How does cultivated land fragmentation affect soil erosion: Evidence from the Yangtze River Basin in China.

Reducing soil erosion (SE) is crucial for achieving harmony between human society and the ecological environment. The cultivated land fragmentation (CLF), directly or indirectly, alters soil structure, diminishes its water-holding capacity, and escalates the risk of SE. Scientific assessment of the effect of CLF on SE can provide new insights into controlling of SE across watersheds in China. However, few studies have quantified the effect of CLF on SE. Therefore, we utilized land use change data in the Yangtze River basin from 2000 to 2020, measuring the levels of CLF and SE using Fragstats and InVEST models. The bivariate spatial autocorrelation model was employed to reveal the spatial relationship between CLF and SE. Additionally, we constructed a spatial Durbin model and introduced the geographically and temporally weighted regression model to analyze the role of CLF on SE. The south bank of the upper and middle reaches of the Yangtze River basin exhibited high CLF and SE. The bivariate spatial autocorrelation results showed a significant positive spatial correlation between CLF and SE. The spatial Durbin model results showed that CLF had a spatial spillover effect and time lag on SE, and the effect of CLF on SE had an inverted "N" curve. The study also confirmed that last SE and neighboring SE areas influenced local SE. Currently, CLF had a negative effect on SE in the Sichuan Basin, Yunnan-Guizhou Plateau, and the middle and lower Yangtze River Plain, and positively in Qinghai, Hunan, and Jiangxi provinces. These findings suggest that the government should enhance cross-regional and cross-sectoral cooperation and monitoring of cultivated land changes to prevent and control SE effectively.

Coupled relationships between landscape pattern and ecosystem health in response to urbanization.

Rapid urbanization has highlighted ecological problems in the metropolitan area, with increasing landscape fragmentation and severe threats to ecosystem health (EH). Studying the spatio-temporal coupled relationship between landscape pattern and EH and its response to urbanization in the Fuzhou metropolitan area (FMA) can provide scientific reference for its long-term development planning. We examined the coupled relationship between landscape pattern and EH and its driving mechanism in the FMA at grid and township scales to address the gap. The results show that landscape heterogeneity, diversity, and dispersion are gradually increasing, and EH is rising progressively in the FMA from 2000 to 2020. The spatial distribution of landscape pattern indices and EH indicators showed a "high in the south and low in the north" trend. During the study period, the coupled relationship between landscape patterns and EH was increasingly powerful but with remarkable spatial heterogeneity. The study also found an inverted U-shaped relationship between urbanization and coupled relationships. Ecological landscapes' heterogeneity, diversity, and connectivity in low-urbanization areas are conducive to EH. The opposite is true for high-urbanization areas. This study provides a valuable reference for optimizing landscape planning and ecological management in metropolitan areas.

Ecological restoration zoning of territorial space in China: An ecosystem health perspective.

Rapid urbanization and high-intensity socio-economic activities in China have caused severe ecological problems. Implementing ecological restoration in China has become an inevitable way to restore the ecosystem. Ecosystem health is crucial for evaluating ecological conditions and trends, but comprehensive national studies that use quantitative ecosystem health assessments to guide specific ecological restoration are lacking. This study constructs the Vigor-Organization-Resilience-Services (VORS) model to evaluate the ecosystem health level of China during 2000-2020. Then, through the natural breakpoint and intelligent clustering correction, we carried out the ecological restoration zoning and proposed corresponding measures. The results show that China's overall ecosystem health declined from 2000 to 2020, and ecological restoration is imminent. The spatial pattern of ecosystem health is generally favorable in the south and usually poor in the north. China protects poor ecosystems' health well but needs more for better ones. To combat this degradation, we propose a zoning strategy that classifies the landscape into five categories: Ecosystem Conservation Areas (3.47%), focusing on biodiversity preservation; Ecosystem Enhancement Areas (10.53%), aiming at increasing ecological resilience; Ecosystem Buffer Zones (23.04%), intending to mitigate human impacts; Ecosystem Correction Zones (33.79%), targeting at restoring degraded ecosystems; and Ecosystem Reshaping Zones (29.17%), designing to revitalize ecological functions. The ecological restoration zoning in China proposed in this study, combined with appropriate and practical restoration tools, will help mitigate ecological problems and improve stability and ecosystem health.

Spatial relationship between land urbanization and ecosystem health in the Yangtze River Basin, China.

