Ecological network(EN) characterization has become an important approach for identifying key weak points in regional ecological connectivity and supporting targeted ecological restoration. Existing studies commonly apply the gravity model to characterize the potential interaction strength between ecological sources; however, source “quality” is often quantified solely by a single resistance context and size-based indicators, which fail to capture true functional differences among sources and ecological flow intensity. To address these issues, this study modified the source quality term in the gravity model by incorporating multidimensional ecological elements and constructed a flow-oriented EN, enabling ecological flow to be represented more realistically. Based on the calculated ecological flow intensity, key corridors were identified more accurately to support differentiated restoration strategies. The results showed that: (1) A total of 1308 ecological corridors were identified, displaying a spatial pattern of higher density in the east and lower density in the west, with relatively weak connectivity in the western and parts of the central regions; (2)High-quality ecological sources were concentrated in the southeastern and northeastern regions, whereas corridors with higher ecological flow intensity were mainly located in the southeastern and central areas, together forming a flow-oriented EN; (3) A total of 36 ecological barrier points located on key corridors were identified, and management and restoration strategies for the topography-restricted, external-barrier, and matrix-degradation types were proposed according to their blocking characteristics and spatial contexts. The proposed flow-oriented EN framework can provide a reliable basis for identifying restoration priorities and formulating differentiated ecological restoration strategies.

The concept of land use multifunctionality (LUMF) is fundamental to national spatial zoning, with its main functions evolving in response to socio-economic development. In this dynamic, maintaining alignment between the actual and the planned main functions is essential for effective spatial planning. This study centers on Sichuan province, where the entropy weight-TOPSIS model was utilized to delineate the spatiotemporal distribution of LUMF and a mechanical equilibrium model was applied to evaluate functional coordination. This approach facilitated an examination of the congruence between the actual and planned main functions. Discrepancy was identified and subsequently excluded from the analysis. Building on this foundation, the propensity score matching-difference-in-differences (PSM-DID) model was employed to quantitatively assess the policy impacts within the matched areas. Key Findings: (1) From 2010 to 2020, the average increase in urban development functions was 10.4, with a decrease in intensity from the urban periphery outward; ecological conservation functions experienced an increase of 1.53, while agricultural functions exhibited a slight decline. (2) Overall, functional coordination showed improvement across 80.32% of the studied areas. However, coordination diminished in key development areas, whereas it was strengthened in agricultural and ecological areas. (3) In 28 counties, a divergence between planned and actual functions was observed, primarily characterized by a focus on agricultural production in key development areas. (4) The planning processes bolstered urban development and ecological conservation functions but exerted limited influence on the major agricultural production areas. The findings provide empirical support for spatial coordination, land allocation, and policy development.

Empirical analysis of the relative effectiveness of the Giant Panda National Park (GPNP) system can promote the optimization and improvement of its management level. Normalized Difference Vegetation Index (NDVI) is a key indicator to measure the health of ecosystems, which can effectively quantitatively reveal the spatial and temporal changes of ecological protection effects. This study evaluated the relative effectiveness of Normalized Difference Vegetation Index (NDVI) protection in the Sichuan area of the GPNP from 2000 to 2020 using the propensity score matching model (PSM). It also explored the influencing factors and interactions of each period by combining the Optimal Parameter-based Geographical Detector Model (OPGD). The results showed that: 1) The study area’s Relative Effectiveness Index (REI) was positive, suggesting effective ecological protection. The REI fell from 0.044 in 2000 to 0.031 in 2015 and although it then increased to 0.034 in 2020 to a small extent, the REI showed an overall decreasing trend, and the conservation effect has weakened. 2)The REI change patterns varied in different functional zones of the area, with a general fluctuation and decline, in which the Minshan and Baishuijiang Core Protection Area (MBJ-CPA) as a whole first rise and then fall, and it is the area with the best relative effectiveness of protection. 3) Natural factors such as temperature and elevation are the main factors affecting NDVI, while the influence of policy and economic factors such as the level of protected areas and distance to towns are increasing. The Qionglaishan and Adjacent Areas General Control Area (QLA-GCA) is dominated by the interaction of landscape pattern index with its remaining factors, and the rest of the functional areas are dominated by the interaction of natural factors such as temperature, evapotranspiration with its remaining factors. Therefore, in future development, the Qionglaishan Areas need to pay more attention to the optimization of landscape patterns, while the other areas need to pay more attention to the impact of climate change on the ecosystem. This study can provide a reference for the improvement and management of ecological protection of the GPNP system in the future.

