policy of “balance of cultivated occupation and compensation” has achieved certain results.

3.3. Analysis of Changes in Land Category

The analysis of the change in the land class level is shown in Figure 5. The left side of the zero-scale line indicates the average annual increase in area and the average annual decrease in area for each category. The right side of the zero-scale line indicates the average annual increase in intensity and the average annual decrease in intensity for each category. The green dashed line indicates the average decrease in intensity for each category during this period. If the intensity of transfer out of this category is greater than the average transfer out intensity, the change in this category is active. In contrast, if the intensity of transfer out of this category to other categories is less than the average intensity of transfer out, it means that the change in this category is dormant.

As seen in Figure 5, the cultivated land in the CZT region increased by 429 km². It decreased by 1077 km² from 1980 to 2020, with the total increase being smaller than the decrease, showing a net decrease. The construction land increased by 1124 km² and decreased by 62 km², with the total increase being larger than the decrease, showing a net increase. On the one hand, due to the massive encroachment of cultivated land in the process of urban development [31] and the limited reserve resources available for cultivated land development, the task of “occupying one to make up for one, occupying the best to make up for the best” promptly is particularly difficult. On the other hand, the high intensity of cultivated land use results in the fragmentation of cultivated land [32]. Even with the expansion of degraded areas, the cultivated land area increased through policy protection and other means, making it difficult to compensate for the reduction in cultivated land area for various reasons [33] and resulting in a net decrease in the amount of cultivated land. If the protection of cultivated land is not increased, food security will be seriously threatened.

From 1980 to 2000, other land shifted to built land, unused land, water bodies, and grassland and avoided shifting to cultivated land and forest land. After the founding of New China, people lived and worked happily. Residents’ living standards kept improving, the number of newborns grew rapidly, and from 1980 to 2000, the population born before 1982, when family planning was not implemented, gradually grew into adults. The demand for production and living space expanded sharply, and some residents used cultivated land and forest land as home bases and factories for living and production construction. From 2000 to 2020, other land types tended to shift to unused land, built land, and water bodies and avoided shifting to forest land, cultivated land, and grassland. Most rural residents have low incomes and choose to leave their hometowns to work in the cities. The land originally used for farming is left seriously abandoned, thus becoming unused land. After entering the new century, China’s economy has developed rapidly; many foreign-funded enterprises have built factories in China, and the area of land for construction has been expanding.

3.4. Analysis of Cultivated Land Transfer Intensity

The results of the intensity of cultivated transfer out of the CZT area in the two study periods are shown in Figure 6. The average annual cultivated land area transferred to other land types is shown to the left of the zero-scale line. The average annual intensity of cultivated land transferred to other land types is shown to the right. The green dashed line in the figure indicates the average turnout intensity. If the turnout intensity of the land category is greater than the average turnout intensity, the cultivated land tends to be in that land category. On the contrary, if the turnout intensity of the cultivated land in that land category is lower than the average, the cultivated land avoids turning into that land category.

As seen in Figure 6, cultivated land tended to be transferred out to forest land, water bodies, and built land and avoids transfer to grassland and unused land from the mid-1980s to 2000s. Cultivated land from 2000 to 2020 tended to be transferred to forest land and water bodies and avoided transfer to built land, grassland, and unused land. In the process of urban–rural integration and development, the living standard of residents has improved, increasing the demand for space for living, production, and travel, which further drives the growth in demand for built land and thus leads to the occupation of cultivated land for built land in some areas [62]. As a result of the “balance of cultivated land” policy, new cultivated land needs to be built in other areas to replenish the amount of cultivated land, thus reclaiming forest land with low soil fertility and filling in water bodies as cultivated land. However, this does not achieve the goal of “occupying the best and replenishing the best” and is not conducive to food security and sustainable development of the ecological environment [63].

4. Discussion

4.1. Land Policy and Suggestion

As cultivated land is the basis of people’s livelihoods, its security is central to food security and its quantity must be ensured. Thus, China must closely adhere to the “red line” of 120,000 km² (1.8 billion mu) of cultivated land to ensure food security. With the growth in demand for built land, the contradiction between built land and cultivated land will be further highlighted; the goal of “balanced occupation” of cultivated land will be more challenging to achieve and the situation of essential farmland protection will be more difficult. If the goal of the policy is not achieved, the local food supply will exceed the demand, which will affect food security and increase the pressure on other food-producing areas. The government should establish a complete system for the allocation of cultivated land resources and balance the quality, quantity, and productivity of cultivated land for compensation after occupation [62].

In the course of social and economic development, land use types are constantly changing. Built land has encroached on a considerable amount of cultivated land, so the corresponding amount of cultivated land must be replenished within a specific boundary to achieve the policy objectives. Whether the policy objective can be achieved depends on the size of the spatial boundary of the policy. The CZT area, as a pilot area of “two types of society,” is a possible boundary of the policy. The policy’s goal will be achieved if there is a net decrease in cultivated land in one area of CZT and a net increase of at least the same amount in the other area.

China as a whole is another possible boundary for this policy. If there is a net decrease in cultivated land in one area of China and a net increase of at least the same amount in another area, then our goal of “balance of cultivated land occupation and compensation” will be achieved. The results of our study show that the CZT region experienced a net decrease in cultivated land from 1980 to 2000 and from 2000 to 2020. Therefore, CZT needs to supplement a considerable amount of cultivated land outside its scope to make up for the decrease in cultivated land in the region, which is undoubtedly a burden to other regions and is not conducive to achieving shared prosperity.

