Impact of Land Use/Cover Change on Ecosystem Service Value in Guangxi

Abstract

Ecosystem service value (ESV) is an important indicator used to measure the quality of the regional ecological environment, and land use/cover change (LUCC) has a crucial impact on it. Based on three periods of land use data for Guangxi, China, in 2000, 2010, and 2020, in this study, the spatial and temporal change characteristics of the LUCC were analyzed, and the equivalent factor method was used to calculate the total ESV in Guangxi. Finally, the spatial autocorrelation and spatial aggregation characteristics of ESV in Guangxi were analyzed to explore the impact of land use/cover changes on ecosystem service values in Guangxi. The results show that the utilization areas of water and artificial surface continuously increased from 2000 to 2020, with the largest increase in the area of artificial surface, which increased by 3390.67 km². The areas of the forest land, shrubland, and sea continuously decreased, of which the forest land area decreased by 5679.39 km². The areas of the cultivated land and grassland initially increased and then decreased, exhibiting a small overall increase. During the study period, the total ESV in Guangxi initially increased and then decreased, with an overall increase of 1.295 billion RMB. This was caused by the increase in the area of water and grassland. The distribution of ESV in Guangxi has a significant positive spatial correlation, and the distribution of ESV in Guangxi shows a high north and low south, and the ESV high-high value aggregation areas were concentrated in the mountainous areas in northeast and northwest Guangxi. The results of this study provide an important theoretical basis for the rational development and utilization of land resources in Guangxi and for the coordination of socio-economic development and environmental protection.

1. Introduction

With the high rate of socioeconomic growth, human activities are increasingly interfering with the natural ecological environment, and the impacts of major changes in the land use/cover structure on ecological and environmental problems are beginning to receive widespread attention [1]. With the implementation of China’s environmental protection policy and the release of Guangxi’s 14th Five-Year Plan (2021–2025) for Ecological Protection, the construction of an ecological civilization has been elevated to a new level to maintain ecological security and adhere to the goal of harmonious coexistence between humans and nature [2]. An important prerequisite for carrying out a regional ecosystem service value assessment is to research land use/cover change. The ecosystem service value (ESV) is defined as the value of the benefits that ecosystems provide to human society [3], and it reflects the ecological environmental quality of a region and plays an important role in measuring the regional ecological quality [4,5,6].

The quantitative assessment of the value of ecological services is a hot topic in research on the quality of the ecological environment and the sustainable development of a region [7]. Gordon [8] was the first to discuss the impact of the ecosystem on human survival and development, and he explored the main types of ecosystem service functions. Costanza et al. [9] published the article “Global ecosystem service value and natural capital” in Nature, making studying the ecosystem service value an international trend. The research on the ecological service value by Chinese scholars has mainly adopted the ecosystem service function system and ecosystem service value evaluation method of Ouyang et al. [10] and Xie et al. [11]. Ouyang et al. [10] used the market value method and the substitution market method to summarize and outline nine ecosystem service functions, including climate regulation and soil and water conservation, from an ecological perspective, and they explored the indirect economic value of ecosystems. Xie et al. [12] investigated the actual biomass in different study areas to redefine ecological benefit evaluation, corrected the ecological service value per unit area, and considered the spatial variability of ecosystem service functions. Many studies have been conducted by scholars in China on the valuation of different types of ecosystem services. Yu et al. [13] divided China’s forest ecosystems according to their zonal distribution characteristics. Then, they further calculated the ecological service values of the different types of forests. Li et al. [14] conducted a study related to the ecological service value of rice fields based on the cultivation mechanism in the Sichuan Basin. Liu et al. [15] analyzed and evaluated the value of wetlands ecosystem services to explore the characteristics of different assessment methods. Over time, the calculation of the value of ecosystem services has been greatly improved. Shi et al. [16] studied land use changes and established a system for evaluating the value of ecosystem services based on the change intensity index. Duan et al. [17] used the market value method and shadow engineering method, combined with remote sensing and geoinformation technology for computing, to obtain the spatial and temporal variation characteristics of the value of ecosystem services in their study area. Xie et al. [18] classified a total of nine ecosystem services, including food production, gas regulation, and soil conservation, and developed an ecological service value equivalent scale more applicable to Chinese ecosystems. Xu et al. [19] further refined the ecological service value equivalent factor table developed by Xie [19] to make it more applicable to study areas in different temporal and spatial states. Xie et al. [20] used the unit area value equivalent factor method for calculation, further revised and supplemented the ecosystem service equivalent factor table, considered the spatial and temporal variation characteristics of different ecosystems, and established a dynamic assessment system for ecological service values.

The current methodological system for ecosystem service valuation is relatively mature, but studies on ecosystem service values have mainly been conducted in river basins [21,22,23], coastal areas, and high-speed economic development areas [24,25,26], while studies of the more ecologically fragile karst landscapes are rare. At present, the research on the value of ecosystem services in Guangxi has mainly focused on the watersheds within Guangxi and on the coastal areas of the Beibu Gulf, as well as studies on the value of the ecosystem services in the counties and municipal areas of Guangxi [27,28,29]. Among them, most studies have focused on the ecosystem service values of the counties and municipalities in Guangxi, the land use data analyzed were relatively old, and more recent land use data for comparison were lacking, decreasing the scientific validity and accuracy of our understanding of the current trend of the ESV in Guangxi [30,31,32,33]. Fewer studies have been conducted to assess the values of ecosystem services and to analyze the spatial autocorrelation of the values of ecological services in Guangxi with those of the entirety of Guangxi. Therefore, a comprehensive and systematic study of land use/cover change in Guangxi, an analysis of its impact on the ecosystem service value, and investigation of the spatial clustering characteristics of the ESVs in Guangxi are conducive to the rational planning of the land use structure; to strengthening the construction of system consisting of mountains, water, forests, fields, lakes, and grassland; and to providing a reference basis for realizing rural revitalization [34]. In addition, the results of this study will also help us to use natural resources more scientifically, to strengthen ecological restoration of the damaged natural environment, to establish a sound ecological compensation mechanism, and to promote the sustainable, green, and high-quality development of Guangxi’s economy, which are of great significance to the sustainable development of the region [35].