The construction of ecological networks(ENs) has become an essential approach to enhancing regional ecosystem connectivity, safeguarding ecological processes, and guiding ecological restoration. However, existing studies have primarily focused on the structural dimension of spatial distribution and connectivity, with limited consideration of the coupling between ecological source quality and ecological flow processes. This limitation has constrained the functional representation of ENs and reduced the effectiveness of restoration efforts. To address this issue, this study developed a heterogeneous EN by integrating ecological source quality with ecological flow magnitude. Key ecological corridors and barrier points were identified through a comprehensive assessment of ecological structure, process, and function, and restoration recommendations were proposed for priority areas. The results showed that: (1) A total of 1,308 ecological corridors were identified, displaying a spatial pattern of higher density in the east and lower density in the west, with relatively weak connectivity in the western and parts of the central region; (2) High-quality ecological sources were concentrated in the southeastern and northeastern parts of the study area, while corridors with strong ecological flow intensity were mainly distributed in the southeast and central regions, indicating a certain spatial mismatch between ecological structure and process; (3) A total of 151 key ecological corridors and 232 ecological barrier points were identified, among which 36 barrier points were located along key corridors. Differentiated restoration strategies were proposed for the 36 ecological barriers located along key corridors to enhance the connectivity of critical ecological processes and improve overall system stability. This study provides theoretical support and practical guidance for optimizing regional ENs and promoting the sustainable development of ecosystems from the multidimensional perspectives of ecological structure, process, and function.

While rapid urbanization drives socio-economic development, it also leads to a decline in regional ecosystem security. Ecological Security Patterns (ESPs) serves as a crucial research pathway for revealing the interactions between humans and nature and their spatial patterns. However, in the face of evolving regional spatial planning functions and shifting development visions, there is an urgent need to adopt a dynamic and holistic approach to design a dynamic ESP assessment framework, enabling the capture of its spatiotemporal changes and revealing future optimization directions. The Minjiang River Basin, serving as a multifunctional area in the upper reaches of the Yangtze River, faces an imbalance between ecological and economic development, necessitating urgent comprehensive optimization. Taking the Minjiang River Basin as a case study, this research characterizes the regional ecological security pattern based on conventional ESP construction methods. Furthermore, innovatively selected evaluation indicators were extracted from pattern elements and integrated into the "Pressure-State-Response" model to evaluate the ESP for the years 2000, 2010, and 2020. The PLUS model is applied to simulate land use changes in 2030, and the ESP for 2030 is constructed using this simulation combined with other data conditions. Finally, the 2030 ESP is re-evaluated using the same indicator system to validate the optimization effect. The results show that, from 2000 to 2020, the ecological source area experienced both expansion and contraction, with low-resistance areas concentrated in the upstream and downstream sections, while ecological corridors and ecological barrier points increase and decrease simultaneously. The overall ecological security level in 2010 was higher than in 2000, but it declined significantly by 2020. In the optimized ESP for 2030, the length of ecological corridors increased by 590.28 km compared to 2020, while the number of ecological barrier points decreased to 13. The final evaluation showed an improvement in the overall ecological security value compared to 2020, indicating that the ESP was successfully optimized and enhanced. This study expands the existing ESP research paradigm by fully considering the temporal evolution and spatial variation of pattern characteristics. By incorporating pattern elements into the evaluation system, this study strengthens the deep integration of ESP and ESA, enabling a more precise assessment of ecological security status. The simulation and optimization of the ESP help provide scientific guidance for achieving more coordinated regional ecological security protection.

