Evolution and Coordination of Cultivated Land Multifunctionality in Poyang Lake Ecological Economic Zone

Abstract

This study had three objectives: (1) to consolidate poverty alleviation achievements and connect them with the current rural vitalization strategy; (2) to inaugurate agricultural modernization development in rural areas of the Poyang Lake Ecological Economic Zone, an important grain production area in China, during the Fourteenth Five-Year Plan in China (2021–2025); and (3) to assess the ecological function area and economic development highland in Jiangxi Province. This study aimed to examine cultivated land multifunctionality (economic, social, and ecological functions) and explore its evolution and coordination in the context of increasingly serious contradiction between man and land in China. This study established an index system based on a mechanical model to evaluate cultivated land multifunctionality, the spatiotemporal pattern of multifunctionally cultivated land, and the coordination among sub-functions in different periods. Its results were as follows: (1) the cultivated land’s multifunctional value generally increased from 2016 to 2020, with spatial characteristics of highland surrounding a lake; (2) the cultivated land functions’ coordination values were generally better in 2020 than in 2016, showing a generally positive development trend; (3) changes in cultivated land function were concentrated in Quadrants Ⅰ, Ⅱ, and Ⅵ; and (4) the ecological function had the advantage in the study areas. Study conclusions were as follows: (1) the development of cultivated land multifunctionality has achieved notable successes through the significant benefits of an ecological economy; (2) the coordination of the cultivated land’s economic, social, and ecological functions has increased dramatically; (3) the ecological significance in the Poyang Lake Ecological Economic Zone, whose ecological economy was flourishing, was outstanding; and (4) most importantly, it supports implementing the rural vitalization strategy in the Fourteenth Five-Year Plan in China.

1. Introduction

Cultivated land is the core resource of agricultural production, providing livelihood resources and production safeguards for humans [1,2,3]. However, with the increasing scarcity of natural resources, accelerated urban–rural development has caused the spatial expansion of built-up areas, squeezing agricultural and ecological spaces and causing both Urban and Rural Problems [4]. It has also intensified competition and conflict among different functional spaces [5], reducing cultivated land resources [6]. The scarcity of cultivated land resources has become increasingly apparent [7]. At present, the scarcity of cultivated land resources has impacted cereal and economic crop production [8,9], grain security [10,11], employment [12], and ecological function [13]. In addition, cultivated land function has been continually evolving into systematic multifunctionality [14]. Therefore, the traditional single-grain production goal of cultivated land resource conservation should be transformed into diversified functional goals under the strategy for rural revitalization in China [15,16]. In addition, exploring the problem of cultivated land resource conservation in the context of cultivated land multifunctionality has become increasingly topical [17].

Many studies have explored cultivated land multifunctionality’s definition, methods, and contexts [18]. Regarding its definition, cultivated land multifunctionality originated in the agriculture field [19]. In addition to its crop productivity function, it also has non-productive functions, including ecological [20,21], landscape [22,23], and social [24,25]. Regarding research methods, Spearman’s rank correlation [26,27], index pulsing [28], coupled coordination degree [29,30], and full permutation polygon synthetic indicator [31,32] methods have mainly been used. Studies have focused on cultivated land multifunctionality’s regional differences [6,33], spatial evolution [34], astringency [35,36], driving factors [29,37], conflict [18,38], and collaboration recognition [39,40]. However, the coordination problems between sub-functions have rarely been studied. Moreover, there has been a lack of quantitative analysis on the coupled coordination degree of the cultivated land multifunctional system.

Cultivated land is an important resource element of the Rural Revitalization Strategy. The 2022 Central Document No.1 highlighted improving the supply capacity of grain and important agricultural products, protecting 1.8 billion mu of cultivated red line land, founding a modern rural industrial system, promoting green development of agriculture, and accelerating integrated urban and rural development in counties. These goals promote cultivated land multifunctionality by strictly maintaining resource boundaries, exploring resource endowment, and using internal and external integration to enhance the quality of resources to support economic development, social progress, and ecological protection. In addition, it facilitated economic, social, and ecological coupling coordination to drive comprehensive rural revival. Therefore, as we begin the Fourteenth Five-Year Plan in China (2021–2025) and the first year of the Rural Revitalization Strategy, a review of multifunctional cultivated land evolution and its coordination could determine the effectiveness and defects of the thirteenth Five-Year Plan in China (2016–2020) and provide a reference for revising the cultivated land control system and special planning.

