Social-Ecological System (SES) is a collection of social subsystems, ecological subsystems, and the interactions between them. It is a common difficulty of cross-multidisciplinary fields to predict the changes in human-earth systems and support the relevant management decisions through clarifying the interaction between the ecological environment and human society. The framework of ecosystem service provides a new perspective for revealing the transmission and the role of various elements in SES. Taking ecosystem service as an entry point, this study follows the context of "Ecological System Supply-Ecological Coupling Human Intervention-Promoting Social Development". And the research progress and trends of existing coupling simulation methods related to SES are summarized. This article argues that in the conduction research of the ecosystem services cascade, the academic cognition has emphasized the "impact of natural ecosystem to social-economic system" rather than the "interaction and feedback mechanisms for ecosystems and social systems". In terms of research content, scholars have trsnsformed their focus from "changes in ecosystems and environmental effects" to "social-economic system and the effect on different groups". The focus of research has shifted from the theoretical inquiry of the "internal mechanism and power mechanism" to the applied practice of "optimization and regulation strategy" among the coupling systems. Future research of SES should strengthen the simulation of social-ecological coupling with equal emphasis on nature and humanities. It is the focus of breakthroughs to comprehensively understand the internal interactions and feedback of complex systems.

Cultural memory is a spiritual, inner, and middle world composed of self-consciousness, memory, and behavior that expresses the cultural phenomenon, local emotions, and identity generated by human practice in the present world space. Geography pays more attention to the human-land relationship and spatial perception in the formation of cultural memory and constructs a unique cultural memory space. This space is the agglomeration of figurative cultural relics in space, as well as the spiritual representation of non-figurative places, such as art, text, and folklore in space. By systematically analyzing the theory of cultural memory, this study summarizes the process of evolution and development context of cultural memory. Based on 1,527 key domestic and international studies on geography, this study analyzes the main content and progress of global cultural memory space research from the perspective of keyword co-occurrence clustering, theme path evolution, and research trend, with the assistance of CiteSpace—the bibliometrics and visualization tool. By reviewing the frontier hot spots of cultural memory space research at home and abroad, this study aims to construct a research paradigm of cultural memory from the perspective of geography, improve the research methods of cultural memory, and provide a reference for the local application and multidisciplinary integration of cultural memory theory. The analysis results focus the research topics of foreign cultural memory space primarily on: 1) the memory representation of the landscape of daily life; and 2) political and ritual studies in memory. Domestic research topics primarily include: 1) cultural and local studies in collective and social memory; 2) research on urban and rural memory carried by space; and 3) research on heritage memory reproduction, promoted by cultural tourism. The literature on cultural memory space at home and abroad has gradually increased in recent years, as has the attention paid to memorial landscape, heritage buildings, ritual celebrations, war trauma, and national memory; however, the research on cultural memory space has not formed a specific theoretical paradigm. Most of the literature only focuses on the integration of cultural memory and other fields, and relatively few studies address the connotation of cultural memory space, media conversion mechanisms, and spatial identification methods. The perspective of the content and trends in domestic and foreign research indicates that Western scholars pay more attention to the study of migration, rights, free will, women, power politics, and war trauma. The focus on space is mainly on cities, emotions, and rights. Domestic geographers focus on deconstructing regionalized and China-seized cultural memory and local identity from the intangible carrier of memory. Most studies are based on obvious policy orientations. War sites, red tourist sites, traditional villages, characteristic folk customs, and festival ceremonies have become important themes in the study of cultural memory space. In the future, geography research should depict the practical process of text, ritual, and language through non-representational means and re-introduce memory into human research in a materialized way. Simultaneously, the connotation of urban and rural cultural memory should be clearly defined, and heritage, immigration, and tourism should be adopted as the new themes of cultural memory space research through digital images.

