Introduction

The Qinling Mountains serve as a crucial ecological safeguard in China and are a significant water source conservation area for the Yellow River and Yangtze River basins1. As the climatic boundary between the north and the south of China, the Qinling Mountains have many functions such as regulating the climate, preserving soil, conserving water, and maintaining biodiversity2,3. A comprehensive understanding of the ecological function enhancement and decline of the Qinling region is instrumental in identifying zones at risk of ecological degradation and delineating critical ecological function areas. Moreover, it is essential for advancing high-quality regional development and fostering harmonious coexistence between humans and nature4.

The assessment of ecosystem patterns and their changes reflects the spatial distribution of ecosystems and the transitions between various types, which are crucial for maintaining ecosystem stability5,6. The patterns and composition of ecosystems directly affect biogeochemical and hydrological cycles, biodiversity, and ecosystem services, and significantly influence socio-economic development7. The Qinling region has experienced intense human activities in recent years, leading to severe soil erosion and frequent illegal mining activities8. Despite the establishment of numerous ecological protection zones, including national key ecological protection areas and biodiversity priority conservation areas, critical ecological spaces remain encroached upon, wetland areas continue to decrease, and biodiversity is under threat9. Consequently, it is imperative to investigate the spatiotemporal dynamics and evolutionary trends of ecosystem patterns in the Qinling region.

The Ecosystem Quality Index (EQI) is a comprehensive indicator used to assess and quantify the overall health of ecosystems in a region10,11. It reflects the functional status of ecosystems, the level of biodiversity, and their responsiveness to environmental pressures by combining a variety of ecological parameters, such as fractional vegetation cover (FVC), net primary productivity (GPP), and leaf area index (LAI). High-quality ecosystems are more resilient and resistant and can cope more effectively with environmental stresses and emergencies (e.g., extreme weather, pests, diseases, and invasive alien species)12. The habitat in the Qinling region is currently sensitive and fragile, and research on the evaluation of ecological environmental quality is notably insufficient and unable to identify the degradation risk areas of the Qinling region13.

Ecosystem services serve as a crucial link between nature and society, connecting the fundamental structures, operational processes, and ecological functions with human well-being14,15. Water conservation and soil retention are crucial ecological service functions within terrestrial ecosystems16. The numerous steep slopes in the Qinling Mountains accelerate runoff, making the region particularly prone to soil erosion16. Seasonal variations, such as heavy rainfall, further exacerbate the risk of soil erosion17,18,19. Severe soil erosion has diminished water retention capacity, leading to increased sedimentation in reservoirs and a significant influx of non-point source pollutants into rivers20. Additionally, in some areas, ecological vulnerability is intertwined with poverty, and extensive production practices present new potential threats to soil retention16. Identifying the improvement and decline in water and soil conservation in the Qinling region is essential for guiding ecological restoration efforts, enhancing regional water security, and optimizing water resource management.

The delineation of protected areas has garnered significant attention, including efforts to establish protected area networks and evaluate ecosystem services21. China has implemented a series of important measures to safeguard the ecological environment, including the designation of key national ecological function zones, priority biodiversity conservation areas, and national nature reserves22. Currently, the delineation of ecological protection areas in the Qinling region often prioritizes a single objective, overlooking a comprehensive consideration of multiple goals, such as ecological quality, functionality, and human needs3. Furthermore, there is an insufficient implementation of dynamic monitoring and adaptive strategies following the delineation of protection areas, and the effects of human activities within and around ecological function zones are inadequately addressed22. With the growing population and continued urbanization, including agricultural cultivation, urban expansion, mining, and tourism development, the Qinling region has experienced significant impacts on its ecological environment, even as local economic growth has progressed16. Therefore, identifying ecological issues and delineating key ecological function zones, along with areas at risk of ecological degradation, are crucial steps for developing targeted restoration strategies tailored to each ecological zone.

This study evaluates the ecological status and changes in the Qinling region by examining ecosystem patterns, quality, and functions. It delineates key ecological function zones and degradation risk zones and proposes future development pathways. The study has four objectives: (1) analyze the nature and human ecosystem patterns in the Qinling region. (2) assess the fractional vegetation cover (FVC), leaf area index (LAI), and gross primary productivity (GPP), and identify the degradation in ecosystem quality (EQI). (3) estimate the water retention and soil conservation data and evaluate the improvement and decline of ecosystem functions. (4) delineate the key ecological function zones and the degradation risk zones.