2. Materials and Methods

2.1. Overview of the Study Area

Guangxi (104°29′–112°04′ E, 20°54′–26°23′ N) is located in the western part of southern China (Figure 1). It consists of 14 prefecture-level cities (prefecture-level cities are one of the administrative divisions of China, governed by a province or autonomous region), with a total population of 56.59 million and a total area of 237,600 km². Guangxi is a border province/autonomous region of China, bordering with Vietnam, located on the southeastern edge of the Yunnan–Guizhou Plateau, bordering the hills of the two regions in the west, and with extensive mountainous terrain in northern Guangxi. Phoenix Mountain and Duoyang Mountain are located in the northwestern part of Guangxi, while Tianping Mountain, Yue Cheng Mountain, and Dayao Mountain are in the northeastern part of Guangxi. The southern-central part of Guangxi is dominated by hills and basins, and the overall landform is a mountainous hilly basin landform. Karst landform is the general name of surface and underground forms formed by soluble rocks dissolved by water with solubility. Karst landform is widely distributed in Guangxi, and karst landform accounts for 37.8% of the total area of Guangxi. The soil layer of karst landform is relatively thin, the soil fertility is low, the surface is more fissured, which is easy to make the surface water into underground water, and it is easy to have the problems of soil erosion and soil desertification, the ecological environment is more fragile, not easy to repair, and easy to be affected by human activities. Therefore, reasonable land use planning for karst landscape areas in Guangxi is conducive to improving regional economic benefits and is of great significance to the protection of ecological environment. Guangxi is located at low latitudes, and the Tropic of Cancer runs through the central part of Guangxi. The climate is a subtropical monsoon climate, with rain and heat in the same period and abundant precipitation. The annual average temperature in Guangxi is 16.0–23.0 °C, and the annual average precipitation is about 1800 mm. Guangxi’s ecological environment has an excellent quality and ranks among the highest in China. There are many rivers and abundant hydraulic resources in this territory, most of which flow from northwest to southeast as the topography undulates. The Pearl River system is a representative area of these hydraulic resources. Guangxi is located adjacent to the Gulf of Tonkin in the south, facing Southeast Asia, and is a convenient outlet to the sea in the southwestern part of China. This plays an important role in promoting the construction of the One Belt, One Road in China.

2.2. Data Sources

The three periods of land cover data for 2000, 2010, and 2020 used in this study were obtained from GlobeLand30 raster data with a spatial resolution of 30 m provided by the Ministry of Natural Resources (source: http://www.globallandcover.com, accessed on 27 February 2022). The land use types included cultivated land, forest, grassland, shrubland, wetlands, water, artificial surface, bare land, and sea area. The overall accuracy of GlobeLand30 V2020 data is 85.72%, and its Kappa coefficient is 0.82, indicating that the data have high accuracy and scientific validity for data analysis. The digital elevation model (DEM) is derived from Aster GDEMV3 data (spatial resolution: 30 m) provided by Geospatial Data Cloud (source: http://www.gscloud.cn, accessed on 15 August 2022). In addition, data on the grain yield, grain sown area, and grain unit price of Guangxi in 2020 used in this study were obtained from the Guangxi Statistical Yearbook (source: http://tjj.gxzf.gov.cn/tjsj/tjnj, accessed on 12 March 2022 ) and the website of the Guangxi People’s government (source: http://lshwzcbj.gxzf.gov.cn/xwdt/t5624385.shtml, accessed on 23 March 2022 ).

2.3. Methods

2.3.1. Single Dynamic Degree of Land Use

The analysis of land use dynamics provides an understanding of the degree of change in the land use structure, which is the degree of change in the area of a land type over a certain time period [36]. The expression is as follows:

$$K=\frac{U_b-U_a}{U_a}\times \frac{1}{T}\times 100\%,$$

(1)

where K is the annual rate of change of a particular land use type. If K > 0, the area of the land use type is increasing. If K < 0, the area of the land use type is decreasing. The greater the absolute value of K is, the greater the range of change of the land area. $U_a$ is the area of the land use type at the beginning of the study; $U_b$ is the area of the land use type at the end of the study; and T is the duration of the study period in years.

2.3.2. Land Use Transfer Matrix

The land use transfer matrix [37] is used to study the transformation of land use types between the initial stage and the end of the study period, which provides a better understanding of the direction of transfer and the changes in the amount of transfer of various land use types. It is also a quantitative description of land use transfer [38]. The expression is as follows:

$$A_{ij}=\left[\begin{array}{cccc}{A}_{11}& A_{12}& \dots & A_{1n}\\ A_{21}& A_{22}& \dots & A_{2n}\\ \dots & \dots & \dots & \dots \\ A_{n1}& A_{n2}& \dots & A_{nn}\end{array}\right],$$

(2)

where $A_{ij}$ refers to the area of land use type i in the initial stage of the study and the area of type i converted into land type j at the end of the study (km²); i (i = 1, 2, …, n) and j (j = 1, 2, …, n) are the land use types at the beginning and end of the study, respectively; and n is the number of land use types.

2.3.3. Unit Area Equivalent Factor Method

This study uses the equivalent factor method to assess the value of ecosystem services. The equivalent factor method is simple and easy to operate in practice, requires less data, and the results are easy to compare, allowing for rapid accounting of the value of ecosystem services. Xie et al. [20] revised and supplemented the ecosystem service value equivalent factor based on the classification of ecosystem service functions by Costanza et al., as well as various literature research and spatial and temporal distribution data of Chinese biomass, and the improved unit area equivalent factor method is more applicable to the assessment of ecosystem service value in China. The unit area equivalent factor method improved by Xie et al. [20] was used to calculate the unit area ecosystem service value equivalent factor in Guangxi, and then the ecosystem service value of Guangxi was calculated based on the land use/cover data of the different periods. The first step in calculating the value of ecosystem services requires calculating the equivalent factor of ecosystem service value in Guangxi, and the equivalent factor method defines the equivalent factor of one standard ecosystem service value as one seventh of the economic value generated by food crops produced on 1 km² of arable land [39]. Since the sales prices of food crops change from year to year, in order to reduce the influence of price fluctuations on the equivalence factor [40] and to better compare and analyze the spatial and temporal changes of ecosystem service values in different periods, this study calculated the 2020 Guangxi ecosystem service value equivalence factor based on the prices of major crops in Guangxi in 2020. The expression is as follows:

$$E_a=\frac{1}{7}{\displaystyle \sum }_{i=1}^n\frac{p_i{q}_i}{M}(i=1,2,\dots ,n),$$

(3)

where $E_a$ is the economic value of food production per unit area of farmland (RMB·km⁻²); $n$ is the type of food crop; $i$ is the type of grain; $p_i$ is the average price of the ith food crop (RMB·kg⁻¹); $q_i$ is the yield of the ith food crop (kg·km⁻²); and M is the total area of food crops.

According to the revised equivalent factor of the ecosystem service value in Guangxi, the ecosystem service value of each ecosystem type was calculated, and the ecosystem service value of Guangxi in the different periods was calculated using Equation (4).

$$ESV={\displaystyle \sum }_{i=1}^n{A}_i\times V{C}_i,$$

(4)

where ESV is the total value of ecosystem services; $A_i$ is the area of land use type $i$ (km²); and $V{C}_i$ is the ecosystem service value coefficient of the ith land use type (RMB·km⁻²·a⁻¹).

2.3.4. Contribution of Ecosystem Service Value Variation

The ecosystem service variation contribution rate [41] refers to the ratio of a single land use type’s ecosystem service value to the total ecosystem service value in the study area. This factor can be used to measure the contributions of the different ecosystem land use types to the total ESV. The expression is as follows:

$$ES{V}_c=\frac{ES{V}_{ib}-ES{V}_{ia}}{ES{V}_b-ES{V}_a}\times 100\%,$$

(5)

where $ES{V}_c$ is the variation contribution rate of the ecosystem service value; $ES{V}_{ia}$ and $ES{V}_{ib}$ are the ecosystem service values of the ith land use type at the beginning and end of the study; and $ES{V}_a$ and $ES{V}_b$ are the ecosystem service values in the initial stage of the study and at the end of the study (RMB·a⁻¹). If $ES{V}_c$ > 0, the change in the ith land use type is consistent with that of the total ESV. If $ES{V}_c$ < 0, the change trends of the two are opposite, and the change in the land use type i makes a negative contribution to the change in the total ESV.