As a crime that threatens public safety and social stability, child trafficking has attracted widespread attention from all sectors of society. Few studies have been conducted on child trafficking, especially in the literature review conducted from the perspective of comparison between China and abroad, which makes it difficult to fully reveal the system and development of current research. This study clarifies the thematic structure and development of child trafficking in China and abroad, based on the "Web of ScienceTM Core Collection" and CNKI data sources, using CiteSpace software. Specifically, the study comparatively examines the progress of child trafficking studies in China and abroad since 2000 and analyzes future development trends from the time of publication, regional and subject distribution, research institutions, and keyword co-occurrence. We hope that this work provides a relatively complete and objective understanding for innovative future research. The results indicate that: (1) the research on child trafficking started earlier abroad, and the theoretical system and research methods are relatively mature. From 2000 to 2020, a total of 215 articles were published in Web of Science, showing two stages of fluctuating and rapid growth, and USA ranks first worldwide. There are 46 core articles published in CNKI, showing two stages of initial exploration and fluctuating growth overall, with a relatively slow growth rate in China. More studies are distributed in the fields of social studies, psychology, pediatrics, family studies and criminology in abroad, while domestic studies are mainly distributed in the field of law, criminology and sociology. In recent years, the research in the field of geography has risen rapidly, and there is ample room for development. (2) Due to the differences in regional environment and national conditions, international child trafficking is part of a study on human trafficking, which is mainly for the purpose of exploitation, including direct and indirect exploitation, involving various topics such as commercial sexual exploitation, labor exploitation, trafficking human organs, child marriage trafficking, and other types of trafficking. Commercial trafficking and sexual exploitation are the main research hotspots of child trafficking. Child trafficking in China is usually discussed in combination with the trafficking of women, focusing on the provincial trafficking for the purpose of adoption, and "family control" and "lured adoption" are common ways of committing crimes. The legal policy and social reasons surrounding child trafficking are hot topics of concern. (3) With the increase in interdisciplinary integration, child trafficking involves suicide risk and well-being, rehabilitation and return to society, child protection and trafficking prevention and control measures, which have become popular topics abroad. The theme of domestic child trafficking has extended from focusing on legal policies and social reasons to spatial-temporal patterns, influencing factors, resettlement, and social integration. In the future, how to integrate the relevant parties involved in child trafficking (criminals, victims or guardians, and other people) with the spatio-temporal environment (social environment, built environment, and surrounding people flow environment), and explore the evolution of geographical factors and the spatio-temporal activity trajectory of child trafficking from the perspective of criminal geography? It is important to deeply analyze the occurrence mechanism of child trafficking from the interactive perspective of time, space, and humans. How to make full use of the modern technological means to track and combat child trafficking in practice, to contribute to the prevention and management of this issue at home and abroad, constitutes a key question.

The Belt and Road Initiative aims to achieve common development and prosperity for all countries. Building a scientific and reasonable geopolitical risk assessment system is an important prerequisite for participating countries to prevent and resolve geopolitical risk. Taking 64 countries in the six economic corridors of the Belt and Road Initiative as the assessment object, this study builds a geopolitical risk assessment system based on post-transaction costs. It analyzes the geopolitical risk level, spatial and temporal distribution characteristics, and influencing factors using the full array polygon graphical indicator method, Global Moran's I, and the spatial Durbin model. The research results show that: 1) From the time dimension, the geopolitical risks of participating countries show a trend of first rising and then falling, reaching a peak in 2015. 2) From the perspective of spatial distribution, high-risk areas are mainly concentrated in the Middle East and South Asia, while medium to high risk areas are concentrated in Indochina and the Arabian Peninsula. Most of the low to medium risk countries are Western Pacific island countries, while low-risk countries are mainly in Central Europe. The clustering characteristics of geopolitical risks are obvious. The results of Global Moran's I show that from 2011-2020, the geopolitical risk concentration area was initially located in the Middle East and South Asia, and then in 2015, Europe and East Asia also experienced high geopolitical risks. By 2020, it was still mainly concentrated in the Middle East and Eastern Europe, however, generally, the regions with high geopolitical risk will still be mainly concentrated in the Middle East and Eastern Europe. 3) The research results on the factors influencing geopolitical risks indicate that political stability, economic freedom, economic growth, increased education expenditure, and better natural resources have a significant inhibitory effect on geopolitical risk, while increases in the unemployment rate, population size, and oil resources, will to some extent, promote the generation of geopolitical risks. The indirect effect results show that political stability, economic freedom, and the unemployment rate of the host country have a significant impact on surrounding countries. Based on this, we believe that countries participating in the Belt and Road Initiative need to improve their government governance capabilities, accelerate their modernization transformation, effectively utilize the resources, funds, and technologies brought about by the Belt and Road Initiative. Furthermore, actively integrate into the regional economic cooperation framework of the Belt and Road Initiative and improve their ability to manage geopolitical risks. This study enriched the evaluation system of geopolitical risks. During the construction of the evaluation indicators, the results emphasized the sudden and violent characteristics of geopolitical risks, further explained the violent confrontation and economic game existing in geopolitical risks, and effectively enriched the literature on the spatial characteristics and influencing factors of geopolitical risks of countries participating in the Belt and Road Initiative. It should be pointed out that there are still some limitations in this study. This study is based on countries participating in the Belt and Road Initiative and there are deficiencies in the discussion of geopolitical risk for countries not in the region. Future research can be based on a global perspective, further enriching the evaluation index system of geopolitical risk, and conducting more in-depth research on the spatial transmission path and geopolitical risk avoidance measures.

