Spatial and Temporal Evolution Characteristics of the Ecosystem Service Value along the Beijing–Hangzhou Grand Canal

Abstract

The study of the spatiotemporal evolution characteristics of ecosystem service values (ESVs) is an important basis for the coordinated development of the regional nature, economy, and society and the optimization of the ecological environment. The ecological zone is an important component of the Beijing–Hangzhou Grand Canal cultural belt. Ecosystem services are a concrete manifestation of land use structure and function. A thorough study of the value of ecosystem services in areas along the Beijing–Hangzhou Grand Canal is important for promoting the long-term and stable sustainable development of the regional economy. Based on a revised equivalent factor table, this study selected land use data from 1991, 2006, and 2021 to analyze the temporal and spatial evolution characteristics of ESVs along the Beijing–Hangzhou Grand Canal. The results show that (1) the ESVs along the Grand Canal first increased and then decreased from 1991 to 2021. The reason for this is the change in land use along the Beijing–Hangzhou Grand Canal. Specifically, the conversion of land use types from farmland to water areas contributed to the increase in the value of ecosystem services, while the conversion of farmland and grassland into construction land led to a decrease in the service value of the region. (2) the value of individual ecosystem services along the Beijing–Hangzhou Grand Canal from 1991 to 2021 varied greatly. The ESV provided by hydrological regulation was the largest and the ESV provided by maintenance nutrients was the smallest. (3) the areas along the Beijing–Hangzhou Grand Canal exhibited a specific pattern in terms of the value of ecosystem services, with the regions centered in Beijing and Tianjin showing relatively low values, while the middle section of the Grand Canal demonstrated relatively high ESV. According to the spatial and temporal distribution characteristics and the leading factor for the changes in ESVs, appropriate policies can be formulated in respective regions to implement ecological protection and land use planning, thereby providing a reference for the adaptation and restoration strategies of the ecosystem along the Grand Canal.

1. Introduction

Ecosystem services cover the ecological functions that support and meet the needs of human survival. The ecosystem service value (ESV) is a common indicator for evaluating the status of ecological services. With the acceleration of urbanization, urban expansion has impacted the ecological environment along the Beijing–Hangzhou Grand Canal [1]. In 2019, the state issued the “Outline of the Planning for the Protection, Inheritance and Utilization of the Grand Canal Culture”, which proposed the construction of a corridor along the Grand Canal to optimize the ecological space. Studying the spatial and temporal distribution of ESV and its evolution along the Grand Canal can provide a blueprint for development along the route that promotes the region’s cultural and ecological environment.

In recent years, scholars have conducted extensive research on ecosystem services. The research methods for ESV mainly include the market value method, environmental cost method, and equivalent factor method. Based on the market value method, Adger et al. [2] calculated the total value of Mexico’s forest ecosystem services in four ways: direct value, indirect value, choice value, and existence value. Wu et al. [3] used the market value method and the shadow engineering method to estimate the value of the ecological services of a plantation in Tianjiling, Changsha, China. Wang et al. [4] calculated the value of ecological products in the Cangzhou section of the Grand Canal using the market value and the alternative engineering methods to evaluate the ecosystem service functions in this region. With its convenience in data acquisition and extensive applicability, this method has become the mainstream choice for research on the value of ecosystem services. It was originally proposed by Costanza et al. [5] aiming to provide a classification evaluation and calculation framework for the global value of ecosystem services. Xie et al. [6] have made localized modifications to form a value assessment method suitable for different ecosystems and different ecological service functions in China. Hu et al. [7] used the equivalent factor method to calculate the ESVs for 25 border counties in Yunnan Province, China, and used the coupling coordination degree and geographic detector to explore the interaction between urbanization level and ESV in the region and to reveal the factors influencing this spatial pattern. Based on land use change, Yu et al. [8] conducted an in-depth analysis of the temporal and spatial evolution characteristics of ESVs in the Dongjiang River Basin from 2010 to 2020 and explored the formation mechanism of differences in the spatial distribution of ESVs in the Dongjiang River Basin using geographical detector tools. The study areas include the GuangdongHong Kong–Macao Greater Bay Area, the Yellow River Basin, the Yangtze River Delta, and the Minjiang River Basin. Yan et al. [9] revealed the spatial and temporal evolutionary characteristics of the coastal wetland ESV in the Yellow River Delta from 1990 to 2020 and explored the mechanisms impacting the changes in the ESV in this region. Liu et al. [10] reported the spatial and temporal evolution characteristics of the ESV in the Guangdong–Hong Kong–Macao Greater Bay Area from 2000 to 2015 and investigated the mechanisms influencing the ESV in the region. Taking the region along the main stream of the Yellow River as the study area, Xu et al. [11] first conducted a detailed analysis of land use changes in this region and further explored the temporal and spatial evolution characteristics of the regional ESV. Ma et al. [12] explored the evolutionary driving characteristics and direction of ESV by using the Yangtze River Delta urban agglomeration as a research object. Guo et al. [13] conducted a comprehensive assessment of the temporal and spatial changes in the ESV of the Yellow River Basin from 2000 to 2018 and revealed the interaction and coordination between the ESV and the intensity of human activities in this region by combining the coupling coordination degree and geographical detector model. Lan et al. [14] evaluated the ESV of the Minjiang River Basin from 2006 to 2016 and analyzed the change in the law and trade-off synergy of the ESV in the basin.