Improving the connectivity of ecological networks (ENs) is a proven strategy for biological conservation. However, without a clear understanding of animal movement, research on ENs may not provide a sufficient reference for maintaining biodiversity. To address this gap, we embraced central concepts of movement ecology and conducted a study in the Qilian Mountains. The predictability and seasonality of environmental conditions were combined to identify ecological sources with rich temporal niches and improve the informed preference character of resistance surface. Then, we constructed ENs with six dispersal thresholds. Further, integrating modularity and circuit theory, we pinpointed priority areas for restoration within the ENs. Our findings indicated that the eastern part of the Qilian Mountains showed higher biodiversity suitability, with terrain being the primary factor limiting dispersal. Additionally, comparative analyses demonstrate that the new method for measuring biodiversity from the perspective of temporal niche is reliable and better aligns with the needs of biodiversity conservation. In light of emerging challenges within the study area, where apex predators seriously suppress the populations of some smaller predators, we propose a novel conservation idea that emphasizes the strategic retention and removal of barriers to maintain biological balance. This study enriches methodologies for biodiversity measurement, provides forward-looking conservation strategies, and offers practical contributions toward mitigating biodiversity loss.

Karst landscapes, characterized by unique soluble geological features, provide essential ecosystem services (ESs). However, they are currently facing significant challenges due to rapid land use/land cover (LULC) changes. Research that combines LULC and karst lithological features with ecosystem service bundles (ESBs) is scarce. Therefore, this study aimed to investigate the future spatial distributions and landscape pattern features of ESBs in different lithological areas based on land use projections, and providing a basis for informing zoning land use planning and management. Firstly, multiple scenario simulations were conducted to project future land use changes in Huanjiang County, China. Next, based on the assessments of ESs and identification of ESBs, the correlations between LULC, ESBs, and landscape features in different lithological areas were explored. The results revealed the following: (1) a potential synergistic relationship between built-up land and ESB3, while a negative impact of transitioning from forest to cropland on ESB2; (2) the limestone area exhibited the highest overall split level of ESBs, while the non-karst area showed the greatest diversity, evenness, cohesion, and largest patches of ESBs; (3) the landscape heterogeneity of ESBs in different lithological areas was mainly reflected in split, cohesion, and division levels rather than aggregation. Finally, implications and site-specific suggestions for zoning land use planning and management in Huanjiang County were discussed.

Regional ecological security is a pressing issue in the context of escalating human-environment conflicts. Ecological networks(ENs), the fundamental tool for characterizing ecosystems, have enabled further quantitative analysis at the micro level by integrating with complex networks in recent years. However, most studies neglect the unreliability of unweighted complex networks and the dynamic characteristics of ENs. This paper takes the Sichuan Basin as the research area and adopts the following methods. Firstly, it integrates landscape ecology and ecosystem services to construct the ENs using Linkage Mapper. Secondly, it introduces the cost-weighted distance as the weight to build complex networks and identifies potential pivot ecological sources and key ecological corridors based on the topological features of the weighted complex networks in 2000, 2010, and 2020. Thirdly, it applies circuit theory to detect ecological pinchpoints and ecological barrier points within the corridors as priority areas for ecological conservation and restoration. The results show that the ENs in the study area are denser on the northern and southern sides, and some ecological corridors change direction due to variations of resistance surfaces and landscape morphology. Through dynamic analysis of the weighted complex networks, 27 potential pivot ecological sources and 25 key ecological corridors are identified; then, 28 priority conservation areas and 10 priority restoration areas within these ecological corridors are extracted based on circuit theory. The study reveals a certain correlation between the distribution of ecological nodes and water bodies. Furthermore, comparing the weighted and unweighted complex network, we find that the weighted complex network is more reasonable, with 64.2% of ecological sources showing lower betweenness centrality than that in the unweighted network, reflecting the obstacles that urbanization poses to ecological networks. This study explores the impact of constantly changing resistance surfaces on the overall ENs and their components through dynamic analysis. The evolving topological features reflect the feedback of the ENs to external environmental changes, as well as the dynamic characteristics of the real ENs. Therefore, the findings of this study provide valuable references for ecological conservation and governance efforts in Sichuan Basin, promoting regional ecological security and the advancement of ecological civilization.