Global climate change caused by human activities results in frequent extreme climate events, and shifts the physiological processes of plants, and the carbon, water cycle and energy balance of terrestrial ecosystems. Vegetation phenology is the most sensitive biological indicator to climate change. In recent years, the responses of vegetation phenology to climate change mainly focus on the mean state of the climate, while the response mechanisms of vegetation phenology to extreme climate are still unclear. In this paper, the response of vegetation spring and autumn phenology to various extreme climatic events and their mechanisms were reviewed. We found that extreme low temperature and extreme precipitation directly delayed the vegetation green-up date and advanced the leaf senescence, while extreme high temperature and extreme drought led to stomatal closure, inhibited photosynthesis and transpiration, and thus advanced leaf senescence at middle and high latitudes of the Northern Hemisphere. Currently, the studies on the response of vegetation phenology to extreme climate events pay less attention to compound extreme climate events, and there are only few studies on the lag effect of vegetation phenology response to extreme climate events and the recovery process of vegetation after the occurrence of extreme events. Under future climate change scenarios, it is necessary to modify the vegetation phenological models by considering the impact of extreme climate events and couple it into the dynamic global vegetation models to improve the simulation accuracy of the carbon cycle in terrestrial ecosystems.

Urban-rural integrated development is an advanced stage in the evolution of the urban-rural relationship, and it is also the basic path and main goal for the implementation of rural revitalization. Scientifically understanding and identifying the integration stage and its current level of urban-rural development in China is the prerequisite basis for promoting urban-rural integrated development and rural revitalization. Based on the concept connotation, this paper constructed a multi-dimensional evaluation system of urban-rural integrated development at the prefecture level. The process status and spatiotemporal divergent characteristics of urban-rural integrated development in 336 prefecture-level regions in China from 2000-2018 were portrayed and revealed. The results show that: (1) The current state of urban-rural integrated development in China is generally at a low-to-middle level, showing a heterogeneous spatiotemporal pattern with apparent gradient divergence. The integrated development level of the Pearl River Delta, Jiangsu and Zhejiang provinces, and the Shandong Peninsula is high, but the regions distributed to the west of the "Hu Line" develops slowly. (2) According to the level and characteristics of integrated development, the 366 prefecture-level regions can be divided into four types: integrated development, tending integration, imbalanced development, and lagging development, with a more active transformation between the latter three types. (3) The development level of urban-rural economic integration is higher than that of demographic and social integration, while the development process of urban-rural spatial and ecological integration shows some natural zonal divergent characteristics. Finally, we identified the problem areas for different types of integrated development and explored the regional promotion path of urban-rural integrated development, which could provide scientific references for the strategies of regional urban-rural development and rural revitalization.

