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Article

Urban–Rural Differences in Cropland Loss and Fragmentation Caused by Construction Land Expansion in Developed Coastal Regions: Evidence from Jiangsu Province, China

by
Jiahao Zhai
1,2 and
Lijie Pu
1,2,3,4,5,*
1
School of Geography and Ocean Science, Nanjing University, Nanjing 210023, China
2
Key Laboratory of Coastal Zone Exploitation and Protection, Ministry of Natural Resources, Nanjing 210023, China
3
School of Environment Engineering, Nanjing Institute of Technology, Nanjing 211167, China
4
NJIT Research Center, Key Laboratory of Carbon Neutrality and Territory Optimization, Ministry of Natural Resources, Nanjing 211167, China
5
International Joint Laboratory of Green & Low Carbon Development, Nanjing 211167, China
*
Author to whom correspondence should be addressed.
Remote Sens. 2025, 17(14), 2470; https://doi.org/10.3390/rs17142470
Submission received: 11 June 2025 / Revised: 9 July 2025 / Accepted: 15 July 2025 / Published: 16 July 2025
(This article belongs to the Special Issue Remote Sensing Applications in Land Cover Changes and Associated Environmental Effects: Progress, Challenges, and Opportunities)
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Abstract

With the acceleration of global urbanization, cropland loss and fragmentation due to construction land expansion have become critical threats to food security and ecological sustainability, particularly in rapidly developing coastal regions. Understanding urban–rural differences in these processes is essential as divergent governance policies, socioeconomic pressures, and land use transition pathways may lead to uneven impacts on agricultural systems. However, past comparisons of urban–rural differences regarding this issue have been insufficient. Therefore, this study takes Jiangsu Province, China, as an example. Based on 30 m-resolution land use data, Geographic Information System (GIS) spatial analysis, and landscape pattern indices, it delves into the urban–rural differences in cropland loss and fragmentation caused by construction land expansion from 1990 to 2020. The results show that cropland in urban and rural areas decreased by 44.14% and 5.97%, respectively, while the area of construction land increased by 2.61 times and 90.14%, respectively. 94.36% of the newly added construction land originated from cropland, with the conversion of rural cropland to construction land being particularly prominent in northern Jiangsu, while the conversion of urban cropland to construction land is more pronounced in southern Jiangsu. The expansion of construction land has led to the continuous fragmentation of cropland, which is more severe in urban areas than in rural areas, while construction land is becoming increasingly agglomerated. There are significant differences in the degree of land use change between urban and rural areas, necessitating the formulation of differentiated land management policies to balance economic development with agricultural sustainability.