In summary, research on the value of ecosystem services has mostly focused on specific administrative regions or natural river basins, exploring in depth the changes in natural ecology and their impact on service value in these regions [15,16,17,18,19,20] but rarely involved the ESV of artificially excavated historical and cultural heritage sites formed by continuous human activities such as those along the Grand Canal. Based on land use data for the Grand Canal region, this study uses the equivalent factor method to evaluate the ESV as well as the spatial and temporal evolution characteristics of cities along the Grand Canal from 1991 to 2021 to provide a reference for the Grand Canal’s protection, restoration, and enhancement.

2. Research Methods and Data Sources

2.1. Overview of the Study Area

With a history of more than 2500 years, the Beijing–Hangzhou Grand Canal stretches for 1794 km. The longitude and latitude of the Beijing–Hangzhou Grand Canal are roughly 115°45′ to 119°42′ east and 30°40′ to 35°50′ north. It is the earliest, longest, and largest man-made river in the history of human civilization. Based on it, the authorities of the feudal dynasty established a thousand-year water transport system that transported materials from all over the world to the capital. The Grand Canal has played an important role in contemporary China’s culture, tourism, economy, ecology, and other aspects. The Grand Canal is located in the central and eastern regions of China. Its main route covers two municipalities (Beijing and Tianjin) and five provinces (Hebei, Shandong, Henan, Jiangsu, and Zhejiang) (Figure 1). These regions differ significantly in natural conditions and social situations, resulting in uneven social and economic development. The areas north of the Yangtze River have relatively poor social and economic development, relying mainly on traditional agriculture and industry, leading to a relatively low socioeconomic standard of living. Because the Grand Canal spans different climatic zones, the vegetation and geographic landscape characteristics also vary from south to north. The average annual precipitation in the region south of the Yangtze River typically exceeds 1000 mm, indicating a prominent humid climate, while the average annual temperature generally surpasses 15 °C. On the other hand, the average annual precipitation on the northern bank of the Yangtze River ranges between 500 and 700 mm, with an average annual temperature of around 10 °C. These unfavorable natural conditions pose certain pressures on the ecological environment of the region [21,22].

2.2. Data Sources and Processing

The data used in this study mainly include basic geographic data, land use data, and socioeconomic statistical data. The basic geographic data were used to show the scope of the area along the Grand Canal and were sourced from the 1:1,000,000 scale national basic geographic database provided by the Ministry of Natural Resources of the People’s Republic of China “https://www.webmap.cn/ (accessed on 10 April 2023)”. The land use data used in this study were produced by Yang and Huang’s research team at Wuhan University and are based on the Google Earth Engine cloud platform and use Landsat data for three periods (1991, 2006, and 2021) along the Beijing–Hangzhou Grand Canal. The data resolution is 30 m [15]. ArcGIS 10.7 software was employed to reclassify the land use data into seven categories: cultivated land, construction land, unused land, woodland, grassland, water body, and wetland. When evaluating the value of ecosystem services, it is necessary to determine the economic value corresponding to the standard equivalent factor in the study area. The calculation of economic value relies on three core data for major food crops in the study area: sowing area, unit yield, and market price per unit yield. The data for sowing area and unit yield of food crops are derived from the statistical yearbooks of various provinces in the study area, while the market price per unit yield of food crops is determined based on the annual price list of national agricultural products market in the Yearbook on Food and Strategic Reserves in China.

