Evolution of ecosystem services under the impact of urbanization using the InVEST model in the xiongan new area, China

Understanding the impact of land use on ecosystem service functions is crucial for guiding land management and ecological environment protection in Xiongan New Area (XANA), China. This paper employs the InVEST model to assess the temporal and spatial characteristics of water yield, carbon storage, water purification, and soil conservation ecosystem services in XANA from 1980 to 2020, analyzing geographical and spatial variations in ecosystem service capabilities. Through correlation analysis and the grid Moran’s I index, we explored the mechanisms of ecosystem action and the trade-offs and synergies among these services. Our results revealed that urban land use in XANA increased throughout the 1980–2020 period, with the fastest growth occurring from 2010 to 2020, primarily due to cultivated land conversion. Prior to 2010, cultivated land expanded rapidly, consuming significant amounts of water resources. Changes in land use structure drove increases in water yield and nitrogen output in the XANA ecosystem while decreasing carbon storage and soil erosion. Urban land area change was the primary factor influencing water yield and nitrogen output, while reduced water area was the main driver behind decreased carbon storage in the region. Cultivated land was identified as the primary contributor to soil erosion. The synergy between carbon storage and water conservation is closely tied to water area and urban land, while the synergies between carbon storage and water quality purification, soil conservation and water quality purification hinge on water areas and cultivated land areas. To ensure the sustainable development of XANA, it is essential to protect the wetland ecosystem in the Baiyangdian Lake basin, enhance forest and grassland coverage, and monitor temporal and spatial changes in different ecosystem services and their interrelationships closely.


Introduction
Ecosystem services include various benefits that humans derive from ecosystems, serving as the fundamental basis and environmental conditions sustaining human survival and development.These services include 17 functions, including atmospheric regulation, the water cycle, and soil formation (Constanza et al 1997, Huang andWu 2023).Rapid global urbanization has led to extensive urban expansion at the expense of ecological spaces, disrupting the balance between regional ecosystem service supply and demand.This disruption has resulted in environmental issues such as air and water pollution, soil erosion, and natural disasters, all of which human well-being (Keller et al 1991, Collin andMelloul 2001).Land use ranks among the primary drivers of ecosystem service alterations, and significantly influences the efficacy of ecosystem service functions (Aziz 2021, Mendoza-Gonzalez et al 2012).Consequently, gaining a clearer understanding of the spatiotemporal changes in ecosystem services driven by land use, and elucidating the trade-offs and synergies among these services, can enrich ecosystem service theories and sustainable development concepts.Moreover, climate change holds critical importance in shaping regional ecological environment management policies (Fiquepron et al 2013, Wang et al 2015, Zhang et al 2023).
The evaluation of ecosystem service functions relies primarily on physical and value assessment methods.These methods differ in whether they express ecosystem service values in monetary units.Value assessment methods are subjective and lack the capacity to measure ecosystem service values in each region, exhibiting limited comparability and scientific applicability for large-scale research areas.In contrast, physical assessment methods overcome these limitations, allowing for the evaluation of ecosystem services based on physical foundations and formation mechanisms.These assessments produce highly interpretative and reliable results, rendering them widely adopted (Yin et al 2019, Yang et al 2022, Chen and Zhong 2023).
Established in 2017, XANA represents a significant national strategic new area.XANA's mandate includes relieving Beijing's noncapital functions and fostering the coordinated development of the Beijing-Tianjin-Hebei region (Ye and Wang 2018).This endeavor requires optimizing territorial space development patterns and harmonizing the three key spaces of production, life, and ecology, striking a balance between economic and social development and ecological environmental protection during XANA's construction.Since XANA's establishment, previous studies have examined ecosystem responses to land use changes.Jiang et al (2017b) focused on regional disparities between construction land's intensive use potential and cultivated land quality based on overall land use change characteristics in the new district from 1993 to 2017.In 2015, Peng et al (2018) assessed ecological security in new districts based on ecosystem service functions, and discussed strategies for optimizing the ecological security patterns in pursuit of a green and liveable new city.Hou et al (2021) utilized the value-equivalent factor method to investigate the impact of land use change on ecosystem service values, the authors revealed a decrease of 1.917 billion yuan in ecosystem service value from 1995 to 2015, driven primarily by changes in water area.In the new district, ecosystem services related to food supply, culture and entertainment, ecological conservation, and urban life exhibited synergistic relationships and fewer trade-offs, revealing spatial co-occurrence clustering (Shen et al 2020).With significant urbanization, ecological functions and ecosystem services will rapidly change .
At present, there are few studies on the use of physical assessment methods to assess the dynamic changes in ecological service functions in the XANA region, and the tradeoff/synergy of ecosystem service functions driven by land use change needs to be further discussed.Therefore, scientific and objective development of the impact of land use on the ecological functions of new areas can provide an important basis for the ecological construction and urban management of XANA in the future.In this study, grounded in land use perspectives, investigated the evolution of ecosystem water yield, carbon storage, water purification, and soil conservation service functions driven by land use changes.We addressed the following questions: (1) How did land cover and land use change over time in XANA? (2) How did the ecosystem service change under land change, especially the rapid urbanization?(3) What are the synergistic and trade-off relationships between ecosystem services?The research findings are expected to provide a scientific basis for urbanization and ecological environmental protection measures in XANA.

