Tropical cyclone activity has undergone significant changes under the impact of global warming since the 20th century. However, the characteristic and trend changes of landfalling tropical cyclones over China still need to be further clarified. The study conducted an analysis of the spatiotemporal characteristics and trends of landfalling tropical cyclones over China from 1949 to 2022 using the dataset of the best tracks of tropical cyclones from the China Meteorological Administration. Additionally, we explored the influences of ENSO and the Pacific Decadal Oscillation (PDO) on landfalling tropical cyclone activities. The results indicate that: (1) The annual average number of landfalling tropical cyclones over China is approximately 8.85, showing a significant decreasing trend, and the decreasing range becomes larger with lower latitude overall. However, both the proportion of landfalling tropical cyclones to the total number and the percentage of higher intensity tropical cyclones increase. (2) The landfall locations of tropical cyclones in China are mainly concentrated between 18°N and 26°N, accounting for approximately 88.2% of the total, and the landfall frequency shows a sharp decline in the regions north of 30°N. The central landfall location of tropical cyclones has shifted significantly northwestward, moving closer to China. Compared to 1949-1969, the central genesis location from 2010 to 2022 shifted 4.5° westward and 2.0° northward. (3) There is a correlation between ENSO and the genesis frequency variation of tropical cyclones in the Northwest Pacific and landfalling over China. El Niño promotes the genesis of strong tropical cyclones and leads to a more southeastern bias in the genesis location of landfalling tropical cyclones, while La Niña has an opposite effect. The PDO also affects the tropical cyclones to a certain extent. During the PDO warm phase, the genesis position of tropical cyclones is westward and the number is smaller than that in the cold phase. This study further clarifies the changing trends and characteristics of landfalling tropical cyclones over China since 1949. It also highlights the impacts of ENSO and the PDO on tropical cyclone activities. The findings can serve as a scientific basis for conducting simulations and assessments of tropical cyclones and for disaster prevention and mitigation efforts.

Drought significantly constrains vegetation growth and reduces terrestrial carbon sinks. Currently, the spatiotemporal patterns and mechanisms of the differential impacts of soil and meteorological droughts on vegetation productivity remain inadequately understood. In this study, we analyzed soil moisture (SM), vapor pressure deficit (VPD), and gross primary productivity (GPP) to investigate their spatiotemporal patterns and the combined effects on GPP over China. The results revealed that: (1) Soil drought and meteorological drought generally exhibited temporally synchronous trends across China. (2) GPP was predominantly affected by the combined and synchronous effects of both SM and VPD, although their effects displayed directional variability differences in certain regions. (3) SM demonstrated a greater relative importance on GPP than VPD across more than half of the regions in China, whereas deciduous broadleaf forests were the only vegetation type primarily affected by VPD. (4) Under the lag effects, both SM and VPD exhibited bidirectional Granger causality with GPP, with the interaction between VPD and GPP proving more pronounced than that of SM. Our research provides valuable insights into the mechanisms through which SM and VPD influence GPP, contributing to improved predictions vegetation productivity and implementing ecological restoration.

Low-carbon urban development in China can pave the way to achieve the dual- carbon goal. Exploring how land use changes (LUCs) impact carbon storage (CS) under multi-climate scenarios in different urban agglomerations helps to formulate differential scientific carbon mitigation policies. In this regard, this study constructs an integrated model of SD-PLUS-InVEST to simulate LUCs and CS changes under multi-climate change-based scenarios (SSP126, SSP245, SSP585) for three major urban agglomerations (3UAs) in the Yangtze River Economic Belt. Results demonstrate that land use demand in the 3UAs changes considerably in each scenario. Construction land in the 3UAs remains the most important growth category for the coming decade, but its increase varies in different scenarios. CS in the Yangtze River Delta Urban Agglomeration (YRDUA) and Mid-Yangtze River Urban Agglomeration (MYRUA) shows a similar downward trend under different scenarios, with scenario SSP245 decreasing the most, to 184,713.526 Tg and 384,459.729 Tg, respectively. CS in the Cheng-Yu (Chengdu-Chongqing) Urban Agglomeration (CYUA) exhibits the opposite upward trend, with scenario SSP126 increasing the most to 153,007.973 Tg. The major cause of CS loss remains the conversion of forest land to construction land in the YRDUA and MYRUA under different scenarios. However, in the CYUA, the conversion of forest land to cultivated land is the major driver of CS loss under scenario SSP126. In contrast, the conversion of cultivated land to construction land dominantly drives CS loss under scenarios SSP245 and SSP585. The conversion of water body to other land use types is the major cause of CS gain in the YRDUA and MYRUA under different scenarios. At the same time, in the CYUA, the driver is the conversion of cultivated land to forest land. These findings demonstrate the significance of the low-carbon development in urban agglomerations at different development stages at home and abroad.