2.3.5. Spatial Autocorrelation Analysis

Global spatial autocorrelation analysis can reflect the spatial distribution characteristics of a certain element, which is mainly measured using Moran’s I index [42]. The spatial autocorrelation analysis of the study area was performed to determine whether the ESV of Guangxi was spatially correlated and if so, to what extent. Moran’s I index is the most frequently used spatial autocorrelation index to study the potential interdependence between the observations of variables within the same distribution area, and it is also used to determine whether they are correlated or not [43]. ArcMap10.5 is used to analyze the spatial autocorrelation of ESV in Guangxi, to determine whether there is a correlation between ESV in each geographical unit of the study area, and to analyze the spatial distribution phenomenon of ESV in Guangxi, so as to understand the spatial distribution characteristics of ESV in Guangxi more intuitively. The expression for the Moran’s I index is as follows:

$$I=\frac{n{\sum }_{i=1}^n{\sum }_{j=1}^n{W}_{ij}\left(x_i-\overline{x}\right)\left(x_j-\overline{x}\right)}{S_1{\sum }_{i=1}^n{\left(x_i-\overline{x}\right)}^2},$$

(6)

$$S_1={\displaystyle \sum }_{i=1}^n{\displaystyle \sum }_{j=1}^n{W}_{ij},$$

(7)

where n is the total number of variable observations; $x_i$ is the value of the variable in region i; $W_{ij}$ is the element in the spatial weight matrix W; and $S_1$ is the sum of the spatial weights of all of the variables. If I < 0, the research object has a negatively correlated spatial distribution, which is a discrete distribution. If I > 0, the spatial distribution of the research object is positively correlated and the distribution is aggregated. If I = 0, the distribution of the research object in the pixel space has no spatial autocorrelation.

2.3.6. Getis-Ord’s Gi*

Getis-Or’’s Gi* [44] can well reflect the distribution of cold hot spots on the local spatial region of Guangxi ESV. Using ArcMap10.5 software to create a fishing net tool, Guangxi was divided into 689 grid cells of 20 km × 20 km. The land use data of each fishing net were obtained through data linkage, and the ESV of each grid was further calculated, using each fishing net cell as the spatial scale for Getis-Ord’s Gi* visualization. Getis-Or’’s Gi* analysis of ESV grids in Guangxi can test whether ESV in Guangxi has significant features, such as cold spots, hot spots, and spatial outliers in spatial distribution. Getis-Ord’s Gi* is an effective method to explore the characteristics of local spatial clustering distribution, which can distinguish the degree of variable spatial distribution aggregation by cold and hot spots. The model equation is:

$$G_i^{*}=\frac{{\sum }_{j=1}^n{W}_{ij}{x}_j-\overline{X}{\sum }_{j=1}^n{W}_{ij}}{S_2\sqrt{\frac{\left[n{\sum }_{j=1}^n{W}_{ij}^2-{\left({\sum }_{j=1}^n{W}_{ij}\right)}^2\right]}{n-1}}},$$

(8)

$$\overline{X}=\frac{{\sum }_{j=1}^n{x}_j}{n},$$

(9)

$$S_2=\sqrt{\frac{{\sum }_{j=1}^n{x}_j^2}{n}}-{\left(\overline{X}\right)}^2,$$

(10)

where $x_j$ is the attribute value of spatial unit j, $W_{ij}$ denotes the spatial weights of spatial units i and j; n is the number of spatial units. $G_i^{*}$ indicates a statistically significant z-score. Under the assumption of normal distribution, the z-score is used to determine the spatial autocorrelation of the study object and is used to express the significance in statistics. If Z > 0, the variable is positively autocorrelated in space. If Z < 0, the variable is negatively autocorrelated in space, and the greater the absolute value of Z, the higher the correlation. If Z = 0, the values of the variables are independent in space and have no autocorrelation.

3. Results

3.1. Analysis of Land Use/Cover Change in Guangxi

3.1.1. Analysis of Land Use/Cover Situation and Land Use Dynamic Attitude in Guangxi

There were obvious regional differences in the spatial distribution of the land use/cover structure in Guangxi. From Figure 2, we can understand the land use/cover of Guangxi from 2000 to 2020, the topography of the northwestern region of Guangxi is mainly mountainous. Most of the hills and basins are distributed in the central and southern parts of Guangxi. The forest land and grassland were mainly distributed in the northern part of Guangxi. From the data in

Table 1. The structure and proportion of land use types in Guangxi.

Land Use Type	2000		2010		2020
	km2	%	km2	%	km2	%
Cultivated land	64,495.02	27.24	66,355.19	28.03	64,802.90	27.37
Forest land	156,002.13	65.89	151,763.08	64.10	150,322.74	63.49
Grassland	9044.16	3.82	11,108.51	4.69	10,667.92	4.51
Shrubland	1970.06	0.83	1693.32	0.72	1549.32	0.65
Wetlands	106.43	0.04	30.74	0.01	47.91	0.02
Water	2567.56	1.08	3134.07	1.32	3468.46	1.46
Artificial surface	2486.55	1.05	2609.72	1.10	5877.23	2.48
Sea area	78.74	0.03	64.50	0.03	16.51	0.01
Bare land	0.17	0.00	-	-	8.43	0.00

Note: - indicates that no data.

, the land use/cover types in Guangxi during 2000–2020 were mainly forest land and cultivated land, the sum of which accounted for more than 90% of the total land use area in Guangxi. From the data in Table 1 and

Table 2. Dynamic degree of land use in Guangxi from 2000 to 2020.

Land Use Type	2000–2010		2010–2020		2000–2020
	km2	%	km2	%	km2	%
Cultivated land	1860.17	0.29	−1552.29	−0.23	307.88	0.02
Forest land	−4239.05	−0.27	−1440.34	−0.09	−5679.39	−0.18
Grassland	2064.35	2.28	−440.59	−0.40	1623.76	0.90
Shrubland	−276.73	−1.40	−144.00	−0.85	−420.73	−1.07
Wetlands	−75.69	−7.11	17.17	5.59	−58.51	−2.75
Water	566.50	2.21	334.39	1.07	900.90	1.75
Artificial surface	123.16	0.50	3267.51	12.52	3390.67	6.82
Sea area	−14.24	−1.81	−47.98	−7.44	−62.22	−3.95

, it can be seen that Guangxi has the largest share of forest cover, which is 156,002.13 km², 151,763.08 km², and 150,322.74 km² in 2000, 2010, and 2020, respectively, and it can be seen that the forest cover is decreasing. The period of 2000–2010 was defined as the first period, and 2010–2020 was defined as the second period. In the first period, the forest cover decreased by 4239.05 km² and in the second period it decreased by 1440.34 km². The dynamic land use attitude of forest cover in the first and second periods was −0.27% and −0.09%, respectively, and compared to the second period, the forest cover decreased to a greater extent from 2000 to 2010 and the forest areas were more severely damaged. The forest area in Guangxi decreased significantly from 2000 to 2020, with a total decrease of 5679.39 km², at a forest area change rate of −3.6%.