2.3. Research Methods

The key issues in ecosystem service valuation are the calculation and driving factor analysis of ESV. In the calculation of ESV, this study uses land use structure analysis and the equivalent factor method to examine the changes in the ecological environment along the Grand Canal.

Based on a survey of more than 200 ecologists and considering the actual situation in China, Xie et al. [6] developed a new ESV classification. This value system is divided into four primary categories: provisioning services, regulating services, supporting services, and cultural services. Specifically, provisioning services cover food production, raw material production, and water supply. Regulating services include gas regulation, climate regulation, environmental purification, and hydrological regulation. In terms of supporting services, the focus is on soil conservation, maintenance of nutrient cycling, and protection of biodiversity. Finally, cultural services emphasize the provision of aesthetic landscapes. The equivalent factors for ESV have been revised to adapt to China’s conditions, ensuring that the assessment results are more in line with China’s actual situation. Based on the research findings, this paper adjusts the equivalent value of ecosystem service in the study area according to the actual land use types along the Beijing–Hangzhou Grand Canal. The cultivated land types in this region include dry land and paddy fields, and for areas where the land use type is cultivated land, the equivalent factor takes the average value of the equivalents for dry land and paddy fields. Given the diversity of forest resources in the study area, the equivalent factor for forest land types takes the average value of the equivalents for coniferous forests, coniferous and broad-leaved mixed forests, broad-leaved forests, and shrub forests. The equivalent factor for grassland types takes the average value of the equivalents for meadows and shrub–grasslands. The equivalent factor for water areas directly adopts the water system equivalent value. For unused land types, the equivalent factor takes the average value of the equivalents for deserts and bare land. After the above adjustments, the table of equivalent factors for ecosystem service values within the study area is finally determined (see

Table 1. Equivalent factors for ESVs per unit area.

Land Use Type		Cultivated Land	Woodland	Grassland	Water Body	Wetland	Construction Land	Unused Land
Provisioning services	Food production	1.105	0.474	0.3	0.8	0.51	0	0.005
	Raw material production	0.245	0.482	0.445	0.23	0.5	0	0.015
	Water resources supply	−1.305	−0.286	0.245	8.29	2.59	0	0.01
Regulating services	Gas regulation	0.89	1.748	1.555	0.77	1.9	0	0.065
	Climate regulation	0.465	4.68	4.115	2.29	3.6	0	0.05
	Environmental purification	0.135	1.372	1.36	5.55	3.6	0	0.205
	Hydrological regulation	1.495	3.532	3.015	102.24	24.23	0	0.12
Supporting services	Soil conservation	0.52	1.86	1.895	0.93	2.32	0	0.075
	Nutrient cycling maintenance	0.155	0.18	0.145	0.07	0.18	0	0.005
	Biodiversity maintenance	0.17	1.734	1.725	2.55	7.87	0	0.07
Cultural services	Aesthetic landscape provision	0.075	0.76	0.76	1.89	4.73	0	0.03

).

Existing studies have shown that the equivalent factors for ESV are closely related to the market value of the average grain yield in the year. The main food crops in the study area are rice, corn, and wheat. Considering the availability of data, this study calculates the ecosystem service value of one equivalent factor in the area along the Beijing–Hangzhou Grand Canal to be 2700.78 yuan/hm² based on the main food production and market prices of yield per unit area in the study area in 2021. According to the basic equivalent factor table for China, the ecosystem service value per unit area along the Beijing–Hangzhou Grand Canal is calculated (

Table 2. ESV per unit area (unit: yuan/hm²).

