As a direct means of a "strong provincial capital" strategy, the administrative boundary expansion of provincial capital cities has attracted wide attention in recent years. In general, local governments increase their economic aggregate by developing organizational boundaries and have high enthusiasm for the expansion policy of administrative boundaries of provincial capitals. But China has been cautious about the procedure, given the risks involved and the uncertainty over its effects. The different policy considerations of the central and local governments put forward realistic demands for the performance evaluation of the administrative expansion of provincial capitals. Scientific assessments of the effect of organizational boundary expansion on provincial economic development can provide a sufficient basis for formulating relevant policies. Based on the panel data of 27 provinces in China from 1997 to 2018, this paper analyzes the economic growth effect of provincial capital city expansions after 2000 using the synthetic control method. It conducts a robustness test by using the placebo method. Then, the mechanism is analyzed from the perspective that the provincial capital city's economic scale accounts for the whole province's proportion. The empirical results show that the expansion of administrative boundaries of provincial capital cities can not significantly promote the economic growth of the whole provinces. The heterogeneity analysis shows that for provincial capital cities whose economic scale accounts for a large proportion of the province, expanding the scale of provincial capital cities by administrative means has a significant inhibitory effect on the economic development of the provinces, and the inhibitory intensity continues to grow over time. For the provinces where the provincial capital cities accounted for a relatively low proportion of the provinces' economy before expansion, it was found that the policy did not inhibit the provinces' economic growth, and the effect was not significant. The policy implication of this paper is that the expansion of the administrative boundaries of provincial capital cities has a high risk. As central cities of provinces, provincial capital cities have not played a role in promoting their economy. Therefore, the central government should carefully consider provincial capitals' administrative boundary expansion demands. The provincial capital city boundary expansion is not the only way to realize the "strong provincial capital" strategy. Considering the existing economic volume of the provincial capital city, the provincial government can carry out concussive and collaborative development through talent strategy, the construction of the metropolitan area, and other means. At the same time, subcentral cities should be cultivated to avoid "One city dominating" which might restrict the province's economic growth.
The merger of prefecture level cities is a new form of administrative division adjustment. Simultaneously, it can be seen as a process of scale rescaling including multi-dimensional social relations. Based on the theory of scale rescaling and the empirical case of administrative division adjustment of Jinan and Laiwu, the article constructs an analytical framework to explore the process and logic of the ''merger of two cities'' from three dimensions of power, capital and perception. The results show that, firstly, the Jinan government has adjusted its functions through scaling up and down of power, ensured the smooth transfer of power, and achieved the rescaling of power. Secondly, the government has implemented policy of industrial optimization and differentiated layout, and achieved the rescaling of capital through driving industrial upgrading and enterprise relocation. Thirdly, through the built environment transformation, such as roads, communication and ecological facilities, and through the integration of public services, cultural and tourism resources, the government has reshaped the residents' sense of place and achieved the rescaling of perceive. In the process of ''merger of two cities'', the coupling coordination of three-dimensional factors of power, capital and perception has improved the scale and hierarchy of Jinan and Laiwu, and achieved the rescaling of space. Consequently, it gives impetus to the completion of the administrative division adjustment and the high-quality urban development. This research has enriched scale theory by constructing the muti-dimensional framework of scale rescaling, and deepened the understanding of process and mechanism of administrative division adjustment.
Traditional settlement space governance, as a small-scale national governance, covers governance issues in economic, cultural, social, and ecological dimensions involved in the "modernization of national governance system and governance capabilities", reflecting the governance of social governance, market governance, and government governance in the process of national governance. Space governance of traditional settlement is one of the basic links that cannot be ignored in the modernization of national governance. Therefore, research on the governance of traditional settlement spaces is of positive significance to help understand the modernization of national governance. The research, taking Zhangguying Village as an example and using text analysis methods, in-depth interview methods, questionnaire surveys and factor analysis methods, based on the perspective of the actor network, reconstructs the traditional settlement space governance mechanism. The research found that: the space governance actors in Zhangguying Village are the government, village committees, villagers, cultural relics protection companies, tourism development companies, cultural industry companies, heritage foundations, physical space, social space, cultural space, and economic space. The spatial governance of Zhangguying Village has such phenomena as the imbalance of subject rights, the construction of multi-dimensional space, and the evolution of spatial functions. Under the reconstruction of the actor network, the administrative subject, the local community subject and the external subject need to adjust the action mechanism to promote the transformation of the material space, the reconstruction of the social and cultural space, and the construction of the economic space. Through the adjustment of the action mechanism of space subjects, the redistribution of space rights can be realized. From the perspective of the actor network, the main subject of the traditional village space should cooperate with each other and participate in governance. The foreign culture and traditional culture urgently need to deepen the integration and interaction, and the traditional village space function urgently needs to be repaired and reorganized. Research innovation combines spatial governance with actor network theory, and introduces it into the research category of rural governance to enrich the connotation of the spatial governance system. Research helps explain how various actors participate in governance in the process of space governance in traditional settlements, and how to allocate space rights and interests rationally, providing references for other similar traditional settlements.