1. Introduction

Rapid urbanization and economic development have led to significant changes in land use patterns worldwide, particularly in developing countries [1,2,3]. Among these changes, the construction land expansion and the consequent cropland loss have become critical issues as they directly impact food security, ecological balance, and sustainable development [4,5,6,7,8]. Urban areas, with their concentrated industrial and commercial activities, tend to exhibit more rapid and extensive construction land expansion compared to rural areas [9,10,11]. However, rural areas are not immune to these changes as they often serve as the hinterlands for urban expansion, experiencing their own patterns of land use transformation [4,12,13]. Understanding the differences in cropland loss and fragmentation between urban and rural areas is crucial for developing targeted land use policies that balance economic development with agricultural sustainability.
With the use of imagery from sources such as Landsat and Sentinel, the monitoring of land use changes has become more accurate, thereby better quantifying the cropland loss. Asia and Africa are the current and future hotspots for cropland loss due to urban expansion [14]. Previous studies conducted in China, India, and parts of Africa have demonstrated that cropland area continue to decrease due to urban expansion, industrial development, and infrastructure expansion [15,16,17,18,19]. Similar trends are observed in Latin America, where countries like Brazil have experienced significant cropland loss due to urban sprawl and the expansion of agro-industrial activities [20]. The conversion of cropland to construction land is driven by various factors, including population growth and economic development, which increase the demand for residential, commercial, and industrial spaces, leading to the transformation of agricultural land [11,21]. The expansion of transportation networks such as highways, railways, and airports often results in the fragmentation and degradation of cropland [22,23]. Weak land use planning, inadequate zoning regulations, and measures that encourage urban sprawl are all contributing factors to the cropland loss [24,25]. It is worth noting that due to significant disparities in rural development levels across different regions, the patterns of cropland resource utilization often vary considerably [26]. In addition to the absolute loss of cropland, there has been increasing attention recently on the issue of fragmentation, where large, contiguous areas of cropland are divided into smaller, isolated plots due to construction land expansion [27,28,29]. Fragmentation reduces farm size, limits mechanization, increases land management costs, and negatively impacts food security [30]. Meanwhile, fragmented cropland often leads to habitat loss, decreased soil fertility, and reduced carbon sequestration capacity [31,32,33,34].
Coastal regions, often characterized by high population density and economic activity, are particularly vulnerable to these transformations [35,36]. Jiangsu Province, located in the eastern coastal region of China, is a prime example of such dynamics. As one of the most economically developed provinces in China, Jiangsu has experienced substantial construction land expansion over the past few decades, resulting in significant cropland loss and landscape fragmentation [37,38,39]. Previous studies have extensively examined land use change in China, particularly urbanization and its impact on cropland. However, the unique “urban cluster–agricultural hinterland” interaction mechanism results in fundamental differences in the driving forces and spatial patterns of cultivated land loss between urban and rural areas. This duality has yet to be systematically quantified, making it difficult for policies to respond with precision. Additionally, studies on the spatial and temporal dynamics of cropland fragmentation caused by construction land expansion are still insufficient, especially in highly developed coastal areas such as Jiangsu Province.
Here, this study quantified the extent of cropland loss and construction land expansion in both urban and rural areas. It also examines the spatial patterns of these changes at the county level, providing insights into the regional disparities within the province. Additionally, we combined landscape pattern indices with the dynamic coupling of urban–rural boundaries to reveal the differentiated spatial stress mechanisms of farmland fragmentation caused by the construction land expansion, offering a deeper understanding of the ecological and spatial consequences of land use changes. The findings of this study have important implications for land use planning and policy-making in Jiangsu Province, and other similar regions. By highlighting the distinct patterns of cropland loss and fragmentation in urban and rural areas, this research provides a basis for developing differentiated strategies to mitigate the adverse effects of construction land expansion. Furthermore, the study contributes to the broader discourse on sustainable land use management in the context of rapid urbanization and economic development.

2. Materials and Methods

2.1. Study Area

Jiangsu Province is situated on the eastern coast of China, in the lower reaches of the Yangtze River, bordering the Yellow Sea to the east (Figure 1a). With a land area of approximately 107,200 km2, the province is predominantly characterized by plains, which account for over 70% of its terrain—the highest proportion of flatland among all Chinese provinces (Figure 1b). These plains, primarily composed of the northern Jiangsu plain and the Yangtze River Delta plain, feature low elevations, dense river networks, and a lake coverage rate of 6%, the highest in China. Low hills and mountains are sparsely distributed in the southwest and north. Jiangsu falls within the East Asian monsoon climate zone, with marked climatic differences between its northern and southern regions: areas north of the Huai River experience a warm temperate humid to semi-humid climate while those south of the Huai River have a subtropical humid climate. The province enjoys distinct seasons, synchronized rainfall and warmth, and an annual precipitation of 715–1280 mm. Maritime climate features are evident, accompanied by abundant solar and thermal resources. The Yangtze River traverses the province for 425 km from west-to-east, and the region hosts over 290 lakes, including Taihu Lake (China’s third-largest freshwater lake) and Hongze Lake (the fourth-largest). The dense water network provides natural advantages for agriculture and transportation.
As one of China’s most economically developed provinces, Jiangsu leverages its position along the Yangtze River Economic Belt and coastal advantages to form a diversified economic structure as the south focuses on high-tech industries and modern services, while the north emphasizes agriculture and manufacturing: regional disparities are significant. Cropland, the dominant land use type in Jiangsu, occupies 43.5% of the total land area, primarily distributed across the northern Jiangsu plain (including Yancheng, Xuzhou, and Huai’an) and the Lixia River region. Urban and rural construction land accounts for 14.2%, exhibiting a “dense south, sparse north” pattern. In the five southern cities (Suzhou, Wuxi, Changzhou, Nanjing, and Zhenjiang), construction land exceeds 25%, closely linked to industrial clusters.
It should be noted that Jiangsu Province consists of 21 counties, 23 county-level cities, and 55 municipal districts. Since some of the municipal districts are small in size, we combined them to obtain 62 county-level administrative districts as the study units [40] (Figure 1b).