Therefore, using the Poyang Lake Ecological Economic Zone, this study develops a mechanical model-based evaluation index system for cultivated land multifunctionality to calculate the coupled coordination degree of cultivated land multifunction in different periods. Recent studies have found that the mechanical model could more directly reflect the coordination degree among subsystems and the functional shortcomings of cultivated land than the traditional coupled coordination degree model. By analyzing the developing status of cultivated land multifunctionality in each county of the Poyang Lake Ecological Economic Zone and determining multifunctional coupled coordination characteristics and their constraints in each period, this study could provide a reference for the utilization and management of cultivated land multifunctionality.

2. Study Area and Data Sources

2.1. Study Area

The Poyang Lake Ecological Economic Zone is in the north of Jiangxi Province, comprising Poyang Lake at its core and the urban circle around the lake. Its prominent landform is plains. It comprises 38 counties (located in Jiujiang City, Nanchang City, Shangrao City, Jingdezhen City, Yingtan City, Fuzhou City, Yichun City, Xinyu City, and Ji’an City, as shown as Figure 1) and the entire Poyang Lake area, totaling 51,200 km². This area represents 30% of the land, 50% of the population, and 60% of the economic aggregate of Jiangxi Province. It is an important economic center, population center, and ecological “green lung” in Jiangxi Province. It is also the national ecological economy demonstration area, low-carbon economy development pioneer area, and commodity grain production base. However, rapid urbanization and population pressure have increased regional pollution and human–land conflicts, whose demand for cultivated land multifunction is representative and typical. This study illustrates this issue by eliminating the urban built-up area and selecting 30 agricultural counties as evaluation units. It could reveal the evolution and coordination of cultivated land multifunction from 2016 to 2020.

2.2. Data Sources

The evaluated data mainly comprised agricultural production, socioeconomic, and land-use data. Agricultural production and socioeconomic data were from the Jiangxi Statistical Yearbook and the statistical yearbook of each city in 2015 and 2020. Statistical bulletins and statistical yearbooks in each county provided additional data. Land-use data comprised land use/cover change data obtained by image interpretation. The images were from a series of Landsat datasets with a spatial resolution of 30 m, taken between June and August, in which the Earth’s surface could be easily identified. In addition, this study attempted to screen images with less cloud cover to reduce atmospheric correction difficulty. After image screening and downloading, data pre-processing was performed in ENVI5.0, including image band synthesis, geometric correction, radiometric calibration, atmospheric correction, de-clouding, and splicing. This study used a supervised classification scheme with 8 primary and 16 secondary categories for the study area’s landscape pattern. Primary geographic vector data came from the 1:1 million National Basic Geographic Database provided by the National Catalogue Service For Geographic Information in China.

3. Research Design

3.1. Construction of Evaluation Index System for Cultivated Land Multifunctionality

Based on literature research, this study was based on a social–economic–natural complex ecosystem [41] and divided the functions of cultivated land into economic, social, and ecological functions [20,42]. In terms of functional importance, the first function of cultivated land was to ensure grain security and the second was to carry human society. The ecological function of cultivated land supplemented the ecological landscape functions of mountains, water, forests, lakes, and grasses and provided an extension of cultivated land resource value. Therefore, cultivated land multifunctionality should be conceptually divided into three levels.

3.1.1. Carriers of Life and Economy: Economic Function of Cultivated Land

The cultivated land’s economic function was based on its production function, such as the supply of grain and economic crops and the contribution of agriculture to economic growth [43]. The cultivated land’s social function was based on its social carrying function, highlighting the supporting roles of grain security, grain safety, and employment [44]. The core of the cultivated land’s ecological function was its ecological service value, which included its ecological security guarantee and landscape value function [45]. This study established an evaluation index system for cultivated land multifunctionality based on research of the literature (Table 1).

