Does industrial collaborative agglomeration become an important carrier to optimize the allocation of manufacturing innovation resources and promote the development of industrial innovation? To this end, based on the panel data of 2013-2018, the DEA-Malmquist index method was used to measure the manufacturing innovation efficiency in 11 provinces of the Yangtze River Economic Belt, and the panel two-way fixed effect model was adopted to explore the collaborative agglomeration of the financial industry and the manufacturing industry（called collaborative agglomeration of the two industries） on the impact of the manufacturing innovation efficiency in the Yangtze River Economic Belt.The research results show that the synergistic agglomeration of the two industries affects different innovation efficiency indexes in the manufacturing industry, and the synergistic agglomeration of the two industries shows a positive correlation with the technological progress index, and a negative correlation with the technological efficiency index.Further decomposition of the technology efficiency index shows that the coordinated agglomeration of the two industries can effectively promote the improvement of pure technology efficiency in the manufacturing industry, but it is not conducive to the improvement of scale efficiency.The further enlightenment is that the financial industry and the manufacturing industry should be actively guided to give full play to the positive role of the industrial collaborative agglomeration in the innovation efficiency of the manufacturing industry, improve the ability of the financial industry to serve the manufacturing industry, and improve the efficiency of financial resource allocation.

The study on the intensive use of industrial land in development zones has an important impact on improving land use efficiency and optimizing industrial layout. This paper takes industrial enterprise land in Jiangsu Province as the research object, adopts the updated survey data of industrial enterprises in Jiangsu Province in 2020, compares the spatial differences and industry differences in the intensive use of industrial enterprise land inside and outside the development zones in Jiangsu Province, and uses the multiple linear regression model to analyze the influence of whether enterprises enter the park on the intensive use of industrial enterprise land. The results show that: (1) The floor area ratio, building density, taxes per hectare and employees per hectare of industrial enterprises in the development zone are higher than those outside the development zone, the level of intensive land use by industrial enterprises inside and outside the development zone is higher in southern Jiangsu than in central and northern Jiangsu. (2) There are industry differences in the intensive use of land by industrial enterprises inside and outside the development zone. The land use intensity of equipment manufacturing and raw material processing industries in the development zone is significantly higher than outside the development zone, and the land use and social benefits of most industries in the development zone are significantly higher than outside the development zone. (3) Factors such as enterprise admission, enterprise investment intensity, technology level and operation time have significant positive effects on land use efficiency of industrial enterprises.

Space of flow can be used to effectively depict the remote investment network of enterprises in special regional urban agglomeration. Based on the registration data of industrial and commercial enterprises and land use data, this paper adopts the equity penetration method to obtain the remote investment data of industrial and commercial enterprises in 42 counties and districts from 1950 to 2020 and reveals the structure and evolution characteristics of the remote investment network of enterprises around Poyang Lake urban agglomeration from the level of “main node-backbone path-spatial pattern” respectively. The research results show that: (1）The weighted in-degree of nodes gradually increases, the radiation driving effect of Nanchang is significant, the problem of unbalanced net flow spatial distribution is prominent, and the characteristics of location tendency are obvious. (2）The backbone path mainly occurs in Nanchang, Jiujiang, Yingtan, Fuzhou, Jingdezhen, and other municipal districts with good economic development, which crosses the obstacles of geographical elements. (3） The industry as a whole is developing towards a multi-center structure, and the remote investment network structure of wholesale and retail enterprises has evolved from a single center to a multi-center, the trend of the financial industry is to evolve to multiple places, flat level, and the interworking pattern, the leasing and business service industries have evolved into triple centers, and the manufacturing industry shows a trend of moving south and east.