2.2. Cropland and Construction Land Data

Cropland and construction land were obtained from the China Land Cover Dataset (CLCD, https://www.ncdc.ac.cn, (accessed on 14 September 2024)), which is a widely used and highly accurate (over 80%) dataset that can meet the needs of this study. The CLCD is based on the Google Earth Engine platform, utilizing Landsat series satellite images and produced using random forest, spatio-temporal filtering, and logical post-processing techniques, which offers a spatial resolution of 30 m and an annual temporal resolution since 1985 [41]. In this study we selected four years, 1990, 2000, 2010, and 2020, for subsequent analysis. The selected years (e.g., 1990, 2000, 2010, and 2020) not only align with decadal intervals to facilitate long-term trend analysis while minimizing short-term fluctuations but also capture pivotal shifts in China’s agricultural and land use policies, including the 1990s reforms, early 2000s sustainability initiatives, and post-2010 ecological conservation efforts. The cropland and construction land data required for this study were obtained using the clipping and mask extraction modules in ArcGIS 10.8.

2.3. Urban–Rural Boundary Demarcation

Jiangsu Province is a highly economically developed coastal region, and it is inappropriate to define urban and rural areas based on administrative divisions. We therefore refer to [42] and define areas larger than 5 km2 in the 2020 Global Urban Boundaries (GUB) dataset (http://data.ess.tsinghua.edu.cn, (accessed on 5 September 2024)) as urban areas. GUB is based on Global High Resolution Artificial Impervious Surface (GAIA) data, which captures the global distribution of impervious surfaces at a resolution of 30 m, encompassing all urban and peripheral settlements in the world with an area of more than 1 km2, with boundaries defined to avoid subjectivity, and is suitable for cross-regional comparisons [43]. The urban–rural boundary was obtained using the symmetrical difference module in ArcGIS 10.8. Ultimately this study produced 280 urban patches, with other patches defined as rural areas (Figure 1c). The ratio of urban to rural areas in Jiangsu Province is approximately 1:4.

2.4. Spatial Transformation and Landscape Pattern Analysis

Spatial transformation and landscape pattern analysis are critical components in landscape ecology and geographic information systems (GIS). These methods are used to understand the spatial structure, composition, and configuration of landscapes, as well as to quantify changes over time. Spatial transformation involves the manipulation and conversion of spatial data to reveal patterns, while landscape pattern analysis focuses on quantifying the spatial arrangement of landscape elements such as patches. In this study, the spatial transformation is mainly to reveal the quantity and spatial distribution characteristics of cropland loss due to construction land expansion. Regarding the landscape pattern analysis, we chose three landscape pattern indicators, namely, Patch Density (PD), Aggregation Index (AI), Mean Patch Area (AREA_MN), to measure the changes in fragmentation and aggregation of cropland and construction land. PD quantifies landscape subdivision, directly reflecting fragmentation intensity—critical for assessing cropland dispersion due to urbanization or rural expansion. AI measures patch connectivity, distinguishing between scattered and clustered patterns (e.g., aggregated construction land vs. fragmented cropland). AREA_MN complements PD by indicating average patch size, revealing whether land use changes lead to finer-grained fragmentation (e.g., cropland division) or consolidation. These landscape pattern indices were calculated using Fragstats 4.2 software, and the calculation formula and meaning are shown in Table 1.