生态安全格局评价是维护生物多样性、改善环境质量的重要途径,对维持区域持续发展具有重要意义.以岷江流域为研究区,综合运用土地利用和归一化植被指数(NDVI)等数据,基于生态系统服务对岷江流域进行生态重要性分析,将生态极重要区识别为生态源地,采用最小累积阻力(MCR)模型中成本路径法提取潜在廊道,结合重力模型提取重要廊道和重要节点,从而实现对研究区生态安全格局的刻画,进而对岷江流域生态安全格局评价并提出优化建议.研究结果表明:(1)岷江流域安全等级总体较好,较高生态安全和高生态安全的面积占研究区面积的55.02％.(2)从空间上看,研究区内重要生态源地面积为818.32km2,破碎化严重,集中分布在岷江流域上游林地区;廊道共190条,总长度为19633.96km,其中重要廊道41条,呈半环状分布于上游和下游段;生态节点共117个,集中分布在上游段南部-西南部.(3)参考生态阻力和廊道节点空间分布特征,划分岷江流域"四区两带"生态安全格局并提出分区管控措施和相关建议.以期研究结果和调控路径可对完善岷江流域生态安全格局、保护生物多样性和增强水土保持有一定的借鉴意义.

为了减少城镇扩张占用耕地的低效率使用问题影响区域粮食安全,基于GIS平台,结合扩张速度、贡献度指数和等扇形分析等研究方法,对成都都市圈2000—2018年城镇扩张占用耕地的时空格局进行刻画,再结合BCC模型对其利用效率演变规律进行揭示.结果表明,研究区域城镇扩张占用耕地面积为470.528 km2,扩张速度为24.765 km2/年,贡献度指数为74.4％,呈现先增强后减弱的趋势;占用耕地的方向整体由西部、北部向东部和南部转移;综合效率、技术效率、规模效率均呈现先下降后上升的趋势;综合效率空间变化上,高效区由中西部向东南部迁移,较高效区2、3时段集中分布在东北部到西南部,低效区总体位于西部.

A program of ecological compensation (EC) is an effective means to solve the potential unfairness caused by the difference in environmental quality between the upper, middle, and lower reaches of river basins, alleviate the conflict of economic interests between regions. By constructing an EC accounting model, this study defines the carbon emissions of construction land as the consumption of ecological services to avoid the problem of lower EC in the upper reaches than the middle and lower reaches when only the ecosystem service value (ESV) is used as the compensation basis. We calculate the cumulative EC standards in the basin from 2000 to 2018 at the county, major functional oriented zone, and basin section scales, divide the subjects unto those provide EC and the subjects receiving EC, and finally introduce the comparative ecological radiation force to simulate the direction and scale of the ecosystem service flow (ESF) of the subjects receiving EC. The findings of this study are as follows: (1) The ESV of the Minjiang River Basin shows a downward trend in time and a spatial distribution pattern of high in the north and southwest parts and low in the middle and southeast parts. (2) Carbon emissions from construction land in all counties (cities and districts) in the Minjiang River Basin show an upward trend in time and a spatial distribution pattern of high in the middle part and low in the north and south parts. (3) The cumulative EC standard in the Minjiang River Basin from 2000 to 2018 is 279.401 billion CNY, which indicates ESV spillover. On the county scale, 22 subjects receive EC and 23 subjects providing EC. The subjects receiving EC are generally located in the southwestern parts of the upper and lower reaches, and the subjects providing EC are concentrated in the national key development zone in the middle reaches. (4) The ESF goes from north to south in the upper reaches, towards the north and south sides in the middle reaches, and towards the east and north in the lower reaches. Our findings provide an important reference for EC practices in the Minjiang River Basin.

