Using the panel data of 11 provinces (municipalities) in the Yangtze River economic belt from 2004 to 2018, this paper analyzes the impact of service industry agglomeration on new urbanization based on spatial econometric model. The results show that: (1) the agglomeration of service industry in the Yangtze River economic belt has significant spatial dependence.（2) The improvement of service industry agglomeration level can effectively promote the process of new urbanization in the Yangtze River economic belt, and produce a significant spatial spillover effect, which shows that service industry agglomeration can not only improve the level of new urbanization in the province, but also drive the development of new urbanization in adjacent areas.（3) Excessive government intervention is not conducive to the construction of new urbanization in this region; The improvement of the level of opening to the outside world can promote the construction of new urbanization in the region.

As a key link in the comprehensive governance and development of China’s major river basins, it is of great significance to explore the coordination between tourism industry and urban human settlement environment in the Yangtze River Economic Belt for the sustainable development of the two systems. By investigating 108 prefectural-level cities along the Yangtze River Economic Belt, this paper constructs the coupling coordination index system between the tourism industry and urban human settlement environment, evaluating the evolution trends of its coupling coordination from the two perspectives of geography and time-interspace, and exploring the interactive responsive relationship between the two systems using PVAR model, the essay reaches three main conclusions as below:(1) The evaluation indexes of tourism industry and urban human settlement environment in prefecture-level cities of the Yangtze Economic Belt show significant spatial disequilibrium. High-evaluation regions tend to be distributed in an agglomeration trend and focus on core cities within each region while low-evaluation regions tend to be distributed in a decentralization trend and focus on the middle west area. (2) The degree of coupling coordination gradually increases, and the overall type of coupling coordination is from low coupling coordination to moderate coupling coordination. The differences among the three regions are gradually narrowing, and the Yangtze River Economic Belt is developing in a balanced and healthy way on the whole. (3) There is a long-term equilibrium relationship between the two systems, which is granger cause for each other. The two have mutual influence on themselves and each other, forming a positive progressive effect between them, and the promotion degree of urban human settlement environment to the tourism industry is greater than that of the tourism industry to improve the urban human settlement environment. Based on the above research results, governance suggestions are put forward in order to provide ideas for the sustainable development of tourism industry and urban human settlement environment in the Yangtze River Economic Belt.

The spatial differentiation and correlation of tourism environmental carrying capacity exist objectively, and scientific evaluation of the carrying capacity and formulation of spatial management and control policies are important ways to promote the sustainable development of regional tourism. Utilizing the panel data of 26 cities in Yangtze River Delta Urban Agglomerations from 2000 to 2018, the evaluation index system of tourism environmental carrying capacity based on DPSIR theoretical model was established by comprehensively considering economic, social, resource and ecological factors which were incorporated into the Driver-Pressure-State-Impact-Response system. The spatial auto-correlation method was applied to reveal the spatial correlation characteristics of tourism environmental carrying capacity of Yangtze River Delta Urban Agglomerations, and then the spatial econometric model and partial differential decomposition method were used to analyze the spatial spillover effect of tourism environmental carrying capacity. The results indicated that: (1) During the study period, the tourism environmental carrying capacity of Yangtze River Delta Urban Agglomerations as a whole maintained a fluctuating upward trend, and showed a spatial distribution characteristics of “high in the southeast and low in the northwest”. (2) The tourism environmental carrying capacity showed strong spatial agglomeration and correlation characteristics, and the intensity of spatial correlation showed an “M” type change trend of “rising-declining-rising-declining”. (3) The tourism environmental carrying capacity had a significant positive space spillover effect, and every 1  Unit growth in a local city will lead to 0.637 Unit growth in neighboring cities. Economic development level, technological progress level, environmental regulation intensity and tourism industry agglomeration had positive direct effect on local cities and different degrees spillover effect on neighboring cities. In order to effectively explore the potential of capacity environmental carrying potential of Yangtze River Delta Urban Agglomerations in the new period, attention should be paid to the spatial correlation and spillover effects of tourism environmental carrying capacity between cities, give full play to the role of inter-city cooperation and linkage, and promote the rational spatial allocation of elements of tourism environment complex systems.