3. Results

3.1. Urban–Rural Differences in the Quantity Changes of Cropland and Construction Land

From 1990 to 2020, the cropland area in Jiangsu Province decreased from 78,849.06 km2 to 68,023.74 km2, a reduction of 15.91% (Figure 2a). In contrast, the construction land area surged from 6924.04 km2 to 17,975.45 km2, an increase of 159.61% (Figure 2b). In urban areas, the cropland area sharply declined from 16,024.51 km2 in 1990 to 8951.29 km2 in 2020, a decrease of 44.14%, while the construction land expanded rapidly from 2811.15 km2 to 10,155.07 km2, an increase of approximately 2.61 times. In rural areas, the cropland area decreased from 62,824.56 km2 in 1990 to 59,072.45 km2 in 2020, a reduction of 5.97%, and the construction land increased from 4412.88 km2 to 7820.37 km2, an increase of 90.14%. It is evident that the construction land expansion and the cropland reduction in urban areas are particularly drastic, while in rural areas the cropland has slightly decreased and the expansion of construction land is also quite noticeable. Notably, before 2005, the construction land area in rural areas was higher than that in urban areas. However, due to the faster expansion rate of construction land in urban areas, the construction land area in urban areas surpassed that in rural areas after 2005.
At the county level, cropland in urban areas has shown a decreasing trend across all counties from 1990 to 2020. The most obvious cropland reduction was found in Wujiang, Fengxian, Taizhou downtown, Suzhou downtown, Kunshan, Hai’an, Peixian, Rugao, and Donghai, with reduction rates ranging from 55.60% to 64.76%. (Figure 3a). Specifically, cropland in Pizhou, Fengxian, Zining, Peixian, Yixing, and Xiangshui decreased most significantly during 1990–2000, with a reduction rate between 16.06 and 20.00% (Figure 3b). During 2000–2010, cropland in southern Jiangsu region decreased most drastically, such as in Suzhou downtown, Wujiang, Kunshan, Changshu, Zhangjiagang, Wuxi downtown, and Changzhou downtown, with a reduction rate of 29.25–37.93% (Figure 3c). From 2010 to 2020, the reduction in cropland was more pronounced in central Jiangsu, particularly in Hai’an, which saw a 41.58% decrease (Figure 3d). Additionally, Taizhou downtown, Rugao, Jingjiang, Jinhu, Funing, and Jianhu all experienced reductions in cultivated land area exceeding 33.30%.
From 1990 to 2020, the construction land in urban areas of all counties experienced rapid growth, and even in the northern Jiangsu region, where the expansion of urban construction land was the slowest, the area of urban construction land at least doubled or more (Figure 4a). The expansion of construction land in urban areas in the southern Jiangsu region is more drastic, especially in Wujiang, Kunshan, Lishui, Yangzhong, and Taicang, where the construction land area of urban areas has increased by 6.11 to 8.60 times. During 1990–2000, the expansion rate of urban construction land area was still higher in southern Jiangsu than in northern Jiangsu, as the rate in southern Jiangsu basically doubled and the rate in northern Jiangsu increased by 25.58–43.62% (Figure 4b). During 2000–2010, the overall trend is basically the same as in the previous period but the expansion rate accelerated, and the urban construction land area in the northern Jiangsu region also increased by more than 30.12% at least (Figure 4c). From 2010 to 2020, most of the fastest expanding areas are in central Jiangsu, such as Dafeng, Hai’an, Yancheng district, Jianhu, Jinhu, and also Lishui and Jurong in southern Jiangsu, where the area of urban construction land has increased by 63.67–88.04% (Figure 4d).
For rural areas, the rate of cropland reduction is much lower than that of urban areas. From 1990 to 2020, Gaochun is the county with the largest reduction in rural cropland, with a reduction of 27.63%, followed by Wujiang and Gaoyou, with reductions of 16.70% and 15.22%, respectively. In particular, the area of rural cropland in Lianyungang downtown, Dafeng, and Xuyi increased slightly (Figure 5a). In terms of the time period, the southernmost Kunshan, Suzhou downtown, Wujiang, and Yixing had the most obvious decrease in rural cropland area from 1990 to 2000, with the decrease rate ranging from 9.10% to 14.46%. While five counties, Xuyi, Haimen, Dafeng, Dongtai, and Rudong, saw a slight increase in the cropland area (Figure 5b). The rural cropland area in Gaochun decreased the most from 2000 to 2010, reaching 26.33%, followed by Kunshan and Wujiang at more than 10.00% (Figure 5c). The rural cropland area of Lianyungang downtown, Guanyun, Wuxi downtown, and Baoying increased, especially the rural cropland area of Lianyungang downtown which increased most significantly by 5.99% in this period. In the last period, the decreasing trend of rural cropland slowed down significantly, and the most obvious decrease was only 5.65% in Haian (Figure 5d). In 20 counties there was an increase in the area of rural cropland, especially in the Suzhou downtown and Kunshan where the increase was most obvious, with increases of 27.68% and 14.88%, respectively.
Construction land in rural areas has also experienced rapid expansion, and, in general, the expansion rate of rural construction land in southern Jiangsu is much higher than that in northern Jiangsu (Figure 6a). In particular, Yangzhong and Jiangyin experienced the most significant expansion of rural construction land, with increases of 13.29 and 9.59 times, respectively. Meanwhile, the expansion of rural construction land in Haimen, Nantong downtown, Suzhou downtown, Taicang, Wujiang, and Zhangjiagang is also quite rapid, with an increase of 3.79 to 6.62 times. In all three periods, the rate of rural construction land expansion in southern Jiangsu is significantly higher than that in northern Jiangsu (Figure 6b–d). It is worth noting that the three coastal counties of Sheyang, Dafeng, and Dongtai experienced a decrease in the area of rural construction land from 2000 to 2010, especially Sheyang, which decreased by 16.55%, and Dafeng and Dongtai, which decreased by 9.25% and 3.35%, respectively (Figure 6c). This may be related to the land use policy of the coastal reclamation area in Jiangsu.