Governance and geography are inextricably linked. The origin of governance thought is geography, governance is based on geographic environment, knowledge and practice. Classical geography has contributed to governance with the world view, regionalization theory, geomancy and cartography. The Age of Exploration has promoted the development of governance. Governance thought formed in the east and west under different geographical conditions continues to blend in the collision, and the focus of governance thought has shifted from the separation of nature and human to the combination of human-earth relationship. Modern geography is constantly integrating with humanities, social sciences, nature sciences, technological sciences and other disciplines, focusing on global, nation, region, place and other spatial scales and their interactions, and exploring governance paths with geographical characteristics. The thought of human-earth system coupling in geography plays an important role in the current interdisciplinary governance research. Geography provides strong support for the research of governance in terms of values, thoughts, methods and techniques. The integration of the two fields will contribute to the development of governance science.
Since the slow progress of cooperation among the governments of Guangdong, Hong Kong and Macao after the reunification, the central government of China is determined to crack the problem of cross-regional collaboration by promoting the construction of the Greater Bay Area through vertical embedding of national strategies. Based on a multidimensional dynamic contextual perspective, this paper systematically analyzes the intrinsic correlation between the industrial structure, inter-governmental relations, socio-cultural changes and cross-regional collaboration, arguing that the industrial structure has compressed the space for economic cooperation and the lack of socio-cultural integration has weakened the momentum of collaboration. While the implementation of comprehensive governance and the Hong Kong National Security Law has reconstructed the inter-governmental political distance, implying that a high level of the strategy to promote cross-regional collaboration has become the inevitable choice of the central government. The study points out that although the top-down national strategy of the central government can mobilize all parties in the short term, it triggers a conflict between the roles of rational person and agent of local governments, making it difficult to maintain long-term dynamism. In the future, a long-term dynamic process control concept should be established, an institutional cross-regional collaboration framework and functional cross-regional governance institutions should be set up, and Hong Kong and Macao should be urged to adopt active industrial policies and pay high attention to the social and cultural integration of the three regions.
In the context of the knowledge economy, scientific knowledge production increasingly becomes one of the key drivers of long-run economic growth and core competiveness.The scientific knowledge production has been an important topic in economics and economic geography. However, there is a paucity of analysis of the worldwide spatial evolution of scientific knowledge production. On the basis of bibliographical data from the InCites database provided by Clarivate Analytics, this study employs spatial analysis, including geographical concentration index, center of gravity and kernel density analysis, and extended knowledge production function model to investigate the spatial-temporal evolution and influential factors of scientific knowledge production in 2000—2019. Our analyses show that the size of the global knowledge production has expanded, and the number of publications and countries has increased over time. The traditional scientific superpowers have maintained slow growth, while the emerging scientific countries or regions shows a rather fast pattern. The former faces increasing competition from the latter, which may pose a challenge to the Anglo-American academic hegemony and try to create a new world order. The count and percentage of internationally co-authored papers have continued to rise over the past two decades, suggests that international collaboration is increasingly the norm. The established economies have joined the global scientific community, by contrast, the majority of research output remains domestic for emerging counterparts. The geography of the global scientific knowledge production presents the two trends: regional concentration and global spread, and the spatial pattern is evolving from a bipolar world dominated by North America and Europe to a tri-polar world including Europe, North America, and East Asia. The mean center of gravity of global science is moving from the West to the East, which is reshaping the world knowledge production landscape. In addition, empirical results indicate that the knowledge base, relational capital, structural capital and cognitive capital have positive and significant effect on the national/regional scientific knowledge production. Finally, this study asks for more attention to knowledge production in the future research agenda, and briefly mentions three of those research challenges.pital have positive and significant effect on the national/regional scientific knowledge production. Finally, this study asks for more attention to knowledge production in the future research agenda, and briefly mentions three of those research challenges.