Under the background of regional integration, it is of great theoretical significance to explore the influence mechanism of factors such as spatial agglomeration, scale change and industrial structure on urban land use efficiency. The paper explores the influence mechanism of Yangtze River Delta regional integration on urban land use efficiency pattern evolution, so as to provide reference for formulating targeted and differentiated urban land use efficiency promotion policies. The results show that: (1) During the study period, the average efficiency from 2000 to 2018 is 1.003, which goes through a three-stage fluctuation process of “growth decline stability”. The global Moran’s I index is greater than 0, the positive autocorrelation is significant, and the spatial spillover effect and agglomeration characteristics are obvious. Shanghai, Nanjing, Hangzhou and other cities have rapid economic development and strong ability to gather migrant population. Therefore, the amount of land in the built-up areas will be revitalized, and the investment intensity of land development will be improved, and the efficiency will be high. Due to the imperfection of sustainable land use policy and the limitation of urban layout, the utilization efficiency of peripheral cities needs to be improved. (2) In the process of Yangtze River Delta regional integration, the spatial agglomeration of factors, the change of scale and the adjustment of industrial structure would have different degrees of impact on urban land use efficiency. There are also ripple effects between economic development and industrial activity agglomeration. The advanced production technology and development opportunities of the city are preferentially diffused to the neighboring cities, which is of great significance to the improvement of land use efficiency of the city and adjacent cities. Under the background of regional integration, the core cities in the Yangtze River Delta gradually transfer their industries to the surrounding cities in the process of upgrading the industrial development level and advanced level. The strong spatial spillover effect is also conducive to the improvement of land use efficiency of adjacent cities.

County-scale eco-efficiency has been recognized as one of the important base unit that supports regional green development. Taking the urban agglomeration in the middle reaches of Yangtze River as the study area, this paper constructed the input-output index system of eco-efficiency based on multi-source data, used the Super-EBM model to measure the county eco-efficiency from 2005 to 2018, and analyzed the dynamic characteristics of its spatial pattern with the help of LISA time path and LISA temporal and spatial transition methods. The spatiotemporal transition types were nested with the panel quantile regression model to explore the driving mechanism. The results showed that the overall level of county-scale eco-efficiency of the urban agglomeration in the Middle Reaches of the Yangtze River increased significantly during 2005 to 2018. The agglomeration development effect of the three provincial capitals as the center was significant. Urban agglomeration in the middle reach of county-scale eco-efficiency of spatial distribution of cohesion was stronger and had a higher path lock feature, there was a transition in each county unit inertia, the local spatial characteristics of eco-efficiency are more dynamic in connecting county units of “Wuhan Metropolitan Circle-Changzhou-Zhuzhou-Xiangtan Urban agglomeration”, Fengcheng in space depended on the direction of maximum volatility, Changsha municipal districts had maximum stability. Four driving-restraining models, including economy-climate drive, industry-resource control, economy-resource control, and industry-precipitation control, presented an evolution pattern from “Wuhan City Circle-Poyang Lake Urban Agglomeration” to “Changzhou-Zhuzhou-Xiangtan Urban Agglomeration” from restriction to drive, each containing different driving mechanisms.