3.2. Urban–Rural Differences in the Conversion of Cropland to Construction Land

From 1990 to 2020, a total of 10,427.88 km2 of cropland in Jiangsu Province was converted into construction land, meaning that 94.36% of the newly added construction land came from cropland (Figure 7a). Specifically, 7112.38 km2 of cropland in urban areas and 3315.50 km2 in rural areas were converted into construction land. In urban areas, the amount of cropland converted into construction land during the three periods was 1665.76 km2, 2948.21 km2, and 2488.20 km2, respectively. In rural areas, the figures for the same periods were 1259.78 km2, 775.14 km2, and 1293.87 km2, respectively (Figure 7b–d). It is evident that the conversion of cropland to construction land in urban areas was most intense during 2000–2010, while this period saw the mildest conversion in rural areas. Spatially, the conversion of cropland to construction land in urban areas was more pronounced in the southern part of Jiangsu, whereas in rural areas such conversions were relatively more common in the northern part of the province.
To further clarify the regional and urban–rural differences in cropland loss caused by construction land expansion, we conducted a statistical analysis at the county level (Figure 8). From 1990 to 2020, the most significant conversion of cropland to construction land in urban areas occurred in Nanjing downtown, with 591.90 km2 of cropland converted, followed by Suzhou downtown, Changzhou downtown, and Wuxi downtown, with 480.56 km2, 422.53 km2, and 394.29 km2 of cropland converted, respectively (Figure 8a). In other counties, the conversion of cropland to construction land in urban areas was less than 300.00 km2, with Jinhu and Hongze having only 23.94 km2 and 21.66 km2 of cropland converted, respectively. In rural areas, the most notable conversions occurred in Xuzhou City in northern Jiangsu, including Xuzhou downtown, Fengxian, Suining, Pizhou, and Peixian, where the conversion of rural cropland to construction land ranged between 104.80 and 134.38 km2. By decade, the conversion of rural cropland to construction land was prominent in northern Jiangsu from 1990 to 2000, while the conversion of urban cropland to construction land was more pronounced in southern Jiangsu (Figure 8b). From 2000 to 2010, the conversion of rural cropland to construction land slowed down across the province, while the expansion of urban cropland to construction land accelerated in southern Jiangsu (Figure 8c). From 2010 to 2020, the conversion of rural cropland to construction land accelerated compared to the previous period, while the pace of urban crop land conversion to construction land slowed but remained significant (Figure 8d).