The economic function was primarily used to measure the contribution of grain and economic crop production to economic growth. Grain and economic crop production was measured as grain and economic crop yield per unit area and cultivated land output value per mu. Agriculture’s contribution to gross domestic product (GDP) was based on the contribution of cultivated land use behavior to economic growth.

3.1.2. Support of Social Development: Social Function of Cultivated Land

Cultivated land’s social function mainly emphasized its carrying capacity for social development, which indexes such as cultivated land pressure, grain qualitative safety guarantees, and employment absorption level could measure. The cultivated land pressure index measures the cultivated land’s grain self-sufficiency, calculated as (self-sufficiency rate of grain × per capita grain demand)/(multiple crop index × [grain acreage/agricultural crop sown area] × agricultural crop sown per unit area yield × per capita actual cultivated land area). According to The National Plan for Medium and Long Term Development of National Grain Security from 2008 to 2020, per capita grain demand would be ≤395 kg, and the grain self-sufficiency rate would stabilize at >95% until 2020. The State Food and Nutrition Consultant Committee proposed that grain security targets in the contexts of a primary moderately prosperous (with significantly increased economic development, expanded socialist democracy, rapidly developing socialist culture, significantly improved living standards, and significantly increased ecological civilization), comprehensive moderately prosperous (with high-quality and high-speed economic development, better socialist democracy, interiorized socialist core value system, fast-growing social undertaking, and high level ecological civilization), and transition to affluent societies were 391, 437, and 472 kg per person, respectively. Based on the degree of urbanization and current socioeconomic development in the Poyang Lake Ecological Economic Zone, per capita grain demand was set at 437 kg per person. A cultivated land pressure index > 2 indicated that the study area had significant regional grain security risks. Therefore, indexes > 2 were assigned 0 in the data processing, while standardized processing was performed for those between 0 and 2 [46]. The grain qualitative safety guarantee was used to measure grain quality level. According to international safety standards for fertilizer application, the safety standard for fertilizer application per unit of cultivated land adopted an upper limit of 225 kg per hectare [47]. Employment absorption level was used to measure the cultivated land’s employment support for the agricultural population [48].

Table 1. Evaluation index system for cultivated land multifunctionality.

Cultivated Land Function	Index	Meaning	Character	References
Economic	Grain crop yield per unit area	Grain yield/grain crop sown area	+	Wang et al., 2023 [43]; Gao et al., 2022 [44]; Peng et al., 2016 [45]
	Cultivated land output value per mu	Agriculture production value/cultivated land area	+
	Cash crop yield per unit area	Total cash crop yield/cash crop sown area	+
	Contribution of agriculture to GDP	Added value of agriculture/GDP	+
Social	Cultivated land pressure index	(self-sufficiency grain rate × per capita grain demand)/(multiple crop index × [grain crop yield per unit area/crop sown area] × grain output per unit area sown × per capita actual cultivated land area)	-	Li et al., 2022 [47]; Huang et al., 2015 [48]; Song et al., 2012 [46]
	Grain qualitative safety guarantee	Safety standards for fertilizer application/(chemical fertilizer consumption/cultivated land area)	+
	Employment absorption level	Cultivated land area/agriculturally employed population	+
Ecological	Cultivated land ecosystem diversity index	-	+	Xu 2018 [49]; Zhu et al., 2018 [50]
	Per capita ecological carrying capacity of cultivated land	Per capita cultivated land area × cultivated land yield factor × cultivated land equivalence factor	+
	Chemical load of cultivated land	([chemical fertilizer consumption/cultivated land area] + [chemical pesticide consumption/cultivated land area])/2	-
	Landscape aesthetic function index	Comprehensive characterization of demand and dominance degrees of cultivated land in the landscape	+

Table 1. Evaluation index system for cultivated land multifunctionality.

