Plant trait biogeography is an emerging field in plant geography and it is about the geographical distribution of plant traits. At present, there are three hotspots in plant trait research, including performance of traits at multiple levels, trade-offs among traits and the relationship between trait diversity (functional diversity) and ecosystem functioning. Important traits include, for example, specific leaf area, leaf dry matter content, leaf nitrogen concentration, seed mass, plant height and stem density. Traits are measured with individual plants and can be scaled up to the community level (community weighted means and trait diversity). Trade-offs contain not only the leaf economics spectrum, but also relationships between traits and the environment. The development of global trait database largely enhances the progress of plant trait biogeography. Mapping plant traits mainly relies on the global database and spatial statistical modeling techniques, but a new method using combined laser scanning and imaging spectroscopy has been developed recently to map regional patterns of plant trait diversity. Spatial pattern analysis is an important part of plant trait biogeography. It helps to explain the distribution of plants, plant adaptability and patterns of community assembly, and then provides evidence to predict how global climate changes would influence plants. By examining plant traits instead of species, the physiological mechanisms behind plant adaptability and distribution can be better explained. Therefore, replacing species with plant traits in global vegetation models would bring new opportunities and challenges for global carbon cycle models and land surface models under global climate changes.

The formation and evolution of landform and landscape on Earth follow unique rules with specific forcing mechanisms. Earth surface processes have affected human environment, resource exploitation, and natural hazards and disasters. As an important branch of geography, geomorphology is an interdisciplinary field with important theoretical and practical values. With the application of remote sensing, geographical information system, digital elevation models, and sediment dating techniques, detection and tracing techniques of geophysics and geochemistry, and numerical simulation, the scope of geomorphology has been expanded and deepened over the past 10 years. Study on geomorphological process modulated by tectonic movement, climatic changes, gravity forcing, and human activities has greatly moved forward. New geomorphological processes and forcing mechanisms have been unraveled, and these recent achievements have significantly improved our understanding of Earth surface processes. In this new era of research, in addition to strengthening the study in traditional areas such as investigating different geomorphological processes at various temporal and spatial scales, bridging geomorphological research with global environment change and Future Earth programs is recommended. In particular, geomorphologists should pay much more attention to human activities, which is a vital agent that modulates Earth surface in the Anthropocene. Quantitatively reconstructing and modeling geomorphological processes are also an important area to explore. In China, to train geography students with more extensive and in-depth geological knowledge and practices, develop quantitative geomorphology and planetary geomorphology, and strengthen research on human impact on landform and topography will improve the quality of research, and promote geomorphology as a key discipline in Earth system science.

Soil as an important study object of physical geography, acts as the essential link between geographical elements such as water, atmosphere, organisms, and so on. Therefore, research on accurate and efficient acquisition of soil information has great significance in the development of modern geography. In this article, the operation principles of various sensors equipped on satellite, aviation, and unmanned aerial vehicle platforms and ground devices for soil information acquisition were introduced. Then the authors summed up the findings on the methods and techniques of rapid acquisition of soil information based on remote sensing and proximal soil sensing and their applications in soil mapping and soil attribute prediction. Applications of soil information acquisition in soil geography were also explained. Finally, this article discussed the prospect of development of remote and proximal soil sensing.

The spatial distribution of soil reflects its formation and development. Digital soil mapping is a new and efficient technique to represent the spatial distribution of soil, which has experienced a rapid development over the last three decades. The theoretical bases are the soil forming factor theory and the first law of geography. Researchers have done significant work on the generation of environmental covariates, soil sampling methods, mapping methods, and production and evaluation of soil maps. The application cases are from small areas to big regions, even at the global scale. Future directions for digital soil mapping include: new techniques for depicting environmental covariates, especially for expressing human activities; efficient use of new data and legacy data; the reconciling of pedometric knowledge and mathematic models; and new computation ways supporting the use of big data.

Soil geography is the sub-discipline of soil science and geography dealing with the spatiotemporal changes of soil, and is a part of the earth surface system science. The research topic of soil geography is gradually changing from soil body to critical zone from the perspective of the earth surface system, meanwhile the research methodology develops toward "digital". Based on an introduction of the theoretical and technical backgrounds, this article reviewed the recent progress of soil geography including on soil genesis, soil morphology, soil classification, soil survey, and digital soil mapping. Future development of soil geography needs to expand the theoretical research, innovate the investigation technology, and simulate the spatiotemporal variations of soil. Furthermore, the main opportunities, trends, and challenges in the future were discussed.