3.3. Urban–Rural Differences in the Landscape Pattern Changes of Cropland and Construction Land

From 1990 to 2020, the landscape pattern of cropland in urban areas became more fragmented in all counties, with the PD value increasing by 1.67–9.64 while the AI value decreased by 3.77–18.74 and the AREA_MN decreased by 3.94–304.65 (Figure 9). The areas with the most severe fragmentation of urban cropland mainly include Wujiang, Hai’an, Kunshan, Qidong, Taizhou downtown, Rugao, and Suzhou downtown. By decade, the increase in PD value and the decrease in AI value accelerated, while the average patch area decreased the most during 1990–2000, followed by a more moderate decline. This indicates that the cropland in urban areas is becoming increasingly fragmented, and large, contiguous areas of cropland were initially divided by other land use types.
Accompanying the increasing fragmentation of urban cropland is the growing aggregation of urban construction land (Figure 10). From 1990 to 2020, except for Dafeng and Liyang, the PD values of urban construction land in all other counties decreased, especially in the northern Jiangsu region. Meanwhile, the AI values in all counties increased, particularly in Yangzhong, Shuyang, Xuyi, Hongze, Zhangjiagang, and Siyang, where the AI values of urban construction land rose by 18.37 to 22.34. Similarly, the AREA_MN in all counties also significantly increased, especially in the Lianyungang downtown and Fengxian where the AREA_MN distribution increased by 38.67 and 37.33, respectively. Looking at the data by decade, the PD values of urban construction land decreased the most from 1990 to 2000. Although the decrease continued from 2000 to 2010, it slowed down, and by 2010–2020, the rate of decrease in PD values increased again. The increasing trend of AI values generally slowed down, while the increase in AREA_MN became faster over time.
For rural areas, cropland has generally become more fragmented, although not as severely as in urban areas. Notably, the degree of fragmentation did not intensify in all counties (Figure 11). From 1990 to 2020, the PD values of rural cropland increased in most counties, with the most significant increases observed in Gaochun, Changshu, Xiangshui, Wujiang, and Yangzhong, showing no clear spatial pattern. Specifically, ten counties experienced a decrease in PD values, primarily located in the western region. As for AI values, all counties saw a decline, with the decrease being more pronounced in southern Jiangsu compared to northern Jiangsu. In terms of AREA_MN, Haian and Rugao experienced the largest reductions, decreasing by 1087.53 and 918.03, respectively. Interestingly, nine counties saw an increase in AREA_MN, almost entirely overlapping with the areas where PD values decreased. This indicates that the disappearance of some small plots of cropland led to a reduction in the number of cropland patches, causing PD values to decline and AREA_MN to increase. As a result, the fragmentation of cropland in some rural areas has instead been mitigated.
The changes in the landscape pattern of rural construction land are not very drastic, with an overall trend towards greater aggregation, although the performance of different landscape indicators varies (Figure 12). From 1990 to 2020, the PD values of rural construction land generally increased in southern Jiangsu, while they mostly decreased in northern Jiangsu. This indicates that the number of rural construction land patches in northern Jiangsu increased rapidly whilst the total area grew more slowly, leading to a decline in PD values. The AI values increased in all counties, with a more noticeable rise in southern Jiangsu compared to northern Jiangsu, suggesting that rural construction land in southern Jiangsu has become more aggregated. As for AREA_MN, the AREA_MN of rural construction land increased slightly in all counties, but the increase was not significant. The northernmost and southernmost regions showed more pronounced increases compared to the central areas.

4. Discussion

The findings of this study reveal pronounced urban–rural disparities in cropland loss and fragmentation driven by construction land expansion in Jiangsu Province, China. Urban areas experienced a 44.14% reduction in cropland and a 2.61-fold increase in construction land from 1990 to 2020, far exceeding the 5.97% cropland loss and 90.14% construction land growth in rural areas. These results align with global patterns of urbanization-driven cropland conversion but provide novel insights into the spatial and temporal heterogeneity of these processes within a rapidly developing coastal region [47,48]. The differentiation between urban and rural dynamics, often overlooked in prior studies, underscores the need for context-specific land management strategies.
The accelerated cropland loss in urban areas, particularly in southern Jiangsu, reflects the region’s economic prioritization of high-tech industries and infrastructure development. Southern cities like Suzhou and Wuxi, integral to the Yangtze River Economic Belt, exemplify how industrial clustering and population influx amplify construction demands [49,50]. By contrast, rural areas in northern Jiangsu, although less economically dynamic, still faced significant cropland conversion, driven by smaller-scale settlements and agricultural modernization [51,52]. This duality highlights the pervasive influence of urbanization, even in regions traditionally reliant on agriculture. The temporal shift in construction land dominance from rural to urban areas post-2005 further underscores the intensification of urban-centric development policies during China’s economic reform era.
Urban cropland fragmentation, evidenced by rising PD and declining AI and AREA_MN values, signals the disintegration of contiguous agricultural landscapes into isolated patches. This trend is most acute in southern Jiangsu where rapid infrastructure expansion (e.g., highways and industrial parks) dissects croplands, hindering mechanization and elevating management costs. Conversely, the aggregation of urban construction land (rising AI and AREA_MN) suggests concentrated development, potentially a result of zoning policies favoring industrial clusters. In rural areas, the modest fragmentation and occasional consolidation (e.g., increased AREA_MN in some counties) may reflect land consolidation initiatives or the abandonment of marginal plots, although these processes require deeper socio-economic investigation. Additionally, cropland fragmentation not only has negative effects, but may also have some positive effects, such as increasing agricultural productivity and adapting to scale management [53].
The spatial disparities in cropland loss and fragmentation necessitate differentiated governance frameworks. Urban areas, particularly in southern Jiangsu, demand stringent enforcement of cropland protection policies, such as urban growth boundaries and incentives for vertical development [54,55]. In rural regions, curbing scattered construction through centralized settlement planning and promoting agroecological practices could mitigate fragmentation [26,56]. The observed reduction in rural construction land in coastal counties (i.e., Dafeng, Sheyang, and Dongtai) during 2000–2010 also highlights the potential of regional land use policies, such as reclamation regulations, to shape outcomes [57,58]. For instance, land reclamation regulations, coastal protection measures, or ecological restoration programs (such as wetland rehabilitation or farmland consolidation) could have driven this decline. Further investigation is needed to determine the specific policy mechanisms—whether through active demolition, land use conversion (e.g., reverting construction land to arable or natural uses), or stricter development controls—that contributed to these trends. However, the rebound in rural conversion post-2010 signals the need for sustained policy vigilance.
Jiangsu’s cropland loss poses direct risks to food security, given its role as a major agricultural producer. The province’s north–south economic divide further complicates this issue as whilst southern urban centers prioritize industrial growth, northern rural areas face pressure to compensate for agricultural losses, potentially exacerbating regional inequities. Balancing economic development with cropland preservation will require integrative policies that address both land use efficiency and interregional resource allocation.
This study’s reliance on satellite-derived data, while robust, may underrepresent small-scale or informal land conversions. Different land use data can produce significantly different results, even for the same study [59]. The CLCD data used in this study has recently been pointed out as potentially systematically overestimating cropland area [60]. Additionally, the 30 m resolution is insufficient to fully capture fine-scale cropland changes, such as marginal cropland loss. These uncertainties suggest that our estimates of cropland loss may be conservative, particularly in regions where cropland fragmentation or gradual degradation is prevalent. The urban–rural demarcation based on patch size (>5 km2) further compounds this limitation as it risks excluding subtle peri-urban transitions and incremental developments at finer scales. Future work could incorporate higher-resolution datasets (e.g., Sentinel-2 or UAV imagery) or ancillary ground-truthing to better account for these underrepresented dynamics. Future research should integrate socio-economic drivers (e.g., labor migration, land tenure systems) and ecological impacts (e.g., soil degradation, biodiversity loss) to deepen understanding of fragmentation consequences. Additionally, longitudinal case studies could elucidate how policy interventions, such as Jiangsu’s “Three Zones and Three Lines” spatial planning initiative, modulate these dynamics.