Cultivated Land Function	Index	Meaning	Character	References
Economic	Grain crop yield per unit area	Grain yield/grain crop sown area	+	Wang et al., 2023 [43]; Gao et al., 2022 [44]; Peng et al., 2016 [45]
	Cultivated land output value per mu	Agriculture production value/cultivated land area	+
	Cash crop yield per unit area	Total cash crop yield/cash crop sown area	+
	Contribution of agriculture to GDP	Added value of agriculture/GDP	+
Social	Cultivated land pressure index	(self-sufficiency grain rate × per capita grain demand)/(multiple crop index × [grain crop yield per unit area/crop sown area] × grain output per unit area sown × per capita actual cultivated land area)	-	Li et al., 2022 [47]; Huang et al., 2015 [48]; Song et al., 2012 [46]
	Grain qualitative safety guarantee	Safety standards for fertilizer application/(chemical fertilizer consumption/cultivated land area)	+
	Employment absorption level	Cultivated land area/agriculturally employed population	+
Ecological	Cultivated land ecosystem diversity index	-	+	Xu 2018 [49]; Zhu et al., 2018 [50]
	Per capita ecological carrying capacity of cultivated land	Per capita cultivated land area × cultivated land yield factor × cultivated land equivalence factor	+
	Chemical load of cultivated land	([chemical fertilizer consumption/cultivated land area] + [chemical pesticide consumption/cultivated land area])/2	-
	Landscape aesthetic function index	Comprehensive characterization of demand and dominance degrees of cultivated land in the landscape	+

3.1.3. Extension of Ecological Value: Ecological Function of Cultivated Land

Ecological function was evaluated using several indexes: the cultivated land ecosystem diversity index, per capita ecological carrying capacity of cultivated land, chemical load of cultivated land, and landscape aesthetic function index. Cultivated land ecosystem diversity reflected cropland ecosystem diversity recovery ability. This study selected ten crop varieties: grain, cash crops, oil, cotton, bast fiber crops, sugarcane, medicinal materials, vegetables, melons, and other crops. The cultivated land ecosystem diversity index was calculated as its Shannon Index, derived from the Phytoplankton Handbook by the United Nations Educational Scientific and Cultural Organization:

S_i = − Σ¹⁰_i=1s_ilns_i, s_i = x_i/x.

(1)

In the formula, S_i is the cultivated land ecosystem diversity index for crop variety i, and s_i is its sown area (x_i) to total crop sown area (x) ratio [49]. The per capita ecological carrying capacity of cultivated land was used to evaluate the tolerance of cultivated land to carry human activity, calculated as per capita cultivated land area × cultivated land yield factor × cultivated land equivalence factor. Because the study object only involved cultivated land without other ecologically productive lands, the cultivated land equivalence factor was 1. The cultivated land yield factor was the ratio of grain yield per unit area in the study area to national grain output per unit area. The higher the per capita ecological carrying capacity of the cultivated land, the better the ecological service function of the cultivated land in the study area. The chemical load of cultivated land was used to measure the cropland’s health level. The landscape aesthetic function index was used to represent the comprehensive characterization of the demand and dominance degrees of the cultivated landscape, measured using the entropy weight method. The demand degree of the cultivated landscape was determined by measuring the nearest prefecture-level city’s total population and per capita GDP. The dominance degree of the cultivated landscape was determined by measuring the radiation range intensity, the agglomeration degree of the cultivated land patch, and the landscape diversity index. The radiation range intensity was the straight-line distance between the county’s center and the prefecture-level city’s center. Radiation distances >50 km were set to 0, and those between 0 and 50 km were reverse normalized. The agglomeration degree of the cultivated land patch was measured by the degree of aggregation for parcels (c):

c = [1 − (Σⁿ_j=1l_ij/Σⁿ_j=1l_ija_ij^0.5)] [1 − (1/A^0.5)]⁻¹ (100).

(2)

In this formula, l_ij is the circumference of patch ij, a_ij is the area of patch ij, and A is the total area. The landscape diversity index was the cropland ecosystem diversity index [51].

3.2. Weight Measurement and Function Index

3.2.1. Weight Measurement

• Data Standardization

Data standardization was used to unify each index’s units and dimensions, which should be nondimensionalized. This study used standard deviation for standardization based on the following formula:

$$M_{ij}= \mid (m_{ij}-{\overline{m}}_j)/{\delta }_j\mid .$$

(3)

In this formula, M_ij, m_ij, ${\overline{m}}_j$, and δ_j are the standardized, original, arithmetic mean, and standard deviation values of the j^th index in province i, respectively.

2.