Primary Type	Secondary Type	Cultivated Land	Woodland	Grassland	Water Body	Wetland	Construction Land	Unused Land
Provisioning services	Food production	3826.80	1233.08	1360.64	2806.32	2168.52	0.00	0.00
	Raw material production	2083.48	2678.76	1913.40	1573.24	2126.00	0.00	0.00
	Water resources supply	−1063.00	1403.16	1063.00	23,130.90	9822.13	0.00	0.00
Regulating services	Gas regulation	3018.92	8801.65	6633.13	5697.69	8078.81	0.00	85.04
	Climate regulation	1615.76	26,362.43	17,858.42	12,543.41	15,307.22	0.00	0.00
	Environmental purification	467.72	7653.61	5782.73	19,474.18	15,307.22	0.00	425.20
	Hydrological regulation	2211.04	16,412.74	12,841.05	268,896.77	103,026.07	0.00	127.56
Supporting services	Soil conservation	3954.36	10,715.05	8078.81	6888.25	9822.13	0.00	85.04
	Nutrient cycling maintenance	552.76	807.88	637.80	552.76	765.36	0.00	42.52
	Biodiversity maintenance	595.28	9779.61	7355.97	22,152.94	33,463.28	0.00	85.04
Cultural services	Aesthetic landscape provision	255.12	4294.52	3231.52	14,074.14	20,111.98	0.00	42.52

). One standard unit of ESV equivalent factor is equal to one-seventh of the average market value of the grain yield in that year [11]. The equivalent ESV per unit area along the Grand Canal is calculated by using Equation (1).

$$e={\displaystyle \frac{1}{7}}{\sum }_{k=1}^l{\displaystyle \frac{p_k{q}_k{s}_k}{S}}$$

(1)

where e is the equivalent ESV per unit area; k represents the number of major food crop types in the study area; p_k is the average price of type k food crop and the three main types of food crops in the region are rice, wheat, and maize according to the statistical yearbook; q_k is the yield of type k food crop; s_k is the planting area of type k food crop, taking into account the economic contribution of each type of grain crop; and S is the total planting area of food crops, reflecting the overall situation of grain production in the region.

The ESVs of different land use types in cities along the Grand Canal are calculated as follows:

$${ESV}_{total}={\sum }_{m=1}^n{V}_m\times A_m$$

(2)

$${ESV}_f={\sum }_{m=1}^n{V}_{m,f}\times A_m$$

(3)

where ESV_total is the total value of ecological services along the Beijing–Hangzhou Grand Canal, yuan; V_m is the ESV per unit area of land for the type of land use along the Beijing–Hangzhou Grand Canal, yuan/hm²; A_m is the area of the land use type, hm²; n is the number of land use types; ESV_f is the value of the ecosystem service in the individual ESV, yuan; and V_m,f is the contribution value of the Land use type m per unit area to the ecological service type f, yuan/hm².

3. Results

3.1. Temporal Changes in ESV

3.1.1. Changes in Total ESV

The changes in the total value of ecosystem services are closely related to the dynamic shifts in land use types during the study period. From 1991 to 2021, the ESV of water bodies was much higher than that of other land use types, followed by that of cultivated land and woodland, with the sum of ESVs of these three land use types accounting for more than 95% of the total ESV, indicating the pivotal role of water bodies, cultivated land, and forests in maintaining the stability of the ecosystem along the Beijing–Hangzhou Grand Canal. The distribution of land use areas along the canal was considered (

Table 3. ESVs of individual land use types along the Grand Canal from 1991 to 2021.

Land Use Type	1991		2006		2021
	ESV (CNY 100 Million)	Area of Land Use Type (km2)	ESV (CNY 100 Million)	Area of Land Use Type (km2)	ESV (CNY 100 Million)	Area of Land Use Type (km2)
Cultivated land	2454.20	140,093.63	2241.60	127,958.19	2095.35	119,609.48
Woodland	2351.04	26,081.39	2353.39	26,107.48	2338.51	25,942.32
Grassland	173.03	2591.98	126.05	1888.28	90.62	1357.50
Water body	4729.23	12,518.13	5455.65	14,440.94	5016.32	13,278.05
Wetland	0.07	0.32	0.06	0.29	0.06	0.28
Construction land	0.00	20,524.04	0.00	31,455.06	0.00	41,763.04
Unused land	0.15	164.20	0.11	123.46	0.02	23.02
Total ESV	9707.72	201,973.69	10,176.88	201,973.69	9540.88	201,973.69

). Cultivated land ecosystems occupy a significant portion, accounting for over 60% of the entire study area, making it the primary land use type in the region, followed by forests and construction land. The water body accounted for a smaller proportion of the area than woodland, cultivated land, and construction land, but had a higher ESV. The increase in the total ESV from 1991 to 2006 was mainly due to the increase in the area of the water body, and the decrease in the ESV from 2006 to 2021 was attributed to the rapid economic development in the region, the accelerated urbanization process, and the significant increase in construction land, resulting in continued reductions in cultivated land, woodland, grassland, and water body areas.