Materials and methods

Study area

This study adopts a narrow definition of the Qinling region, extending southward to include the Daba Mountains. It encompasses six provinces—Shaanxi, Gansu, Henan, Sichuan, Chongqing, and Hubei—and one municipality, Ningxia, covering a total of 104 counties and an area of approximately 270,000 km2 (Fig. 1a). The Ministry of Ecology and Environment of the People’s Republic of China established a cross-regional ecological protection cooperation mechanism for the Qinling area, defining its scope based on 104 counties, following consultation with experts and a review of relevant information. The elevation of the study area gradually increases from the southeast to the northwest, with the highest elevations found in Qinghai and Gansu, reaching up to 4,981 m (Fig. 1b). The Qinling region exhibits significant spatial variability in temperature and precipitation, with a marked climate difference between the northern and southern areas. The overall spatial pattern is characterized by drier conditions in the north and wetter conditions in the south. Temperature ranges from − 9.05 °C to 16.88 °C, while precipitation varies between 400.13 mm and 1,298.66 mm (Fig. 1c-d).

National key ecological function zones are designated areas that serve important ecological functions such as water conservation, soil retention, sand stabilization, and biodiversity maintenance (Tan et al., 2023). The Qinling region encompasses four ecological function zones, with an area of approximately 151,400 km², accounting for about 55.55% of the total administrative area. These zones include the Sanjiangyuan Water Conservation and Biodiversity Protection Area, the Three Gorges Reservoir Soil Retention Area, the Gannan Mountain Water Conservation Area, and the Qinling-Daba Mountain Biodiversity Protection and Water Conservation Area (Fig. 1e). Additionally, the Qinling region includes four priority biodiversity conservation areas, with a total area of approximately 138,200 km2, accounting for about 48.15% of the total administrative area. These areas are the Daba Mountain Area, the Qinling Area, the Minshan-Hengduan Mountain Northern Section Area, and the Qiangtang-Sanjiangyuan Area (Fig. 1f).

Fig. 1
figure 1

The ___location of Qinglin (a: geographic ___location; b: elevation; c: temperature; d: precipitation; e: key ecological function area; f: priority biodiversity conservation area). (this figure was drawn by ArcGIS10.7 http://www.esri.com/arcgis/).

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Data sources

Temperature, precipitation, and evapotranspiration data were obtained from the China Meteorological Data Service Center. These data were interpolated into a time series for the Qinling region, covering the period from 2000 to 2023, using the professional interpolation software AUNSPLIN.

The ecological pattern data were derived from land use data, which were sourced from the Resource and Environment Science Data Platform (https://www.resdc.cn/). The data cover the time series from 2000 to 2020, with a spatial resolution of 30 m. Spatial changes in the ecosystem patterns of the Qinling region were analyzed using a land use transition matrix.

The Normalized Difference Vegetation Index (NDVI), Gross Primary Productivity (GPP), and Leaf Area Index (LAI) were selected as indicators to reflect the quality of the Qinling ecosystem. The data were sourced from MODIS and span the time series from 2000 to 2023, with a spatial resolution of 250 m. The remote sensing data were processed using the MRT TOOLS software, which handled projection transformation, mosaicking, fusion, and clipping. Finally, the data underwent accuracy validation to ensure reliability.

Based on the cubic method, all data were resampled to 250 m.

Ecosystem quality

Fractional vegetation coverage (FVC) is a crucial indicator reflecting the status of surface vegetation and monitoring the ecological environment23. The strong correlation between vegetation indices and vegetation coverage makes the NDVI a recognized method for calculating vegetation coverage23. According to the pixel binary model theory, the NDVI value of a pixel is considered to be a combination of the information contributed by the green vegetation and the information contributed by the non-vegetated portion. FVC can be obtained using the following:

$$F_{c} = \frac{{NDVI - NDVI_{{soil}} }}{{NDVI_{{veg}} - NDVI_{{soil}} }}$$
(1)

Where:

Fc: Fractional vegetation coverage; NDVIveg: the NDVI value of fully vegetated pixels.

NDVIsoil: the NDVI value of non-vegetated pixels.

Ecosystem quality reflects the overall condition of the regional ecosystem and is determined by the relative densities of fractional vegetation coverage (FVC), leaf area index (LAI), and gross primary productivity (GPP)24. The method is derived from the national ecological standard of the People’s Republic of China: Technical specification for investigation and assessment of national ecological status-Ecosystem quality assessment (HJ 1172–2021). Relative density is defined as the ratio of each ecosystem type value to the maximum value within that region, with the results for the three indicators normalized to a range from 0 to 1. The final measure of ecosystem quality (EQI) is then calculated using the following formula:

$$EQI=\frac{{LA{I_k}+FV{C_k}+GP{P_k}}}{3}$$
(2)

where:

EQI: Ecosystem Quality Index. FVCk: Normalized relative density of vegetation coverage. LAIk: Normalized relative density of leaf area index. GPPk: Normalized relative density of gross primary productivity.