In order to understand the composition of fish species diversity and assemblage structure in the Dianshan Lake and the upper reaches of Huangpu River, the quantitative and qualitative fish samples were collected from 10 sampling sections in June (summer) and October (Autumn) of 2020, and their species diversity and assemblage structure were analyzed. A total of 11 408 fish specimen were collected, comprising 49 species belonging to 9 orders, 14 families, and 37 genera. In summer and autumn, there were 29 and 30 species in the Dianshan Lake, 37 and 29 species in the upper reaches of the Huangpu River, respectively. The main dominant species were Coilia nasus、Carassius auratus and Acheilognathus macropterus. The average of Shannon Wiener diversity index (H’), Pielou evenness index (J’), Simpson dominance index (C) and Margale richness index (D) in autumn were higher than those in summer. The fish assemblage in the Dianshan Lake was highly similar to those in the upper reaches of the Huangpu River. The abundance-biomass comparison curve (ABC curve) revealed that fish assemblage was unstable, especially in the Dianshan Lake. The cluster analysis and non-metric multidimensional ordination indicated that the fish assemblage could be divided into three groups, e.g. The upper reaches of the Huangpu River group, the Dianfeng Ⅱ and the Dianshan Lake group Ⅲ. Pseudobrama simoni, Coilia nasus, Acheilognathus macropterus, Hemiculter leucisculus, Carassius auratus were the main discriminating species causing the differences among the three groups. Compared with previous survey data, the species of fishes showed an increasing trend. However, the fish assemblage in the Dianshan Lake and the upper reaches of the Huangpu River was still dominated by small-sized fishes, obviously disturbed by human activities. It is necessary to continue to improve water quality, carry out fish proliferation and release, reduce fishing pressure, and control the fishing area and time of shellfish bottom trawl, so as to improve stabilization of fish assemblage and protect the ecosystem health of the Dianshan Lake.

Three soil profiles (yellow soil, red loam and red soil) from Jiulongjiang river catchment were selected to research. The results showed that the total rare earth elements (ΣREEs) of red soil and red loam were in the following order of different depths: leaching layer＜sedimentary layer＜semi-weathered layer, and the enrichment of REEs in semi-weathered layer was closely related to the leaching during pedogenesis. ΣREEs in leaching and sedimentary layers of yellow soil profile was significantly higher than that of the semi-weathered layer, which may be related to agricultural activities in shallow soil. The shale-normalized REEs pattern displayed obvious negative anomalies of Eu in all soil profiles, which may attribute to the inheritance of negative Eu anomalies in parent rock and the change of soil redox environment. Positive Ce anomalies in yellow soil and red soil profiles may be caused by the difference during weathering process. Initial soil REEs concentration in Jiulong river catchment is mainly determined by soil parent material, and soil mineral composition and physical/chemical properties affected the migration and fractionation of soil REEs. The higher composition of oxide minerals, higher clay content and organic matter content in soil are more conducive to the enrichment of REEs.

Soil aggregate stability is a key factor of soil productivity and soil health. In order to provide a basis for the restoration and reconstruction of the ecological environment in the riparian zone, the distribution and stability of soil aggregates in different types of land-use, and the distributions of organic carbon and nitrogen in various aggregates, were explored. Of three typical land-use types (corn fields, paddy fields, and abandoned grasslands) in the riparian zone of the Three Gorges Reservoir, soils were classified using the wet sieving method. The distribution of aggregates and their organic carbon and nitrogen contents were clarified at soil profile depths of 0-10, 10-25 cm for each land-use type. Additionally, the organic carbon and nitrogen content of the bulk soil and different soil aggregates fractions were measured. The relationships between organic cement of the aggregates, soil physicochemical properties and soil aggregate stability were analyzed by structural equation modeling (SEM). The results showed that: (1) Soil depths have different effects on aggregate stability, organic carbon and nitrogen content in the riparian zone of the Three Gorges Reservoir; (2) In the 0-10 cm soil layer, the proportion of soil macroaggregates and the stability of aggregates were significantly enhanced following farmland abandonment; soil aggregate carbon and nitrogen of different soil aggregates fractions in abandoned grasslands were significantly higher than that of farmlands; the relative contribution rate of organic carbon and nitrogen of >0.25 mm fraction aggregates to the bulk soil organic carbon and nitrogen content significantly increased; (3) In the 10-25 cm soil layer, soil aggregate stability, aggregate-associated carbon and nitrogen have been insignificantly improved following farmland abandonment; (4) Structural equation model analysis found that soil organic carbon (path coefficient of 0.76) and total phosphorus (0.58) had a significant positive effect on soil aggregate stability, and pH (-0.42) had a significant negative effect on soil aggregate stability; total potassium (0.23) and total nitrogen (0.15) indirectly promoted the soil aggregate stability via promoting the formation of soil organic carbon; soil bulk density (-0.11) indirectly weakened the soil aggregate stability by inhibiting soil organic carbon. All of the findings from this study may serve as theoretical bases for evaluating soil structure effects and ecological restoration.