Globally, land-based urbanization had far-reaching impacts on ecosystem health. Determining the spatial relationship between land urbanization and ecosystem health is important for sustainable socioeconomic development and ecological protection. However, existing studies lack research on these relationships in basin regions, which may limit the implementation of effective basin ecological management measures. Based on multi-source data, this study analyzed the spatiotemporal patterns and spatial correlations of land urbanization rate (LUR) and ecosystem health index (EHI) in the Yangtze River basin (YRB) with a series of spatial analysis methods. The results showed that EHI in the YRB decreased by 0.024 during 2000-2020, with a decreasing range of 3.133 %, while LUR increased by 0.216, with an increasing range of 54.135 %. LUR has a significant negative spatial correlation with EHI, with high EHI and high LUR (9.814% in 2020) and high EHI and low LUR (12.397% in 2020) being the main types of agglomeration. The global regression results showed that LUR significantly negatively affected EHI. At the local scale, the LUR positively affected the EHI in the mountainous region, while the opposite was confirmed in the plain region. This study can provide scientific reference for the development of sustainable urban land control measures and basin ecological management measures.

Urbanisation and ecosystem health in the Middle Reaches of the Yangtze River urban agglomerations, China: A U-curve relationship.

Rapid urbanisation in global urban agglomerations has caused serious disturbances to the structure, function, and health state of ecosystems. Investigating the driving mechanisms behind the impact of urbanisation level (UL) on ecosystem health index (EHI) is important for constructing ecological civilisation and developing superior urban agglomerations in China. However, no in-depth studies exist on these mechanisms in various urban agglomerations, which makes formulation and implementation of effective ecosystem management and control policies difficult. In this study, we estimated UL and EHI based on multisource data, and a set of spatial regression models were then used to analyse the driving mechanisms at global and local scales in the Middle Reaches of the Yangtze River urban agglomeration (MRYRUA) in China between 1995 and 2015. Our results demonstrated that EHIs in the MRYRUA were 0.627, 0.613, and 0.610 in 1995, 2005, and 2015, respectively, with 2.71% decreases during the study period. The EHI in the surrounding mountainous regions was considerably higher than that in the plains. There was a significant spatial dependence between the UL and EHI. Low UL and high EHI, high UL and low EHI, and low UL and low EHI were the dominant relationship types in the MRYRUA (25.61%, 11.83%, and 11.27%, respectively). A 10% increase in UL resulted in 1.79%, 2.50%, and 2.99% decrease in EHI for each reference year in the spatial error model with lag dependence model. A U-shaped relationship was identified between UL and EHI in different urban agglomerations and cities of different administrative levels. Therefore, the results of this study can provide a scientific basis for the formulation of macro-control policies and locally specific control policies for ecosystem protection in the MRYRUA.

Identifying the driving forces of cultivated land fragmentation in China.

Cultivated land fragmentation (CLF) has severely affected China's agricultural production efficiency, large-scale operations, agricultural modernization, and food security. Exploring the spatiotemporal evolution patterns and driving forces of CLF is crucial for agricultural modernization. However, the driving forces of CLF in different agricultural regions in China still need to be clarified. In this study, CLF was measured in 2000, 2010, and 2020 based on remote sensing data with landscape pattern metrics, and the driving forces of spatial differentiation were detected based on a geographical detector model. The overall cultivated land area has slightly declined during the study period while the CLF has intensified. CLF showed significant spatial autocorrelation, with CLF increased-cultivated land decreased (2000 to 2010) and CLF decreased-cultivated land decreased (2010 to 2020). The contribution rate of land use intensity on CLF was the highest among all agricultural regions, excluding the Qinghai Tibet Plateau. In contrast, the contribution rates of other factors significantly varied across agricultural regions. These findings provide scientific support in formulating policies to conserve cultivated land for sustainable use of agricultural resources and CLF management in China.

Regional differences and driving forces of ecosystem health in Yangtze River Basin, China.

Ecosystem health in the Yangtze River basin (YRB) shows significant regional differences. Analysis of regional differences and drivers of ecosystem health in YRB is of practical significance for sustainable basin ecological management. However, existing studies lack research on regional differences and driving forces of ecosystem health, especially in big basin regions. Based on multi-source data, this study adopted spatial statistics and distribution dynamics models to quantitatively analyze the regional differences of ecosystem health in the YRB during 2000-2020 and employed the spatial panel model to reveal the driving forces of ecosystem health in the YRB. The ecosystem health index of the upper, middle, and lower reaches of YRB and the entire basin in 2020 was 0.753, 0.781, 0.637, and 0.742, respectively, while they all decreased during 2000-2020. Regional differences in YRB ecosystem health increased during 2000-2020. From the perspective of dynamic evolution, low-level and high-level ecosystem health units evolved to high-level, while medium-high-level ecosystem health units evolved to low-level. High-high (accounting for 30.372% in 2020) and low-low (accounting for 13.533% in 2020) were the main cluster types. Regression result showed that urbanization was the main reason for ecosystem health deterioration. The findings can provide enlightenment to further understand the regional differences of ecosystem health in YRB and provide theoretical reference for the coordinated management of ecosystem at macro-level and the differential regulation of local ecosystem at micro-level in the basin region.