Revealing regional-scale differences in microbial community structure and metabolic strategies across different land use types and soil types and how these differences relate to soil carbon (C) cycling function is crucial for understanding the mechanisms of soil organic carbon (SOC) sequestration in agroecosystems. However, our understanding of these knowledge still remains unclear. Here, we employed metagenomic methods to explore differences in microbial community structure, functional potential, and ecological strategies in calcareous soil and red soil, as well as the relationships among these factors and SOC stocks. The results showed that the bacterial absolute abundance and diversity were higher and the fungal absolute abundance and diversity were lower in calcareous soil than in red soil. This may be attributed to stochastic processes dominated the assembly of bacterial and fungal communities in calcareous soil and red soil, respectively. This in turn was closely related to soil pH and Ca2 + content. Linear discriminant analysis showed that genes related to microbial growth and reproduction (e.g., amino acid biosynthesis, central carbon metabolism, and membrane transport) were enriched in calcareous soil. While genes related to stress tolerance (e.g., bacterial chemotaxis, DNA damage repair, biofilm formation) were enriched in red soil. The great difference in soil properties between calcareous soil and red soil may be the cause of this result. Compared with red soil, the higher soil pH, SOC, and calcium and magnesium content in calcareous soil increased the bacterial absolute abundance and diversity, thus increasing the SOC sequestration potential of microorganisms, but also increased the decomposition of organic carbon by fungi, thus increasing the SOC loss potential. However, the bacterial absolute abundance and diversity were much higher than that of fungi. Therefore, soil carbon sequestration potential was still greater than its loss potential in karst agroecosystems. Agricultural disturbance intensity may be the main factor affecting these relationships. Overall, these findings advance our understanding of how soil microbial metabolic processes are related to SOC sequestration.

BackgroundPlant invasion affects plant community composition, biodiversity, and nutrient cycling in terrestrial ecosystems, particularly in vulnerable ecosystems. As an invasive parasitic plant, Cassytha filiformis has caused extensive damage to the native vegetation of the Paracel Islands. However, the effects of C. filiformis invasion on litter decomposition and nutrient release in native plant communities remain unclear. We conducted an in-situ decomposition experiment in native plant communities on a coral island to explore the litter decomposition dynamics varying across enzyme activities, soil properties and C. filiformis invasive degrees.ResultsThe mass loss of litter was determined during the decomposition process. The data showed that litter mass loss under severe invasion was significantly lower than in uninvaded sites after nine months of decomposition. The invasion of C. filiformis accelerated the nitrogen release and lignin decomposition with increased litter quality and polyphenol oxidase activity. Besides, soil phosphorus availability and potassium content also induced the oxidase activity. Meanwhile, the decomposition of litter organic carbon was delayed because beta-1, 4-glucosidase activity was low in the first six months. Besides, peroxidase activity maintained a high level in invasive plots, indicating that the residues of C. filiformis may have allelopathy.ConclusionOur results suggested that the invasion of C. filiformis accelerated litter mass loss and element release on coral islands by regulating litter quality and enzyme activity. However, the short-term rapid litter decomposition may result in nutrient loss, which is not conducive to the growth of native plants.

In the summer of 2022, a record-breaking heatwave and drought event occurred in the Yangtze River (YR) Basin of China, causing great damage to the society and ecosystem. However, the role of land-atmosphere (LA) interactions in driving and reinforcing this event has not been fully studied. In this study, using air temperature, soil moisture (SM), surface sensible heat fluxes, surface latent heat fluxes and radiation fluxes data from ERA5, we analyze the process of this event and reveal the contribution of the LA feedbacks. The results indicate that during the 2022 YR Basin heatwave and drought event, the regional average maximum air temperature and SM reached unprecedented levels of 2.7 standard deviations (SDs) and -3.5 SDs, respectively, compared to the climatology from 1980 to 2021. In August 2022, SM rapidly declined, pushing the region into a rare dry state. The dry soil increased the sensitivity of daily maximum air temperature to SM, intensifying the occurrence of heatwaves in the area. Simultaneously, increased downward solar radiation reached surface and most of that converted to sensible heat fluxes due to low soil moisture limitations leading to elevated air temperatures. While similar events have been reported multiple times in regions like Europe and western North America, their occurrence in the moist region of the YR Basin of China is exceptionally rare, which suggests an increasing likelihood of such extreme events in this region. Land-atmosphere interactions play an increasingly crucial role in exacerbating extreme conditions, and therefore, more studies such as this are needed for improving predictability of extreme events on a sub-seasonal time scale.