5. Conclusions

In this study, we used the CLCD dataset, GIS spatial analysis, and landscape pattern indices to deeply explore the urban–rural differences in cropland loss and fragmentation caused by construction land expansion over the past 30 years in Jiangsu Province, China. The main conclusions are as follows:
(1)
The urban cropland area plummeted from 16,024.51 km2 in 1990 to 8951.29 km2 in 2020, marking a decrease of 44.14%. Concurrently, the urban construction land area expanded rapidly from 2811.15 km2 to 10,155.07 km2, an increase of approximately 2.61 times. In rural areas, the cropland area decreased from 62,824.56 km2 in 1990 to 59,072.45 km2 in 2020, a reduction of 5.97%, while rural construction land grew from 4412.88 km2 to 7820.37 km2, an increase of 90.14%.
(2)
From 1990 to 2020, a total of 10,427.88 km2 of cropland in Jiangsu Province was converted to construction land, accounting for 94.36% of the newly added construction land. Among this, 7112.38 km2 were converted in urban areas, while 3315.50 km2 were converted in rural areas. Spatially, the conversion of urban cropland to construction land was primarily concentrated in southern Jiangsu, whereas the conversion of rural cropland to construction land was more prevalent in northern Jiangsu.
(3)
The cropland in Jiangsu Province has become increasingly fragmented, with the PD value rising significantly and the AI value and AREA_MN declining markedly. Among these, urban cropland in southern Jiangsu has experienced the most severe fragmentation, while urban construction land has become more aggregated. Rural cropland fragmentation is less pronounced, and rural construction land also shows a trend toward aggregation, particularly in southern Jiangsu, although changes in landscape metrics vary. Overall, compared to rural areas, urban cropland exhibits a more severe trend of fragmentation.
This study highlighted the significant urban–rural disparities in cropland loss and fragmentation caused by construction land expansion in Jiangsu Province, China. Urban and rural areas within the same region face distinct land use challenges, necessitating targeted strategies to harmonize development with sustainability. By bridging the urban–rural divide in land use research, this work contributes to developing a more nuanced framework for managing rapid transformations in global coastal regions.

Author Contributions

Conceptualization, J.Z. and L.P.; methodology, J.Z.; funding acquisition, L.P.; validation, J.Z. and L.P.; resources, J.Z. and L.P.; data curation, J.Z.; writing—original draft preparation, J.Z.; writing—review and editing, L.P. All authors have read and agreed to the published version of the manuscript.