The prediction of rainstorms and floods in small and medium-sized watersheds, as well as the synthesis of related parameters, plays a pivotal role in preventing flood disasters. Environmental changes have led to an increase in hydrological extremes such as rainstorms and floods, presenting unprecedented challenges for small and medium-sized river basins. In this review, we systematically categorize, and summarize the processes involved in predicting rainstorms and floods in these watersheds, along with advancements in correlated parameter synthesis research. Furthermore, we analyze and discuss the most commonly employed runoff and confluence estimation methods and their associated parameters in practical applications, as well as their limitations. First, we establish the concept of small- and medium-sized watersheds across various academic disciplines. From a hydrological perspective, these watersheds typically exhibit slope confluence and have relatively small catchment areas. In terms of eco-hydrology, the ecological water demand of the basin must be calculated based on the different communities occupying the river basin and divided by area according to the ecological samples from each district after the investigation. Thereafter, we summarized the methods and types of runoff calculation and parameter synthesis in small- and medium-sized basins, and the methods and principles of runoff analysis, such as rainfall–runoff correlation diagram, infiltration curve method, deduction method, runoff coefficient method, and hydrological model method as well as the methods of parameter synthesis, such as rainfall-runoff correlation diagrams and loss methods are introduced. Second, we summarize and discuss the assessment of confluence and its associated parameters in small- and medium-sized river basins. This encompasses background information and various calculation methods, such as the instantaneous unit line, comprehensive unit line, inference formula method, and empirical formula method. We also examine how the three major elements of parameter synthesis convergence influence confluence parameters. We emphasize that combining radar rainfall measurements, high-resolution remote sensing, high-performance computing, and deep learning can facilitate research on simulating and forecasting rainstorms and flood processes in small- and medium-sized basins. However, a significant portion of these basins lacks data, limiting the application of simulation and flood forecasting. To address this, integration with geographical parameters specific to small- and medium-sized basins is necessary to enhance regional reliability and forecasting accuracy. Additionally, when applying deep learning to simulate basins with limited or no data, the significance of parameter synthesis becomes even more pronounced. Finally, we discuss the problems and challenges associated with storm flood calculations and parameter synthesis methods in small- and medium-sized basins and offer predictions regarding future research and technical developments. We recommend strengthening the use of emerging technologies for watershed runoff and runoff parameter calculations and advocate for their application in storm flood design.

The rise of global neoliberalism and reflexive governance has driven the political flows at the global level. Policy movements thus have shown new dynamics and characteristics. Political science, within the sphere of rational formalism, whose dependence on traditional frameworks, as well as the neglect of geographic mobility in sociology, have limited the explanatory power of existing concepts. The geographical orientation and spatial correlation of policy mobility offer the possibility of a theoretical breakthrough by introducing human geography in the policy research. Based on the literature in geography, this study traces the process of resembling rolling conversation through transdisciplinary research on policy mobility, and further clarifies the conceptual connotations, commitments, and research starting points of policy mobility. As an effective conceptual tool for understanding how policymaking operates, how policy knowledge and models flow, and how these mobilities shape places in the context of neoliberal globalization, policy mobility seeks to clarify the geographic positions, power relations, spatial characteristics, and social and geographical formation processes that are involved in the movements of policies. Policy mobility thus becomes a core field in the social sciences exploring "ideas in motion" and "production of mobilities". In addition, the theoretical orientation and research elements in the study of policy mobility also enhance the explanatory powers of literature from other disciplines to this subject. To a certain extent, this study compensates for the lack of empirical analyses of ideas and knowledge in mobility studies and insufficient research on power theory in human geography. It provides an important research field for applying geography in transdisciplinary research.

Carrying capacity, a concept entrenched in the natural resources and environmental field for nearly two centuries, has continually evolved to address the conflicts and sustainability of the human-nature relationship. This paper introduces an analytical framework for understanding carrying capacity within the context of the human-nature relationship. It systematically reviews the progression of international carrying capacity studies, analyzes global research trends, and compares these with Chinese studies, highlighting key research directions in China. Historically, carrying capacity traces its roots to (neo)Malthusian theories. Its evolution spans four distinct stages: resource carrying capacity (since the 1800s), environmental carrying capacity (since the 1970s), ecosystem carrying capacity (since the 1990s), and natural system carrying capacity (since the 2010s). The concept of carrying capacity varies widely across global disciplines and even within the same discipline, showcasing diverse applications. Carrying capacity has sparked controversy due to its connection to political economy theories and factors such as technological progress, market mechanisms, and spatial and temporal constraints. Therefore, it is imperative to engage in a restrained and explicit discussion and application of carrying capacity. Presently, China's carrying capacity studies align closely with the international community, capitalizing on regional-scale studies employing a holistic and systematic human-nature relationship approach. However, there is an opportunity for enhancement in terms of global-scale perspectives and the integration of natural and social sciences theories and methodologies. This paper proposes fostering innovation and application in carrying capacity research within the Chinese context. This entails integrating various disciplines and theories, exploring scale effects and mechanisms, utilizing model-data fusion and integration, applying case studies in various spatial units and typical zone types, and improving policy systems and institutions.