Highway tunnels are occasionally built under difficult ground conditions and technical limitations, in a surrounding ground mass with weak mechanical characteristics, specifically the Cretaceous soil, which is a significantly weathered and deteriorated rock exhibiting a scaly composition. These tunnels are typically dug with wide cross sections and commonly in double-tube configurations, maintaining a distinct gap between them to promote traffic flow and safety services. Tunnels with high sections often cause considerable stress changes and distortions that can lead to ground collapse under misinterpreted conditions of the ground mass, especially in freeway twin-tunnel with defined spacing. This study examines a paired 3-lane tunnel, which is a component of a nationwide freeway initiative covering approximately 1200 km, characterized by a horseshoe configuration with a cross of 190 m2 each and a clear gap of 17 m. Considering the surrounding rock conditions, at a specific phase of the project, significant displacements peaked at 41 mm/day; additionally, concrete fractures were noted before a major failure extending up to 130 m toward the tunnel. This study suggests a back assessment for main disturbance factors before and after collapse, evaluates support force, and employs numerical modeling to reconstruct ground behavior. It has been observed that the decompression was quite significant, particularly above the tunnel's crown. The monitoring activities emphasized the effectiveness of both the original and enhanced support systems, showing a decrease in displacement from 47 to 64%. Given the surrounding rock's inadequate mechanical properties, the noticeable distance between the tunnels and the extensive excavation area raises concerns about support effectiveness. As excavation advances, the need for prompt responses is also highlighted to facilitate feedback contributions.

The Tibetan Plateau (TP) has experienced accelerated warming in recent decades, especially in winter. However, a comprehensive quantitative study of its long-term warming processes during daytime and nighttime is lacking. This study quantifies the different processes driving the acceleration of winter daytime and nighttime warming over the TP during 1961-2022 using surface energy budget analysis. The results show that the surface warming over the TP is mainly controlled by two processes: (a) a decrease in snow cover leading to a decrease in albedo and an increase in net downward shortwave radiation (snow-albedo feedback), and (b) a warming in tropospheric temperature (850 - 200 hPa) leading to an increase in downward longwave radiation (air warming-longwave radiation effect). The latter has a greater impact on the spatial distribution of warming than the former, and both factors jointly influence the elevation dependent warming pattern. Snow-albedo feedback is the primary factor in daytime warming over the monsoon region, contributing to about 59% of the simulated warming trend. In contrast, nighttime warming over the monsoon region and daytime/nighttime warming in the westerly region are primarily caused by the air warming-longwave radiation effect, contributing up to 67% of the simulated warming trend. The trend in the near-surface temperature mirrors that of the surface temperature, and the same process can explain changes in both. However, there are some differences: an increase in sensible heat flux is driven by a rise in the ground-atmosphere temperature difference. The increase in latent heat flux is associated with enhanced evaporation due to increased soil temperature and is also controlled by soil moisture. Both of these processes regulate the temperature difference between ground and near-surface atmosphere.