From 1991 to 2021, the ESV along the Beijing–Hangzhou Grand Canal exhibited a significant fluctuating trend of increasing first and then decreasing, with an overall decrease of CNY 16.684 billion. Among them, the ESVs of cultivated land and grassland continuously declined, reflecting the weakening of the ecological service supply capacity of these two land use types. The ESV of forest land experienced a slight increase and then gradually declined, eventually stabilizing at a level of CNY 233.851 billion. Although the ESV of water bodies first increased significantly and then decreased, it still showed an overall growth trend (

Table 4. Changes in the ESVs of individual land use types along the Grand Canal from 1991 to 2021.

Land Use Type	1991–2006		2006–2021		1991–2021
	Value Change (CNY 100 Million)	Value Change Rate (%)	Value Change (CNY 100 Million)	Value Change Rate (%)	Value Change (CNY 100 Million)	Value Change Rate (%)
Cultivated land	−212.59	−8.66	−146.25	−6.52	−358.85	−14.62
Woodland	2.35	0.10	−14.89	−0.63	−12.54	−0.53
Grassland	−46.98	−27.15	−35.43	−28.11	−82.41	−47.63
Water body	726.42	15.36	−439.33	−8.05	287.09	6.07
Wetland	−0.01	−10.86	0.00	−2.79	−0.01	−13.35
Construction land	0.00	0.00	0.00	0.00	0.00	0.00
Unused land	−0.04	−24.81	−0.09	−81.35	−0.13	−85.98
Total value	469.16	4.83	−636.00	−6.25	−166.84	−1.72

). From 1991 to 2006, the ESV increased by CNY 46.916 billion, reaching its highest total value in 2006, with an increase of 4.83%. The ESV of water bodies experienced the largest change, with an increase of CNY 72.642 billion, accounting for 99.68% of the total increase in value during this period. From 2006 to 2021, the ESV decreased by CNY 63.6 billion or 6.25%. The ESVs of water bodies and cultivated land changed greatly, with a total decrease of CNY 58.558 billion.

3.1.2. Changes in Individual ESVs

The ESVs can be divided into 11 types: food production, raw material production, water resource supply, gas regulation, climate regulation, environmental purification, hydrological regulation, soil conservation, nutrient cycling maintenance, biodiversity maintenance, and aesthetic landscape provision. Detailed calculations have been made for the ESV of each service and its changes (

Table 5. Values and changes in individual ecosystem services along the Grand Canal from 1991 to 2021.

Ecosystem Services	ESV (CNY 100 Million)			1991–2006		2006–2021
	1991	2006	2021	Change (CNY 100 Million)	Change Rate (%)	Change (CNY 100 Million)	Change Rate (%)
Food production	606.93	564.96	528.82	−41.97	−6.92	−36.14	−6.40
Raw material production	386.40	362.87	342.19	−23.54	−6.09	−20.68	−5.70
Water resources supply	179.99	236.66	217.84	56.66	31.48	−18.82	−7.95
Gas regulation	741.03	710.90	674.09	−30.12	−4.06	−36.81	−5.18
Climate regulation	1117.24	1109.87	1067.96	−7.37	−0.66	−41.91	−3.78
Environmental purification	523.99	551.87	520.94	27.88	5.32	−30.93	−5.60
Hydrological regulation	4137.24	4618.83	4278.13	481.59	11.64	−340.70	−7.38
Soil conservation	940.63	900.48	853.39	−40.15	−4.27	−47.09	−5.23
Nutrient cycling maintenance	107.09	101.01	95.28	−6.07	−5.67	−5.73	−5.68
Biodiversity maintenance	634.87	665.31	629.05	30.45	4.80	−36.26	−5.45
Aesthetic landscape provision	332.32	354.12	333.20	21.80	6.56	−20.93	−5.91
Total value	9707.72	10,176.88	9540.88	469.16	4.83	−636.00	−6.25

). From 1991 to 2021, the region along the Beijing–Hangzhou Grand Canal exhibited different trends in individual ecosystem services. Among them, the values of hydrological regulation, water resource supply, and aesthetic landscape experienced fluctuations of first increasing and then decreasing, but showed an overall increasing trend, indicating that these ecological services possess considerable resilience and recovery capabilities in the region. However, the two ecosystem services of environmental purification and biodiversity showed a trend of “first increasing and then decreasing”, but overall, they exhibited a decreasing trend. Food production, raw material production, gas regulation, climate regulation, soil conservation, and nutrient cycling maintenance all continued to decrease in ESV due to the expansion of construction land into woodland and grassland areas, which damaged the ecological environment. The decrease in the ESVs of food production and raw material production was mainly attributed to the high volume of cultivated land transfer.