Weight Calculation

The weight calculation formula was as follows:

V_coe = δ_j/m_j, W_j = V_coe/Σⁿ_jV_coe.

(4)

In this formula, V_coe is the coefficient of variation for each index and W_j is the weight of the jth index.

3.2.2. Functional Index Measurement

The formulas for the cultivated land multifunctional index (F) and each functional index (economic [F_eco], social [F_soc], and ecological [F_ecol]) were as follows:

F_eco = ΣW_j(eco)M_ij(eco), F_soc = ΣW_j(soc)M_ij(soc),
F_ecol = ΣW_j(ecol)M_ij(ecol), F = F_eco + F_soc + F_ecol.

(5)

3.2.3. Identification of Cultivated Land Function Coordination Degree

By controlling for other conditions, this study abstracted the coupling coordination relationships between the economic, societal, and ecological sub-functions into the vector relationship of three forces in different directions in a Cartesian coordinate system [51,52,53]. When the three forces reached the expected goals, the resultant force was 0, indicating that the cultivated land functions were coordinated, with origin O as the resultant point. However, the cultivated land function system was unbalanced when it deviated from origin O. In Figure 2, vectors OA, OB, and OC are economic, social, and ecological function indexes, respectively. The radian of the angle was 2π/3. The three parts’ resultant force (F_rf) was the degree of cultivated land function coordination. The declination angle (θ) was its matching.

The polar coordinate (F_rf, θ) represents the cultivated land function’s coordination state. The higher the F_rf value, the lower the degree of cultivated land function coordination in the evaluation unit. The declination angle (θ) represents the deviation direction, which reflects the matching problem among subsystems. The directional angle of vectors OA, OB, and OC were defined as θ/2, 11θ/6, and 7θ/6, respectively [51,52,53]. Based on the vector operation rules, the polar coordinate (F_rf, θ) formula was as follows:

$$\begin{gathered} \overline{OA}=(x_A, y_A)=(0, OA) \\ \overline{OB}=(x_B, y_B)=\left(\cos \right([1-(\mid OB\mid /OB\left)\right]\pi /2-5\pi /6)\mid OB\mid , \sin ([1-(\mid OB\mid /OB\left)\right]\pi /2 \\ -5\pi /6)\mid OB\mid ) \\ \overline{OC}=(x_C, y_C)=\left(\cos \right([1-(\mid OC\mid /OC\left)\right]\pi /2-\pi /6)\mid OC\mid , \sin ([1-(\mid OC\mid /OC\left)\right]\pi /2 \\ -\pi /6)\mid OC\mid ) \\ \overline{F_{rf}}=(x_{\mathit{rf}}, y_{\mathit{rf}})=\overline{OA}+\overline{OB}+\overline{OC}=(x_A+x_B+x_C, y_A+y_B+y_C) \end{gathered}$$

(6)

F_rf = (x_rf² + y_rf²)^0.5,

(7)

θ = arctan(y_rf/x_rf), y_rf ≥ 0
                 θ = arctan(y_rf/x_rf) + 2π, y_rf < 0

(8)

In the formulas, $\overline{OA}$, $\overline{OB}$, $\overline{OC}$, and $\overline{F_{rf}}$ are the vector quantities of the economic, social, and ecological functions and resultant force, respectively, and x_A, x_B, x_C, x_rf, y_A, y_B, y_C, and y_rf are the x and y axis coordinates.