Urban green belt is an important means to prevent urban sprawl and improve urban ecological security pattern. However, the city is a complex and open giant system, the actual development and construction process will often break through the planning expectations. In order to explore the non-linear changes of urban green belts with urban development in different periods and different cities, based on the perspective of resilient city construction, this study measured and analyzed the fragmentation and connectivity of green belts in three typical circular megacities of Beijing, Xi'an and Chengdu from 2000 to 2020 by using quantitative methods such as land use transfer matrix and landscape pattern index. The results showed that: 1) From 2000 to 2020, the expansion modes of the three cities were mainly the outlying expansion, and the green belts were continuously eroded by urban construction land. The distribution range of cultivated land in the three urban green belts and their buffer zones decreased significantly from the center to the periphery, and the distribution range of grassland and forest expanded and showed the characteristics of fragmentation and dispersion. 2) The proportion of construction land in the green belts of the three cities continued to rise. The rapid expansion of construction land occupied the most significant ecological land in the green belt of Beijing, followed by Xi'an and Chengdu, accounting for 44.09%, 43.21% and 37.02% respectively. The proportion of construction land area decreased first and then tended to be gentle from the inside to the outside of the green belt and its buffer zones, the proportion of cultivated land area increased first and then tended to be gentle, and other ecological land such as forest and grassland showed slight fluctuations. 3) From 2000 to 2020, the fragmentation degree of green belts in the three cities decreased as a whole, the connectivity of green belts in Beijing gradually decreased, and the connectivity of green belts in Xi'an and Chengdu showed a ''V'' trend of decreasing first and then increasing. However, the changes of landscape fragmentation and connectivity in different urban green belts were significantly different. The fragmentation degree of cultivated land in the green belts of the three cities increased, the connectivity decreased; the fragmentation degree of grassland, water body and construction land decreased, and the connectivity increased.
The domestic trade container transportation of port is an important part of modern logistics system. Clarifying the space-time law of the development of port domestic trade container transportation and its internal relationship with local economic development is the key link to achieve higher-quality development of regional economy under the new "dual circulation" development pattern. Based on the data of container throughput, cargo throughput of domestic container routes and GDP, this paper analyzes the development trend, spatial-temporal pattern of domestic trade container transportation of the Fujian coastal port group and its dynamic relationship with local economy from 2002 to 2019, using methods such as Sankey diagrams and VAR model. Results indicate that: 1) The domestic trade container transportation shows a rapid growth trend and has now become an important component of the container transportation of Fujian coastal port group. 2) There are obvious differences in the development trend of domestic trade container transportation business in Fujian coastal ports, forming a spatial structure of domestic trade container transportation with Xiamen port as the main port and Quanzhou Port and Fuzhou port as the auxiliary. 3) Domestic trade container cargo flow has obvious spatial-temporal differentiation characteristics, except for Putian port, the number of routes and spatial coverage of other ports have shown a significant growth trend. 4) There is a long-term and balanced relationship between the domestic trade container transportation of coastal ports and the local economy, which have an obvious positive interactive response relationship and tends to be stable in the end. The contribution rate of domestic trade container transportation of coastal ports and local economic development to each other's variance decomposition shows an increasing trend, indicating that the interaction between them is obvious and tends to strengthen.
Based on the enterprises' non-local investment data, this paper constructs the global, national and regional urban networks in the Yangtze River Delta from 2003 to 2018, and then uses the spatial panel econometric model to comprehensively analyze the impact of urban networks on urban economic growth, so as to reveal the urban network externalities in the Yangtze River Delta. The results indicate that: 1) Urban networks of all scales in the Yangtze River Delta continue to expand and present a typical characteristic of core-periphery structure during the study period. 2) Urban networks of all scales have a positive impact on urban economic growth, but the degree of impact shows global > national > regional scale heterogeneity. 3) And over time, the economic benefits brought by embedding national and regional urban networks gradually exceed the impact of global urban networks, which shows that from the perspective of multi-scale urban networks, the Yangtze River Delta turns to internal circulation under a "dual circulation" development pattern, which is not only a realistic manifestation, but also an inevitable choice. This result provides direct research support for the dual circulation strategy in the Yangtze River Delta. 4) Due to different resource endowments and development stages in different regions of the Yangtze River Delta, the impact of urban network on urban economic growth has obvious regional heterogeneity. Cities located in the core region benefit more from the urban network, but the impact of urban network on cities located in the outer region gradually increases over time. 5) The agglomeration externality is an important factor affecting the improvement of urban economic performance. The externality and knowledge spillover effect brought by economic agglomeration under spatial constraints are still important driving forces in the evolution of economic geographical landscape. However, compared with agglomeration externality, the importance of urban network externality is becoming more and more prominent. This study can provide decision-making support for incorporating development strategies of urban network into the spatial policy system of national and local governments.