基于2013年、2016年、2019年的夜间灯光数据和社会经济数据,使用空间自相关分析、重心分析、标准差椭圆工具对成渝地区双城经济圈县域经济空间格局进行分析,并进一步使用地理加权回归模型(GWR)和二阶聚类对县域经济发展影响因素及驱动机制进行探究.结果表明:①2013—2019年,成渝地区双城经济圈经济发展水平不断提高,经济空间格局呈现为以成都、重庆主城区为核心的两极式不平衡发展格局,区域中部连绵地带是经济发展短板所在.②成渝地区双城经济圈县域经济存在显著的空间集聚性.③县域经济空间分布方向为西北—东南走向,经济空间重心逐渐向东南偏移.④人口密度、城镇化率对研究区县域经济发展贡献显著,政府作用、投资水平、产业结构、教育水平、公路路网密度对经济发展作用呈现正负差异性.⑤根据空间差异,将142个区(县)划分为政策敏感型、投资敏感型和基础设施敏感型3种经济发展类型.

Protected areas constitute a global strategic resource for enhancing the effectiveness of ecological protection, which can alleviate the impact of unsustainable human production and living activities on the ecological environment. However, the spatiotemporal evolution of ecological protection effectiveness needs to be quantitatively revealed. The net primary productivity (NPP) of plants is an important measure of the effectiveness of ecological protection efforts. The main purpose of this study is to use the relative change in the annual average NPP to evaluate the ecological protection effectiveness of protected areas. We compared the historical changes in the annual average NPP of protected areas in Sichuan Province from 2000 to 2019. We added the spatial coordinates to the impact factor system and adopted propensity score matching (PSM) in a quasi-natural experimental method to determine the experimental group and the control group. The ecological protection effectiveness of the protected areas in the study area in 2000, 2005, 2010, 2015, and 2019 was measured and classified into three types of changes in protection effectiveness, namely effective, ineffective, or fluctuating. According to the administrative level, type, and spatial distribution, we determined the number and type of changes in the protection effectiveness of different protected areas. The results show that the annual average NPP of the protected areas in Sichuan Province generally fluctuated. The annual average NPP increased in 95.47% of the total protected area and decreased in 4.53%. The overall protection effectiveness of protected areas was positive and significant and gradually improved. Effective protected areas at the national, provincial, and county levels accounted for 40.27% of the total number of protected areas, and the other 14.77% of effective protected area was managed at other administrative levels. Among the different types of protected areas, the proportion of effective protected areas was highest in wild animal protected areas, followed by forest ecology protected areas, wild plant protected areas, and wetland ecology protected areas. The results of this study can provide an important reference for the verification and improvement of the ecological protection effectiveness of various protected areas.

生态系统服务价值评估作为土地资源合理配置、生态环境保护和生态补偿标准制定的重要前提,是当前的研究热点之一.以乐山市为研究区域,基于2000年、2005年、2010年、2015年4期土地利用数据,运用生态系统服务价值动态当量法、地理探测器模型等方法,定量分析乐山市2000-2015年间生态系统服务价值时空变化规律及驱动机制.结果 表明:(1)2000-2015年乐山市生态系统服务价值整体呈下降趋势,仅在2005-2010年有所回升,总量共减少了23.22亿元,主要与林地大量减少和建设用地大量增加有关;(2)空间上呈现西南高、东北低的分布态势,且各区域变化不同,西南方向山地以下降为主,东部平原丘陵以上升为主,河流两侧上升明显;(3)影响生态系统服务价值时空分布的主导因素为土地利用、NPP、降水量和坡度,除此之外气温、高程、土壤类型也有较大决定力;(4)自然因子决定力大于社会经济因子,但社会经济因子的影响越来越突出.研究揭示了乐山市生态系统服务价值的时空变化规律及驱动因子,为该地区土地利用规划与生态环境保护机制的建立提供了科学参考.