In view of the change of inflow flood rule of the Three Gorges Reservoir caused by the regulation and storage of Xiluodu and Xiangjiaba cascade reservoirs during the operation period, which leads to the unreasonable design flood limit water level, the study of seasonal flood limit water level of Three Gorges Reservoir is carried out. Firstly, the discharge process of Xiangjiaba Reservoir is obtained according to the dispatching rules of Xiluodu and Xiangjiaba Reservoirs. Then, the multi-dimensional Copula function is used to analyze the occurrence time and flood peaks magnitude of the main and tributaries of Xiangjiaba-Three Gorges interval, and the inflow of the Three Gorges Reservoir is calculated. Further, the mathematical statistics method and the improved Fisher optimal segmentation method are adopted to divide the flood season, and then the flood limited water level of flood season is calculated by flood regulation. Finally, the risk of flood control and benefits are compared and analyzed.The results show that the flood season of the Three Gorges Reservoir can be divided into three periods: the pre-flood season from June 10 to June 30, the main flood season from July 1 to August 31, and the post-flood season from September 1 to September 30. The corresponding flood limit water levels are 159.1, 148.7 and 159.2 m, respectively. Without increasing the risk of flood control, the flood season can increase water storage by 180.20×108 m3 and the power generation by 10.33×108 kW·h.

Vegetation coverage is an important indicator to measure the growth status of regional vegetation and describe the quality of the ecological environment. Based on MODIS MOD13A3 remote sensing data and meteorological data, this paper uses trend analysis to analyze the spatio-temporal characteristics of vegetation coverage in the growth season in the upper Yangtze River basin, and further uses partial correlation analysis the residual analysis method reveals the response mechanism of vegetation coverage changes to climate and human activities. The results show that: (1) The vegetation coverage in the growing season of the upper Yangtze River basin from 2000 to 2019 showed a significant upward trend (P<0.05), the growth rate was 1.3×10-3/a, and the multi-year average vegetation coverage was 0.64, showing an eastward trend. The northwestern part is gradually decreasing; (2) The spatial distribution of vegetation coverage has significant heterogeneity, with 61.5% of the area showing an improvement trend, mainly for cultivated plants distributed in the Jialing River Basin and Wujiang River Basin, and the degraded area accounts for 38.5%, mainly distributed in Coniferous forests, meadows and shrubs in the Jinsha River Basin and the upper reaches of the Minjiang River; (3) The vegetation coverage is bounded by an altitude of 3.5 km, which rises first and then declines. The altitude is lower than 3.5 km, and the vegetation coverage varies with altitude the change gradient is small, the altitude is higher than 3.5 km, and the vegetation coverage varies greatly with altitude; (4) The area of pixels whose main influencing factor of vegetation coverage is precipitation accounts for 57.5%, and the distribution is mostly concentrated in the Jialing River Basin and Wujiang River Basin, with temperature as the main influencing factor, the distribution is relatively scattered; (5) From 2000 to 2019, the influence of human activities in the upper reaches of the Yangtze River on the change of vegetation coverage was higher in areas with positive values than in areas with negative values, indicating that human activities promoted the growth of vegetation in the upper reaches of the Yangtze River.