The distribution of the cultivated land is closely related to the topography, and the cultivated land was mainly distributed in the hills and flatlands in central and southern Guangxi and the coastal area of the Beibu Gulf. Guangxi’s cultivated land coverage area is second only to forest coverage area. Although the overall rate of change in the area of the cultivated land was small, the amount of change in the area of the cultivated land during the different periods was large, the cultivated land coverage area in 2010 is 66,355.19 km², which is 1860.17 km² more than that in 2000, indicating that the cultivated land area in Guangxi has been well protected and developed in 2000–2010. The cultivated land coverage area in 2020 is 64,802.90 km². The cultivated land area decreased by 1552.29 km² compared to the 2010, which is closely related to the development of urbanization in Guangxi in recent years, and the development and expansion of cities and towns have occupied a large amount of cultivated land. In general, the amount of change in cultivated land cover has the smallest change, with a dynamic attitude of only 0.02% of cultivated land area from 2000 to 2020. The area of grassland cover in Guangxi first increased and then decreased, from 9044.16 km² in 2000 to 11,108.51 km² in 2010, an increase of 2064.35 km² in the 1st period. The area of grassland cover in 2020 is 10,677.92 km², a decrease of 440.59 km² compared to 2010, but the increase is greater than the decrease. The overall increase of grassland area from 2000 to 2020 is 17.95%.

The shrubland was mainly distributed in the mountainous areas in northwestern Guangxi and was concentrated in Baise City. The area of the shrubland continuously decreased from 2000 to 2020. The shrubland area decreased by 276.73 km² in the first period and 144.59 km² in the second period, with a land use dynamic attitude of −1.40% and −0.85%, respectively, with a greater trend of decrease from 2000 to 2010 and shrubland area decreased by 21.36% from 2000 to 2020. The area of wetlands initially decreased sharply and then increased slightly. The wetland areas in 2000, 2010 and 2020 were 106.43 km², 30.74 km² and 47.91 km², respectively. The land use dynamic attitude of wetlands in the first period was −7.11%, which was the largest change among all land cover types in the first period. The area of wetlands in the second period increased by only 17.17 km², and in the period 2000–2020 the wetland areas decreased by a total of 54.98%. The area of water maintained stable growth. The area of water bodies in 2010 is 3134.07 km², which is 566.50 km² more than in 2000. The area of water bodies in 2020 is 3468.46 km², which is 10.7% more compared to the area of water bodies in 2010. From 2000 to 2020, the area of water bodies maintains positive growth with a land use dynamic of 1.75%.

The artificial land surfaces were mainly distributed in the flat basin in central Guangxi and the coastal areas in the south and was concentrated in the economically developed urban areas, such as Nanning, Liuzhou, and Guilin. By comparing the three phases of land use data for Guangxi (2000, 2010, and 2020), the area of artificial surface maintains positive growth, and the growth trend is most obvious. In the 1st period, the artificial surface area increases 123.16 km²; in the second period, the area of artificial surface grows the fastest, and the land use motive attitude is 12.52%, and the total increase in the 2nd period is 3267.51 km². The ratio of artificial surface area to total area increased from 1.05% in 2000 to 2.48%, an increase of 1.36 times in 20 years. Due to the influence of human economic and social activities, the area of sea in Guangxi decreased. In 2000, 2010, and 2020, the sea areas were 78.74 km², 64.50 km², and 16.51 km², respectively. In the first period, the sea area decreased by 14.24 km² and in the second period by 47.92 km². In the second period, the land use rate of the sea area was −7.44%. From 2000 to 2020, the sea area decreased by a total of 79%. The area covered by bare land from 2000 to 2020 was highly variable, increased from 0.17 km² in 2000 to 8.43 km² in 2020, a total increase of 8.26 km².

In 2000–2020, the area of water bodies and artificial surfaces in Guangxi was increased; the area of forest cover, shrubland, and sea area was decreased; the area of cultivated land and grassland increased first and then decreased, and the increase in the first period was greater than the decrease in the second period, while the area of both increased. The area of wetland first decreased sharply, then increased slightly, and decreased by 58.51 km² in total.

3.1.2. Analysis of Land Use Transfer Matrix for Guangxi

The land use transfer matrix analysis was performed on the land use/cover data of Guangxi, and the land use transfer matrix for different study periods is presented in

Table 3. Land use transfer matrix for Guangxi from 2000 to 2020 (unit: km²).

	Land Use Type	Cultivated Land	Forest Land	Grassland	Shrubland	Wetlands	Water	Artificial Surface	Bare Land	Sea Area	Total
2000–2010	Cultivated land	56,418.88	5479.02	1170.57	181.17	5.69	723.79	513.70	-	0.53	8074.48
	Forest land	7339.31	143,170.65	4235.09	691.35	2.20	446.73	100.81	-	1.78	12,817.27
	Grassland	1548.21	2092.26	5222.51	89.99	0.82	68.40	20.02	-	0.06	3819.76
	Shrubland	286.53	554.52	399.76	722.08	0.00	1.79	5.16	-	-	1247.77
	Wetlands	23.32	16.55	2.52	0.05	17.73	44.56	0.82	-	0.54	88.37
	Water	357.48	309.20	61.58	6.33	3.65	1811.02	12.83	-	2.12	753.19
	Artificial surface	374.10	125.71	9.75	0.43	0.12	24.88	1950.53	-	0.73	535.72
	Sea area	2.38	2.61	0.12	-	0.27	8.75	6.32	-	57.40	20.44
	Total	9931.33	8579.87	5879.40	969.32	12.75	1318.92	659.66	-	5.75	-
2010–2020	Cultivated land	57,192.05	5522.45	595.37	92.81	6.30	468.86	2461.26	-	0.56	9147.62
	Forest land	5925.81	140,540.49	3247.80	529.59	5.74	493.00	916.47	-	1.75	11,120.17
	Grassland	834.45	3271.69	6629.32	155.56	1.27	111.79	88.60	-	0.05	4463.41
	Shrubland	171.79	595.12	136.02	768.87	0.01	3.34	17.79	-	-	924.06
	Wetlands	2.60	3.06	0.40	0.01	15.83	8.00	0.39	-	0.07	14.52
	Water	435.48	238.79	22.41	1.68	16.32	2360.28	50.13	-	0.95	765.76
	Artificial surface	230.24	54.93	7.13	0.37	0.40	16.30	2298.21	-	0.24	309.62
	Sea area	1.11	1.94	0.03	-	1.28	3.11	43.47	-	12.24	50.95
	Total	7601.48	9687.98	4009.15	780.02	31.34	1104.41	3578.12	-	3.62	-
2000–2020	Cultivated land	53,376.84	6434.11	1106.08	197.21	13.85	746.08	2618.02	0.69	0.35	11,116.38
	Forest land	8644.43	140,499.30	4512.39	708.69	6.34	631.72	981.71	1.76	1.78	15,488.82
	Grassland	1706.44	2378.05	4624.13	86.54	0.95	135.34	110.88	0.12	0.03	4418.34
	Shrubland	391.71	635.38	364.65	551.62	0.01	2.78	23.73	-	-	1418.25
	Wetlands	30.25	12.96	1.74	0.03	13.58	44.51	2.24	0.24	0.41	92.39
	Water	343.18	248.36	43.78	4.52	10.16	1872.07	36.48	3.85	1.65	691.97
	Artificial surface	305.40	91.11	10.83	0.22	0.43	24.38	2051.89	1.24	0.74	434.36
	Bare land	0.12	0.03	-	-	-	0.02	-	-	-	0.17
	Sea area	3.84	2.57	0.06	-	1.42	7.51	50.79	0.39	10.73	66.59
	Total	11,425.36	9802.59	6039.53	997.20	33.17	1592.33	3823.86	8.29	4.96	-

Note: - indicates that no transfer occurred.