4. Empirical Analysis of Cultivated Land Multifunctionality

4.1. Spatiotemporal Pattern of Cultivated Land Multifunctional Evolution

4.1.1. Cultivated Land Multifunctionality Value

As shown in Figure 3, the economic, social, and ecological functions of cultivated land in the Poyang Lake Ecological Economic Zone increased significantly from 2015 to 2019. Comparing the three functions showed that the economic function was on top, followed by the ecological and social functions. The result conformed to the study area’s location, focusing on poverty alleviation with excellent economic function, significant ecological function, and steadily increasing social function from 2016 to 2020. Figure 4 shows that the cultivated land’s multifunctional value in the Poyang Lake Ecological Economic Zone from 2016 to 2020 was characteristic of a highland around a lake, with the areas with high cultivated land multifunctional values mainly found in the counties of Jiujiang City, Nanchang City, Shangrao City, and other prefecture-level cities. In addition, the rates of change of multifunctional cultivated land values in these areas were significantly higher than those in other areas from 2016 to 2020. These findings indicate strong correlations between cultivated land resource endowment, location advantage, and total cultivated land function. Moreover, the lower total cultivated land function generally appeared in areas far from the location core and with relatively poor cultivated land resources. For example, Yushui District and Fuliang County had low cultivated land multifunctional indexes and declining total cultivated land functions. The main causes of these changes were affected by system. In recent years, the Chinese government and international organizations have focused on the protection of the Poyang Lake ecosystem, while a series of coordinated policies of human–land relationship have promoted the formation of a highland around a lake ecological pattern.

4.1.2. Economic Function

Between 2016 and 2020, the cultivated land economic function in the Poyang Lake Ecological Economic Zone showed an upward trend. The cultivated land economic function index in the Nanchang–Fuzhou–Yingtan City Belt tended to grow rapidly. In Figure 5a, most regions showed significant economic function growth from 2016 to 2020, mainly benefiting from poverty alleviation efforts to increase agriculture and rural economic development. During this period, a series of cropland infrastructures further increased investment. New field road, land consolidation, and water engineering projects were completed. Funds to support and assist farmers were invested. Agricultural development’s weaknesses have gradually been remedied while cultivated land resource endowment has increased. In addition, some regions have vigorously developed cash crop planting to ensure grain security and actively develop facility agriculture. High-quality agricultural product planting projects with high-tech, security, and value-added characteristics were enacted, effectively increasing the cultivated land’s economic function. In the urban built-up areas of Changjiang, Linchuan, and Yushui Districts, cultivated land’s economic functions were weakened by accelerating urbanization. In Figure 5b, increases in economic function indexes were significantly higher in Xinjian District, Jinxian County, Anyi County, and some surrounding counties than in others, indicating that the Nanchang–Fuzhou–Yingtan City Belt centered around Nanchang City promoted cultivated land economic function. Rural–urban integration and three agricultural industries developed rapidly from 2016 to 2020, including rural complexes that planted high-value-added cash crops to enhance the cultivated land’s ecological function and release its economic value, quickly improving the regional cultivated land economic function index.

4.1.3. Social Function

From 2016 to 2020, 73% of the Poyang Lake Ecological Economic Zone’s counties significantly improved their social function, with greater increases in peri-urban areas. The cultivated land social function index decreased significantly in Xinjian District, Anyi County, Gongqingcheng County-level City, and Yushui District from 2016 to 2020 (Figure 6). With rapidly developing non-agricultural industries and urbanization, intensified population-carrying pressures on the cultivated land, and prominent non-agricultural pollution sources, severe grain quality and safety issues and greater non-agricultural sector employment of rural labor forces have appeared, decreasing the regional cultivated land’s social function. Lianxi District is located in Jiujiang City, where the cultivated land’s social function increased rapidly. Withdrawal of the city and establishment of this district (upgrading the administrative level) drove the region to increase funding for agriculture and upgrade agricultural and rural infrastructures. Similarly, the thriving Mount Lu Scenic Area also drove the integration of agriculture and tourism. Therefore, thriving businesses and a pleasant living environment could be achieved with further support of the poverty alleviation policy, effectively reducing the pressure on cultivated land, improving grain quality, and enhancing employment absorption capacity. In addition, similar changes also appeared in Nanchang County, Jinxian County, Linchuan District, and Dongxiang District.

4.1.4. Ecological Function

From 2016 to 2020, 57% of the Poyang Lake Ecological Economic Zone’s counties significantly improved their ecological function, including in major grain-producing counties (e.g., Nanchang County), scenic area locations (e.g., Lianxi District), and areas far from the city (e.g., Yugan County) (Figure 7). From 2016 to 2020, the Jiangxi Province Government implemented poverty alleviation and double-cropping rice projects. The major grain-producing counties also continued to improve the cultivated land’s ecological level to drive the win-win between agricultural economic development and ecological protection. Scenic area locations have actively implemented a pollution control project to optimize the surrounding cultivated land ecosystem. This project has extended landscape and tourist capacity to improve the overall scene. Counties far from the city were less exposed to population pressure, preserving more original cultivated landscapes and ecological relics. Therefore, they had relatively high cultivated land ecological levels.