The upper reaches of Minjiang River play important roles in resource support, ecological service, and environmental regulation. It is the soil erosion sensitive control region of the national ecological red line and an important natural basis for the survival and development of the country. At present, the spatial superposition of the ecological, economical, and social processes in this region not only affects resources, environmental, and ecological functions but also poses a serious threat to the ecological security and regional sustainable development of the Minjiang River basin and even the upper reaches of the Yangtze River. Recognizing and understanding the temporal and spatial variation of vegetation Normalized Difference Vegetation Index (NDVI) and its topographic response mechanism in the upper reaches of Minjiang River and analyzing the best topographic position of vegetation changes can provide direction, guidance, and scientific reference for ecological environmental construction in this region. In this study, the spatial and temporal changes of vegetation NDVI in the upper reaches of Minjiang River were analyzed using remote sensing and GIS technology. Through spatial overlay analysis, the response of spatial-temporal variation of NDVI to topographic factors such as elevation, slope, aspect, and topographic relief was discussed in detail. Combined with the distribution index of different types of vegetation change, the regional differentiation rule of vegetation change under the background of different topographic factors was further defined, and the best topographic position of different types of vegetation change was obtained. The results showed that: (1) vegetation coverage in the upper reaches of Minjiang River was good and stable, and approximately 26.62% of the vegetation increased significantly, while only 1.21% of the vegetation decreased significantly during 2000-2020. (2) The types of vegetation change had significantly different distribution patterns under different topographic positions, such as elevation, slope, aspect, and relief degree. Overall, the area proportion fluctuated slightly under different topographic positions, and the distribution index was different. (3) The best topographic position of the regions with significant vegetation degradation was the "dominant" zone, which was affected by human activities and the "inferior" zone, which was restricted by natural conditions. The best topographic position of the regions with significant vegetation growth was mainly distributed in the areas with relatively low elevation, large slope, and relief and shady slope of human settlement radiation.

Vegetation is an important ecological landscape element for mountain scenic spots. It is of great significance to study the dynamic change of vegetation coverage and its causing factors for the sustainable development of mountain scenic spots. The vegetation coverage research of mountain scenic areas was mainly focused on a single scenic area, while their general change rules were few investigated with a combination of long time series data, multiple impact factors, and comparative analysis of different scenic areas. We calculate the NDVIs of seven national mountain scenic areas of China to derive their vegetation coverage information based on the Landsat images during 1984-2018. Then the spatial-temporal changes of vegetation coverage in mountain scenic spots were estimated through the regression analysis, correlation analysis, and trajectory tracking of gravity centers. The results showed that the degradation trend of vegetation cover in most of the scenic spots and the phenomenon ofdegradation trend of vegetation cover along the tourist routes in all of the scenic spotsis obvious. The high vegetation coverage areas were the largest proportions of the scenic spots, and increased first and then decreased in most of them. Besides, the vegetation gravity centers trajectory of mountain scenic spots showed an obvious relationship with their climate zones, and the gravity center movements were similar in the same climate zone. In general, the major climatic driving factors of vegetation cover change were different in different climatic regions. The impact of yearly increasing passenger flow on vegetation cover is more complex.

Cities are the core carrier of the high-quality development of the Yellow River Basin. Scientific analysis of the temporal-spatial changes of tourism urbanization level in the Yellow River Basin can provide a scientific reference for the realization of the high-quality development in the Yellow River Basin. Based on methodologies such as spatial autocorrelation, Markov-chain, spatial Markov-chain and geographical weighted regression, this paper analyzes the spatial-temporal evolutionary characteristics and heterogeneity of influencing factors in tourism urbanization level of cities in the Yellow River Basin during 2005 to 2018. The results show that: (1)The level of tourism urbanization has steadily increased in the Yellow River Basin, but the characteristic of regional spatial differentiation is significant, among which, Shaanxi Province can maintain its leading position, Shanxi Province has great potential for tourism urbanization, but the characteristic of tourism urbanization in Inner Mongolia and Ningxia provinces is not significant enough. (2)The overall Moran’s I index is positive, that is, the level of tourism urbanization in the Yellow River Basin has a significant positive correlation in spatial distribution, and shows the characteristic of spatial agglomeration, with prominent neighborhood effects. (3) The horizontal spatial spillover effect of tourism urbanization level in those regions is significant. The convergence of spatial clubs which are “the high clustering, the high drives the low” is relatively prominent. There are significant spatial-temporal inertia and path dependence in different types of cities transferring. (4) Industrial structural level, per capita consumption level and degree of tourism industry agglomeration are the primary factors driving the development of tourism urbanization level, and each presents significant spatial-temporal heterogeneity. 