Deconstructing rural spatial characteristics is the precondition for building rural spatial governance system in the new era, and multi-scale rural spatial characteristics and its governance path would effectively support the modernization of the national governance system. Based on the comprehensive, regional and mobile thinking paradigm of geography, this paper deconstructs the multi-scale rural spatial characteristics, identifies its internal operating logics, summarizes its governance dilemmas, constructs a multi-scale rural spatial governance framework that is based on geographical analysis paradigm, explores feasible governance paths, and constructs a multi-scale rural spatial governance system research plan, namely, "characteristics identification-dilemma analysis-governance framework-governance path". The paper finds that: (1) to analyze the operating logics of the multi-scale rural space through the comprehensive, regional and mobile analytical thinking of geography, it is necessary to understand the mechanism of action of scale synthesis, scale differentiation and scale flow to the multi-scale rural spatial characteristics, highlighting the comprehensive characteristics of rural space, strengthening rural spatial heterogeneity, and integrating rural spatial mobility. (2) The lacking urban-rural spatial overall planning, unsmooth spatial mobile network and not-reflected different types of rural spatial value are the key dilemmas in the rural spatial governance, which need to be addressed. (3) The multi-scale rural spatial governance framework of "comprehensive spatial governance-spatial zoning governance-spatial mobile governance" could effectively solve the problems of urban-rural spatial integration, regional spatial coordination and spatial network blockage. (4) Integrating urban-rural comprehensive governance, innovating regulation control to improve regional governance and balancing the configuration of spatial development right to achieve mobile spatial governance are feasible paths for multi-scale rural space governance. In conclusion, clarifying the multi-scale rural spatial characteristics in the new era and constructing a scientific governance system could provide theoretical support to promote integrated urban-rural development and rural vitalization strategy.

The crime of human trafficking is an abnormal (involuntary, passive) phenomenon of population migration (disappearance, persecution); it has attracted great attention from the public and academic community because of its resultant social harm and far-reaching impacts on individuals and families. Constrained by the concealment, dispersion, variability, and complexity of the crime of human trafficking in China, the perspectives of earlier research topics were relatively clustered and limited. During the last 10 years, geographers have gradually achieved certain new understandings and progress through continuous exploration. From the perspective of the related sub-disciplines of geography, this study focuses on the main progress, existing issues, future trends, and crime governance paths to review studies on the crime of human trafficking in China. The results indicate the following: (1) Regarding the interdisciplinary situation: The crime of human trafficking is a social pain point of common concern among multiple disciplines. Geography has the advantage of being a latecomer and its integration with other disciplines will help understand the problem in depth and solve it systematically. Geographers will have a broad stage for future research in the field of human trafficking crimes. (2) Regarding the research objects: The earlier studies on the crime of child trafficking in China in the international context were actually subject studies of human trafficking in the Chinese criminal law context. The crime of human trafficking in China is unique compared to other countries and other types of crimes. (3) Regarding the research data: In the past, the data sources mainly comprised non-governmental organizations and individuals. The current data sources show the co-occurrence of non-governmental and official sources and the trend of the integration of offline and online availability. The integration and utilization of multi-source data will be the main path to future studies. (4) Regarding field investigation: In the context of the COVID-19 pandemic's impact and the upgrading of related family tracing means, field investigation has opened up new ways, and online investigations (online interviews, participatory observation in live broadcasting rooms, etc.) have become complementary or alternative channels of traditional field investigations and surveys. (5) Regarding patterns and trends: Based on the update and verification of available data, it is found that the stability of the spatiotemporal pattern of trafficking crimes and the dependence on the main routes in China, and cross-border and inter-provincial border areas, are worthy of attention. Future research trend will shift from being independent to comprehensive—from a quantitative study to a qualitative or mixed study; from case numbers to individuals, families, and their social networks; from the source area to the bridging of source, flow, and sink areas; and from a type of human trafficking to multi-type comparisons of missing persons. (6) Regarding measures and suggestions: Combined with the existing research knowledge and current crime trends, this study presents overall strategies and specific paths for dealing with the crime of human trafficking and assisting the abducted and their relatives.