Soil erosion (SE) is a critical form of land degradation that significantly threatens the health of terrestrial ecosystems worldwide. The Qinba Mountains represent a vital geo-ecological transition zone in China. Therefore, analyzing the dynamics of SE in relation to climate changes and land use/cover (LULC) change is essential for guiding ecological conservation efforts in this region. The soil erosion intensity (SEI) from 2001 to 2020 was estimated using the Revised Universal Soil Loss Equation (RUSLE). For the period of 2021-2040, SEI projections were made based on CMIP6 data, utilizing the Statistical Downscaling Model alongside the CA-Markov model. Variations in SEI under four distinct shared socio-economic pathways were compared. Additionally, statistical methods were employed to evaluate the long-term impacts of climate and LULC change on SE. Findings indicate that between 2021 and 2040, both precipitation and rainfall erosivity are expected to increase by approximately 8%-12% and 3%-14%, respectively. Based on differing socio-economic pathways, the soil erosion rate (SER) is predicted to rise by 12%-32%, with SSP2-4.5 anticipated to result in the highest SER. An analysis of contributing factors revealed that precipitation intensity and total precipitation are likely to escalate SE, while elevated temperatures may mitigate it. Among all types of LULC, barren land is particularly susceptible to erosion and remains a priority for conservation. The generated SEI maps will aid in promoting sustainable land use and provide crucial support for mitigating ecological risks from climate change.

Medicinal plant diversity (MPD) is an indispensable part of global plant diversity, serving as the foundation for human survival by offering remedies and preventive measures against diseases. However, factors such as overexploitation, competition from invasive alien species, and climate change, threaten the habitats of medicinal plants, necessitating a comprehensive understanding of their spatial distribution and suitable habitats. We leveraged a decade of field survey data on medicinal plant distribution in the Yinshan Mountains, combined with spatial analysis, species distribution modeling, and the Carnegie Ames Stanford Approach (CASA) to explore the MPD spatial distribution and suitable habitats. Spatial analysis revealed that the central and eastern parts of Yinshan Mountains were the primary MPD hotspots, with no cold spots evident at various spatial scales. As the spatial scale decreased, previous non-significant regions transformed into hotspots, with instances where large-scale hotspots became insignificant. These findings offer valuable guidance for safeguarding and nurturing MPD across diverse spatial scales. In future climate change scenarios within the shared socioeconomic pathways (SSP), the habitat suitability for MPD in the Yinshan Mountains predominantly remains concentrated in the central and eastern regions. Notably, areas with high net primary productivity (NPP) values and abundant vegetation coverage align closely with MPD habitat suitability areas, potentially contributing to the region’s rich MPD.

How the strong segmentation of cascade reservoir dams and the spatiotemporal changes of sediment retention volume affect the river morphology adjustment in the reservoir area is a scientific issue worthy of exploration. This study aims to reveal the adjustment mechanism of the thalweg longitudinal profile of cascade reservoirs. This study focuses on the Xiangjiaba and Xiluodu reservoirs located in the lower reaches of the Jinsha River. Utilizing multi-period observational data of thalweg elevation in reservoir reaches both before and after dam construction, the research employs statistical, geomorphological, and sedimentological methodologies to analyze variation characteristics in the measured curves, trend curves, and theoretical fitting curves of the thalweg longitudinal profile. The investigation ultimately reveals two distinct adjustment patterns in the longitudinal profiles of these cascade reservoirs: the concave curve type and the convex curve type. The former is characterized by weak riverbed scouring and silting changed to rapid aggradation in the upstream section of the reservoir area after dam closure, then changed to slow aggradation in the whole reservoir area, which is the common feature of reservoirs that were built earlier and are relatively located in the downstream (such as the Xiangjiaba Reservoir). The latter is characterized by a straight line or concave curve type with weak riverbed scouring and silting before the dam closure changed to a convex curve type with strong siltation after dam closure, which is the characteristic of reservoirs that were built later and are relatively located in the upstream (such as the Xiluodu Reservoir). The adjustment of the cascade reservoir longitudinal profile is controlled by the spatiotemporal changes of the sediment deposition volume and sedimentation rate in the reservoir area, and the alternating changes of the hydrodynamic gradient and regulation mode affect the spatial heterogeneity of the sedimentation rate. The research results are helpful for understanding the adjustment mechanism of the cascade reservoir longitudinal profile in similar areas and have a guiding role in predicting the adjustment trend of the cascade reservoir longitudinal profile without observation data.