As an important bridge for the transformation of the two-mountain theory, ecological assets accounting is conducive to clarifying the regional ecological resources and providing objective basis for ecological compensation. The study selected Liyang City as a case of the humid hilly area of Southeast China, listed the ecological assets, and put forward zoning and management strategies according to the spatial distribution of ecological asset value. Multiple ecosystem services (i.e., water conservation, water purification, biodiversity protection, recreational service and product supply services) were quantified and mapped by integrated InVEST model, Market Value Method and Replacement Cost Method. Results showed that the total ecological assets of Liyang City were valued to about 310.59 billion Yuan, with per unit area value of 2.45 million Yuan /hm2 through the Net Present Value Method. Comparing with biodiversity protection and water purification, the value of recreational service, product supply services and water conservation have a greater contribution to the total value of ecological assets. The study found that tangible ecological assets and intangible ecological assets have significantly varied spatial distribution. There are lots of repetitive regions between high-value areas of water conservation, recreational service, water purification and biodiversity protection, which are mainly composed of forests, indicating Liyang made the utmost of natural resource endowments to realize the transformation of ecological resource value. As the important carriers of ecological asset value, the total value of ecological assets in water bodies and woodland are larger than other land-use types. According to the distribution of ecological asset value, different grades of ecological asset value in Liyang City were obtained. High-value areas are mainly composed of woodland and the water bodies in hilly areas, which are the key protected areas in Liyang City, while low-value areas are mainly consisted of cultivated land and attention should be paid to the trade-off and synergy relationships among different ecological asset values in cultivated land and garden land. The study of valuation and ecological zoning of ecological assets in Liyang City had important theoretical and practical significance of promoting the harmonious coexistence between man and nature in Liyang City and constructing the national territory development and protection pattern.

Quantitative researches on the spatial structure and spatial-temporal evolution characteristics of the net carbon sink of regional farmland ecosystem are of great significance to explore the multiple functions of farmland ecosystem and to formulate emission reduction policies appropriate to agricultural regions. Based on the input and output data of major crops at county level units in Jiangsu Province, this paper calculated the net carbon sink of farmland ecosystem in Jiangsu Province from 2005 to 2019. Further by using methods of standard deviation ellipse, spatial autocorrelation, exploratory spatio-temporal data analysis method（ESTDA）, this paper also studied the spatial-temporal evolution characteristics of the net carbon sink of farmland ecosystem in Jiangsu Province. The main results were shown that: (1) The net carbon sink of farmland ecosystem presented a spatial distribution pattern of “from northwest to southeast” in Jiangsu Province, and tended to be concentrated in the shrinking process. The gravity center of net carbon sink had generally moved towards northwest in Jiangsu Province. (2) By observing the Moran's I from 2005 to 2019, this paper found that the net carbon sink of farmland ecosystem in Jiangsu Province had a significant spatial positive correlation, the Global Moran's I value increased from 0.183 in 2005 to 0.528 in 2019. The local spatial agglomeration was stable, which was high in the north and low in the south of Jiangsu Province, while among them, the HH cluster areas and LL cluster areas accounted for more than 70% of the total number of counties. (3) The local spatial pattern of net carbon sink of farmland ecosystem in Jiangsu Province was obviously different in dynamic evolution, while the local spatial structure and spatial dependence direction were both characteristic of strong stability. In comparison, the dynamics of local spatial structure of farmland ecosystem net carbon sink in Central Jiangsu was stronger than that in Southern and Northern Jiangsu. Yancheng, Qidong and Taizhou had greater fluctuation in spatial dependence direction. (4) The occurrence probability of net carbon sink type IV was 68.33% from 2005 to 2019, indicating that the local spatial correlation pattern of net carbon sink of farmland ecosystem was stable, the local spatial linkage weak, as the spatial agglomeration was of high characteristics of path locking.