Most of Asian major international rivers originate from China. Their abundant transboundary water resources play an important role in regional "water-energy-food-ecology" security. In recent decades, influenced by global change, especially by the construction of large hydraulic and hydroelectric engineering, the changes in hydrological and ecological processes and their transboundary impacts in the international river regions have attracted more and more attention. The research on these issues in China has achieved prominent results in several aspects, including the changes in hydrological and ecological processes and their attributions, the transboundary impacts and risk regulation, the "water-energy-food-ecology" nexus in transboundary watersheds, and the construction of transboundary water resources coordination mechanism to adapt to global changes. In the face of the increasing risks of transboundary water security and ecological security under global change, the hydro-geographical research on international rivers needs to make use of space-air-ground integrated monitoring technology, modern spatial geographic information technology, intelligent technology, and so on. By providing quantifiable, participatory, and public results, these researches can better provide scientific basis and decision support for the rational utilization of international rivers and geopolitical cooperation, health maintenance and risk control, transboundary water diplomacy and environmental diplomacy.

The transition from fossil energy to renewable energy will change the structure of global energy geopolitical power structure, national relations, and the driving factors of geopolitical game, which will have a far-reaching impact on the geopolitical shaped by fossil energy. On the basis of combing the origin of energy and geopolitics, this paper expounds the internal logic of the energy transition to reconfigure geopolitics and provides an outlook on the geopolitics of the energy transition. The conclusions are as follows: (1) The connotation and attributes of energy, as well as the differences between energy and geopolitics, determine that energy geopolitics presents significant intergenerational transformation characteristics. (2) The competition for key minerals, the game of low-carbon technology, the reconstruction of geopolitical pattern and the global energy governance are the four dimensions of the geopolitics of energy transformation reconstruction, of which the competition for key minerals is the basis of the geopolitical game of energy transformation, the game of low-carbon technology is the new focus of the geopolitics of energy transformation, and the reconstruction of geopolitical pattern is the direct characterization of the geopolitics of energy transition, energy governance is the path to ease the geopolitical game of energy transformation. (3) In the process of energy transformation and reconstruction of geopolitics, the competition for key minerals, the game of low-carbon technology, the reconstruction of geopolitical pattern and global energy governance are interrelated and interacted, which aggravates the complexity and uncertainty of energy geopolitics in the era of renewable energy. (4) Looking forward to the future, to better promote the development of energy geography and serve the major strategic needs of national energy security, the geopolitical research of energy transformation urgently needs to strengthen the theoretical innovation of energy transition reshaping geopolitics, promote the quantitative research of the geopolitical impact of energy transformation, construct the path of China's deep participation in global energy governance, and pay attention to the energy security issues caused by energy transformation under the background of "carbon neutrality".

As an important land and water transition zone on Earth, wetlands are good places for birds to breed and roost. Bird monitoring has become an important index for assessing the biodiversity and ecological environment of a region. Nansha Wetland Park in Guangzhou is rich in biological resources and provides an important resting and wintering ground for global migratory birds as it is located on their migration route from East Asia to Australasia. To understand the migration patterns and annual dynamic changes of birds in the Nansha Wetland Park, line- and point-transect surveys were conducted to collect bird species and abundance data from January 2014 to December 2018. First, our results showed that 139 birds were recorded during the study period, of which migrant species were dominant. Combined with the available literature, a total of 186 bird species were recorded, belonging to 17 orders and 49 families. Of these bird species, 165 are under various levels of protection. Second, while the interannual changes in bird abundance were substantial, those of bird species richness were not, indicating that bird species tended to reach maximum abundance in bird communities. When compared to bird abundance in 2015, the number of individuals was relatively stable in other years of investigation, and the number of investigated species was the highest in 2017. Finally, monthly changes in bird species were in accordance with the annual rhythms of migration. Specifically, bird species richness increased rapidly during the wintering period, but remained constant during the breeding period. In addition, the migration time of waterbirds tended to increase over time. This may be related to a warming climate that prompts birds to migrate earlier. Differences in habitat patches are important influencers of bird feeding habits, and thus bird distribution and habitat. Among the habitat patches investigated, birds were primarily distributed in shallow tidal flats with rich food sources and in tall and lush mangrove communities, such as those containing the species Sonneratia apetala. Notably, the number of Platalea minor, a key indicator bird species, has increased steadily, with an increase of 346.15% from 26 in 2014 to 116 in 2018. The annual and monthly dynamic changes of birds in different areas showed subtle changes in individual numbers but generally showed a stable trend, which may be related to the environmental capacity of the habitat. The number of species and individuals that can be sustained by the environment tended to be saturated; that is, the maximum number of species that can be accommodated by the Nansha Wetland Park. Taken together, these findings suggest that bird species diversity could be promoted by expanding the area of tidal flats, increasing the planting area of mangroves, reasonably reclaiming wetlands, and maintaining the proportion of shallow water tidal flats and mangroves.