. It can be seen from Figure 3 that there are close conversion links between land use types in Guangxi from 2000 to 2020. During the study period, the transferred out cultivated land was mainly transferred to forest, grassland, and artificial surface, and a large area of forest was converted into cultivated land and grassland. Grassland was mainly transferred to forest and cultivated land. In terms of the amount transferred, the amount transferred in was greater than the amount transferred out for grassland. Water bodies and artificial surface cover areas were significantly larger than the amount of transfer out of all three. Among them, the increased area of artificial surface in 2020 is mainly converted from cultivated land and forest.

From 2000 to 2010, the highest amount of forest land was converted into other types in Guangxi, was accounting for 46.6% of the total amount of land converted into other types. The forest land was mainly converted into cultivated land (7339.31 km²) and grassland (4235.09 km²). The total conversion of arable land into other types in Guangxi was 8074.48 km², and the area of cultivated land converted into forest land accounted for 67.9% of the total conversion of cultivated land into other types, while the conversion of cultivated land into grassland was the second largest, accounting for 15% of the conversion of cultivated land into other types. The conversion of wetlands into other types was much greater than the conversion of other types into wetlands, and the rate of land use change of the wetlands was the greatest during this decade, with the transfer of wetlands to water bodies accounting for 50.4% of the total conversion of wetlands into other types, followed by the conversion of wetlands into cultivated land and forest land. The water bodies were mainly converted into cultivated land and forest land, and a lesser amount was converted into other land use types. The area of artificial surface converted into cropland accounted for 69.8% of the total conversion of artificial surface into other types. Among the various land use types, the conversion of cultivated land accounted for 36.3% of the total conversion of all land use types, which was the highest percentage; and 7339.31 km² of forest land and 1548.21 km² of grassland were converted into cropland during period 1.

From 2010 to 2020, the areas of cultivated land, forest land, and grassland utilization in Guangxi decreased, and the cultivated land was mainly converted into forest land and artificial surface, among which the area of cultivated land converted into artificial surface accounted for 27% of the total conversion of cultivated land into other types. A large amount of grassland was converted into forest land, and these transfer areas were mainly concentrated in the western and northeastern parts of Guangxi. The water bodies were mostly converted into cultivated land, accounting for 47.4% of the total conversion of water bodies into other types. In the second period, the sea area was mostly converted into artificial surface, accounting for 85.3% of the total conversion of sea area into other types. In 2010–2020, the highest conversion of forest land area occurred, accounting for 36.2% of the total transfer of all land use types. The transfer of the artificial surface exhibited the largest change, increasing from 659.66 km² in period 1 to 3578.12 km² in period 2. The increase in the area of artificial surface was mainly through the conversion of cultivated land and forest land into artificial surface, accounting for more than 94% of the total transfer of artificial surface.

From an overall perspective, the forest land, cultivated land, and grassland exhibited the largest changes in the land use/cover structure from 2000 to 2020, with all three having much higher transfer areas than the other land use types. The combined conversion into other types and conversion from other types of the three accounted for 92% and 80.8% of the total changes, and the conversion from other types was smaller than the conversion into other types. The conversion of other types to cultivated land was the highest, but the area converted into other types was nearly the same as the area converted from other types, so the net change in the area of cultivated land was very small. Most of the wetlands were converted into water and cultivated land, accounting for 70.2% of the total wetland area in Guangxi in 2000. The area of bare land increased, and it was mainly formed through the conversion of water, forest land, and artificial surface into bare land.

During the study time period, the increased area of water bodies and artificial surface was mainly converted from cultivated land and forest. From 2000 to 2020, the area of forests, shrublands, wetlands, and sea areas decreased. The decreased forest area was mainly transferred to cultivated land and grassland, the majority of the converted shrublands was transferred to forests, the decreased wetland area was transferred to water bodies, and the decreased sea area was mainly transferred to artificial surfaces. The increased area of grassland is mainly converted from forest. The difference between the transferred out and transferred in of cultivated land is small, and the area change is the smallest.

3.2. Valuation of Ecosystem Service Values in Guangxi

Based on the equivalence factor table improved by Xie et al. [20], the equivalence table of the ecosystem service value per unit area was revised by combining the ecological environmental conditions in Guangxi. The type of farmland cultivation in Guangxi was mainly rice, so the cultivated land ecosystems corresponded to the ecological service value equivalents of paddy fields under the farmland classification system. Guangxi had high forest cover and the main type of forest was evergreen broadleaf, so the ecological service value per unit area of Guangxi’s forest ecosystems corresponded to broadleaf forests. The type of grassland in Guangxi was mostly scrub, so the ecological service value equivalent in Guangxi’s grassland ecosystem corresponded to the secondary grassland classification of scrub. The ecological service value of the artificial surface was defined according to the opinion of Costanza et al. [9] and related scholars, and the ecological service value of the artificial surface is defined as 0. Finally, we obtained an ecological service value equivalent table per unit area for Guangxi (

Table 4. Equivalent value of ecological services per unit area in Guangxi (unit: RMB·km⁻²).

Type 1	Type 2	Cultivated Land	Forest Land	Grass land	Shrubland	Wetlands	Water	Bare Land	Artificial Surface
Provision of services	Food production	1.36	0.29	0.38	0.19	0.51	0.80	0.00	0.00
	Raw material production	0.09	0.66	0.56	0.43	0.50	0.23	0.00	0.00
	Water supply	−2.63	0.34	0.31	0.22	2.59	8.29	0.00	0.00
Regulation service	Gas regulation	1.11	2.17	1.97	1.41	1.90	0.77	0.02	0.00
	Climate regulation	0.57	6.50	5.21	4.23	3.60	2.29	0.00	0.00
	Purify environment	0.17	1.93	1.72	1.28	3.60	5.55	0.10	0.00
	Hydrological regulation	2.72	4.74	3.82	3.35	24.23	102.24	0.03	0.00
Support service	Soil protection	0.01	2.65	2.40	1.72	2.31	0.93	0.02	0.00
	Maintain nutrient cycle	0.19	0.20	0.18	0.13	0.18	0.07	0.00	0.00
	Biodiversity conservation	0.21	2.41	2.18	1.57	7.87	2.25	0.02	0.00
Cultural service	Entertainment culture	0.09	1.06	0.96	0.69	4.73	1.89	0.01	0.00
Total		3.89	22.95	19.69	15.22	52.02	125.31	0.20	0.00

).

From 2000 to 2020, the main grain crops in Guangxi were early rice grain, late rice grain, and corn. Using Equation (3) and the Guangxi grain crop production and unit price data (

Table 5. Output and unit price of main grain crops in Guangxi in 2020.