Study area
XANA is situated within the Beijing-Tianjin-Hebei Region hinterland, as depicted in figure 1.It includes an expansive area of 1770 km 2 , teeming with diverse landforms such as flood plains, lake plains, and lake depressions.The region's topography rises in the northwest and gently descends in the southeast, with elevations ranging from 7-19 m and relatively sparse vegetation coverage.XANA has a warm temperate monsoon continental climate, with an average annual precipitation of 522.9 mm and an average annual temperature of 12.7 °C.However, it is also susceptible to droughts and floods.
XANA is crisscrossed by several rivers, including the Nanjuma River, Daqing River, and Baigou River.Notably, Baiyangdian Lake, the largest freshwater lake in the North China Plain, graces the southeastern region of XANA and forms a core component of the New Area's planning.Baiyangdian Lake serves as a vital water storage hub in the Daqing River system, and palys a significant ecological role in water supply, aquatic resource provision, climate regulation, floodwater storage, and ecological diversity preservation (Jiang et al 2017a).However, in recent years, due to urban development, inadequate water resource management, extensive groundwater overexploitation, water scarcity, and water eutrophication, groundwater overexploitation and flood risk ranking have been the primary water-related challenges facing sustainable development in the area (Xia and Zhang 2017).

Data
(1) Raster data of land use types: Land use data for the years 1980, 1990, 2000, 2010, and 2020 were obtained from remote sensing imagery interpreted by the Data Center for Resources and Environmental Sciences, Chinese Academy of Sciences.These data were provided at a resolution of 30 m × 30 m. (2) Meteorological data: Potential evapotranspiration was computed using the FAO Penman method based on meteorological data from nine stations in XANA and its surrounding areas, sourced from the Hebei Meteorological Information Center.Interpolation was employed to generate raster data using the inverse distance weighting method.(3) Soil data: Soil data were sourced from the World Soil Database (HWSD).(4) Digital elevation model (DEM): The Environmental Science Data Center, Chinese Academy of Sciences provided the digital elevation data.All the datasets were processed in raster format with a uniform raster resolution of 30 m and converted into a consistent projection coordinate system.

Methods
The InVEST model is utilized to assess potential shifts in the supply of ecosystem service functions and the tradeoffs between these functions across various geographical and socioeconomic scales.This study employs InVEST version 3.13.0, in which ecosystem service functions are closely linked to human and social well-being, and for which data are readily accessible, to explore the likely consequences of various management and climate scenarios while evaluating trade-offs across sectors and services (Natural Capital Project, NCP 2024).Specifically, four submodules were chosen for analysis: water yield, carbon storage and sequestration, water purification, and soil conservation (Parmaters in models were shown in table 1).

Trade-off and synergic relationship analysis
Pearson's correlation coefficient was used to assess the correlation between ecosystem services.Furthermore, the bivariate Moran's I index was used to explore trade-offs (Wei et al 2022), synergies, and spatial variations in ecosystem services during the 1980-2020 period.However, the bivariate Moran's I index provides an overall description of the trade-offs and synergistic relationships among ecosystem services.To explore the differences in local regions, it is necessary to further calculate the local Moran's I index for the basin.The calculation formula is as follows: where I is the bivariate global Moran's I index, is the spatial weight, and and represent the two ecosystem service indices of factor I. Furthermore, and represent the average values of the two ecosystem service indicators,