To provide food safety information of Bellamya aeruginosa in Lake Taihu Basin , the population from six water systems of the Lake Taihu Basin were collected for analyzing their bioaccumulation characteristics of seven heavy metals (Cu,Zn,Pb,Cr,Cd,As and Hg) in foot masses. The pollution and dietary risk of heavy metals were assessed using three methods, including the single factor pollution index，the weekly /monthly average intakes and the target hazard quotient (THQ).The results showed that the average contents of Cu, Zn, Pb, and Cr in the Taoge water system were highest, which were 112.108, 248.625, 4.422, and 7.791 mg/kg, respectively. The average contents of Cd, As, and Hg in Tiaoxi water system was highest, which were 0.290, 2.943, and 0.059 mg/kg, respectively. The results of THQs showed that there is no single heavy metal potential health risk in each water system,with except As, but the total target hazard quotient results showed that the TTHQ value of heavy metals in each water system was greater than 1, and the contribution rate of As exceeds 80%, indicating there were potential health risks of B．aeruginosa via long-term consumption by residents in Lake Taihu basin and the risk of total target hazard quotient mainly ascribed the pollution of As element. The ranking of the total target hazard quotient in the five water systems was Taoge water system> Tiaoxi water system> Yanjiang water system> Huangpu River water system> Hangzhou Bay-Yangtze River Estuary water system. 

Urban ecological security is the basis and premise to ensure the sustainable utilization of urban resources and regional sustainable development.Wanjiang City Belt has promoted the economic progress of the whole Anhui province, but ecological system which is crucial for social and economic has sustained various threats and oppression for years.In this paper, the ecological security evaluation index system of Wanjiang City Belt was constructed from four dimensions of driving-force,pressure,state and response,and we used entropy weight method and standard deviation coefficient method to determine the index weight. The comprehensive index method, the spatial variation model and the grey GM(1,1) modelwere used to analyze the characteristics of the dynamic spatial and temporal evolution and alsothe development trendof the ecological securityin Wanjiang City Belt from 2007 to 2018. Research results showed that:(1) The comprehensive index of ecological security in Wanjiang City Belt showed a fluctuating growth trend over time, but the improvement of each city was different. During the research period, the annual growth rate of the ecological security index in Hefei was the highest (1.14%), and that in Ma 'anshan was the lowest (0.77%). (2) Chizhou and Xuancheng in the south of the study area had high ecological security level, Chuzhou and Hefei in the north gradually transform to ideal security level, and Maanshan, Wuhu, Anqing and Tongling along the river in the middle were in poor ecological security level. (3) The evolution of ecological security pattern in Wanjiang City Belt had a certain continuity and regularity, and the characteristics of spatial differentiation level were significant. On the whole, it presented a spatial evolution pattern from "southern > northern > central " to "northern >southern > central". (4) The indicators of driving force and response layer had a good impact on ecological security. (5) The prediction results showed that the spatial distribution of ecological security center in Wanjiang City Belt will further change to the pattern of "southwest-northeast" during 2020-2030.

The evaluation of habitat quality is of great significance to the protection of regional biodiversity and the sustainable development of ecological environment. This study explored the spatiotemporal changes of habitat quality in Four Lakes Basin of Jianghan Plain from 2000 to 2020 by means of invest model, spatial autocorrelation analysis and hotspot analysis, and integrated CA-Markov and InVEST models to simulate the habitat quality in 2030 under different scenarios. The results show that: (1) the spatial distribution of habitat quality degree in Four Lakes Basin is high in Northwest and Southeast, and low in central. The average value of habitat quality is decreasing from 0.497 7 in 2000 to 0.484 2 in 2020, and the intensity of habitat degradation is increasing. The maximum value of habitat degradation index is increasing from 0.155 5 to 0.159 3 in recent 20 years, and the spatial diffusion trend is obvious;(2) Habitat quality and habitat degradation have significant spatial agglomeration, with obvious cold and hot spots;(3) Compared with the results of habitat quality and habitat degradation degree under natural change scenario, the degradation intensity of ecological protection scenario is weaker, and the habitat quality is improved, which indicates that the implementation of ecological protection measures is conducive to the protection of regional biodiversity and the improvement of ecosystem services.