Funding

This work was supported by the National Natural Science Foundation of China (42476239, 42171245 and 42201278), the Jiangsu Province Carbon Peak Carbon Neutral Technology Innovation Project (BK20231515), the Research Initiation Fund for Introduced Talents of Nanjing Institute of Technology (YKJ202336), the Science and Technology Project of the Natural Resources Department of Jiangsu Province (2023003), and the Open Fund of Key Laboratory of Coastal Zone Exploitation and Protection, MNR (2023CZEPK02).

Data Availability Statement

The original contributions presented in this study are included in the article.

Conflicts of Interest

The authors declare no conflicts of interest.

References

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Figure 1. The location (a), elevation (b), and urban–rural boundaries (c) of the study area.
Figure 1. The location (a), elevation (b), and urban–rural boundaries (c) of the study area.
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Figure 2. Changes in cropland (a) and construction land (b) area in urban and rural Jiangsu.
Figure 2. Changes in cropland (a) and construction land (b) area in urban and rural Jiangsu.
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Figure 3. Changes of urban cropland area in Jiangsu counties.
Figure 3. Changes of urban cropland area in Jiangsu counties.
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Figure 4. Changes of urban construction land area in Jiangsu counties.
Figure 4. Changes of urban construction land area in Jiangsu counties.
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Figure 5. Changes of rural cropland area in Jiangsu counties.
Figure 5. Changes of rural cropland area in Jiangsu counties.
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Figure 6. Changes of rural construction land area in Jiangsu counties.
Figure 6. Changes of rural construction land area in Jiangsu counties.
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Figure 7. Spatiotemporal distribution of cropland converted to construction land in Jiangsu.
Figure 7. Spatiotemporal distribution of cropland converted to construction land in Jiangsu.
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Figure 8. Urban–rural differences of cropland converted to construction land in Jiangsu counties.
Figure 8. Urban–rural differences of cropland converted to construction land in Jiangsu counties.
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Figure 9. Changes in landscape patterns of urban cropland in Jiangsu counties.
Figure 9. Changes in landscape patterns of urban cropland in Jiangsu counties.
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Figure 10. Changes in landscape patterns of urban construction land in Jiangsu counties.
Figure 10. Changes in landscape patterns of urban construction land in Jiangsu counties.
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Figure 11. Changes in landscape patterns of rural cropland in Jiangsu counties.
Figure 11. Changes in landscape patterns of rural cropland in Jiangsu counties.
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Figure 12. Changes in landscape patterns of rural construction land in Jiangsu counties.
Figure 12. Changes in landscape patterns of rural construction land in Jiangsu counties.
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Table 1. Indices and definitions of landscape patterns.
Table 1. Indices and definitions of landscape patterns.
Landscape MetricFormulaMeaningReference
Patch Density (PD)PD = N[patch]/A(1)The number of patches per unit area. N represents the number of patches in the landscape and A represents the total area of the landscape.[44]
Aggregation Index (AI)AIi = patchii/max_patchii(2)The AI level of pixels sharing the most possible edges is the highest. patchii is the number of similar adjacent patches of the corresponding landscape type.[45]
Mean Patch Area (AREA_MN)AREA_MN = mean (A[patchij])(3)This indicator reflects the relationship between the total area of land type i and the number of land type i patches.[46]
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Zhai, J.; Pu, L. Urban–Rural Differences in Cropland Loss and Fragmentation Caused by Construction Land Expansion in Developed Coastal Regions: Evidence from Jiangsu Province, China. Remote Sens. 2025, 17, 2470. https://doi.org/10.3390/rs17142470

AMA Style

Zhai J, Pu L. Urban–Rural Differences in Cropland Loss and Fragmentation Caused by Construction Land Expansion in Developed Coastal Regions: Evidence from Jiangsu Province, China. Remote Sensing. 2025; 17(14):2470. https://doi.org/10.3390/rs17142470

Chicago/Turabian Style

Zhai, Jiahao, and Lijie Pu. 2025. "Urban–Rural Differences in Cropland Loss and Fragmentation Caused by Construction Land Expansion in Developed Coastal Regions: Evidence from Jiangsu Province, China" Remote Sensing 17, no. 14: 2470. https://doi.org/10.3390/rs17142470

APA Style

Zhai, J., & Pu, L. (2025). Urban–Rural Differences in Cropland Loss and Fragmentation Caused by Construction Land Expansion in Developed Coastal Regions: Evidence from Jiangsu Province, China. Remote Sensing, 17(14), 2470. https://doi.org/10.3390/rs17142470

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