The normalization process scales each indicator between 0 and 1, with 0 representing the minimum value and 1 representing the maximum value within the region. This method yields a comprehensive index that reflects the overall ecosystem quality by integrating multiple indicators.

According to the national ecological standard of the People’s Republic of China (HJ1172-2021), the ecosystem quality (EQI) is categorized into five levels: Excellent, Good, Moderate, Poor, and Bad (Table 1). The specific criteria for each level are outlined in the table below:

Table 1 The level, description, and range of EQI.
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Ecosystem function

The ecosystem function (water conservation and soil conservation) method is derived from the national ecological standard of the People’s Republic of China: Technical specification for investigation and assessment of national ecological status --Ecosystem services assessment (HJ 1172–2022). Based on this standard, we calculated the water conservation and soil conservation in Qinling Regions from 2000 to 2023.

Water conservation encompasses the total volume of water resources secured through intercepting and retaining precipitation, enhancing soil infiltration and accumulation, conserving soil moisture, regulating surface runoff, and replenishing groundwater10. The calculation is derived from the water balance equation, as represented by the following formula:

$${Q_{wr}}=\sum\limits_{{i=1}}^{n} {{A_i} \times ({P_i} - {R_i} - E{T_i}) \times {{10}^{ - 3}}}$$
(3)
$${R_i}={P_i} \times a$$
(4)

Qwr: Water conservation capacity (mm) (the total amount of conserved water); i: The specific type of ecosystem (i.e., each ecosystem category considered in the study). n: The total number of ecosystem types. Ai: The area of the i-th ecosystem type (m²). Pi: Precipitation for the i-th ecosystem type (mm/a). Ri: Surface runoff for the i-th ecosystem type (mm/a). ETi: Evapotranspiration for the i-th ecosystem type (mm/a). a: the ratio of surface runoff to rainfall. The water conservation was calculated using the InVEST model25.

Assessing soil retention capacity evaluates changes in soil conservation effectiveness26. This metric is the difference between the potential soil erosion rate without vegetation cover and the actual soil erosion rate under current conditions27. Soil conservation was calculated using the Universal Soil Loss Equation (USLE) and InVEST model25. The formula is as follows:

$${A_{retention}}={A_{pot}} - {A_{act}}$$
(5)
$${A_{pot}}=V \times K \times L \times S$$
(6)
$${A_{act}}=V \times K \times L \times S \times C$$
(7)

where:

Aretention: Soil retention capacity (t/hm²). Apot: Potential soil erosion rate (t/hm²) represents the erosion that would occur without vegetation cover. Aact: Actual soil erosion rate (t/hm²), representing the erosion occurring under current land cover conditions. R: rainfall erodibility factor, MJ∙mm/(hm2∙h∙a). Soil erodibility reflects the sensitivity of soil particles to erosive forces and it is an internal factor affecting soil erosion that is closely related to soil attributes; K: soil erodibility factor, t∙hm2∙h/(hm2∙MJ∙mm). which using the soil clay, silt, sand, and organic carbon content; L: slope length factor; S: slope length factor; C: vegetation cover factor, which was assigned to the vegetation cover factor after referring to Ouyang et al. (2016)25.

The value of ecosystem services was summed up, and 50% and 80% of the total ecosystem services were taken as the turning points for the ecosystem services assessment classification so that the importance of ecosystem services was classified into three levels: extremely important, important, and generally important.

Trend analysis

The Mann-Kendall test is a non-parametric statistical method commonly employed to detect monotonic trends in time series data.This method does not require the data to adhere to a specific distribution and does not assume a linear relationship28. It has notable advantages in identifying trends in time series data, especially when handling complex, nonlinear data29. Consequently, this study employs the Mann-Kendall method to analyze trends in ecosystem quality and functions.