Through an in-depth analysis of the ESVs along the Beijing–Hangzhou Grand Canal, the proportion and ranking of each individual service value were obtained (Figure 2). Hydrological regulation ranks first, followed by temperature regulation, soil conservation, gas regulation, biodiversity, food production, environmental purification, raw material production, aesthetic landscape, water resource supply, and nutrient maintenance. From 1991 to 2021, hydrological regulation contributed most significantly to the total ESV in the study area, accounting for more than 40% of the total ESV. This highlights its central role in maintaining regional ecological balance. Additionally, the four ecosystem services of gas regulation, temperature regulation, soil conservation, and biodiversity also had significant impacts on the total ESV in the study area, demonstrating high levels of contribution. In contrast, nutrient maintenance, water resource supply, and aesthetic landscape contributed relatively limitedly.

3.2. Spatial Changes in ESVs

Most of the areas along the Grand Canal showed high ESVs, areas with medium ESVs were scattered, and areas with low ESVs were few and concentrated (Figure 3). In 1991, low-value centers formed in Beijing and Tianjin, while high-value areas were contiguous in the middle and southern sections of the Grand Canal. In 2006, high-value areas were mainly concentrated in water bodies such as Hongze Lake, Gaoyou Lake, and Taihu Lake, medium-value areas were mainly distributed across cultivated land, woodland, and grassland areas, and low-value areas were mainly concentrated in the Beijing–Tianjin region. In 2021, medium-value areas were mainly distributed across the cultivated land, woodland, and grassland areas in the middle section of the Grand Canal, and high-value areas extended beyond water bodies such as Hongze Lake, Gaoyou Lake, and Taihu Lake to include the initial and southern sections of the Grand Canal, where the ESVs shifted from medium to high. From 1991 to 2021, the ESVs in the Grand Canal areas showed a trend of first decreasing and then increasing, and medium-value areas were the most widely distributed and relatively stable. During the same period, low-value areas gradually expanded, with Beijing and Tianjin as centers, and the expansion changed significantly from 2006 to 2021.

Comparison of ESVs of the areas along the Grand Canal from 1991 to 2006, 2006 to 2021, and 1991 to 2021 showed similar trends in changes in ESVs (Figure 4). This was due to the relatively fast urbanization as a result of economic development along the Grand Canal, leading to the conversion of grassland and cultivated land into construction land. Except for the northern and southern sections of the Grand Canal as well as water bodies such as Hongze Lake, Gaoyou Lake, and Taihu Lake, where ESVs increased, most areas experienced a decrease in their ESVs.

4. Discussion and Conclusions

4.1. Discussion

Previous research on ecosystem service value has predominantly focused on specific administrative regions or natural river basins; however, this study addresses the ESV along the artificially excavated Grand Canal, shaped by ongoing human activities. Taking the regions along the Grand Canal as the study area, this study modified the equivalent factor coefficients proposed by Xie et al. [6] to obtain the ESV coefficients adapted to the region along the Beijing–Hangzhou Grand Canal, and then investigated the spatial and temporal evolutionary characteristics of the region’s ESVs.

The study revealed that from 1991 to 2021, the ESV along the Grand Canal generally followed a trend of initial increasing and then decreasing, which is closely associated with the acceleration of urbanization. This conclusion is similar to existing research results [7], where an increase in the level of urbanization typically leads to an initial increase and subsequent decrease in ESV. The urbanization process has a significant impact on the ESV, highlighting the importance of harmonious development between urban growth and the ecological environment in the 25 border counties in Yunnan Province, China. This study also indicates that changes in land use along the Beijing–Hangzhou Grand Canal have a significant impact on the ecosystem service value. The changes in the areas of land use types are the direct causes of changes in ecosystem service value [23,24], which has also been demonstrated in the Dongjiang River Basin and the main stream of the Yellow River [8,11]. The study also has certain limitations, such as the subjective nature of the selection process of value equivalents per unit area. This is because there is currently no unified and widely accepted parameter system to guide the implementation of this process. In addition, the study area spans several provinces, and different provinces and cities vary in the management and governance of the Grand Canal. Lastly, the differences in the types and prices of food crops have a certain impact on the results of this study.