Collaborative changes in the hydro-sediment regime and erosional base level are vital factors that influence the evolution of wandering rivers. In the wandering Xiaobeiganliu reach of the Middle Yellow River (MYR), the rapidly decreasing sediment discharge and lowering base level, i.e., the Tongguan elevation, have resulted in new features of thalweg migration in river morphology. In this work, on the basis of topographic measurements of the reach from 2003-2021, the thalweg migration distance and intensity were calculated at both the section scale and reach scale. The results revealed that the annual sediment discharge decreased by 72% from 1986-2002, and the reach exhibited sustained scouring from deposition, leading to the Tongguan elevation decreasing by 1.69 m compared with that in 2002. Accordingly, the distance and intensity of thalweg migration have been reduced to varying degrees in both section and reach scales. The maximum section-scale thalweg migration distance was reduced by 11%, whereas the average thalweg migration distance and intensity at the reach scale decreased by 14% and 43%, respectively. During this sustained scouring period, the fluvial erosion intensity at the reach scale increased as the sediment discharge decreased. However, because the base level remained high, riverbed undercutting was deeply limited, which exacerbated lateral erosion of the bank and floodplain, enhancing thalweg migration. Flow-sediment regulation and training can be coupled to increase undercutting efficiency in the main channel and to protect banks from lateral erosion in river reach management.

Damming is a major geomorphological event characterized by catastrophic consequences and profound impacts on fluvial landscape evolution. Extensive Quaternary detrital deposits (DD) have been discovered in the Daju Basin. Some research suggests that these deposits are potentially associated with Great Flood events in the mainstream region. However, considering the multiplicity and complexity of the deposition, they may also result from catastrophic debris flows in local gullies. Consequently, we conducted a comprehensive investigation of detrital deposits and collected 64 provenance samples. The sediment provenance was analyzed by grain size distribution and elemental composition characterization. The results are as follows: (1) The detrital deposits in the basin are predominantly composed of sand and gravel, with some clay. (2) The results of the elemental ratios and multivariate statistical analysis confirmed the similarity in material composition between the detrital deposits in the basin and those from the Muduoluo Gully. (3) The discovery of palaeolandslides and lacustrine deposits in the study area indicates the existence of ancient dammed lakes and historical river damming events. The detrital deposits likely represent fan delta sediments formed by water-land interactions caused by damming events. Our study highlights new insights into discriminating the provenances of detrital deposits in localized regions, providing a new perspective for investigating geological hazards in the Jinsha River Basin.

Migration is a potential strategy to reduce poverty in the Global South. In China, the Poverty-alleviation Relocation (PAR) is a government-led, large-scale migration initiative aimed at eliminating poverty and promoting environmental sustainability. To examine the ecological and socio-economic effects of the PAR, we quantified the changes in five types of ecosystem services (ES) as well as the subjective well-being of rural residents in Fuping county, Hebei province of China, by using ES mapping, household survey, and semi-structured interviews. We found that the PAR improves people’s quality of life, with the well-being scores associated with transportation, communication, education, and healthcare increasing by 0.45-0.81. Additionally, the PAR enhances the supply of ES, evidenced by the increases in four types of ES in both in-migration and out-migration areas. The ES growth rates in in-migration areas ranged from 0.7% to 3.9%, while in out-migration areas, the rates ranged from 0.4% to 2.5%. However, the changes in income and food well-being are minimal, with scores at 0 and 0.32, respectively. More importantly, the elderly and low-educated residents experience minimal improvements in well-being after relocation. Our findings suggest that for other developing countries seeking to adopt PAR, it is crucial to provide targeted support for livelihood transitions, particularly for marginalized social groups, restore out-migration areas, and strengthen cross-regional cooperation to better address ecological constraints on livelihoods.

Enhancing urban ecological resilience (UER) is a new concept for modern tourism-oriented cities to cope with environmental crises. Revealing the impact of the urbanization on UER is critical to the sustainability of urban ecosystems. Taking Zhangjiajie, a typical tourism-oriented city, as an example, urbanization level (UL) and UER evaluation system were constructed, and the change trend was analyzed. The Granger Causality Test model was used to discuss the relationship between UL and UER. The results showed that: (1) the urbanization rate of Zhangjiajie significantly increased by 0.531 from 2011 to 2020. Cili county has the highest UL, and Wulingyuan district including a large number of scenic spots has the fastest development trend. (2) The ecological restoration was more sensitive in the face of rising pressure, and showed a synchronized change trend with pressure. The high pressure in 2016 had the most significant impact on resistance. This effect continued into 2019, with an average decline in resistance of 0.802. (3) The UL has significantly promoted the improvement of urban ecological restoration. Specially, tourism urbanization was the most significant in scenic spots, while economic and social urbanization played a major role in other regions for the improvement of ecological restoration.