The Arctic is undergoing unprecedented climatic and terrestrial environmental changes. The Arctic primary industry has experienced a wide and significant effect from these shifting environmental factors, such as rising temperatures, greening vegetation, thawing permafrost, and frequent wildfires. It is essential to integrate the knowledge of impacts caused by climatic and terrestrial environmental changes on Arctic primary production in order to support the sustainable development of primary industry and inform the formulation of industrial policies. The four main sectors of primary industry (cultivation, livestock husbandry, forestry, fishery and aquaculture) were discussed in this work. This study synthesized the types and extent of the impacts caused by climatic and terrestrial environmental changes on each sector, and provided a summary and outlook from five aspects with a cross-sector perspective: (1) the specific ways of climate changes affecting primary production; (2) the challenges of integrating knowledge from local researches; (3) the enactment and implementation of adaptation strategies; (4) the demand for integration and innovation in data and methods; and (5) the inspiration of the climate change-induced alteration in Arctic primary industry for China. This study concluded the priorities of researching the impact of climate changes on Arctic primary industry, and the results would be capable to aid China's participation in the sustainable development of Arctic primary producing activities.

The digital economy, an essential engine for the high-quality development of China's economy, has the potential to become a breakthrough in promoting the rapid recovery of tourism. From a spatial perspective, this study used panel data from 284 prefecture-level and higher cities in China from 2011 to 2019 and constructed a spatial Durbin model (SDM) to empirically test the spatial effect and mechanism of the digital economy on tourism development. (1) Digital economy and tourism development showed significant positive global spatial autocorrelation during the study period. Hotspots of the digital economy have long been located in southeastern coastal areas, and cold spots in central and western China have shrunk significantly. Tourism development hotspots are mainly distributed in the Yangtze River Delta urban agglomerations and in Yunnan, Guangxi, Guizhou, and Chongqing. Cold spots were distributed in the central and western cities of the Shandong Peninsula and gradually expanded southward. (2) In China, the digital economy has a significant direct effect and positive spatial spillover effect, which was confirmed by a series of robustness tests were conducted. From the perspective of different regions, although the direct effect was significantly positive in all regions, the influence coefficient in the eastern region was significantly larger than that in the central, western, and northeastern regions. The spatial spillover effect is entirely significant in the eastern region, partly significant in the central and northeastern regions, and not significant in the western region, indicating that "digital segregation" exists in the western region. (3) The positive spatial spillover effect of the digital economy on tourism development is optimal at 300 km. Subsequently, the spatial spillover effect followed the law of geographical distance attenuation. The spatial spillover effect reaches the critical point of the practical effect at 800 km and almost disappears at 1500 km. (4) Among the digital economy components, digital infrastructure, digital industry development, and digital inclusive finance can significantly promote local tourism development. However, only digitally inclusive finance has a significant positive spatial spillover effect, and the effects of the remaining components are insignificant. This study constructs an analytical framework for the spatial effects of the digital economy on tourism development and conducts rigorous empirical research to compensate for the limitations of current research from a local perspective. This study also examined the spatial effects of various components of the digital economy, which helped identify the source of the impact of the digital economy on tourism development more accurately. In addition, the regional heterogeneity and distance attenuation law of the spatial effect of the digital economy on tourism development were analyzed, and customized policy implications were proposed based on the research conclusions. Overall, this study has essential reference value for achieving high-quality tourism development and expanding the scope of digital economy application.