For the ecosystem quality or ecosystem function time series, the statistic \({S_k}\)is defined as follows30:

$${S_k}=\sum\limits_{{i=1}}^{k} {{r_i},(k=2,3, \cdots ,n)}$$
(8)

\({x_i}\) and \({x_j}\) are the ith data value in time series.

$${r_i}=\left\{ {\begin{array}{*{20}{l}} {1,{x_j} - {x_i}>0} \\ {0,{x_j} - {x_i} \leqslant 0} \end{array},} \right. \quad (j=1,2, \cdots ,i)$$
(9)

The ecosystem quality or ecosystem function trends can be identified by utilizing the standard normal test statistic (\(U{F_k}\)), which can be calculated as follows:

$$U{F_k}=\frac{{[{S_k} - E({S_k})]}}{{{{[Var({S_k})]}^{1/2}}}} \quad (k=2,3,4, \cdots n)$$
(10)

Where UF1 = 0. \(E({S_k})\) and \(Var({S_k})\) are the mean and variance of \({S_k}\), which can be calculated as follows:

$$E({S_k})=n(n - 1)/4$$
(11)
$$Var({S_k})=n(n - 1)(2n+5)/72$$
(12)

Positive (negative) values \(U{F_k}\) indicate ecosystem quality and functions exhibit increasing (decreasing) trends. A typical significance level \(\alpha =0.05\)was used in the test with\(U{F_{1 - \alpha /2}}\) = 1.96. If \(\left| {UF_{k} } \right|\)>1.96, ecosystem quality or ecosystem function passed the significant test. The Mann-Kendall test was done in MATLAB R2019.

Delineation of the ecological protection zones

The delineation of ecological protection zones requires a comprehensive approach that considers various factors, including ecosystem quality, ecological functions, and the impacts of human activities3. This study delineates ecologically significant functional zones and areas at risk of degradation due to human activities in the Qinling region and provides policy recommendations. The specific steps are as follows:

  1. (1)

    The ecosystem types are classified into natural and anthropogenic categories. Ecosystems such as grasslands, forests, shrubs, wetlands, and deserts are considered natural landscapes, while crops, urban areas, rural areas, industry, mining, and roads are classified as anthropogenic. are classified as anthropogenic landscapes.

  2. (2)

    In both natural and anthropogenic ecosystems, areas with ecosystem quality rated as “excellent” or “good” and with “extremely important” water conservation and soil retention functions are designated as core ecological function zones. These core zones collectively form important ecological function zones.

  3. (3)

    Natural ecosystems with ecosystem quality rated as “poor” or “bad”, where water and soil conservation is considered “unimportant” are classified as natural degradation risk zones. Similarly, areas within anthropogenic ecosystems that exhibit low ecosystem quality, along with reduced water conservation and soil retention functions, are identified as zones at risk of anthropogenic degradation. These collectively constitute degradation risk zones.

  4. (4)

    Building on the delineation of important ecological function zones and degradation risk zones, and considering pre-existing biodiversity priority protection areas (Daba Mountain Area, the Qinling Area, the Minshan-Hengduan Mountain Northern Section Area, and the Qiangtang-Sanjiangyuan Area) and national key ecological function areas (Sanjiangyuan Water Conservation and Biodiversity Protection Area, the Three Gorges Reservoir Soil Retention Area, the Gannan Mountain Water Conservation Area, and the Qinling-Daba Mountain Biodiversity Protection and Water Conservation Area), and various geographical and administrative units, the Qinling region is further categorized into two main categories with sixteen subcategories. These subcategories are labeled A1-A7 for key ecological function zones and B1-B9 for ecological degradation risk zones.

  5. (5)

    Considering the various geographical units, core ecological functions, and primary ecological challenges, specific ecological restoration strategies are proposed for key ecological functions and degradation risk zones. These strategies are tailored to meet the unique needs of each zone, ensuring targeted and effective ecological management and restoration.

Results

Analysis of the changes in ecosystem patterns

In 2020, the terrestrial natural ecological space in the Qinling region comprised approximately 75.57% of the total land area, mainly consisting of ecosystems like grasslands, forests, shrublands, wetlands, and deserts (Fig. 2). Crop and urban areas accounted for 22.23% and 1.74%, respectively. Forests were primarily distributed in the Funiu Mountains, Wudang Mountains, Daba Mountains, and Taibai Mountains, the main peaks of the Qinling Mountains. Grasslands and shrublands were mainly found between the Qilian Mountains. Wetlands were primarily located in the Danjiangkou Reservoir, Yako Reservoir, Zhaoping Reservoir, Sanmenxia Reservoir, the Weihe River, and Bailong Rivers. Deserts were mainly found in Guinan County, Hainan Tibetan Autonomous Prefecture. Crops were concentrated in the Weihe Plain, Guanzhong Plain, and Huangshui Valley. Urban areas were concentrated along riverbanks.

Fig. 2
figure 2

Spatial distribution and area proportions of ecosystem patterns in the Qinling region (2020).(this figure was drawn by ArcGIS10.7 http://www.esri.com/arcgis/).