The cultivated land ecological function index increased faster in the north of the Poyang Lake Ecological Economic Zone (including Pengze County, Lianxi District, Chaisang District, Duchang County, Gongqingcheng County-level City, and Lushan County-level City), benefiting from Poyang Lake’s prolonged protection. These areas have actively implemented the grain-for-green program and a fishing ban in the Yangtze River basin, where the regional ecosystem has been quickly restored. In the study area, cultivated land was used to produce grain and cash crops and became the habitat of migrant birds. The harmony between humans and nature created by regional cultivated land landscape restoration enhanced biodiversity, reduced population carrying pressures on cultivated land, and effectively controlled non-agricultural pollution sources to significantly improve the cultivated land’s ecological function.

4.2. Coordination Analysis of Cultivated Land Multifunctionality

This study used Equations (6)–(8) to measure the F_rf of each evaluation unit in the study area. The division of cultivated land multifunctional coordination degree was based on natural breaks, which were divided into four levels (Figure 8): high coordination [0.020, 0.136], moderate coordination (0.136, 0.253], lower coordination (0.253, 0.369], and imbalance (0.369, 0.486].

The coordination degree of cultivated land function in the Poyang Lake Ecological Economic Zone was generally higher in 2020 than in 2016. This change was mainly due to institutional support, policy inclination, thriving-scale agricultural entities, and modern agriculture development driving overall cultivated land function in the study area. The highly coordinated counties were mainly around Poyang Lake. As the distance from the lake increased, the coordination degree decreased. There were two possible explanations for this pattern. First, most of these areas comprised important agriculture countries with high agricultural resource endowments that could effectively coordinate regional cultivated land function with the support of poverty alleviation and rural revitalization from 2016 to 2020. Second, most of these counties were adjacent to big cities. With market orientation and policy inclination, new agricultural operation modes, such as urban agriculture and eco-agriculture, have flourished. They have implemented modern agricultural developments in crop production and increased employment to relieve social pressure. Moreover, they have continuously upgraded the landscape and improved ecological environment, driving harmonious economic, societal, and ecological development.

Multifunctional cultivated land coordination showed a generally benign development trend in the Poyang Lake Ecological Economic Zone. The mean coordination value increased from 0.147 in 2016 to 0.163 in 2020, the median value from 0.111 in 2016 to 0.118 in 2020, and the overall spread from 0.440 in 2016 to 0.486 in 2020 (

Table 2. Coordination degree of cultivated land function in the Poyang Lake Ecological Economic Zone from 2016 to 2020.

Year	Coordination Degree				Proportion of Different Zones (%)
	Mean	Overall Spread	Median	Standard Deviation	High Coordination	Moderate Coordination	Lower Coordination	Imbalanced
2015	0.147	0.440	0.111	0.101	57	33	7	3
2019	0.163	0.486	0.118	0.188	60	30	0	10

). This pattern indicates that the multifunctional coordination of regional cultivated land increased slightly, was generally stable, and tended to be reasonable.

Coordination change was mainly high to moderate. The proportion of high coordination increased slightly from 57% in 2016 to 60% in 2020. In contrast, the proportion of moderate coordination decreased slightly from 33% in 2016 to 30% in 2020. Moreover, the proportion of lower coordination was 70% in 2016 but nonexistent in 2020. The proportion of imbalanced zones increased from 3% in 2016 to 10% in 2020 (Table 2). Therefore, medium-high coordination zones were stable in the Poyang Lake Ecological Economic Zone, but local imbalance zones showed an increasing trend.

4.3. Identification of Deviant Direction of Cultivated Land Function

Vectors OA, OB, and OC extended in opposite directions. The results were placed into six quadrants. The vector power in each quadrant could reflect the deviant direction and match the cultivated land function coordination degree in each evaluation unit. As shown in Figure 9, deviant direction θs were found in quadrants I, II, and VI, with proportions of study units of 23.33%, 26.67%, and 20%, respectively.