Land use change analysis
Due to XANA's flat terrain and its location in the continental monsoon climate zone, it is well-suited for cultivation.Consequently, cultivated land is the primary land use type in XANA.Table 2 indicates that cultivated land, as the largest land type in XANA, accounts for 70.72% of the total area, of the country and is significantly greater in area than other land types.The areas of water bodies and urban land are 16.72% and 12.03%, respectively.Woodland and grassland are the smallest land use types, with area ratios of 0.47% and 0.07%, respectively.
To clearly depict the direction of land use change, we quantitatively expressed the conversion relationships between land use types in different periods using a chord diagram.Figure 3 illustrates the change process in the land use structure in XANA from 1980 to 2020.The results indicate that the primary reason for the increase in urban land use is the conversion of cultivated land, which accounts for 172.78 km 2 , or 51.7% of the existing area.This was followed by the conversion of water bodies, which covered 18.14 km 2 , or 5.4% of the existing area.The main outflow from water bodies was to cultivated land, with an area of 106.56 km 2 , or 28.4% of the previous water area.This suggests that urban expansion in XANA primarily occurs at the expense of cultivated land, steadily encroaching on regional cultivated land resources and accelerating the regional urbanization process.The decrease in cultivated land is mainly due to the demand for increased crop production.After 2010, with the establishment of XANA, urban development accelerated, resulting in the conversion of arable land (123.0 km 2 ), woodland (2.18 km 2 ), and water bodies (14.62 km 2 ) into urban land.There was also a need for ecological restoration projects to return cultivated land to the lake area, covering 59.08 km 2 , or 4.5% of the cultivated land area.different periods, with lower values in the central region and higher values in the surrounding areas.This distribution is closely linked to land use types.Water yield is inversely proportional to the evapotranspiration of vegetation.Urban land without vegetation intercepts less precipitation, resulting in higher water yield, while water bodies exhibit strong evapotranspiration, resulting in lower water yield.From 1980 to 2020, urban land expanded rapidly, increasing its total water yield from 25 million m 3 to 55 million m 3 , and its contribution to regional water yield rose from an initial 35.7% to 56.1%.Therefore, the expansion of urban land was the main reason for the continuous increase in water yield in XANA (figure 5).

Carbon storage
The The carbon storage in cultivated land decreased from 425.16 × 10 4 t in 1980 to 352.44 × 10 4 t in 2020.Water body carbon storage decreased during these stages from 1980 to 2010, with a slight increase occurring in 2020 but an overall decrease of 76.51 × 10 4 t, reflecting a rate of 19.68 t/10a.Woodland area initially increased and then decreased, with a carbon storage of 10.84 × 10 4 t in 2020, which was 8.08 × 10 4 t lower than the highest point in 2000.From 1980 to 2020, the reduction in total water body carbon storage was twice that of the overall regional carbon storage reduction.A 29% reduction in cultivated land and water bodies accounted for the majority of the regional carbon storage reduction in XANA (figure 6).

Water purification
The evaluation of the ecosystem water purification service function, based on the InVEST model, is expressed through the output of ecosystem nutrients (nitrogen and phosphorus).A higher nitrogen output indicates more severe non-point source pollution, weaker water purification function.
The nitrogen outputs in the new district for the five periods were 5.76 kg hm −2 , 6.09 kg hm −2 , 5.91 kg hm −2 , 6.26 kg hm −2 , and 5.98 kg hm −2 , respectively.The surface nitrogen output fluctuated, resulting in an overall decline in the water purification service function of the new district.The areas with increasing nitrogen outputs were mainly located west of the new district, while the areas with decreasing nitrogen outputs areas scattered  ).The highest nitrogen outflow per unit came from cultivated land, followed by urban land, grassland, woodland, and water bodies.In the new district, cultivated land and urban land are significant sources of nitrogen output, primarily due to urban domestic sewage discharge, fertilizer use in cultivated land, and livestock and poultry manure discharge, among other factors.The expansion of urban land is the primary driver of increased nitrogen output in new districts.