Based on three dimensions of "production, living, ecology", the assessment index system of rural regional functions was optimized. The optimal functional clustering of 187 counties in the Central Plains Urban Agglomeration was achieved by the SOFM network, Geodetector mode, and the Mann-Kendall method. The results showed that: 1) The development pattern of "production, living and ecology" functions in the Central Plains Urban Agglomeration had obvious spatial heterogeneity, and from the point of evaluation index, the top-down number structures of counties were characterized as "olive", "pagoda" and "pyramid" respectively. The spatial distribution characteristics of hot and cold spots analysis and number structure analysis are relatively consistent. 2) The rural functional zoning model proposed in this paper could accurately identify the functional characteristics of the "production, living, ecology" at the county-level, based on these, the 187 counties were divided into 3 major categories: dominant functional area, complex development functional area, and complex coordination functional area, and 7 sub-categories, including grain production dominant functional area, etc. 3) The functional zoning of rural areas is characterized by differentiated structure and spatial differentiation, which is an intuitive manifestation of the collision between the background characteristics of traditional agricultural areas and the multiple elements of rural transformation and is in line with the regional development trend. 4) Combined with the development status of various counties, targeted development countermeasures were put forward, aiming to enrich the connotation of rural regional functions theory, further clarify the rural development pattern of traditional agricultural areas, and promote the coordinated development of the "production, living, ecology" function in the Central Plains Urban Agglomeration region.
The types of tourism resources are abundant in China. The vitality of tourism economy has not been fully bloomed, which is reflected in the mismatch between tourism resources and the vitality of scenic spots from view of the level of scenic spots. Using web crawler technology to obtain the Area of Interest (AOI) boundaries of 304 5A-level scenic spots in China, and based on Tencent's location big data, the vitality intensity of 5A-level scenic spots is measured. Combining points of interest, interest surface data and location big data, an effective method for gradually synthesizing tourism vitality indices at different spatial scales is an effective method. The article reveals the spatial distribution characteristics of resources and vitality intensity of high-grade scenic spots in China and the matching status of the two scales of provinces (autonomous regions) and municipalities (municipalities directly under the central government and prefecture-level cities). The influencing factors of spatial differentiation of the vitality intensity of China's 5A-level scenic spots are identified by the geo-detector method. The results show that: 1) There is a spatial difference between the 5A-level scenic spots and the vitality intensity of China's provinces and cities, and there is a spatial mismatch; 2) The results of factor detection show that the vitality of China's 5A-level scenic spots is affected by multiple factors, the influencing factors at the provincial scale and the municipal scale are different, and the provincial scale is more affected by traffic conditions and economic development level. The city scale is more affected by the market scale, and the combination of resource endowments and other factors has a decisive impact on the vitality of scenic spots.
Rural settlement plays an important role in the settlement system, but for a long time there has been a lack of in-depth research on the internal mechanism of the spatio-temporal evolution of rural settlement scale, resulting in the lack of effective theoretical guidance for the planning, construction and management of rural settlement. In this study, the spatial distribution data of rural settlements in Guangdong Province in 1980, 1995, 2005 and 2015 were obtained based on remote sensing images. Taking rural settlement patches as the unit, the spatio-temporal geographical weighted regression model was used to reveal the spatio-temporal differences of the factors influencing the evolution of rural settlement scale, and the periodic rules of the influencing mechanism were summarized. The conclusions are as follows: 1) The evolution of rural settlement scale in Guangdong Province showed a trend of increasing, stable and decreasing, and the total settlement scale decreased slightly in the past 35 years, but the regional structural difference was obvious. The evolution of rural settlements in the Pearl River Delta region is consistent with the trend of the whole province. The continuous expansion of the original rural settlements in east Guangdong led to a continuous increase in the total scale, but the trend gradually weakened. In northwest Guangdong Province, some rural settlements mainly expand in situ and some shrink gradually. The urbanization rate of new rural settlements and rural settlements is not high. 2) There are obvious spatio-temporal differences in the influencing factors on the evolution of rural settlement scale. The influence of terrain conditions, road network density, county GDP per capita and base period settlement area on rural settlement scale generally presents an "inverted U-shaped" trend, while the driving direction of other natural environment background, location accessibility and socio-economic factors is stable, but the influence changes with the stage. 3) In the past 35 years, Guangdong Province experienced three development stages: Rural-urban division, rural-urban impact and rural-urban integration. The dynamics of rural settlement scale evolution in each stage showed significant differences. In the stage of rural-urban division, rural settlement development had obvious path dependence. In the stage of urban-rural impact, the settlements with high level of social and economic development, superior natural conditions and complete transportation infrastructure are more likely to be urbanized. In the stage of urban-rural integration, the influence of natural environment background gradually weakens, while the importance of location accessibility gradually becomes prominent.