The species composition, relative abundance and spatial distribution of alien fish were studied in 8 typical sections of the Three Gorges Reservoir from April to June and November to December 2020. The results showed that: (1)There were 108 species of fish in the main and tributary streams of the Three Gorges Reservoir area, belonging to 8 orders and 21 families, of which 16 species were alien fish, accounting for 14.81% of the total number of fish species collected. (2)The alien fish, Coilia brachygnathus, Neosalanx taihuensis, Oreochromis niloticus, were dominant species. Except Wujiang River, Coilia brachygnathus was the dominant species in other seven sampling sections, and the relative dominance were 2.05%-18.71%; In the tributaries of Xiaojiang River and Daning River, Neosalanx taihuensis was the dominant species, with a relative dominance of 2.83% and 8.39%, respectively; Oreochromis niloticus was the dominant species only in the Xiaojiang River, with a relative dominance of 1.56%. (3)The relative abundance of alien fish in the main stream was significantly lower than that in the tributary, and the weight percentage of alien fish in the tributary of Xiaojiang was the highest, 12.30%; the abundance percentage of alien fish in the tributary of Daning was the highest, 57.55%. In view of results, to avoid the possible impact of alien fish on fish resources in the Three Gorges Reservoir, the comprehensive control measures were proposed to manage and control the population of alien fish.

In order to quantitatively analyze the effect of gravel groups on the restoration and improvement of damaged habitats of fish, the Bamaoba fish spawning ground at the upstream of Daoliu River, a tributary of Chishui River, is taken as the research area. As an endemic fish to Zhaotong, Schizothorax grahami is selected as the indicator species, and the layout and size of boulder clusters are determined by stability analysis. Based on the fish habitat model, the changes of suitable habitats of the indicator species before and after the arrangement of boulder clusters are studied and analyzed. The results showed that it is suitable to set the minimum size of the generalized boulder unit as 0.5 m, the span of a single boulder clusters as 1.60 times the boulder length, and the span of boulder clusters at the downstream as 2.10 times the boulder length. The weighted usable-habitat area (WUA) of fish corresponding to five different types of boulder clusters increase in different degrees. Under the dominant discharge parameter, the continuous V-shaped and diamond-shaped arrangements of boulder clusters have more obvious effects on restoration than the other three types. The water depth and velocity in the area where boulder clusters are arranged are diversified and the proportion of the weighted usable-habitat area to the total area is increased by 21.77% and 18.3% respectively. Reasonable arrangement of boulder clusters can provide technical support for the restoration of fish spawning grounds by Chishui River.

In order to understand the current situation of phytoplankton in the lower reaches of the Yalong River after the operation of cascade hydropower stations, 22 sections of the lower reaches of the Yalong River were sampled and investigated for phytoplankton and environmental factors in the spring and autumn of 2020, to analyze the spatial-temporal variation of phytoplankton community structure and explore environmental driving factors. A total of 123 species (including varieties) belonged to 7 phylum, 10 classes, 20 orders, 36 families and 72 genera were identified. They were mainly diatom, chlorophyta and cyanophyta. The number of species in spring was significantly higher than that in autumn, and there were 55 common species. The number of species in main stream was similar to that in tributary, and there were 82 common species. There were five dominant species in the whole year, namely Cyclotella meneghiniana, Synedra acus, Achnanthidium minutissima, Chroomonas acuta and Raphidiopsis sp. There were five dominant species in spring, four in autumn, six in main stream and four in tributary. During the investigation, the average abundance of phytoplankton in the lower reaches of Yalong River was 3.17×106  cells/L. The average abundance in autumn was higher than that in spring. The average abundance in four tributaries was higher than that in main stream. Correlation analysis showed that TP, SS, CODMn, DO, SD, WT, NO3-N, Chl.a, TN and EC were significantly correlated with different dominant phytoplankton species. RDA results showed that the environmental driving factors in spring were TN, PO4, WT, SD and DO. The main stream sections were divided into two parts, and the tributary sections were obviously separated. The environmental driving factors in autumn were WT, SD and SS.

The Yangtze River economic belt is one of the main carriers of China’s economic development whose problem of water resource utilization continues to be concerned. To explore the spatio-temporal correlation pattern and driving factors between water footprint and provincial scale from 2006 to 2020, the spatio-temporal relationship was calculated by decoupling model and disequilibrium index. The factors affecting regional water resource consumption were explored by geographically and temporally weighted regression model and to be discussed from the perspective of heterogeneity. The results showed that: (1)The growth rate of the water footprint in the Yangtze River Economic Belt decreases year by year, and the spatial distribution pattern of water footprint intensity of each province is similar to that of per capita water footprint.（2)There is a weak decoupling between water footprint and economic scale from 2006 to 2020, but 6/11 regions have reached an ideal state of strong decoupling during The thirteenth Five-Year Plan period. Provinces with abundant water resources have good coordination with population size while the balance between water footprint and spatial scale is related to the topography. （3)The water footprint is affected by provincial scale, water-saving technology, industrial structure, and water resources management. Moreover, the effects have spatio-temporal heterogeneity changing with the development stage and regional change.