Soil erosion
The regional average soil erosion rate exhibited a decreasing trend, decreasing from 0.77 t/hm 2 in 1980 to 0.73 t/hm 2 in 2020, for a decrease rate of 5.2% 3).Soil erosion exhibited fluctuations, reaching a maximum of 0.83 t/hm 2 in 2010 and a minimum of 0.73 t/hm 2 in 2020.The most significant decrease occurred between 2010 and 2020, with a rate of 12.0%, the largest of which occurred over the four decades.Different land use types made varying contributions to soil erosion, with cultivated land having the highest impact, followed by woodland and grassland.Due to water and urban land having zero soil and water conservation measures, their soil erosion rates were also zero.The spatial distribution of soil erosion showed lower erosion rates in the central water area and the surrounding scattered urban land, while the surrounding cultivated land exhibited the highest erosion rates (figures 4(p)-(t)).Total soil erosion in cultivated land fluctuated, peaking at 11.8 × 10 4 t in 2010 and reaching a minimum of 10.4 × 10 4 t in 2020.Woodland area  experienced an initial increase followed by a decrease, with soil erosion decreasing from 7.0 × 10 2 t in 2000 to 3.8 × 10 2 t in 2020.Soil erosion in grasslands showed a continuous increase, reaching a maximum of 2.5 × 10 2 t in 2020 (figure 7).The expansion of cultivated land contributed to increased areas of soil erosion, while areas where cultivated land was converted to water and urban land experienced reduced soil erosion.

Correlation analysis
Water yield exhibited negative correlations with carbon storage with linear correlation coefficients less than −0.6 (P < 0.01), indicating that regions with higher water yield demonstrated lower carbon storage.The correlation between the two first decreased and then increased.There no significant correlation between water yield nitrogen output and soil erosion, while the correlation coefficient with soil erosion showed an increasing trend.Carbon storage exhibited negative correlations with nitrogen output, with linear correlation coefficients less than -0.4 (P < 0.01) indicating a decreasing trend.No significant correlation was found between carbon storage and soil erosion, which indicated a compatible relationship.Nitrogen output was positively correlated with soil erosion, with a correlation coefficient above 0.26 (P < 0.01), suggesting that areas with higher nitrogen output also experienced more significant soil erosion, highlighting a greater level of soil conservation in regions with strong water purification capabilities.The change in the relationship between nitrogen output and soil erosion was stable from 1980 to 2020.There was a trade-off relationship between the four ecosystem service functions of water conservation, carbon storage, water purification and soil conservation in XANA in 1980 (figure 8).

Analysis of coordination and trade-off relationships
The analysis of coordination and tradeoff relationships between pairs of ecosystem services in XANA was conducted using Moran's I index based on grid units.The bivariate Lisa clustering map, derived from the calculation of the bivariate local Moran's I index, is depicted in figure 9.The categories 'high-low' and 'low-high' distinctly represent local trade-off relationships between the two ecosystem services, while 'high-high' and 'lowlow' signify local cooperative relationships between these services and the associated increase and unified construction.
As illustrated in figures 9(a)-(e), the proportion of regions displaying a 'low-high' trade-off relationship between water yield and carbon storage falls within the range of 14.1% to 16.7%, and these regions are primarily concentrated in the central water regions.The regional distribution of the 'high-low' equilibrium is scattered across the northern expanse of the new district, accounting for approximately 5.6% 8.9%, with these areas primarily designated as urban The 'low-low' coordination area occupies 0.56% to 0.66% of the territory, and is distributed sporadically in the eastern and northern peripheries of Baiyangdian Lake.Figures 9(f)-(j) shows the regional distribution of significant 'low-low' coordination between water yield and soil erosion in the water area, the change in which determined the change in synergistic area.The 'high-low' area was concentrated in urban areas and showed an increasing trend.Figures 9(k)-(o) shows the spatial distribution of carbon storage and nitrogen output according to the cluster analysis.The proportion of regions exhibiting 'high-low' characteristics in both carbon storage and nitrogen output ranges from 10.6% to 13.9%.Conversely, the 'lowhigh' category spans 12.1% to 13.8%.The 'low-low' cluster region sprawls along the coastline and the interior of Baiyangdian Lake, with urban land being the dominant land type.Figures 9(p)-(t) shows the spatial distribution of nitrogen output and soil erosion according to the cluster analysis.Regions indicating a 'low-low' cooperative relationship between the two are situated within the central water area, accounting for approximately 12.2% to 13.5% of the territory.The 'high-high' category accounts for 4.2% to 4.8% of the total area and exhibits a sporadic distribution, with cultivated land as the primary land type.