The social integration of urban floating population is the key task of the new-type urbanization in China. In view of the deficiencies of existing studies on the spatial characteristics of social integration and the role of destination city (place of inflow) factors, based on the China Migrants Dynamic Survey in 2017, this paper employs spatial analysis and hierarchical linear model to reveal the spatial pattern and influencing mechanism of social integration of migrants in cities above prefecture level in China. The results show that: (1) the overall social integration index of China's urban migrants is 0.43, which has the dimensional characteristics of behavioral integration (0.71) > psychological integration (0.61) > economic integration (0.33). (2) The social integration of migrants has spatial autocorrelation and agglomeration. The high-level social integration areas are mainly distributed in Northeast China, Shandong Peninsula, and Sichuan and Chongqing, and the low-level social integration areas are mainly found in the southeast coastal areas, Guanzhong Plain and North China Plain. These regions have the basic characteristics that the social integration level of migrants in small cities with a population of less than 0.5 million is higher than that in large cities. (3) Both the destination city and migrant individual factors jointly affect and shape the level and spatial pattern of migrants' social integration. Moreover, it is found that the population size, house price level and public services in the destination city regulate the impact of individual factors by four regulatory mechanisms: positive polarization, negative polarization, positive homogenization and negative homogenization. This paper calls for the research on the social integration of migrants from the human-land interaction perspective highlighting the relation of destination-individual factors to reveal the effect of destination factors on individual factors. This approach can provide a place-based policy implication for promoting the construction of new-type urbanization in China.

Climbing dunes are important barrier dunes that are widely distributed in highland mountain regions, and their formation is mainly controlled by topography, sand sources and wind regime. Existing researches mainly focus on simulation experiments, distribution patterns, field observations, and morphological characteristics. From a regional scale, there is a lack of research to analyze the variations in sediment characteristics and environmental significance of climbing dunes in different climatic regions. In this study, the wind regime, near-surface airflow, sediment characteristics and material sources of climbing dunes on the Qinghai-Tibet Plateau were comprehensively analyzed from the aspects of aeolian geomorphology, grain-size sedimentology, and geochemistry. The results show that: (1) Due to differences in material sources, the grain-size composition of climbing dunes sediments in different climatic areas varies, primarily fine and medium sands, with good sorting in the semi-humid areas and poor sorting in arid areas. The grain-size difference of sediments in different geomorphic parts is small, and it responds well to near-surface airflow, and in-situ sand accumulation is the basic formation form, with fine sand having the strongest climbing ability. (2) The chemical element content of sediments is influenced by the parent rock characteristics and the climatic environment, and the particle size is also important to its spatial variation, and trace elements are primarily concentrated in river floodplains, with little variation between geomorphic sites. (3) Except for SiO₂ enrichment, all macronutrients in the sediment show varying degrees of leaching or enrichment, and the majority of trace elements are deficient, as leaching and enrichment are closely related to particle size. (4) Climbing dunes sediments are in the early stage of continental weathering, with higher weathering levels in the semi-humid zone. The weathering of sediments in different geomorphic sites varies substantially, which is related to the parent rock, climatic environment, and grain size.

The study of influencing mechanisms of intercity knowledge collaboration networks is an important research topic of innovative geography. Most existing research focuses on the influence of exogenous forces (e.g., urban resources endowment, multidimensional proximity), whereas less attention has been paid to endogenous factors (e.g., preferential attachment, transitivity). This research constructs an intercity knowledge collaboration network of Chinese cities based on the co-publication data from the Web of Science, analyzes its evolving characteristics of spatial and topological structures from 2006 to 2016, and quantitatively explores the endogenous and exogenous forces underlying the network formation through exponential random graph modelling. The results show that: (1) From the spatial structure perspective, the intercity knowledge flows are dense in the eastern region but spare in the western region, which is stable during 2006-2016. The overall network has developed from a dual-core structure of Beijing and Shanghai to a polycentric structure, in which five national-level urban agglomerations have become important bases for nurturing multiple centers. The nodal regions centered on highly administrative cities have become increasingly consistent with the planned urban agglomeration, which plays the dual role of proximal spillover and remote interaction of knowledge resources. (2) From the topological structure perspective, the scale and density of intercity knowledge flows have increased significantly, and the preferential attachment to big cities is obvious. However, with the rise of multiple centers, the network polarization and disassortativity have been weakened. With the optimization of intercity knowledge collaboration paths, the network cohesion has improved, thus becoming a small-world network. (3) From the influencing mechanism perspective, self-evolution and preferential attachment are important driving forces of knowledge collaboration networks, showing an overlapping effect with urban hierarchy. The positive impact of urban knowledge-related attributes on intercity flows is weaker than multidimensional proximity and path dependence. The presence of high-speed railways promotes knowledge collaboration, while the influence of geographic distance is not significant.