Turkey adopted the cadastral system for the protection of cultivated land and, at the same time, implemented the dynamic monitoring of land use through GIS [33,34]. China also has its own cadastral system, and the law stipulates that land ownership belongs to the state or collective ownership. The government administers them for rural homestead sites and urban residential areas by issuing real estate registration certificates. To protect cultivated land, Turkey also uses the method of reasonable confiscation without requirement of a zoning plan [64]. China sets up optimized development zones, key development zones, restricted development zones, and forbidden development zones according to the level of environmental carrying capacity, whether it is suitable for large-scale economic and population agglomeration, and whether it is related to national ecological security [65].

Numerous cultivated lands have become heavily contaminated by heavy metals throughout social and economic growth, and it is vital to remediate these cultivated lands to support the region’s green development [66]. The CZT region should follow the law of spatial and temporal evolution of land use, reduce the interference of land use change on the hydrological cycle and other ecosystems [67], enhance its regional development grade, and expand its influence in the central region and even the whole country according to the relevant requirements of ecological civilization construction. This expansion can be achieved while improving the level of land conservation and intensification, accelerating the excavation of sites with potential development sites, and promoting the organic renewal of land resource use. It should also develop scientific land use planning and actively explore a networked spatial layout model, combining concentration and clustering to promote high-quality regional economic growth [52]. It is also necessary to coordinate the country’s three major strategies of land development and protection, namely cultivated land protection, social and economic development, and ecological protection [68]. Additional strategies include rational and focused planning of the national space through zoning plans [64,69] and improving the value of ecosystem services of cultivated land [70].

4.2. Comparison with Other Studies

Our study’s findings align with prior findings on changes in land usage in the CZT region. According to Zhu, there are four stages to the rise of constructed land in the CZT region: moderate growth (1990–1995; fast growth (from 1995 to 2000), explosive growth (from 2000 to 2015), and a declining growth rate (from 2015 to 2019) [71]. Li discovered that between 1995 and 2014, the amount of constructed land in the CZT region increased [49]. These changes happened in the context of national economic development and industrial production. However, the state hopes that the CZT region can realize sustainable land use that is “resource-saving” and “environment-friendly” [46]. In order to safeguard the amount and quality of farmed land, it has implemented the policy of “balance of land occupancy and compensation”. However, the findings of our study indicate that the cultivated land in the CZT region has been declining and has not yet attained the policy’s aim.

4.3. Uncertainty and Future Research Direction

The land use data used in this study are 30 m, which may deviate from the real land use situation. For example, boundary areas of pixels and areas smaller than one pixel may be classified as the wrong land use category. Secondly, the time points selected for this study are 1980, 2000, and 2020, which is a long time span. Since the study shows the overall land use changes in 20 years, it does not show the land use changes in one year and the specific effects of the implementation of the policy of “balance of cultivated land occupation and compensation”. Last but not least, since this study is about land use changes within the CZT region, it does not take into account the differences between urban and rural areas. In future studies, the problem of the long time span should be solved by showing the land changes over five or ten years, so that the government can modify the policy implementation measures according to the specific implementation effect of the policy of “balance of cultivated land occupation and compensation”. A comparative analysis of the intensity of urban and rural land use change should also be conducted.

5. Conclusions

In this paper, three change components were calculated and the intensity of land use change analysis was conducted to reveal the change patterns of six land types in the CZT region over two time intervals. The aim is to explain the policy results of maintaining cultivated land area by understanding land change. The results show that (1) land use change accelerated from 1980 to 2000 and from 2000 to 2020. The net decrease in cultivated land and forest was the largest, with a net decrease of 677 km² in cultivated land and a net decrease of 465 km² in forest land, while the net increase in built land was the largest in both time periods, with a total increase of 1101 km². This confirms that the policy is focused on socioeconomic development issues that urgently need to be addressed. (2) Since the CZT region has experienced the conversion of cultivated land to other land types in some of the areas affected by various aspects such as economic construction, the compensation for cultivated land is somewhat different. This is because the land types in other parts of the region were converted into cultivated land at the same time due to the policy of cultivated land occupancy balance. (3) There has been a loss of cultivated land area and a continuous expansion of floor space. If the policy is to succeed in achieving its goal of increasing cultivated land area quantity, the increase in the cultivated land area must be at least as significant as the loss of cultivated land area within the policy boundary. (4) The CZT region experienced a loss of cultivated land area in some places and increased cultivated land area in other places simultaneously. The results showed that the cultivated land area was compensated to some extent. There was a net decrease in cultivated land in the CZT region, so the cultivated land protection policy did not maintain the cultivated land area in the CZT region. If the cultivated land area is to be maintained at the national level, then we must rely on areas outside of CZT to compensate for the cultivated land already lost in CZT.

As the world’s largest developing country, China has attracted all countries’ attention for balancing social and economic development with the protection of cultivated land during urbanization [72]. However, China has a large population and a severe shortage of cultivated land per capita. In addition, to develop the economy, it has to occupy a part of cultivated land to build factories, office areas, and residences. These are needed to develop the secondary and tertiary industries to alleviate the contradiction between built and cultivated land and in order to avoid excessive occupation of cultivated land by built land, which causes food security problems. China put forward the “balance of occupation and compensation” policy for cultivated land protection. According to our research results, the policy of “balance of cultivated land occupation and compensation” played a specific effect in the CZT area. However, it failed to ultimately achieve the goal of the policy. China has attracted all countries’ attention as the world’s fourth “national metropolitan area” and the largest developing country.