The human body dissipates heat mainly by evaporation of sweat in a hot environment, this ability to dissipate heat is diminished by increased humidity, hence the combined extreme heat-humid condition poses a serious threat to human health. Traditional studies on extreme heat that consider only the role of temperature potentially underestimate the threat to human health from increased heat stress in the context of global warming. In this study, we adopt wet bulb globe temperature (WBGT), a comprehensive index for indicating the synergistic effect of temperature and humidity, to examine future changes in population exposure to compound extreme heat-humidity events in China (excluding the data of Hong Kong, Macao and Taiwan) in the 21st century based on high-resolution simulations from regional climate models. Future projections are performed under two typical combinations of climatic scenarios and socio-economic scenarios, which respectively represent the "best" (SSP1-2.6: low-warming sustainable and development, consistent with the long-term temperature goal of the Paris Agreement) and the "worst" (SSP3-8.5: high-warming and uneven development without policy intervention) scenarios. The results indicate that although the nationally total population will not change much under the SSP3-8.5 scenario, the population exposure to extreme heat events will increase significantly to approximately 3-5 times the reference period (1986—2005). The nationally total population decreases remarkably under the SSP1-2.6 scenario, and the increment of the number of heat days in different severity by the end of the 21st century is only about one-fifth of that under the SSP3-8.5 scenario, however, the population exposed to extreme heat events will still increase. Changes in population exposure are dominated by climate change factors, with a small contribution from factors related to population change. The coastal region of Southern China is the most prominent region for the increase in extreme heat events. Our results reveal the substantially increasing threat of moist heat stress in China in the context of global warming, and emphasize the benefits of avoiding negative climate change-related impact by strengthening mitigation actions.
This paper assessed the spatial distribution of heat risk in Beijing based on multi-source spatial data, including EOS/MODIS remote sensing data, NPP/VIRRS remote sensing data, meteorological data, population census data and Statistical yearbook. This period experienced a severe extreme heat event with daily maximum temperatures all exceeding 35 degrees Celsius. The gridded population density was mapped based on NPP/VIIRS nighttime light data and other auxiliary data by random forest algorithm. The remotely sensed gridded population density was integrated with the Normalized Difference Vegetation Index (NDVI), Modified Normalized Difference Water Index (MNDWI) and Normalized Difference Building Index (NDBI) to calculate the exposure index of heat wave by subjective and objective weighting methods. The gridded daily maximum air temperature was mapped from MODIS land surface temperature and other and other auxiliary data using machine learning technology. The average daily maximum air temperature and the number of high temperature days were derived from the remotely sensed air temperature to calculate the hazard index of heat weave. Six indicators that derived from the population census and statistical yearbook were used to calculate the vulnerability index. Then the high-resolution heat risk of Beijing was mapped by combining the exposure index, hazard index and vulnerability index. According to the developed heat risk map, the spatial pattern of the heat risk in Beijing was analyzed. The heat risk map can effectively reflect the spatial difference of heat risk in Beijing. The western and northern mountainous areas of Beijing showed low risk, whereas the south-east region experienced obviously high risk. The main district of Beijing showed the most obvious heat risk and the high risk spread outward in a radial pattern. The urban areas of Huairou, Miyun and Pinggu districts also reflected high level of risk, but the high risk areas were much smaller than that in the main urban area. The extreme heat risk was mostly located between the second and fourth rings, and the relatively low risk levels were mostly located in the second ring, especially in the Dongcheng District. Among 16 districts, Fengtai, Xicheng, Chaoyang and Haidian districts had obviously high proportions of higher risks than other districts, which can mainly be attributed to the urban heat island effect and high population density of these regions. At the township scale, Chaowai, Xiangheyuan, Xiluoyuan, Dongtiejiangying, Balizhuang in Chaoyang District, Zuojiazhuang and Fangzhuang experienced the highest heat risk. This study proposes a comprehensive study of heat risk assessment based on remote sensing, which provides valuable data for heat wave adaptation in Beijing, and also serves as a reference for heat risk assessment in other regions.