The level of ecosystem services is intricately linked to human welfare and the pursuit of sustainable development, and they are instrumental in the resilience of ecological systems and environmental recovery. Consequently, forthcoming studies on the ecosystem service value along the Beijing–Hangzhou Grand Canal might consider initiating discussions on the formulation of a cohesive set of parameters and governance benchmarks. Within the framework of standardized research protocols, such studies could delve into identifying the equilibrium between urbanization and ecosystem services, as well as the enduring sustainability of the ecosystem service value along the canal’s corridor. This endeavor seeks to deepen the comprehension of the intricate nature of ecosystem service values and safeguard and augment these services with the ultimate goal of fostering regional sustainability.

4.2. Conclusions

Based on the research by Xie et al. [6], the changes in land use in areas along the Grand Canal from 1991 to 2021 and their impact on ESVs were analyzed using land use data for three periods (1991, 2006, and 2021) in combination with the ecosystem service coefficients per unit area modified by equivalent factors. The main conclusions are as follows:

(i)

The ESV along the Grand Canal generally showed a trend of first increasing and then decreasing, with an overall decrease of CNY 16.684 billion, which can primarily be attributed to the acceleration of the urbanization process. The temporal change in the total ESV along the Grand Canal was mainly related to the transfer between the areas of different land use types during the study period. The above trend led to a reduction in the areas of cultivated land, woodland, and grassland, while the substantial expansion of construction land decreased positive contributions and increased negative contributions to the ESV.

(ii)

The temporal changes in the individual ESVs along the Grand Canal varied greatly from 1991 to 2021, with hydrological regulation and nutrient cycling maintenance providing the highest and lowest ESVs, respectively. The ESVs of hydrological regulation, water resource supply, environmental purification, biodiversity maintenance, and aesthetic landscape provision showed a trend of first increasing and then decreasing, while the ESVs of food production, raw material production, gas regulation, climate regulation, soil conservation, and nutrient cycling maintenance decreased continuously.

(iii)

The spatial pattern of ESV along the Beijing–Hangzhou Grand Canal exhibited distinct regional characteristics. High-value areas are often found scattered amidst what can be described as ‘tiger-striped water’, a metaphorical representation of the patchy and irregular distribution of water bodies in the upstream, midstream, and downstream regions. These areas are typically rich in natural resources and support a favorable ecological environment, contributing to their high ecosystem service values. In contrast, mid-value areas were contiguously distributed across cultivated land, forests, and grasslands in the middle section of the Grand Canal, where ESVs were relatively moderate and widely distributed. Low-value areas are primarily concentrated in urban clusters in the Beijing–Tianjin region, which may be related to the urbanization process and human activities that disturb the ecosystem. The ESV along the Beijing–Hangzhou Grand Canal has undergone a trend of “first decreasing and then increasing”. The low-value areas centered in Beijing and Tianjin have gradually expanded, which may be linked to the acceleration of urbanization and increased ecological and environmental pressures in these regions. As the most widely distributed area, the mid-value region exhibited relatively stable ESVs, indicating a certain degree of resilience in maintaining ecosystem services in these regions. Furthermore, ESVs have increased in the northern and southern sections of the Grand Canal, as well as in water bodies such as Hongze Lake, Gaoyou Lake, and Taihu Lake. However, most areas exhibited a decrease in ESVs.

The conclusions we described are instrumental for formulating more scientifically sound ecological protection and land use planning to ensure the sustainability of ecosystems. The study discovered that the ESV in moderate-value areas is relatively stable, indicating that these regions possess a certain resilience in maintaining ecosystem services, providing insights into the adaptability and recovery strategies for ecosystems along the Grand Canal. The land use forms on both sides of the canal should be enhanced, considering the current ecological service supply situation, and there should be a strong emphasis on developing high-quality farmland to meet higher standards. The value of ecosystem services in different sections of the Grand Canal and their temporal and spatial evolution trends necessitate the designation of more rational ecological protection measures and land use planning to enhance the overall health of the region’s ecosystem, thereby exerting a positive influence on gross ecosystem product.