Exploring the changing characteristics of land use over time and space and their driving attribution in village areas under different rural revitalization paths is of great importance for optimizing land-use patterns and formulating rural revitalization paths. Two administrative villages with similar topography and geomorphology, close historical development but quite different rural revitalization paths-Fangyin and Hengshan villages in the shallow hill valley area of the Yangtze River Basin are taken as examples. Based on unmanned aerial vehicle (UAV) aerial surveys and multi-period Google Earth satellite images, the land-use shifts, expansion patterns of core land, binary changes of parcel attributes and parcel boundaries at the pixel level were synthesized to explore the characteristics of land-use change in the two villages from 2017-2021. Along with a geodetector model was introduced to quantify the drivers from various aspects such as natural, socio-economic and policy factors. The results show that: (1) Both villages underwent a dramatic land-use change process during the study period, mainly spreading expansion of the orchard. Fangyin and Hengshan villages respectively formed the development pattern of integrated agro-tourism and integrated agroforestry, and the land-use change process in Fangyin was more diverse and balanced than in Hengshan. (2) At the pixel level, both parcel attributes and parcel boundaries changed dramatically in Fangyin, and there was a significant spatial clustering effect between the two at over 50% of the village area, while only parcel attributes changed obviously in Hengshan, and the degree of parcel boundary change was overall lower than in Fangyin. (3) Land-use change in village area is influenced by the interaction of multiple factors, such as natural, socio-economic and policy factors. There are differences in types of drivers and the strength they can explain to land-use change in the village area under different rural revitalization paths. In the case of Fangyin, which has a clear policy zoning drive, policy factors occupy a dominant explanatory effect, while natural factors explain more in Hengshan, which has no clear policy zoning.

The Lixia River hinterland is a typical aquaculture base in plain river network area. Lakes in this area are mostly developed for polders. Affected by complex water systems and slow flow, heavy metal is easy to be detained once it enters into the aquatic ecosystem, leading to a series of water environmental problems and food safety danger. Geoaccumulation index and Hakanson potential ecological risk index were used to evaluate heavy metal pollution in sediment phase of 28 typical lakes in the Lixia River hinterland. The sources of heavy metal pollution were analyzed partly qualitatively and partly quantitatively based on principal component analysis. Correlation analysis was conducted to find out the influences of industry discharge and polder aquaculture on heavy metals concentration. The results showed that the Hg, Zn and Cd in sedimentary phase were the major pollution elements with the concentrations 5.6, 1.9 and 1.4 times of the background values, respectively. The comprehensive potential ecological risk index of heavy metals ranged from 152.4 to 599.4. The source of Hg in sediment phase is different from the other 7 elements, perhaps affected by historical thermal power production. The closer the distance between lake and chemical plants, the higher concentration of Hg in sedimentary phase (r=0.42). Organic matter is easy to combine with Hg in sediments. The higher concentration of TOC, the higher concentration of Hg in sedimentary phase (r=0.54). The closer the lakes to the metal processing industry (such as alloy factory, electroplating factory), the higher concentration of Zn (r=0.68) and Cd (r=0.59) in sedimentary phase. Zn and Cd can easily accumulate in sediments due to the slow and uncontinuous water flow caused by the polder aquaculture. The above research conclusions can provide scientific basis for heavy metal pollution control and food safety protection in plain river network area.