The Inverse Distance Weighted (IDW) is one of the commonly used interpolation methods to generate the Digital Elevation Model (DEM). The appropriate order of distance of IDW should be used to interpolate in different terrains. In order to study the influence of different terrain conditions on the value of Optimal Order of Distance (OOD) in IDW, five types of terrain, including flatlands, hilly low rolling uplands, middle rolling uplands and high rolling uplands, are selected in this paper. In each terrain area, 30 random samples were taken, and each sample contained 2 000 points, and two groups of experiments were designed to study the influence of terrain on the OOD from two aspects of landforms macro and micro morphology. For the macro morphology of the terrain, the wolf pack algorithm (WPA) was used to calculate the OOD of IDW interpolation in different terrain areas. The difference of the OOD was analyzed among different terrain areas. For the micro morphology of the terrain, three terrain factors of slope, aspect and curvature were selected, and the OOD of different sampling points under different terrains was calculated by using WPA, and statistics were made to analyze the influence of different terrain conditions on the OOD of sampling points. The results show that the accuracy of DEM constructed by OOD is higher than that of the order of distance using the value 2, and the value of OOD varies greatly in different terrain areas. From the macro aspect of topography, the OOD is decreasing with the increase of relief and slope from flatland areas to high rolling uplands. From the micro aspect of topography, the proportion of the high-value OOD of sampling points decreases with the increase of slope. The change of aspect makes little influence to the OOD. With the increase of curvature, the proportion of the high-value OOD increases, and the low-value OOD decreases. On the whole, when the influence of terrain factors on the degree of elevation variation increases, that is, when the characteristics of elevation variation change obviously, the smaller OOD gets higher interpolation accuracy. According to different terrain, the different OOD should be chosen. In relatively flat areas, such as flatlands areas and hilly areas, it is recommended to use the OOD in the range of 3≤a≤4 for IDW interpolation. It is recommended to use the OOD in the range of 1≤a≤2 for IDW interpolation in mountain areas such as low rolling uplands, middle rolling uplands, and high rolling uplands areas.
It is of great significance to explore the formation of water resources and the water balance in Tianchi area for the protection of water resources and ecological environment. Based on the topographic and geomorphologic conditions, the special geological lithology and ring-radial fault structure characteristics of Tianchi area, the water circulation conditions and hydrodynamic characteristics of Tianchi Lake were analyzed. The "hydraulic peak elimination" effect of the ring fault structure and the water conduction effect of the radial fault are clarified, and the possibility of groundwater divide expansion in Tianchi recharge area is demonstrated. Based on the analysis of water circulation and hydrodynamic conditions in Tianchi area, and meteorological and hydrological monitoring data of Tianchi area from 2003 to 2020, the water balance of Tianchi Lake was calculated and analyzed based on the water balance method. The results show that the precipitation conditions in Tianchi area can maintain the water level balance of Tianchi Lake. The water balance of annual excretion of 3.6×107m3 of Tianchi Lake can be maintained when the precipitation is within 850-2 200 m from the outside of the surface watershed around Tianchi Lake. The average surface elevation of the water balance area is 125 m higher than that of Tianchi water surface (2 189.7 m). many ring faults and radial faults in Tianchi area. All the above faults are tensile faults. The ring faults all inclined to Tianchi which provided favorable conditions for groundwater recharge to Tianchi Lake. The formation above 1700 m in Tianchi area is mainly composed of pumice rock and pyroclastic rock, mostly of porosity structure and strong permeability. The special geological structure conditions and stratigraphic lithology in Tianchi area make the surface divide around Tianchi not coincide with the underground watershed in the groundwater recharge area. The dominant seepage conditions of the fault structure around Tianchi constitute the "peak elimination" effect of groundwater potential energy. The ring-radial fault structure and the good permeability of the stratum lithology in Tianchi area make it possible to expand the groundwater watershed. Combined the synthetic analysis result of the of water circulation and hydrodynamic conditions in Tianchi area, and meteorological and hydrological monitoring data of Tianchi area from 2003 to 2020, the water balance of Tianchi Lake was calculated and analyzed based on the water balance method. The results show that the precipitation conditions in Tianchi area can maintain the water balance of annual excretion of 3.6×107 m3 of Tianchi Lake. The distance of the water balance zone boundary is within 850-2 200 m from the outside of the surface watershed around Tianchi Lake. The average surface elevation of the water balance area is 125 m higher than that of Tianchi Lake water surface (2 189.7 m). The factors that may affect the calculation result of water balance, such as precipitation, runoff of Tianchi Lake water, calculation parameter value, condensation water amount and evaporation amount, are analyzed and discussed.