Quadrant Ⅰ represented positive ecological function and negative social function. Seven counties were located in Quadrant Ⅰ, found north of Poyang Lake. Important agricultural counties dominated these areas. The double restraints of the grain-for-green program and fishing ban in the Yangtze River basin significantly strengthened ecological function. However, restricted resource utilization weakened the population-carrying and employment absorption capacities, while social function showed the opposite pattern.

Quadrant II represented positive economic function and negative social function. It comprised the Xinjian–Nanchang–Yugan–Wannian–Leping–Fuliang County Belt, concentrated south and east of Poyang Lake, dominated by agricultural production and urban–rural integration. From 2016 to 2020, agricultural development increased in scale, intelligence, ecologicalization, and urbanization. The agricultural economy function was significantly strengthened. Land transactions and peasant disintegration drove regional human resource diversion, improving agricultural modernization. The surplus labor forces were mainly transferred to the regional center cities and the eastern coastal areas, having an opposite effect on social function.

Quadrant VI represented positive ecological function and negative economic function. Six counties were in Quadrant Ⅵ, found in Poyang Lake’s external zone except for Yongxiu County, including Ruichang County, Wuning County, and Zhangshu County-level City in the Mufu Mountains and Dongxiang District and Yujiang District in the Ganfupingyuan Irrigation Area. These areas were lakeside and intermontane, with fertile soil and rain-heat moisture. Moreover, their urban density and industrial pollution were low. Therefore, their ecological function was positive. However, they mostly depend on traditional primary production. While cash crops, such as Chinese medicinal plants, had been planted, external agricultural secondary and tertiary industries diluted their value chain extension. Therefore, while their regional agricultural resource endowment was strong, their economic function was relatively weak.

5. Conclusions

This study focused on the Poyang Lake Ecological Economic Zone and cultivated land multifunctionality and coordination. The spatiotemporal pattern of cultivated land multifunctionality and coordination among sub-functions was examined through a mechanical model in different periods. The following conclusions can be drawn from its empirical study:

• From 2016 to 2020, cultivated land multifunctionality development was effective, and the ecological economy around Poyang Lake had significant advantages. During this period, cultivated land multifunctionality values in these areas showed an overall increasing trend. The temporal and spatial distribution was consistent with a highland around a lake characteristic. The cultivated land’s economic, social, and ecological functions were increasing in most counties, and their fluctuations tended to be stable.
• The system’s effectiveness was excellent, and the coordination of the cultivated land’s economic, social, and ecological functions significantly improved from 2016 to 2020. The coordination of cultivated land functions was generally higher in 2020 than in 2016. The coordination showed a generally benign development trend and moderate-to-high change. Moreover, coordination degree fluctuation tended to be stable and reasonable.
• The ecological significance of the Poyang Lake Ecological Economic Zone was excellent, with a flourishing ecological economy. The cultivated land functions’ deviation directions were focused in Quadrants Ⅰ, Ⅱ, and VI, showing that the ecological function had an absolute advantage. From 2016 to 2020, poverty alleviation has created a series of industries with ecological capital, including several secondary and tertiary industries developed around ecological advantages. During this period, the ecological economy played a leading role in Jiangxi’s agricultural development.

At present, deficiency of natural resources is becoming more apparent. It was urgent to further explore resource endowment to support the sustainable development of human beings and protection of natural resources. Cultivated land multifunctionality could manifest its economic, social, and ecological functions to support high-quality regional development. Therefore, this paper obtained the following policy implications:

• The resource endowment of cultivated land should be further explored to support the transformation of regional development modes. The ecological economic function of cultivated land should be highlighted in order to reduce the disturbance of households to wildlife habitat in Poyang Lake Ecological Economic Zone. It aimed to realize the transformation of regional economic development modes, while supporting the harmony of a “social–ecological” system.
• The exploration of cultivated land multifunctionality could drive the transformation of resources into assets in order to energize the regional economy, society, and ecology.
• The multifunctional use of cultivated land drives the transformation of resources into assets and empowers regional economy, society and ecology. Stakeholders needed to dig deep into limited resources to identify more endowments, which could help to revitalize dormant assets. These actions could alleviate resource scarcity conflicts, while supporting sustainable development strategies.