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.

Wetland is an important natural resource for human beings and plays an irreplaceable ecological function in the terrestrial ecosystem. In order to curb the continued loss of wetlands around the world, international organizations and many countries have taken a series of major protection and restoration measures. This paper reviews the wetland protection and restoration measures of international organizations and some countries, comprehensively interprets China's wetland protection and restoration management experience, and proposes that future research on wetland resources should be carried out from the aspects of international frontier and national strategy, social economy and intelligent services. The results show that: (1) The 27 International Wetlands Day from 1997 to 2023 provide new goals and tasks for the protection and management of wetlands in corresponding years. The important topics and outcomes of the 14 International Convention on Wetlands Conferences from 1980 to 2022 provide new directions and new challenges for wetland development in the coming period. In the future, we should enhance ecological functions of wetlands, promote the sustainable development of wetlands, and overcome the technical bottleneck of ecological restoration of fragile wetland ecosystems from 2020 to 2035. (2) During the 30-year period from 1992 to 2022, China embarked on a new phase of wetland protection and restoration. The overall experience of wetland protection and restoration with Chinese characteristics has been formed through "national strategic deployment-legal policy establishment-project planning and implementation". Emphasis was placed on the need to provide for and prepare planning for the long-term protection of wetlands at the national legal level, to innovate restoration and management techniques and application systems, and to effectively address the complex issues of wetland protection and restoration through collaborative division of labor among multiple departments. (3) The research on the future trend of wetlands should be directed towards the exploration and practice of "United Nations Sustainable Development Goals and several international conventions" in support of the sustainable development of wetlands. Wetland protection, restoration and management services should be promoted for "national strategic needs and local social and economic high-quality development". Research on the cross-integration and academic innovation development also should be enhanced for "disciplinary development - global supervision - comprehensive assessment-intelligent decision-making".

Topography largely contributes to the spatial heterogeneity of regional climate change and thus influences the response of vegetation to climate change. In this paper, using Three-River Headwaters Region of the Qinghai-Tibet Plateau as the study area, and structural equation modeling is utilized to explore the regulatory effect of topography factors on the Normalized Difference Vegetation Index through temperature and precipitation. The study shows that slope and aspect in the Three-River Headwaters Region mainly affect the response of vegetation to climate change by regulating precipitation, while elevation mainly affects the response of vegetation to climate change by regulating temperature. Elevation has the largest effect, which slows down the response of vegetation to climate change, with a total effect of -0.35; slope has the second largest effect, which intensifies the response of vegetation to climate change, with a total effect of 0.31; aspect has the smallest regulatory effect, with a total effect of 0.03; the total effect of topographic factors is -0.01, indicating that the three types of topographic factors have offsetting effects. In the Three-River Headwaters Region, the effect of topographic factors on vegetation regulation is the largest at slopes 5°-15°, shady slope and elevations 3000-3500 m, and their effects are 0.23, 0.08 and 0.39, respectively. At slopes 5°-15° and elevations 4500-5000 m, the aspect makes the vegetation respond to climate change the most by regulating precipitation; at slopes 5°-15°, shady slope and elevation lower than 4000 m, the elevation intensifies the vegetation response to climate by regulating temperature, and at elevation more than 4000 m, the elevation slows down the vegetation response to climate mainly by regulating precipitation. This paper can provide a basis for the study of the response pattern of mountain vegetation to climate change.

In the context of climate change and human activities, flood disasters in arid mountainous areas become increasingly frequent, and the safety of people's lives and property has been seriously threatened. Rapid and accurate flash flood inundation modeling is an important and basic work to reduce casualties and disaster losses, and it is also a bottleneck problem that needs to be solved urgently in flash flood forecasting and warning. This paper aims to construct a numerical modeling method for flash flood in drylands. Based on a 2D high-resolution flood numerical model (FloodMap-HydroInundation2D), we hindcast the dynamic process of flash flooding and reveal the spatio-temporal characteristics of flash flood inundation for the "8.18" flash flood disaster that occurred in Datong county, Qinghai province. The results show that the model output agrees well with the observed inundation after the event, in terms of both spatial extent and temporal process. The extensive flooding mainly occurred between 00:00 and 1:00 on August 18, 2022. Qingshan, Hejiazhuang and Longwo villages are most heavily affected. We further conduct model sensitivity analysis and find that the model is highly sensitive to both roughness and hydraulic conductivity in drylands, and the effect of hydraulic conductivity is found to be more pronounced. This study confirms the good performance of the model for the simulation of flash flooding in arid areas, unlocking the potential for flash flood assessment and management in arid areas.

Based on previous studies, aeolian sand activity in northeastern Tibetan Plateau (NETP) had strengthened during the past 1500 years, but the reasons are still unknown, concerning climate change, human activities, or a combination of both. In this study, according to the natural environment and population distribution, the NETP is divided into two regions: Zone I, which mainly includes Qinghai Lake Basin, Gonghe Basin and Hehuang Valley, has better hydrothermal condition and the larger population than Zone II that is comprised of Yellow River source area and Qaidam Basin, with cold and dry climate and sparse population. Then, this paper summarizes the published ages of aeolian sand, aeolian sand activity records, paleoclimate proxy indicators and the related records of human activities in these two zones. Also, we analyze the spatio-temporal differences and influencing factors among the increasingly enhanced aeolian sand activity during the past 1500 years in the NETP. The results show that there are spatio-temporal differences of enhanced aeolian sand activity in the NETP over the past 1500 years. Aeolian sand activity in Zone I significantly strengthened during the relatively warm and humid period of 1.5~1.0 ka ago, while that in Zone II did not enhance until since 1.0 ka. The time when the aeolian sand activity began to strengthen in Zone I was 0.5 ka earlier than in Zone II. Through the comprehensive analysis, the study shows that the destruction of natural vegetation caused by increased human activities is the reason why the enhanced aeolian sand activity in Zone I was 0.5 ka earlier than that in Zone II. The enhanced aeolian sand activity in Zone II were mainly caused by climate change over the past 1.0 ka. This study provides an insight in the spatio-temporal differences of the enhanced aeolian sand activity in the NETP over the past 1500 years, as well as a reference for ecological environment governance and predicting the change of aeolian sand activity under the trend of global warming in the future.