Grain Type	Seeded Area/km2	Total Production/kg	Unit Price/RMB
Early rice	8051.80	4,767,500,000	2.54
Late rice	8212.00	4,431,900,000	3.04
Corn	5969.70	2,733,300,000	2.40

), the unit area service value of the farmland ecosystem in Guangxi in 2020 was calculated to be 20.65 × 10⁴ RMB·km⁻²·a⁻¹, and the table of the ecological service value per unit area of the ecosystem in Guangxi (

Table 6. Value equivalent of ecosystem services in Guangxi (unit: 10⁴ RMB·km⁻²·a⁻¹).

Type 1	Type 2	Cultivated Land	Forest Land	Grassland	Shrubland	Wetlands	Water	Bare Land	Total
Provision of services	Food production	28.09	5.99	7.85	3.92	10.53	16.52	0.00	72.90
	Raw material production	1.86	13.63	11.57	8.88	10.33	4.75	0.00	51.01
	Water supply	−54.32	7.02	6.40	4.54	53.49	171.21	0.00	188.35
Regulation service	Gas regulation	22.92	44.82	40.69	29.12	39.24	15.90	0.41	193.10
	Climate regulation	11.77	134.24	107.60	87.36	74.35	47.29	0.00	462.62
	Purify environment	3.51	39.86	35.52	26.44	74.35	114.62	2.07	296.36
	Hydrological regulation	56.17	97.89	78.89	69.19	500.41	2111.51	0.62	2914.68
Support service	Soil protection	0.21	54.73	49.57	35.52	47.71	19.21	0.41	207.35
	Maintain nutrient cycle	3.92	4.13	3.72	2.68	3.72	1.45	0.00	19.62
	Biodiversity conservation	4.34	49.77	45.02	32.42	162.53	46.47	0.41	340.97
Cultural service	Entertainment culture	1.86	21.89	19.83	14.25	97.69	39.03	0.21	194.75
Total		80.34	473.97	406.65	314.33	1074.34	2587.96	4.13	4941.72

) was further calculated according to Table 4. The ecosystem service values were expressed as 11 types, among which the ESVs of the hydrological regulation, climate regulation, and biodiversity accounted for a relatively high proportion, indicating that hydrological regulation and climate regulation play an important role in measuring the regional ecological service values in Guangxi. The contribution rate of the ESV of the hydrological regulation per unit area was 59%. The ecological service values of the water and forest ecosystems were high and played important roles in increasing the total ESV and maintaining the stability of the ecological service values in Guangxi.

Equation (4) was used to calculate and obtain the service values of the different ecosystem types in Guangxi in 2000, 2010, and 2020. Then, the data were further analyzed for the rate of change to obtain

Table 7. Ecosystem service value and its changes in Guangxi from 2000 to 2020.

Land Use Type	ESV (108 RMB)			2000–2010		2010–2020		2000–2020
	2000	2010	2020	108 RMB	%	108 RMB	%	108 RMB	%
Cultivated land	518.14	533.08	520.61	14.94	2.88	−12.47	−2.34	2.47	0.48
Forest land	7394.09	7193.17	7124.91	−200.92	−2.72	−68.27	−0.95	−269.19	−3.64
Grassland	367.78	451.72	433.81	83.95	22.83	−17.92	−3.97	66.03	17.95
Shrubland	61.92	53.23	48.70	−8.70	−14.05	−4.53	−8.50	−13.22	−21.36
Wetlands	11.43	3.30	5.15	−8.13	−71.12	1.85	55.87	−6.29	−54.98
Water	664.47	811.08	897.62	146.61	22.06	86.54	10.67	233.15	35.09
Total	9017.85	9045.60	9030.80	27.75	0.31	−14.80	−0.16	12.95	0.14

on the change of ESV in Guangxi. From 2000 to 2020, the ESV in Guangxi initially increased and then decreased, increasing by 2.775 billion RMB in the first period and decreasing by 1.480 billion RMB in the second period. The increase in the ESV was greater than the decrease. Overall, the ESV in Guangxi increased by 1.295 billion RMB. The ESV in Guangxi in 2000 was 901.79 billion RMB, and the total ESV in Guangxi in 2020 was 903.08 billion RMB, i.e., it increased by 0.14% overall.

From 2000 to 2010, the wetlands exhibited the largest rate of change in the ESV, decreasing from 1.143 billion RMB in 2000 to 0.330 billion RMB in 2010, with a dynamic change in the wetlands ecosystem service value of −7.1%. The grassland and water ecosystem service values had rates of change of 22.83% and 22.06%, with their ESVs increasing by 8.395 billion RMB and 14.66 billion RMB. The decrease in the forest ecosystem service value was the largest, with a total decrease of 20.09 billion RMB. During period 1, due to the large increases in the areas of the cultivated land, grassland, and water, the sum of the increases in the ESVs of the three was greater than the sum of the decreases in the ecosystem service values of forest, shrubland, and wetlands. So, overall, the ESV in Guangxi increased by 2.775 billion RMB.

From 2010 to 2020, the ESVs of the forest land, grassland, cultivated land, and shrubland in the non-artificial surface ecosystems decreased, among which the ESV of the forest decreased by 6.827 billion RMB, the ESV of the grassland decreased by 1.792 billion RMB, and the ESV of the cultivated land decreased by 1.247 billion RMB. The ESV of the shrubland exhibited the largest rate of change of −8.5%. During period 2, the areas of cultivated land, forest land, grassland, and shrubland decreased, and the sum of the increases in the ESVs of the water and wetlands was smaller than the sum of the decreases. Overall, the ESV in Guangxi decreased by 1.480 billion RMB. Large amounts of cultivated land and forest were converted into artificial surface, and the large reduction in the forest land area exacerbated the reduction of the ESV in Guangxi. This was an important reason for the reduction of the ESV in Guangxi during the second period.

From 2000 to 2020, the amount of change in the ESV of the forest was the largest, with a decrease of 26.919 billion RMB. The change in the ESV of the cultivated land was the smallest, with an increase of only 0.267 billion RMB. The rate of change of the ESV was the smallest for the cultivated land, and the rate of change in the ESV of the cropland was 0.48%. The wetlands ecosystem exhibited the largest rate of change of the ESV, with a rate of change of −54.98%. In the different periods, the ESV of the forest accounted for more than 75% of the total ESV in Guangxi, and the ESVs of the forests and water accounted for more than 88% of the ESV in Guangxi, indicating that the forest and water ecosystems were important supporting components of the ESV in Guangxi. Overall, the increase in the ESV in Guangxi from 2000 to 2020 was due to the increases in the grassland and water areas.