The problem of separate governance of blue and green and construction of waterfronts are often faced when is concerned with urban planning and development. As an important part of urban landscape ecology, “blue-green space” has a great impact on the quality of human settlements. Based on the integration characteristics of blue-green space, this research has selected and constructed the blue-green space integration index evaluation system from three aspects: water body, biology and landscape ecology, and 5 criterion layers, 12 index layers and index weights were determined through expert consultation and the analytic hierarchy process (AHP). The integration degree of the blue-green space construction of typical rivers and lakes were evaluated by using AHP in Shanghai. The results showed that: (1) The average score of blue-green space fusion of the river system in the selected survey area was 70.575, and the artificial lake area was 65.774. Among the selected 8 river sample points and 8 lake sample points, the number of sample points has reached a high level of fusion was sample 4 and 6, respectively. The river system was healthier than the blue-green space around the lake area, the ecosystem was more complete, and the ecological service was more functional. (2) The blue-green spatial integration degree of the river system was mainly affected by the hydrological morphological characteristics (0.325) and the riparian zone (0.438), and the lake area was mainly affected by the water quality (0.480) and the hydrological morphological characteristics (0.454). (3) The differences in the spatial integration of blue and green in the selected rivers and lakes were mainly reflected in the two indicators of bank protection ecology and green accessibility. By evaluating the degree of integration of blue-green space, the problems existing in the construction of blue-green integration could be analyzed, which is expected to provide a reference for the planning and designing of urban blue-green space, and to give a theoretical basis for the restoration and management of urban ecosystems.

In order to explore the historical variation and potential ecological risk of heavy metal pollution of lake Shengjin in the lower reaches of the Yangtze River, a sediment core was drilled and analyzed from the sediments. Based on AMS14C dating results, the historical distribution characteristics and main sources of heavy metal pollution in the lower reaches of the Yangtze River during the past millennium were analyzed by using the enrichment coefficient and potential ecological risk index method combined. the results show that the mean contents of As, Mn, Pb, Cu, Zn, Cr, V and Ni are 19.2, 623.7, 28.6, 42.4, 115.7, 83.7, 153.1 and 46.5 mg/kg respectively. The comprehensive potential ecological risk (RI) of heavy metals in the sediments of Lake Shengjin gradually increased over time. The potential ecological risk of element As before 1600 A.D.is a slight ecological hazard, after 1900 A.D.,which rises to medium ecological hazard, and the elements Cu, Mn, Ni, Pb, Zn, V and Cr are all slight ecological hazards. The order of potential ecological risk of elements is As > Cu > Ni > V > Pb > Cr > Mn > Zn, As and Cu are the main contributing factors. before 1600 A.D., the element As was slightly enriched and the anthropogenic pollution was small. After 1600 A.D., which was moderately enriched and the proportion of anthropogenic sources increased significantly. Before 1600 A.D., the element Cu fluctuated, and after 1600 A.D., the stable variation range was moderately enriched. The remaining heavy metals Mn, Pb, Ni, Cr, Zn, V enrichment degree is small, after 1900 A.D., there is a certain degree of anthropogenic sources. The results of multivariate statistical analysis showed that the heavy metals before 1600 A.D.,were mainly deposited in the natural state, 1600-1900 A.D.,were the combined effects of human activities and natural deposition, and human activities after 1900 A.D.,were the main sources of heavy metal pollution. Among them, industrial pollutant emissions, mining and agricultural activities are the main influencing factors of heavy metal pollution sources. Based on the above findings, the possible ecological risks of Lake Shengjin basin in the future were analyzed, which provided a useful reference for the ecological environment protection and sustainable development of the lake basin in the lower reaches of the Yangtze River.

Urban agglomerations have become the hardest-hit areas of air pollution in China today, seriously damaging the regional ecological environment and human health. However, few existing studies have considered how to optimize the land use structure to maximize the natural purification capacity of the atmospheric environment, thereby reducing the established pollution. In view of this, this study takes the urban agglomeration in the middle reaches of the Yangtze River with rapid urbanization and serious air pollution as the empirical object. From the perspective of land use structure, using the high-precision PM_2.5 data retrieved independently, based on the generalized additive model and spatial regression model, this study reveals the nonlinear impact of land use change on PM_2.5 pollution and its spatial spillover effect from 2005 to 2020. The research results show that: (1) From 2005 to 2020, the construction land in the urban agglomeration in the middle reaches of the Yangtze River increased significantly, while the cultivated land continued to decrease. The PM_2.5 pollution increased before 2011 and then decreased, and there was a significant spatial autocorrelation. (2) The impact of land use change on PM_2.5 pollution is a complex nonlinear relationship, in which the impact of construction land and cultivated land changes on PM_2.5 pollution has a marginal decreasing effect. (3) The impact of land use change on PM_2.5 pollution has significant spatial spillover effects, and except for grasslands, the direct effects of landcover on PM_2.5 pollution are greater than the indirect effects. (4) Forest land and grassland effectively reduced PM_2.5 pollution in the region and its neighborhood, and the direct effect of forest land was much higher than that of grassland. On the contrary, construction land significantly increased the PM_2.5 pollution in the region and its neighborhood. However, the impact mechanism of cultivated land on PM_2.5 pollution is complicated, reducing PM_2.5 pollution within the region, but aggravating the neighboring PM_2.5 pollution. The research results help to provide new ideas for the prevention and control of air pollution in China′s urban agglomerations.