The campaign of rural revitalization gives a political incentive to a sustainable development of villages in China. To examine the potential of rural revitalization and correspondingly categorize the types of villages in China, both establish a scientific research base for innovation of development path of rural revitalization. Although most of previous studies had explored the revitalization path in the circumstances of Chinese rural revitalization strategy, they hardly involved with the spatial data of a research area and bore no relation to a quantitative analysis of rural revitalization potential, and neither did they paid full attention to areas with relatively poor resources; therefore, the efforts in research to support and guide the practice of rural revitalization strategy were quite insufficient. In this study, Mianyang city, Sichuan, China was designed as a case study for exploration of rural revitalization potential and paths. It reexamined the concept and content of rural revitalization; introduced a set of spatial data into an evaluation index system, which was constructed on a town scale to evaluate the potential from four dimensions, production-life-population-ecology. It revealed the distribution law of the potential and categorized the types of villages by the K-means clustering method. Detailed results are listed here:（1） The rural revitalization potentials were subject to natural and human factors of Mianyang city, demonstrating a pattern of distinct spatial heterogeneity according to the scoring of the potentials, with an overall pattern of higher in the south than those in the north. The high score and higher were attached to the central and the southwest of Mianyang city. The areas with median values were mainly concentrated in the northwest and southeast. The low-value areas comprised the north and northwest.（2） In consideration of the pattern of the rural revitalization potentials and the associated driving force, the villages in the study area were grouped into industrial-type, agglomeration-type and specialization-type, with the number accounting for 39.38%, 45.17% and 15.45% of the study area respectively. The industrial-type villages had the highest scores, with densely populated, a better industry development potential; The agglomeration-type villages got less scores than the industrial-type did, which mostly lived on traditional agriculture, with insufficient local competitiveness, nearly loss of rural subjects; The most distinctive feature of the specialization-type villages was their advantages in ecological factor scores, but poor performances in others, leading to low score of rural revitalization potential.（3） According to village types, we proposed the following paths toward rural revitalization. The development of the industrial-type villages should be dominated by high-tech industries, to strengthen the development of advantageous industries, to promote the construction of leading industrial parks, and to optimize the agricultural industrial structure to form specialized industries; The agglomeration-type villages should take synergistic growth as a top priority, to strengthen infrastructure construction, to develop characteristic tourism and leisure agriculture, and to build a countryside complex model; The specialization-type villages should pay attention to eco-tourism, to create unique tourism resources and eco-tourism-based models in terms of local cultural and natural reserves. This study can provide data reference for rural revitalization in Mianyang city, and promote the realization of the goal of rural revitalization in mountainous areas of China.

"5.12"地震对汶川县的生态环境造成了巨大破坏,评价生态环境质量的恢复程度是汶川县灾后重建的一项重要基础工作.基于TM和OLI数据,利用ENVI平台的主成分分析技术,计算出研究区3个时期的遥感生态指数(RSEI),用于分析2003～2017年研究区的生态环境质量变化及恢复情况.结果表明:(1)2003～2017年,汶川县的生态环境质量以中等及以上为主,3个时期中等及以上等级所占比例分别为90.21％、82.01％、94.65％;(2)3个时期的RSEI指数的均值分别为0.627、0.617、0.716,生态环境质量经历了未恢复到恢复提升的过程,且研究末期的生态环境质量超过研究初期.(3)2003～2017年,汶川县生态环境质量中的较差、中、良这3个等级的面积转移明显,差和优两个等级变化不大.T1时间段,中等和良等向较低等级转移;T2时间段,较差、中、良等均向较高等级转移;T3时间段,除优等以外,其余等级均主要向较高等级转移.(4)海拔1 498～4 466 m和坡度15.～63.之间,是生态环境质量恢复最明显的区域.