The impact of human activities on hydrological processes becomes remarkable in Anthropocene, and many problems go beyond the scope of traditional hydrology. As two important sub-disciplines in hydrology that focus on human interventions, socio-hydrology and urban hydrology have attracted increasingly more attention. With the strengthened interactions between human and water, hydrological and human systems are becoming tightly coupled, and socio-hydrology emerged to investigate the feedbacks between the two systems and their coevolution processes. Cities are places where human activities and the natural system interact most intensively, and the hydrological processes in urban regions are becoming more complicated, therefore urban hydrology has been developed. The two disciplines are of great importance for the medium- and long-term planning and management of water resources and related socioeconomic development, as well as for guiding urban planning and construction, enhancing urban water security, and improving urban water environment. This article reviewed the patterns of development and characteristics of research of the two disciplines. It also analyzed the research status and development trends, including the study of social factors, case study in representative basins, comparative study of different cases, and model simulation in socio-hydrology, as well as the impact of urbanization on precipitation and flood, and the response relationship between urbanization and environment in urban hydrology. Key study areas in the two disciplines are discussed. For socio-hydrology, the key study areas include constitutive relation study, comparative socio-hydrology, and interdisciplinary study while the key study areas of urban hydrology include the mechanism and simulation of urbanization impact on hydrological processes, monitoring and forecasting technology of urban rainstorm and flood, and urban rain-flood management and resource utilization technology.

Hydrology is the science that describes the continuous movement of water, the related biogeochemical and geophysical processes, and their interactions with the environment. Hydrology research has evolved from experience-based to theories, from single process to complex systems, and from qualitative interpretations to quantitative models. The progress and evolution of hydrology has been intimately intertwined with the scientific and technological progresses and socioeconomic development, which creates many branches and interdisciplinary areas of hydrology, such as ecohydrology, hydrometeorology, cryosphere hydrology, hydrologic remote sensing, isotope hydrology, urban hydrology, and socio-hydrology. Hydrology research has made notable progress in the fields of multi-scale observations, coupled land surface-hydrology-society modeling, and multi-source data and model assimilation techniques, which further expands the connotation of hydrological study. In the future, hydrology research will focus on the characteristics and mechanism of the changes of water cycle, prediction of the changes of water cycle, and natural and social impact assessment of the changes of water cycle, in order to offer sustainable solutions to water security. In summary, the research paradigm of hydrology would shift from the traditionally self-focused approaches to the emerging integrated approaches that focus on all the water-related processes across multiple scales and sectors in the earth system.

Risk assessment is a core area of climate change research. Quantitative assessment methods have been developed particularly due to the needs for theory of mitigation and adaptation strategies, and have been applied to a great number of specific assessments. However, there have been different viewpoints of the risk composition of climate change, and overall, integrated classification by coupling risk causing factors and risk bearing bodies is lacking. This article illuminates the risk composition of climate change, including the danger of risk causing factors, the exposure and vulnerability of risk bearing bodies, and their interrelations. The emergence and change of risk were clarified. Based on the integrated analysis of risk causing factors and risk bearing bodies, this study divided the climate change risk quantitative assessment methods into sudden onset hazard risk and slow onset hazard risk assessment methods, then the theoretical elaboration and case analysis were conducted for the two types of risks respectively. Finally, according to the current status and needs, this article proposes the future development directions of climate change risk research, including risk assessment under different warming amplitude, vulnerability curve construction, and adaptation.

As a key subfield in climatology, the study of climate changes is the research focus of physical geography in China. In this article, we review recent progress in such study, which focused on past climate changes and climate change impacts and adaptations in the context of present global warming. The highlights and results of the studies are summarized, especially on the following issues: reconstruction of past climate in China, analysis of the spatiotemporal patterns of climate changes and their impacts during historical times in China, characteristics of changes on climate regionalization in China under global warming since 1950, regional difference of impacts of recent global warming on natural ecosystems, water resources, and agriculture in China, and comprehensive climate change risk regionalization of China. These results provided a solid scientific basis for forming disciplinary development strategies and further studies of related issues in the field of physical geography in China.

Due to the rapid urbanization in recent decades, globally cities have become the regions loaded with highly developed economy, dense population, and intensive human-environment interactions. Because of the formation of “the second pattern” in artificial environment and effects of intensive urban land use and land cover change, the discipline of urban physical geography has significant theoretical and practical values in the research of intricate urban systems. In this article, we reviewed the origin and disciplinary development of urban physical geography, and the theoretical framework, research contents, and outlooks for frontier research areas are clarified. We aimed to extend and enrich the research contents of urban physical geography, and promote its further development. In the future, prospective studies on urban physical geography should focus on the following areas: (1) theoretical studies for facilitating disciplinary development; (2) inter-disciplinary research for extending the knowledge base of urban surface system changes; (3) the giant urban physical-human system for revealing the coupling relationships and driving mechanisms of multiple urban elements; (4) applications in urban service research for supporting decisions of sustainable urban development.