Quantitative analysis of the relationship between urban thermal environment and urban morphological characteristics can provide a basis for urban territorial space planning and improvement of urban ecological environment. Local Climate Zones (LCZ) can well reflect the difference in local climate in cities. Therefore, the quantitative relationship between local climate and urban morphology can be constructed based on LCZ to study the urban thermal environment. In this paper, the Landsat-8 remote sensing data is used to invert the surface temperature, and the deep learning method is used to classify the local climate zone based on the Sentinel-2 data. The results show large differences in the surface temperature between different LCZ categories, and the urban morphology had a greater impact on the surface temperature. Among them: (1) LCZ10 (heavy industry) had the highest temperature, LCZG (water body) had the lowest temperature, and the temperature difference of each category in summer was greater than that in winter; (2) The surface temperature of dense buildings (LCZ1-3) was higher than open buildings (LCZ4-6), and the surface temperature of low-rise buildings was higher than high-rise buildings; (3) In urban morphology, the water proportion (WSF), building height (BH) and building proportion (BSF) had a greater impact on the surface temperature, of which the water proportion (WSF) and building height (BH) were significantly negatively correlated with land surface temperature, and building proportion (BSF) was positively correlated with land surface temperature.

It is of theoretical and practical significance to explore the spatial and temporal changes of carbon stocks in regional terrestrial ecosystems over long periods of time and their influencing factors to achieve the carbon neutrality goal. This study couples the PLUS-InVEST-Geodector model to investigate the spatial and temporal changes of carbon stocks in the Three Gorges Reservoir Area under different scenarios from 1990 to 2035, and to quantitatively reveal the attribution factors affecting the changes of carbon stocks from the perspectives of land use changes and natural-socio-economic complex relationships. The results show that (1) the carbon stock in the Three Gorges Reservoir Area shows a fluctuation of “decrease-increase-decrease” from 1990 to 2020, with an overall decrease of 6.66 Tg, or 1.25%, among which a large area of arable land is transferred to construction land as the main reason for the decrease of carbon stock; (2) The spatial distribution of carbon stocks in the Three Gorges Reservoir Area from 1990 to 2035 is highly consistent with land use changes, and its spatial heterogeneity is significant, showing the distribution characteristics of “high in the east and low in the west, low in the south and high in the north, and head of the reservoir > belly of the reservoir > tail of the reservoir”. (3) The carbon storage of the natural development scenario and the ecological protection scenario in 2035 will be reduced by 7.53 Tg and 0.37 Tg respectively compared with the year 2020, and the ecological protection scenario can significantly reduce the carbon storage loss in the reservoir area compared with the natural development scenario; (4) The factors affecting the spatial and temporal changes of carbon storage are significant, among which land use change is the dominant factor, followed by temperature, population density, elevation and soil type, and the interaction of all factors increases the explanatory power of carbon storage changes. This study can provide scientific reference for the management of carbon pools in the reservoir area and the sustainable development of carbon storage function.