The elevational distribution pattern of biodiversity is an essential topic in biogeographic research. As typical representatives of soil mesofauna, Oribatida and Collembola are key biological drivers that regulate soil ecological processes and functions. However, the changes in the vertical zone pattern of soil mesofauna in the Changbai Mountains under climate warming are still poorly understood. This research investigates the biodiversity aggregation patterns of soil oribatid mites and collembola at 9 altitudinal gradients (600 m, 800 m, 1000 m, 1200 m, 1400 m, 1600 m, 1800 m, 2000 m, and 2200 m) on the northern slopes of the Changbai Mountain. In July 2021, a total of 10 688 soil oribatid mites, belonging to 45 genera and 55 species in 36 families, and 6 155 Collembola, belonging to 54 species and 32 genera in 12 families, were collected. NMDS and PERMANOVA showed that the community structure of soil oribatid mites and Collembola differed significantly across the 9 altitudinal gradients and exhibited significant separation between the 4 typical vegetation zones (coniferous and broadleaved forests, mixed coniferous forests, birch forests, and alpine tundra) in the Changbai Mountains. The species richness of oribatid mites exhibited a decreasing distribution pattern with increasing altitude, and the Shannon diversity index showed a U-shaped distribution, while the species richness and the Shannon diversity index of Collembola suggested a hump-shaped with increasing altitude, reaching a maximum at 1200 m above sea level. The results of the RDA and VPA analyses indicated that total soil nitrogen, available phosphorus, mean annual temperature and mean annual precipitation were important drivers that jointly influence the soil mesofauna. Understanding the distribution patterns of soil fauna under changes in elevational gradients can provide a basis for biodiversity conservation and ecological stability studies in forest ecosystems.
Xixia (1038―1227 A D) was a non negligible local regime in Northwest China in the historical period of China. Its national strength was relatively weak, but its survival stage coexisted with several imperial regimes such as the Northern Song Dynasty, the Southern Song Dynasty, the Jin Dynasty and Mongolia for a long time, and through frequent wars, it settled in the northwest corner for centuries. Many scholars have made a variety of discussions on its survival. This paper selects the coexistence period of the two regimes from the actual formation of the independent regime in Xixia (982 A D) to the southern migration of the Song Dynasty (1127 A D) as the research period, analyzes the reasons for its founding from the perspective of human ecology, and discusses the reasons for the frequent wars between the early Xixia and the Northern Song Dynasty in combination with high-resolution climate data. Records of wars between Xixia and the Northern Song Dynasty were cited from credible historical documents. Each war record in the literature is regarded as an independent war, each independent war is assigned 1, the war frequency is defined as the sum of the number of independent wars in a year, and the war frequency curve is obtained. High-resolution paleoenvironmental records of lake and stalagmite or historic records from this area or surrounding regions were selected to give a solid climatic background of this time and space. Then, carefully contrast of the two series of evidence to check if there is some relevance between wars and climate. The research shows that due to its own geographic conditions, Xixia's life needs cannot all be self-sufficient, nor can it be obtained through normal trade, considering its poor relations with the Northern Song Dynasty during most of the time they co-existed. Under such ecological pressure, Xixia chose to enrich and expand its strength in the continuous war in order to survive, so as to support the war with war and finally establish the country. The relatively warm climate conditions provided the necessary material guarantee for the war of Xixia. As for the three largest battles between Xia and the Northern Song Dynasty, it can be attributed to the material shortage caused by the deterioration of climate and environment and the social pressure brought by it. Other wars do not stem from the deterioration of environmental conditions, which may be due to the internal political and social factors of Xixia.