Biomass burning is one of the important factors influencing the atmospheric environment. As a major agricultural province in China, Hubei Province is rich in agricultural resources. A comprehensive analysis of the biomass burning in Hubei Province can provide an important basis for Hubei Province to strengthen the management and control of biomass burning and improve air quality. Based on VIIRS 375 m thermal anomaly products, land use data and high-resolution remote sensing images, the main types of fire points of biomass burning in Hubei Province from 2012 to 2019 were extracted, revealing the temporal-spatial evolution process of biomass burning and its influencing factors .The results show that:(1)The fires are mainly concentrated in the central Jianghan Plian, and the low mountain and hilly regions in eastern Jianghan Plain .(2)The number of fire spots in Hubei Province showed a clear downward trend during the period 2012-2019, and the straw burning is the main type of biomass burning in Hubei Province. Straw burning fire spots and forest fire spots accounted for 67.43%and 32.57% respectively. (3)After 2015, the number of straw burning fire points decreased significantly, and maintained at a low level. It showed that the control effect was significant. However, the straw burning in Xiaogan City, Suizhou City, Wuhan City and Huanggang City have experienced serious rebounds due to lack of way of comprehensive utilization. Therefore, in addition to further strengthening the ban on burning, it is necessary to find more ways to form scientific and long-term control measures of straw burning. (4)The peak period of straw burning is mainly concentrated in the harvest season,with some small peaks of straw burning appeared in spring and winter.(5)The spatial distribution of straw burning fire spots has expanded and then shrunk. The fire points of the original straw burning hotspots have been significantly reduced in Xiangyang City , Jingzhou City, Xiantao City, Qianjiang City and the western Tianmen City. Forest fire points are mainly distribute in the northern and eastern regions of Hubei Province. Since 2016, the forest fire density in Hubei Province has been at a relatively low level.

Spatio-temporal heterogeneity and succession patterns of water quality were examined in Lake Changdang and Lake Gehu based on quarterly survey from February 2017 to November 2019 and historical data. The results showed that the main pollutants were total nitrogen (TN, inferior grade V), total phosphorus (TP, between grade Ⅲ and grade V) and permanganate index (CODMn, between grade Ⅱ and grade Ⅳ). In general，the trophic status of Lake Changdang and Lake Gehu were between light eutrophication and moderate eutrophication. The evolution trend analyzed of TN and TP and their relationship with social economic development factors were also analyzed based on literature research and remote sensing interpretation. The water quality of the two lakes continued to deteriorate, and the comprehensive water quality deteriorated from grade Ⅲ to grade V from 1990 to 2005. The water quality of the two lakes fluctuated greatly from 2006 to 2014. At this stage, it was mainly affected by a series of ecological restoration policies of Changzhou government (including the removal of the Seine net, the renovation of the catering industry in the lakes, the reduction of nitrogen and phosphorus). TN and TP concentrations was maintained at a relatively high level from 2017 to 2019. The species abundance and coverage of aquatic plants decreased sharply. After 2016, submerged plants in Lake Gehu almost disappeared, and the main dominant species changed from submerged plant Phragmites australis to emergent plant Phragmites australis. The significant positive relationships were calculated between TN or TP and social economic development factors through Spearman correlation analysis, while agricultural non-point source pollution, urbanization, industrialization and aquaculture were the main reasons for eutrophication. But enclosed aquaculture was not the decisive factor for eutrophication in Lake Changdang and Lake Gehu. So the eutrophication managements of Lake Changdang and Lake Gehu should follow the principles of “source controlling-reduction-restoration”. Furthermore, it is necessary to promote rural domestic sewage and livestock wastewater discharge standards, strengthen the protection of lakeshore zone and implement ecological restoration.