In this study, paleoflood slackwater deposits (SWD), loess and aeolian sand were surveyed and sampled in the middle reaches of the Yarlung Zangbo River valley in the Tibetan Plateau in China. Their macroscopic characteristics were observed and sediment experimental analyses (i.e., grain size, magnetic susceptibility and geochemical elements) were conducted. The primary goal of the study is to summarize the sedimentological identification marks of the paleoflood SWD in the middle reaches of the Yarlung Zangbo River valley in the Tibetan Plateau in China. Results showed that the SWD trapped in the Zangmu profile (ZM), Langxian profile (LX) and Milin profile (ML) all demonstrated horizontal wavy lamination with uniform structure and its macroscopic characteristics are obviously different from those of the aeolian deposits (e.g., loess and aeolian sand). The grain size composition of the paleoflood SWD, loess and aeolian sand are generally coarse, mainly fine sand (>0.063 mm). Among them, the grain size of the aeolian sand is obviously coarser than that of the paleoflood SWD and loess. The sortability of the paleoflood SWD is the best among the three sediments, followed by loess, and aeolian sand in the middle reaches of the Yarlung Zangbo River valley in the Tibetan Plateau in China. The reason is that the paleoflood SWD is a suspended sediment sorted by water. The higher magnetic susceptibility content of the paleoflood SWD is probably related to the increase of ferromagnetic minerals in SWD due to the surface scouring of the middle reaches of the Yarlung Zangbo River valley by floods. The grain size characteristics, major and trace element contents of the paleoflood SWD are close to those of the loess in the middle reaches of the Yarlung Zangbo River valley in the Tibetan Plateau in China. However, there are obvious different occurred in the grain size characteristics and major and trace element contents between the paleoflood SWD and aeolian sand. These suggested that the sediment provenance of the paleoflood SWD may be closely related with that of the loess in the middle reaches of the Yarlung Zangbo River valley in the Tibetan Plateau in China.

The meteorological conditions of grain filling stage affect the grain yield and quality of high-quality rice, so it is very important to adjust the appropriate sowing date (grain filling period) for high-quality rice production. In this study, 10 high quality rice varieties with three sowing dates (C1, C2, C3) in Jingzhou, Hubei Province. The changes of grain yield and rice quality under different sowing dates and their relationship with meteorological factors were compared. The results show that, the meteorological conditions significantly affected the grian yield and quality of high-quality rice with in the first15 days of the grain filling period (FFD). On the whole, the yield was the highest in the second sowing date-C2 (8.3 t/hm²), and C2 treatment had higher aboveground dry matter accumulation, grain number per panicle and seed setting rate; among the rice quality indexes, head rice rate was better in C2 and C3, which were 62.1% and 61.8%, respectively; chalkiness had little difference among the three sowing periods; the amylose content of most varieties increased significantly with the delay of sowing date. The grain yield and rice quality were closely related to the key meteorological factors during the grian filling stage, and the yield was significantly correlated with the meteorological factors in the first 15 days of the grian filling stage, and the 1000-grain weight was linearly correlated with the meteorological factors during the grian filling period. among them, it was positively correlated with the daily temperature range and sunshine hours, but negatively correlated with relative humidity, and the relationship between head milled rice rate and meteorological factors during the grian filling period is a “parabola” with the opening downward. Therefore , it was found that the daily average temperature of about 26℃, daily range of 9℃, relative humidity of 85% and sunshine hours of about 6 hours during the first 15 days of grian filling period were the best meteorological conditions to improve the grain yield and quality of high-quality rice. Therefore, there is an obvious optimal cultivation period (grain-filling period) for the cultivation of high-quality rice in Jianghan Plain, and reasonable arrangement of sowing date should be a key technology in the production of high-quality rice.

It is of great significance to explore the distribution characteristics and regularity of selenium in cultivated soil in hongjiang city and analyze the influence of soil physical and chemical properties on soil selenium distribution, which can promote the rational development and utilization of local land resources.Soil selenium (Se) content and related soil physical and chemical indexes of 1 480 samples were collected and analyzed by using indoor grid distribution, field investigation and sampling, analysis and determination, GIS spatial analysis and other methods and techniques in Hongjiang City. Combined with correlation analysis, geostatistical analysis and spatial autocorrelation, the spatial distribution characteristics and influencing factors of soil selenium in Hongjiang City were revealed.The results showed that the average soil selenium content in Hongjiang City was 0.54 mg·kg-1, which was 1.35 times that of the global average surface soil selenium content (0.4 mg·kg^-1) and 1.86 times that of the national average surface soil selenium content (0.29 mg·kg^-1).The selenium content in the soil developed from limestone was significantly higher than that of soil developed from other parent materials;Selenium content is highest in purple soil and lowest in Alluvial soil. Soil selenium content was affected by organic matter content, pH, copper and zinc content.When pH was between 5.0~6.0, soil selenium content was positively correlated with pH, and when pH > 6.0, soil selenium content was negatively correlated with pH;Soil selenium content was positively correlated with soil organic matter, total copper and total zinc content.The area of selenium-rich cultivated land in Hongjiang City accounted for 90.53%, showing a trend of high in the east and low in the north and north, and gradually decreasing from the east, south and west to the middle and north, which was suitable for the development of characteristic selenium-rich products.