3.3. Analysis of the Drivers of the Changes in the ESV in Guangxi

3.3.1. Spatial Autocorrelation Analysis of ESV in Guangxi

From Figure 4, it can be seen that the global Moran’s I index values for Guangxi were positive in 2000, 2010, and 2020 (0.336, 0.310, and 0.335, respectively). The Z-scores were 20.22, 18.68, and 20.14, which reflected the high spatial agglomeration of the ESV in Guangxi in terms of the spatial distribution. From 2000 to 2020, the trend of Moran’s I index in Guangxi decreased and then increased, and the overall change was not significant. This was mainly because the forest land and grassland were mainly concentrated in the northern part of Guangxi, while the cultivated land and artificial surface were concentrated in the central part of Guangxi and the coastal area of the Beibu Gulf, so the land use structure exhibited high spatial aggregation. Figure 5 presents the local indicators of spatial association (LISA) aggregation map of the ESV in Guangxi. It can be seen that the spatial aggregation status of the ESV in Guangxi changed significantly from 2000 to 2020, the range of the high-high value aggregation areas and the range of the low-low value aggregation areas decreased, but the range of the high-high value aggregation areas was much larger than that of the low-low value aggregation areas. The change in the spatial aggregation of the ESV was larger during period 1, and the range of the low-low value aggregation areas decreased significantly. The distribution of the ecosystem service values in Guangxi exhibited significant spatial aggregation, and the high-high value aggregation areas were mainly distributed in the northeastern and northwestern parts of Guangxi because the land use types in the northern part of Guangxi were mainly forest and grassland. The high ESV areas were concentrated in the cities of Hechi, Liuzhou, and Guilin in the northern part of Guangxi. In 2000, the high ESV aggregation areas were mainly distributed in northern Guangxi; while the low ESV aggregation areas were relatively scattered and mainly distributed in the border area of Guangxi Province, the coastal area of the Beibu Gulf, and the cities of Laibin and Guigang in central Guangxi. The predominant land use type in the coastal area of the Beibu Gulf was artificial surface, with few land cover types and a comparatively singular structure, constituting low-low value ESV aggregation areas. In 2020, the high ESV aggregation areas were mainly distributed in the cities of Hechi, Liuzhou, and Wuzhou. The scope of the ESV low-low value aggregation areas was greatly reduced, and they were concentrated in the border area between Guangxi and Vietnam and in Beihai City. The ESV aggregation of the insignificant areas in Guangxi accounted for a large proportion and was mainly concentrated in southern-central Guangxi.

3.3.2. Impact of Land Use/Cover Change on ESV in Guangxi

Changes in the land use structure had a certain influence on the direction of change and the degree of change in the ESV in Guangxi. As can be seen from

Table 8. Contribution rate of ESV variation in Guangxi from 2000 to 2020 (unit: %).

Land Use Type	2000–2010	2010–2020	2000–2020
Cultivated land	53.85	84.28	19.10
Forest land	−724.05	461.36	−2078.28
Grassland	302.51	121.08	509.79
Shrubland	−31.35	30.59	−102.10
Wetlands	−29.30	−12.47	−48.53
Water	528.33	−584.84	1800.04

, the absolute values of the contribution of variation of forests, water bodies, and grasslands in the three time periods were relatively high. In the 1st period, the total ESV in Guangxi increased by 0.31%, reflecting that the increase in the area of cultivated land, grassland, and water bodies had positive contribution to the increase of ESV in Guangxi in this period, among which the increase in the area of water bodies had the largest contribution to the increase of total ESV, and the variation contribution rate of water bodies was 528.33%. In period 2, the change rate of total ESV in Guangxi was −0.16%, while the contribution rates of variation of arable land, forest, grassland, and shrubland were all positive from 2010 to 2020. Moreover, the decrease of their areas also contributed to the decrease of total ESV in Guangxi, and the contribution rate of variation of forest was 461.36%, indicating that the decrease of forest area had the greatest influence on the decrease of ESV in this period.

The rate of change of the ESV in Guangxi from 2000 to 2020 was 0.14%. In general, the change in the ESV in Guangxi was not significant, but the conversions of each land type were very obvious, and the rates of change and the contributions of the various changes were large. From the data in Table 8, it can be seen that the absolute values of the contributions of the ecological service value variation from 2000 to 2020, in descending order, were forest land > water > grassland > shrubland > wetlands > cultivated land, among which the changes in the forest land and water areas had the greatest impacts on the ecosystem service values. The rate of change of the ESV of the forest land was relatively small, but the decrease in the ESV of the forest land was the largest, and the absolute value of the contribution rate to the ESV variation was the highest (−2078.28%). The change in the ESV of the forest made a negative contribution to the change in the ESV in Guangxi, indicating that the decrease in the forest area was the main reason for the decrease in the ESV in Guangxi during the second period. The $ES{V}_c$ was greater than 0 for the water and grasslands, and the changes in the ESVs of the water and grasslands made positive contributions to the change in the ESV in Guangxi, indicating that the increases in the water and grassland made an important contribution to the increase in the ESV in Guangxi and was the main reason for the increase in the ESV in Guangxi from 2000 to 2020. The contribution rate of the forest and water ecosystems to the ESV in Guangxi was as high as 88%, indicating that they were an important part of the ESV in Guangxi.

The rate of change and contribution rate of the ESV of the cultivated land were relatively small, and the change in the area of the cultivated land was also very small since the difference between, the destruction and creation of cultivated land, was not large, which ensured the dynamic balance of the area of the cultivated land in Guangxi. Based on the above analysis, the higher the ecological service value equivalent of a single land use type and the larger the land use/cover area, the greater the influence on the change in the total ESV in Guangxi, and the degree of land use/cover area change affects the change trend of ESV, which shows that land use/cover change is the main driving force of the change in the ESV in Guangxi.

4. Discussion

The analysis conducted in this study revealed that the land use/cover changes in Guangxi from 2000 to 2020 mainly consisted of large decreases in the areas of the forest land, shrubland, and sea area, and the area of forest decreased by 5679.39 km² in 20 years. The area of water bodies and artificial surface increased a lot, and the area of water bodies increased by 900.90 km², and the area of artificial surface area increased rapidly with a total increase of 3390.67 km². The area of cultivated land and grassland first increased and then decreased, and the increase of both areas was greater than the decrease. The area of grassland increased by 1623.76 km², and the cultivated land area increased by 307.88 km² in total. The overall change in the cultivated land area was small, and the area change rate was 0.48%. The area of wetland first decreased a lot and then increased slightly, and the area of wetland decreased by 58.51 km² during the study period.

During 2000–2020, the total ESV in Guangxi initially increased and then decreased, and the increase was greater than the decrease, with a total increase of 1.295 billion RMB. In the first period, the increase of ESV in Guangxi by 2.775 billion RMB is due to the large increase of cultivated land, grassland, and water body area in the first period, and the increase of artificial surface area is relatively small, among which the increase of water body area contributes the most to the increase of ESV in Guangxi, thus it can be seen that the degree of change of water body area has great influence on the change of ESV in Guangxi. In the second period, the ESV of Guangxi decreased by 1.480 billion RMB, mainly affected by the large decrease of forest and grassland area and the large increase of artificial area in the second period, among which the decrease of forest area has the biggest influence on the decrease of ESV of Guangxi. The forest area decreased by 1440.34 km², the grassland area decreased by 440.59 km², while the artificial surface increased by 3267.51 km² in the 2nd period. A large amount of forest and cultivated land was transferred to artificial surface, which intensified the decrease of ESV in Guangxi. It can be seen that the higher the ecological service value equivalent value of the ecosystem, the greater the degree of change in its land cover area and the greater the magnitude of influence on the change of ESV in Guangxi, and the increase or decrease of ESV in Guangxi is mainly influenced by the change of forest, water body, and grassland area.