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Between 2000 and 2020, the areas of ecosystems like forests, wetlands, grasslands, and urban spaces in the Qinling region expanded, whereas shrublands, crops, and deserts decreased (Fig. 3). The magnitude of change in crops, forest, and shrubland areas increased faster in 2010–2020 than in 2000–2010, while the rate of grasslands, wetlands, urban, deserts, and other ecosystems decelerated. The annual growth rate of forest areas rose from 0.05 to 0.45%, whereas shrubland ecosystems shifted from a growth rate of 0.06% to a decline of 0.95%. The annual growth rate of wetland ecosystems declined from 0.94 to 0.52%, and the annual growth rate of urban areas decelerated from 3.25 to 1.62%. Overall, rapid urban expansion led to extensive encroachment on ecological land. In recent years, a series of ecological restoration projects have been implemented in the Qinling region, including mountain and forest closures, the restoration of inefficient forests, and the rehabilitation of shrublands. Additionally, non-utilized land has been developed, and the area of farmland has expanded. As a result, the areas of forests, scrublands, and farmland increased at an accelerated rate.

Fig. 3
figure 3

Ecosystem area changes in the Qinling region from 2000 to 2020.

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Study on the degradation risk areas in ecosystem quality

Based on the distribution and trend changes of key vegetation parameters, areas exhibiting high-quality GPP and FVC, classified as “excellent” or “good”, were predominantly situated in the southern sections of the Qinling-Daba Mountains (Fig. 4). Conversely, regions such as the Sanjiangyuan area in Qinghai, the Loess Plateau in Henan, and the Minshan-Hengduan Mountains in Gansu exhibited relatively lower GPP and FVC levels. The trends for GPP and FVC predominantly indicated an upward trajectory, with over 75% of the areas demonstrating an increase. The proportions of areas experiencing declines or exhibiting no significant change were minimal, with declines constituting less than 2% of the total. For LAI, the majority of regions were classified as “moderate” quality, with a smaller proportion rated as “excellent” or “good”, and a significant 25.56% categorized as “poor”. The trend in LAI indicated a slower rate of improvement compared to GPP and FVC, with a greater proportion of regions experiencing declines. These findings underscore that GPP and FVC have generally improved, but the quality of LAI is still worrying, especially considering its declining trend and lower quality level. This emphasizes the need for targeted ecological interventions to address LAI quality deficiencies.

Fig. 4
figure 4

Classification and trend changes of ecosystem quality (EQI) in Qinling region from 2000 to 2023 (a-b: the classification and trend changes of FVC; c-d: the classification and trend changes of LAI; e-f: the classification and trend changes of GPP: FVC: fractional vegetation coverage, LAI: leaf area index: GPP: gross primary productivity). (this figure was drawn by ArcGIS10.7 http://www.esri.com/arcgis/).

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Based on key vegetation parameters (GPP, LAI, FVC), the ecosystem quality index (EQI) for the Qinling region was assessed and categorized into five levels (Fig. 5). The majority of ecosystem quality was classified as “good”, accounting for 46.21% of the total area. This quality level was predominantly observed in the southeastern part of the Qinling-Daba Mountains, including Wudang Mountain and the southern slopes of Funiu Mountain. The western and northern parts of the Qinling region, including the Hehuang Valley in the Sanjiangyuan area of Qinghai, the Huangnan Basin, and the Minshan-Hengduan Mountains, generally exhibited lower average ecosystem quality values over the years. The trend in ecosystem quality indicated that 48.07% of the region experienced quality improvements, while only 5.76% showed a decline. Additionally, 46.18% of the area exhibited no significant change in quality. Areas with no significant changes are primarily situated in the northwest of the Minshan-Hengduan Mountains, the Daba Mountains, the western Qinling Mountains, the Hanzhong Plain, and parts of Funiu Mountain. Regions at risk of ecological degradation require particular attention. These areas with relatively stable or declining quality, underscoring the need for targeted ecological management and restoration efforts.

Fig. 5
figure 5

Classification and trend of the EQI in the Qinling region from 2000 to 2023 (a: the classification of EQI; b: the trends of EQI). (this figure was drawn by ArcGIS10.7 http://www.esri.com/arcgis/).

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Research on the improvement and decline in ecosystem function

The spatial distribution of water conservation capacity in the Qinling region showed higher values in the southern areas and lower values in the northwest (Fig. 6a). In 2023, the total volume of water conservation in the Qinling region was 4.48 × 1010 m3. High water conservation zones were mainly located in the southern parts of Chongqing, Hubei Province, and the Qinling-Daba Mountains. These regions benefited from abundant vegetation and complex topography, which create favorable conditions for water conservation, classifying them as core water conservation areas. In contrast, regions such as southern Qinghai Province and Gansu Province exhibited relatively lower water conservation service values, with a significant portion categorized as low importance, accounting for 51.96% (Fig. 7a). From 2000 to 2023, the water conservation function in the Qinling region showed a predominantly increasing trend, with 81.20% of the area experiencing improvement. Areas with no significant changes and declines accounted for 18.49% and 0.31%, respectively (Fig. 7b). Overall, improving water conservation functions in the Qinling region helps alleviate regional water scarcity and provides critical support for ecological safety and sustainable development in downstream areas.