Impacts of policies on land use change
During the initial three decades, development within the study area underwent a process marked by population growth, urban expansion, and substantial encroachment on ecological lands, leading to noticeable changes in the ecosystem structure.Following the establishment of XANA, the development paradigm shifted from rapid, extensive growth to a planned, high-quality approach, with greater emphasis placed on ecological land preservation.This shift had positive impacts on the ecosystem.Findings from the Remote Sensing Survey and Ecological Environment Assessment in China for the 2000-2010 decade (CMEP 2014) align with the results of this study.In our research, the water area si from 2000 to 2010, and a substantial rebound occurred 2010 to 2020.These findings are consistent with earlier studies (Zhu et al 2019, Bu et al 2021) and are closely linked to the results of the Yellow River diversion project to Ji Budian initiated in 2018 (Wang et al 2018).
The 'Planning Outline of Xiongan New Area in Hebei Province' proposed on April 21, 2018 that XANA establish an ecological spatial layout characterized by 'one lake, three belts, and nine corridors'.Guided by this outline, XANA will actively engage in environmental management and ecological restoration efforts for Baiyangdian Lake, creating a large-scale ecological buffer zone and forming nine extensive forest patches in the future.By comparing land use changes between 2015 and 2020, it is evident that the annual change rate of cultivated land, water area, and urban land was minimized from 1980 to 2020.Moreover, the rates of decrease in water conservation capacity, carbon storage ability, water purification capability, and soil conservation ability significantly slowed.According to the plan's vision for the future development of XANA, a substantial amount of farmland will be converted into water bodies and forested areas to effectively enhance water conservation capacity as well as carbon storage potential.With the control of water pollution at the 'entrance' of Baiyang Lake, the water quality will increase, and the synergistic relationship between the three ecosystem services will increase.Usually, the expansion of urban land will further strengthen the tradeoff between water conservation and soil conservation.However, the concept of a 'sponge city' will be introduced in the urban construction of XANA to improve the infiltration, regulation, storage, purification, utilization and discharge capacity of runoff and rainwater, and the tradeoff relationship between water conservation and soil conservation will be reduced.

Effects of climate change and land use on ecosystem services
Climate change and land use stand as crucial driving forces behind shifts in ecological services.In this study, we adopted the research methodology of Xiao et al (2023) to quantitatively gauge the distinct contributions of factor to the alteration of ecological services.The impact of climate is decreasing, while the influence of land use is increasing in terms of water yield and soil retention.In the future, there will be significant changes in land use in XANA, and the contribution of land use to ecological service functions will further increase.

Limitations
XANA encompasses a relatively modest area of 1,770 km 2 , thus necessitating the use of high-resolution data for assessing changes in the ecological service system within this region.This study is limited by the use of lowresolution soil data, which leads to reduced accuracy following interpolation and introduces errors in water yield and soil loss calculations.Furthermore, ecosystem services can be categorized into support, supply, regulation, culture, and other types.This study exclusively analyzes supply and regulation services.Future assessments of ecosystem services in XANA should embrace a more comprehensive approach.Subsequently, based on the spatial distribution of ecosystem services, measures and recommendations for managing and controlling ecosystem services and human activities should be formulated.
Studies on the trade-off synergies between soil conservation and carbon storage have yielded different conclusions in distinct regions.For instance, Bai et al (2013) reported a significant positive correlation between the two parameters in the Baiyangdian Lake area.In contrast, Zhu et al (2022) and Liu et al (2023) indicated that woodland and grassland exhibit relatively high levels of soil conservation and carbon storage, coinciding with the substantial woodland and grassland coverage in the upper reaches of the Baiyangdian Valley.Consequently, the two ecosystem services in the entire basin exhibited a strong correlation, while XANA's lower woodland and grassland coverage exhibited different relationships between Baiyangdian Lake and Baiyangdian Valley.