The spatial autocorrelation analysis shows that the distribution characteristics of ESV in Guangxi are high in the north and low in the south; the Moran’s I index of ESV in Guangxi is greater than 0 in 2000, 2010, and 2020, which were 0.336, 0.310, and 0.335, respectively, indicating that ESV in Guangxi has autocorrelation in spatial distribution. Getis-Or’’s Gi* analysis of ESV in Guangxi obtained Z-scores of 20.22, 18.68 and 20.14 in 2000, 2010 and 2020, respectively, indicating that ESV in Guangxi showed high aggregation in spatial distribution. The ESV high-high value aggregation areas in Guangxi are distributed in the mountainous areas in northeastern and northwestern Guangxi, and the land cover types of ESV high-high value aggregation areas are mainly forests and grasslands, which indicates that forest and grassland cover areas have higher ecosystem service values compared with other land cover types. From 2000 to 2020, the ESV high-high value aggregation areas in Guangxi show a decreasing trend, indicating that the decrease of forest area affects the distribution range of ESV high-high value aggregation areas. The change of ESV in Guangxi was closely continuous with the change of land cover area. In order to maintain and increase the value of ecosystem services in Guangxi, it is necessary to strengthen the protection and restoration of forest, grassland, and water body cover areas, and the contribution of forest and water body ecosystems to ESV in Guangxi is high, which determines the trend of total ESV in Guangxi to a certain extent.

In order to better implement the 14th Five-Year Plan (2021–2025) for Eco-environmental Protection in Guangxi and to improve the ESV in Guangxi, it is necessary to strengthen the protection and restoration of the forest and water ecosystems, focusing on the ecological protection and repair projects in the old revolutionary areas of the Left and Right River Basin in Guangxi. Comprehensive management of stone desertification in Baise, Hechi, Liuzhou, and Guilin encourages the return of farmland to forests and grassland to prevent soil erosion. The principles of green development and high-quality development should be adhered to, the construction of coastal protection forests in coastal areas should be strengthened, the single land use structure in coastal areas should be improved, the Beibu Gulf forest city cluster should be created, and the vegetation coverage in the coastal cities should be improved. In the mountainous areas in northern Guangxi, the unique natural environment features can be used to create ecological tourism areas and obtain maximum ecological value. Regarding the use of land resources, Guangxi should develop a scientific and reasonable land utilization model while developing the economy and should prevent the excessive expansion of urban artificial surface. Second, the increase in the use of land for urban and rural residents should be reasonably regulated, and the area of urban construction in the central basin in Guangxi and the Beibu Gulf city cluster should be reasonably planned to give full play to the overall benefits of the land resources.

Due to the limited cultivated land resources, poor land quality, and low land use efficiency in the southwest border area [45], the area of basic farmland land should be protected, and land preparation and development should be promoted to create modern farmland. In recent years, the arable land area in Yunnan Province has been decreasing, the massive expansion of artificial surface and encroachment on arable land still exist, and the significant reduction of arable land area is the trend of future land use changes [46]. The area of artificial surface in Xinjiang is increasing rapidly, and the artificial surface is mainly converted from arable land and grassland [47]. In Guangxi in 2010–2020, the cultivated land area decreased sharply, a large area of cultivated land was transferred to artificial land surface, and the cultivated land resources were seriously damaged. It can be seen from the land use/cover changes of Chinese frontier provinces/autonomous regions that with the development of urbanization, the area of artificial surface increases faster and the construction of artificial surface takes up a large area of arable land. In order to optimize the land use pattern of Guangxi, we should plan urban land reasonably, implement cultivated land protection policy strictly, and promote the good development of ecosystem service value. In addition, the ecological construction of farmland should be strengthened, the ecological cycle of agricultural farmland should be realized, and full play should be given to the production and ecological functions of farmland. Finally, the areas of forest and grassland should be improved and protected, and the protection and restoration of ecological land, such as nature reserves, should be strengthened to promote the sustainable growth of the ESV in Guangxi.

Currently, the valuation of ecosystem services is a popular research topic in human geography, ecological economics, and environmental economics [48]. Changes in the land use structure and changes in the degree of utilization can affect biodiversity and ecosystem productivity [49], and the land use structure plays a decisive role in the maintenance of ecosystem service functions [50]. Ecosystems are closely linked to socioeconomic activities [51], and the current rapid development of urbanization has accelerated the rate of change of the land use structure in Guangxi. The large increase in the area of artificial surface has damaged the ecological balance to a certain extent. In this study, the land use dynamic attitude was investigated, a land use transfer matrix was created, ecosystem service value evaluation was conducted, and the ESV spatial autocorrelation of the land use structure in Guangxi was analyzed, but there are still shortcomings to this study in terms of using the equivalent factor method to evaluate the ESV in Guangxi because this method ignores the negative impact of artificial surface on the ecosystem service value. Since the evaluation of the urban ecological service value is comparatively complex, the growth of urban residential land is accompanied by the construction of urban ecological green space, and there are great differences between the green area and ecological environmental quality in different cities, so the methods of assessing the ecosystem service value in different cities will change and need to be scientifically evaluated in conjunction with the actual situation [52]. Scientific assessment of urban ecological service values requires a comprehensive and systematic comparison of the similarities and differences between urban ecosystems and natural ecosystems [53], as well as continuous improvement and refinement of the ecosystem service value assessment system.

5. Conclusions

With the analysis of land use dynamics and land use transfer matrix based on the land use data of Guangxi in 2000, 2010, and 2020, this paper calculates the ecosystem service value of Guangxi based on the land use/cover in different periods and further analyzes the spatial autocorrelation of ESV in Guangxi. The following conclusions were obtained.

(1)

During 2000–2020, the areas of the forest land, shrubland, and sea area in Guangxi decreased continuously, among which the area of the forests decreased by 5679.39 km² (3.64%). The areas of the cultivated land, grassland, water, and artificial surface have increased, among which the area of the artificial surface increased by 3390.67 km² (by 1.36 times). The increase in artificial surface was mainly achieved through the conversion of cultivated land and forest land.

(2)

From 2000 to 2020, the ESV in Guangxi initially increased and then decreased, with a net appreciation of 1.295 billion RMB. In the first period, Guangxi’s ESV increased by 2.775 billion RMB due to the large increases in the areas of the cultivated land, grassland, and water. In the second period, the areas of the cultivated land, forest land, grassland, and shrubland decreased, and the ESV in Guangxi decreased by 1.480 billion RMB. Large amounts of cultivated land and forest land were converted into artificial surface, which was an important reason for the decrease in the ESV in Guangxi during the second period. From 2000 to 2020, the increase in water bodies contributed the most to the increase in total ESVs in Guangxi.

(3)

The distribution of the ESV in Guangxi exhibited significant spatial aggregation. The spatial distribution of the ESV in Guangxi was high in the north and low in the south. ESV high-high value aggregation areas were mainly distributed in northeastern and northwestern Guangxi. ESV low-low value aggregation areas were mainly distributed in the coastal areas of Beibu Gulf.

This article was not detailed and comprehensive enough to assess the ecosystem service value of Guangxi, and this study is based on the whole area of Guangxi to analyze the change of ESV in Guangxi, which lacks the guidance significance for the land use planning of a city or a county in Guangxi. Hence, the next step could be to subdivide the study area according to the administrative divisions of Guangxi to analyze the land use/cover change and ESV change of each area in more depth.