The spatial distribution of soil conservation capacity had higher values in the central and southern areas compared to the northwest and eastern regions (Fig. 6b). In 2023, the total soil conservation capacity in the Qinling region was 28.56 billion tons, with a per-hectare rate of 0.11 tons. The most critical soil conservation areas were in the southeastern Qinling-Daba Mountains, where complex topography and abundant vegetation contribute to strong soil conservation capabilities (Fig. 7c). Conversely, regions such as the Sanjiangyuan region, the Minshan-Xiaodong Mountains, the Loess Plateau, and the Qinling in Henan exhibit lower soil conservation capacities. Soil conservation in the Qinling region predominantly showed an increasing trend, with a relatively low proportion experiencing a decline. Areas experiencing declines were mainly concentrated in the Sanjiangyuan region and the Minshan-hengduan Mountains (Fig. 7d).

Fig. 6
figure 6

Spatial distribution of water conservation and soil conservation(a: water conservation; b: soil conservation). (this figure was drawn by ArcGIS10.7 http://www.esri.com/arcgis/).

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Fig. 7
figure 7

Importance classification and trend changes of water conservation and soil conservation (a: spatial distribution of water conservation; b: trend changes in water conservation; c: spatial distribution of soil conservation; d: trend changes in soil conservation). (this figure was drawn by ArcGIS10.7 http://www.esri.com/arcgis/).

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Delineation of ecological protection zones and degradation risk zones

Based on the ecological patterns, quality, and functions of the Qinling region, combined with geographical and topographical considerations, the region has been classified into two primary categories (Ecological Function Zones and Ecological Degradation Zones) and further subdivided into 16 subzones (Fig. 8).

Ecological Function Zones (A1-A7) were predominantly situated in the central and southern parts of the Qinling region, including Hubei, Shaanxi, Chongqing, and the Daba Mountains in Sichuan, as well as the Three Gorges Reservoir area in Sichuan and Hubei. This region was designated as the core area for ecological quality and function, with minimal human disturbance. Zones A1, A5, A6, and A7 (Hubei, Chongqing, Sichuan) were characterized by the dominance of forest ecosystems and exhibit overall stability and improvement in ecological quality and functions. Enhancing forest protection and reducing deforestation was crucial for adapting to climate change impacts in these zones. Zones A2 and A3 (Daba Mountains and the Qinba Mountains in Shanxi) were characterized by croplands and forests. These zones, featuring dense forests and developed agriculture in the central basins, were significant for water conservation and soil retention. Therefore, it is recommended to implement green crop initiatives aimed at promoting the protection and improvement of crop quality, while enhancing agricultural productivity in these areas.

Ecological Degradation Risk Zones (B1-B9) were predominantly located in the following areas: Qinling in Henan, the Loess Plateau in Shaanxi, Henan, and the Loess Plateau in Gansu, Sanjiangyuan in Qinghai, Minshan-Hengduan Mountains in Gansu, and the Qinling in Gansu). These zones were characterized by low ecological quality and functional importance, coupled with significant human disturbance, which contributed to a high risk of ecological degradation. B5 (Henan Qinling): This zone, predominantly covered by forests, has experienced degradation, leading to decreasing ecological quality and functionality, exacerbated by significant human interference. Therefore, it is recommended to strengthen forest management and restoration efforts, gradually expand forest area, optimize forest structure and function, and enhance the overall quality of forest ecosystems in regions B1, B4, and B9 (the Loess Plateau in Shaanxi, Gansu, and Henan). Predominantly characterized by agricultural development and residential areas, this zone requires a transition from traditional crop practices. Promoting crop rotation, intercropping, and other sustainable crop practices will enhance land use efficiency, mitigate degradation, and reduce reliance on chemical fertilizers and pesticides. Essential strategies include implementing projects to convert crops to forests and grasslands, establishing ecological protection zones, strictly limiting development activities, and encouraging urban migration to alleviate rural population density and pressure. B2, B3, B7, and B8 (Minshan-Hengduan Mountains in Gansu, Qinling in Gansu, Sanjiangyuan in Qinghai, and the Loess Plateau in Qinghai). Predominantly consisting of grasslands and shrublands, this zone should focus on restoring degraded grasslands, improving pest control, and managing rodent and insect infestations. Seasonal grazing restrictions should be enforced to enhance grassland productivity.