The cultivated land fallow system has been an important measure to implement the strategy of “food crop production strategy based on farmland”, which is of far-reaching significance for ensuring the food security and achieving the sustainable development of the agriculture. This paper is based on the connotation and technology about spatial allocation of the cultivated land fallow, to solve the low-efficiency and profit-loss problem due to the unreasonable spatial allocation of the fallow land. This paper takes Songtao County, a severely degraded area and one of the first batch of pilot fallow counties of Guizhou Province in China, as an example to illustrate how to diagnose and identify fallow land by using comprehensive health evaluation method,and to select different fallow land according to different requirements. The research results indicate that: (1) The essence of spatial allocation of the cultivated land fallow in the broad sense is to optimize the combination of the scale, the distribution, the time sequence and technical pattern of the fallow land, in order to realize the mocro-control of “quantifying, locating, sequencing and technology-selecting of the fallow land”. (2) The important basis of spatial arrangement in the fallow regions is the diagnosis and identification of the fallow cultivated land based on comprehensive health evaluation of the cultivated land, which is determined by the quality goal and production capacity goal of the cultivated land; the essence of spatial arrangement in the fallow regions is spatial testriction, with area concentration and contiguity as its main trestriction. (3) The health condition of the cultivated land in Songtao County is at the average level, it’s of great potential to carry out the fallow land system and it’s suggested that dry land is of greater potential than paddy fields, combining moderate fallow measures with prioritized fallow measures. (4) The fallow area of the paddy field is mainly distributed in northeast, west, and southern towns; the fallow area of the dry land is distributed in entire county, mainly distributed in the eastern and central part of the county.

It is necessary to understand the spatial variation characteristics of cropland soil organic carbon and its influencing factors for the purpose of enhancing soil carbon sequestration ability and improving cropland soil quality. Based on 4 362 surface (0~20 cm) soil sample points collected during 2017-2019, this study explored the spatial distribution pattern of cropland topsoil organic carbon content in the Sichuan Basin of China using geostatistical methods, and then revealed the influence of climate, topography, soil type, agricultural land-use type and nitrogen application intensity on the spatial heterogeneity of topsoil organic carbon content by correlation analysis, variance analysis and regression analysis. The results showed that the average of topsoil organic carbon content in the study area ranged from 1.58 to 42.40 g·kg^-1, with an average of 13.85 g·kg^-1, which was slightly lower than the national average level; the coefficient of variation was 45.82%, with moderate spatial variability. The semi-variance analysis showed that exponential model was the best theoretical model of cropland topsoil organic carbon in the study area, with the nugget effect of 59.73% and the range of 145 km, which indicating that the spatial distribution of cropland topsoil organic carbon has large autocorrelation range and was determined by both structural and random factors. The results of spatial interpolation showed that the cropland topsoil organic carbon content in the Sichuan Basin generally showed a patchy distribution pattern, with the cropland topsoil organic carbon content being lower in the middle of the basin and higher in peripheral areas. Soil type was identified to be the primary factor affecting the spatial distribution of cropland topsoil organic carbon in the study area, followed by agricultural land-use type, climate and topography, which can explain 19.7%, 14.0%,12.0% and 9.2%, respectively, of spatial variability of topsoil organic carbon. Therefore, it is concluded that the regulation of farmland use type is the key to realizing the increase in cropland topsoil carbon sequestration in this region, while the impacts of soil type, climate and topography should be also fully considered.