土地利用综合效益是反映土地利用状况重要指标,平原-山地过渡地区的土地利用结构复杂且生态脆弱,对其进行研究为土地合理规划提供有益支撑.以平原-山地过渡地区乐山市下辖各县(市、区)为研究对象,从经济、社会、生态效益等3个方面构建土地利用综合效益评价指标体系,运用变异系数法和熵值法进行组合赋权确定综合权重,基于耦合协调度模型,分析2000—2016年土地利用各效益之间耦合协调性及其演变规律.结果表明:1)各县(市、区)土地利用综合效益空间差异大,两极分化明显,效益高分值集中分布在平原区,而低分值分布在山地区,两者相差0.65,且差异有逐渐扩大的趋势;2)各县(市、区)土地利用经济-社会-生态效益三者之间的耦合度主要表现为低度耦合和拮抗阶段两种状态,平原与山地差异较小,耦合度水平较低;3)其协调度平原与山地差异较明显,平原区大约0.29,山地区大约0.1,均处于失调状态,主要呈现是山地为极度失调、丘陵为严重失调和平原为中度失调,但其协调度整体存在着上升的趋势.

利用信息熵模型和偏移—份额模型测度分析了四川省18个城市2002—2016年用地结构变化的时空特征。基于包含非期望产出的超效率SBM模型,测算分析了城市用地效率的变化规律;基于STIRPAT模型,构建了用地结构对用地效率影响的扩展模型,并分析了结构对效率的影响特征。结果表明:生活用地、生产用地、生态用地、公共设施用地、居住用地和绿地在城市建设用地结构中占额分配率的不同,对城市用地效率具有直接的影响作用。

基于生态足迹模型,对德阳市耕地近10年来的生态足迹、生态承载力、生态赤字、脆弱性指数进行测算,再结合ArcGIS进行空间可视化表达,分析出其空间分布规律.结果表明:1)德阳市近10年来耕地的生态足迹呈略微下降趋势,各区县内部耕地的生态足迹变化相对较稳定;2)生态承载力呈现出低速下降趋势,在各区县的空间分布有一定的差异;3)生态盈亏状态表现为多数区县属于生态盈余区域,少数区县属于生态赤字区域;4)脆弱性总体呈现出增加的趋势,空间分布上的特点呈现出"两翼极脆弱,中间较稳定"的状态.

To elucidate the impacts of changes in the land use type use changes on soil retention capacity in Zhangjiakou City, the spatial and temporal variations in land use type and soil retention capacity from 2005 and 2015 were assessed using USLE and GIS tools. The results showed that the main land use types in Zhangjiakou were cultivated land, forests, and grasslands. Areas of forests and construction increased as the other land use types decreased from 2005 to 2015. The fastest increase in area was observed for forests, which were converted from grasslands, and the lowest decrease in area was found for cultivated land, which was converted into construction land. Meanwhile, a two-way flow between forestland and grasslands appeared. An evident difference in soil retention capacity in Zhangjiakou was found among different land use types. Grasslands were respondible for the most pronounced increase in the rate of soil retention, while forests constituted the most dramatic increase in the amount of soil retention. Soil retention amounts in grasslands and forestsaccounted for 50% of the total retention across all land use types. Soil retention capacity increased by 1.752 × 107 t in Zhangjiakou City over the past 10 years, and this result could be ascribed to increased land cover. The amount of soil conservation had increased in each county over the past 10 years; Yu County witnessed the greatest increase in the amount of soil conservation, and Qiaoxi district owned witnessed the smallest increase in the amount of soil conservation among all counties. Furthermore, the soil retention capacity was lower in the northwest regions and higher in the southeast regions of Zhangjiakou City. The highest soil retention capacity was observed in Chicheng County, and Qiaoxi District exhibited the lowest soil retention capacity among all counties. Finally, soil retention capacity was evidently higher in the Bashang Regions than in the Baxia Regions, and the amount of soil retention in Bashang accounted for 80% of the total of Zhangjiakou City, and the increase in the amount of soil retention in the Bashang Regions was 1.163 × 107 t. The results of this study help us to understand the changes to land use and soil retention function after the implementation of ecological engineering in Zhangjiakou City, and this provide a scientific basis for promoting ecological protection and developing soil erosion control plans in the future.