Fig. 8
figure 8

Ecological Functional Zoning of the Qinling Region. (a) Ecological Quality and Function Core Areas, Degradation Zones, and Human Activity Interference Zones. (b) Ecological Function (A1-A7) and Ecological Degradation Risk Zones (B1-B9). (this figure was drawn by ArcGIS10.7 http://www.esri.com/arcgis/).

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Discussion

The degradation risk regions in the Qinling

This study investigates the spatial distribution and temporal changes in ecological patterns, quality, and functions in the Qinling region from 2000 to 2023. The findings reveal that the natural ecosystem has increased, including forests, grasslands, and wetlands. Notably, the forest ecosystem has exhibited the most substantial growth, expanding by approximately 3,980 km2, with an average annual growth rate of 0.25%. This growth is mainly concentrated in key areas of China’s natural forest conservation projects, such as the Qinling Daba Mountains and Hubei Province. Through measures such as forest closure, afforestation, and returning crops to forests and grasslands, natural forests in this region have been protected and restored, thereby reducing deforestation, illegal logging, soil erosion, and land degradation26,31. These ecological restoration projects have improved the quality and functionality of regional ecosystems and established a robust ecological foundation for the sustainable development of the regional economy and society32. However, the rapid expansion of urban areas in the Qinling region has increased by approximately 1,800 km², with an average annual growth rate of 2.43%. Concurrently, shrubland areas have decreased at the fastest rate, with an average annual reduction of 0.45%. This trend is primarily concentrated in the Loess Plateau regions of Henan, Shaanxi, and Gansu provinces. The accelerated urbanization in these areas continues to encroach upon ecological spaces, further exacerbating environmental issues.

From the perspective of ecosystem quality and function, approximately 20% of the Qinling region exhibits low ecosystem quality, while 50% of the region has limited water conservation and soil retention capacities. These areas are predominantly located in the northwestern parts of Qinling, including the Sanjiangyuan and the Minshan-Hengduan Mountains. The quality and functions of ecosystems in these areas are experiencing a declining trend. Located in the arid and water-scarce northwest of China, these regions have long struggled with insufficient water resources, leading to grassland degradation and severe soil erosion. Recently, the frequency of extreme climatic events, such as high temperatures, droughts, and heavy rainfall, has increased in these regions13. These extreme conditions have caused significant fluctuations in river water levels, uneven distributions of droughts and floods, and an increase in seasonal rivers, further deteriorating ecosystem quality and weakening ecological functions. This has intensified the instability of the Qinling ecosystem and increased the region’s environmental vulnerability33. The Qinling-Daba Mountain region is noted for its high ecological quality, featuring robust water conservation and soil retention functions. The region has implemented measures such as terraced field restoration and afforestation on barren mountains, which promote vegetation restoration and soil and water conservation, thereby effectively reducing soil erosion33. The establishment of nature reserves, delineation of ecological protection red lines, delineation of important ecological function areas, and priority protection areas for biodiversity have significantly strengthened the protection of endangered wildlife and the restoration of habitats34. These efforts have contributed to preserving ecological balance and biodiversity, thereby enhancing the overall ecological quality and function of the region.

Revealing the functions zones and degradation risk zones

The implementation of differentiated ecological protection and restoration strategies is crucial for regional ecological planning35,36. Previous studies seldom considered the implementation of ecological projects in the study area, and only delineated ecological functional zones based on land use change data or used qualitative methods to assess the ecological risk of a single ecosystem type35,37,38. In this study, we quantitatively synthesized the ecological pattern, ecological quality, and ecological function by combining geography and topography, and divided the Qinling area into two categories: ecological functional areas and ecological degradation areas, which were further subdivided into 16 subareas. Our study bridges the gap between landscape indices in assessing ecological risks, enhancing the precision of the results and more effectively addressing the practical needs of ecological management.

The delineation of ecological function zones in the Qinling region reveals distinct regional characteristics. Specifically, the Qinling-Daba Mountain range within Shaanxi, Hubei, and Chongqing provinces primarily comprises ecological function areas, while the Loess Plateau, Three Rivers Source Region, and Minshan-Hengduan Mountain Range are predominantly classified as ecological risk areas. In these ecological function zones, it is crucial to enhance the protection of key natural ecosystems, including forests, shrubs, grasslands, wetlands, and the natural habitats of wildlife. This will enhance ecosystem diversity and promote the sustainable development of these areas39. Concurrently, a modern ecological protection framework should be established, and the ecological monitoring system should be optimized and adjusted40. Additionally, it is essential to establish a multi-source satellite remote sensing dataset to monitor climate and ecological variables, including dust storms, smog, forest fires, snow cover, drought and flood conditions, and crop growth, while also facilitating data sharing21. This will strengthen the support and application of satellite remote sensing technology for ecological and environmental monitoring in the Qinling region and facilitate multi-scale data sharing for ecological monitoring and assessment.