Conclusions
Ecosystem services are intimately intertwined with climate change and human activities.As urbanization continues to expand rapidly, with the conversion of more vegetated land into urban terrain, the scrutiny of changes in ecosystem functions and services has gained prominence.In this investigation, we examined four ecosystem services, (a) water yield, (b) carbon storage, (c) water purification, and (d) soil erosion, and analyzed the spatiotemporal evolution characteristics of these four ecosystem services driven by land use change.These characteristics were determined by carrying out a quantitative evaluation of the relationship between ecosystem services, and the impacts of land use types on ecosystem service trade-offs and synergies.The key findings include the following: (1) Urban land use in XANA expanded at a staggering rate of 1.18 times.(2) Ecosystem services related to carbon storage and soil erosion in XANA exhibited a declining trend, whereas water yield and nitrogen output exhibited an upward trajectory.(3) Trade-offs occur between carbon storage and water yield, while a synergistic relationship occurs between carbon storage and water quality purification.To foster the development of a green, ecological, and livable new city, there is a pressing need to strengthen ecological and environmental protection efforts, enhance forest and grassland coverage rates, and optimize the composition of forest species.
The expansion of urban lands is the main reason for the continuous increase in water production and water purification.The design scheme of the comprehensive function of plants and sand has been adopted in the construction of XANA, which can purify rainfall through the comprehensive effects of plants and sands, and promote groundwater conservation.Additionally permeable paving technology applied on roads will realize a benign hydrological cycle in cities through infiltration, stagnation, storage and purification.However, as the main land type affected by soil loss and water pollution in the new district, the cultivated land lacks scientific management measures.The government should guide farmers in carrying out accurate fertilization and pesticide management in a reasonable and efficient manner, reducing the use of pesticides and fertilizers, and establishing ecological bags at the edge of the field to stabilize the gully with the native ability of plants.

Figure 1 .
Figure 1.Topographic map of (a) the Jing-Jin-Ji region and (b) the XANA region (the black lines represent the boundaries between different prefecture-level cities).

Figure 3 .
Figure 3. Chord chart of land use change in XANA from 1980 to 2020.

Figure 2 .
Figure 2. Spatial distribution of land use types in the XANA region from 1980 to 2020.

Figure 4 .
Figure 4. Distribution and changes in ecosystem services in XANA from 1980 to 2020 (a-e for water yield, f-j for carbon storage, k-o for nitrogen export, p-t for soil loss).

Figure 5 .
Figure 5. Change in the total water yield of the different land use types.

Figure 6 .
Figure 6.Changes in carbon storage in different land use types.

Figure 7 .
Figure 7. Changes in soil erosion in different land use types (left ordinate for cultivated land and right ordinate for woodland and grassland).

Figure 8 .
Figure 8. Correlation between different ecological service functions (X1 represents water yield and carbon storage, X2 represents water yield and nitrogen output, X3 represents water yield and soil loss, X4 represents carbon storage and nitrogen output, X5 represents carbon storage and soil loss, X6 represents nitrogen output and soil loss).

Figure 9 .
Figure 9. Cluster analysis of ecosystem services in XANA based on the bivariate Moran's I index from 1980 to 2020.

Table 2 .
Changes in the land use structure in XANA from 1980 to 2020 (%).

Table 1 .
The selection of model parameters.
regional carbon storage exhibited a declining trend, dropping from 649.40 × 10 4 t in 1980 to 574.68 × 10 4 t in 2020, for a decrease of 11.5% from 1980 to 2020.The central region showed significantly greater carbon storage than the surrounding areas, primarily due to greater soil carbon storage under water bodies.The carbon sequestration values ranged from 12 t/hm 2 to 191 t/hm 2 in the XANA region.Urban expansion and a reduction in water bodies have resulted in carbon sources being distributed southwest of XANA and scattered north of the new area (figures 4(f)-(j)).Carbon storage in the different land types followed subsequent orders: cultivated land (390.82 × 10 4 t) > water bodies (191.70 × 10 4 t) > urban land (22.0 × 10 4 t) > woodland (13.04 × 10 4 t) > grassland (1.06 × 10 4 t).

Table 3 .
Changes in the quality of average ecosystem services in XANA.

Table 4 .
Contribution of climate change and land use change to ecosystem services.
Table 4 illustrates that climate change predominantly drives changes in water yield and soil conservation in the XANA region(Dai et al 2020, Wang and Lei 2023, Xiao et al 2023).Precipitation in XANA measured 297.6 mm in 2000, escalating to 387.7 mm in 2010.Climate change accounted for 94.2% of the change in water yield and 100.9% of the change in soil conservation, surpassing the influence of land use.Regarding nitrogen output change, land use primarily contributed 90.2% of the total nitrogen output (Wang and Lei 2023), while climate change contributed 13.7%.The dynamic change in land use from 2010 to 2020 (Liu et al 2022) reached 6.78.