For the ecological degradation risk areas in the Loess Plateau regions of Henan and Shaanxi, where human-induced degradation is prevalent, it is crucial to delineate urban development boundaries and rigorously control the unchecked expansion of urban spaces27. Additionally, it is necessary to enhance the management of agriculture, forestry, and grasslands and rigorously regulate the use and access to ecological spaces. In the ecological degradation areas of the Gansu Sanjiangyuan region and the Minshan–Hengduan Mountains in Qinghai, where grassland degradation is predominant, continuous and comprehensive monitoring and assessment of grassland and shrubland ecosystems are essential. Moreover, efforts should be intensified to restore and sustainably manage degraded grassland ecosystems. Key ecological engineering areas should be strategically planned, and the implementation of natural forest protection projects, the conversion of cropland to forest and grassland, and the establishment of the Three-North Shelter Forest Program should be reinforced40. This includes optimizing tree species, expanding forest cover in the region, and improving the quality and functionality of the ecosystem. Additionally, a comprehensive ecological protection framework should be established, incorporating ecological redlines, nature reserves, key ecological engineering areas, and biodiversity priority protection areas to enhance the protection and management of ecological functions41. Moreover, stringent ecological and environmental protection policies and regulations must be established to ensure the effective safeguarding of ecosystems in these areas and to mitigate the pressure on their carrying capacity.

Limitations and uncertainty

The uncertainties and limitations of this study are as follows: (1) The study focuses primarily on the analysis of two ecological functions (water and soil conservation) control within the Qinling region, omitting other critical ecological functions such as biodiversity and wind and sand prevention. Consequently, the exclusion of these additional functions may impact the accuracy and comprehensiveness of the research findings, introducing uncertainties. (2) This study lacks attribution analysis concerning ecological quality and function, particularly about long-term climatic factors. Climate change could alter precipitation patterns, volumes, and frequencies, thereby impacting groundwater recharge and, consequently, water conservation and soil erosion control functions. Furthermore, extreme climatic events, such as prolonged high temperatures or heavy rainfall, may lead to the overutilization or depletion of water resources, influencing the quality and function of ecosystems42. The failure to adequately account for these climate variations may affect the accuracy of the research results. (3) In delineating ecological function zones, this study primarily draws on the definitions of key ecological function areas and biodiversity priority protection zones, without fully incorporating the boundaries of nature reserves and ecological protection redlines. Ecological function zone delineation should be further optimized to include the boundaries of these protected areas, thereby improving the scientific and rational foundation of the zoning results.

Conclusions

Based on the estimation of ecosystem quality and functions (water conservation and soil erosion control) from 2000 to 2023, this study identified the types and core distribution areas of ecosystem functions in the Qinling region, analyzed spatiotemporal changes in ecosystem patterns, quality, and functions, and delineated the region’s ecological protection zones. The main conclusions are as follows:

  1. (1)

    From 2000 to 2020, the areas of forests, wetlands, and grasslands in the Qinling region increased, with the most notable increase observed in forest areas, which expanded by approximately 3,980 km2, reflecting an annual growth rate of 0.25%. Conversely, urban areas expanded the most rapidly, increasing by around 1,800 km2 at an annual growth rate of 2.43%.

  2. (2)

    Between 2000 and 2023, 48.07% of the Qinling region’s areas exhibited an increasing trend in ecosystem quality, while only 5.76% experienced a decline. Core areas for water source conservation and soil erosion control account for 17.92% and 10.47% of the region, respectively, and are predominantly located in the Qinling-Daba Mountains. Areas with declining ecological quality and function are primarily concentrated in the Sanjiangyuan region, the Minshan-Qinghai-Tibet Plateau, and the Loess Plateau.

  3. (3)

    Based on ecological patterns, quality, functions, and ecological protection and restoration projects, the Qinling region has been divided into two majority categories and 16 subcategories: 7 ecologically key functional areas and 9 degradation risk areas. In the ecological function zones, emphasis should be placed on protection, restoration, and monitoring to maintain the stability of ecological quality and functions. Conversely, in the ecological degradation risk zones, it is crucial to control the expansion of construction land and strategically plan important ecological engineering areas to mitigate the degradation of ecological quality and functions.