Drought may impact plant-soil biotic interactions in ways that modify aboveground herbivore performance, but the outcomes of such biotic interactions under future climate are not yet clear. We performed a growth chamber experiment to assess how long-term, drought-driven changes in belowground communities influence plant growth and herbivore performance using a plant-soil feedback experimental framework. We focussed on two common pasture legumes-lucerne, Medicago sativa L., and white clover, Trifolium repens L. (both Fabaceae)-and foliar herbivores-cotton bollworm, Helicoverpa armigera (H & uuml;bner) (Lepidoptera: Noctuidae), and two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae). Soil was collected from a field facility where rainfall had been manipulated for 6 years, focussing on treatments representing ambient rainfall and prolonged drought (50% reduction relative to ambient), to consider the effects of biological legacies mediated by the prolonged drought. All soils were sterilized and re-inoculated to establish the respective home (i.e. where a given plant is cultivated in its own soil) and away (i.e. where a given plant is cultivated in another species' soil) treatments in addition to a sterile control. We found that the relative growth rate (RGR) and relative consumption of larvae were significantly lower on lucerne grown in soil with ambient rainfall legacies conditioned by white clover. Conversely, the RGR of insect larvae was lower on white clover grown in soil with prolonged drought legacies conditioned by lucerne. Two-spotted spider mite populations and area damage (mm2) were significantly reduced on white clover grown in lucerne-conditioned soil in drought legacies. The higher number of nodules found on white clover in lucerne-conditioned soil suggests that root-rhizobia associations may have reduced foliar herbivore performance. Our study provides evidence that foliar herbivores are affected by plant-soil biotic interactions and that prolonged drought may influence aboveground-belowground linkages with potential broader ecosystem impacts.

Globally, land subsidence (LS) often adversely impacts infrastructure, humans, and the environment. As climate change intensifies the terrestrial hydrologic cycle and severity of climate extremes, the interplay among extremes (e.g., floods, droughts, wildfires, etc.), LS, and their effects must be better understood since LS can alter the impacts of extreme events, and extreme events can drive LS. Furthermore, several processes causing subsidence (e.g., ice-rich permafrost degradation, oxidation of organic matter) have been shown to also release greenhouse gases, accelerating climate change. Our review aims to synthesize these complex relationships, including human activities contributing to LS, and to identify the causes and rates of subsidence across diverse landscapes. We primarily focus on the era of synthetic aperture radar (SAR), which has significantly contributed to advancements in our understanding of ground deformations around the world. Ultimately, we identify gaps and opportunities to aid LS monitoring, mitigation, and adaptation strategies and guide interdisciplinary efforts to further our process-based understanding of subsidence and associated climate feedbacks. We highlight the need to incorporate the interplay of extreme events, LS, and human activities into models, risk and vulnerability assessments, and management practices to develop improved mitigation and adaptation strategies as the global climate warms. Without consideration of such interplay and/or feedback loops, we may underestimate the enhancement of climate change and acceleration of LS across many regions, leaving communities unprepared for their ramifications. Proactive and interdisciplinary efforts should be leveraged to develop strategies and policies that mitigate or reverse anthropogenic LS and climate change impacts.

Brown carbon (BrC) has been recognized as an important light-absorbing carbonaceous aerosol, yet understanding of its influence on regional climate and air quality has been lacking, mainly due to the ignorance of regional coupled meteorology-chemistry models. Besides, assumptions about its emissions in previous explorations might cause large uncertainties in estimates. Here, we implemented a BrC module into the WRF-Chem model that considers source-dependent absorption and avoids uncertainties caused by assumptions about emission intensities. To our best knowledge, we made the first effort to consider BrC in a regional coupled model. We then applied the developed model to explore the impacts of BrC absorption on radiative forcing, regional climate, and air quality in East Asia. We found notable increases in aerosol absorption optical depth (AAOD) in areas with high OC concentrations. The most intense forcing of BrC absorption occurs in autumn over Southeast Asia, and values could reach around 4 W m(-2). The intensified atmospheric absorption modified surface energy balance, resulting in subsequent declines in surface temperature, heat flux, boundary layer height, and turbulence exchanging rates. These changes in meteorological variables additionally modified near-surface dispersion and photochemical conditions, leading to changes of PM2.5 and O-3 concentrations. These findings indicate that BrC could exert important influence in specific regions and time periods. A more in-depth understanding could be achieved later with the developed model.

Skill in predicting where damaging convective storms will occur is limited, particularly in the tropics. In principle, near-surface soil moisture (SM) patterns from previous storms provide an important source of skill at the mesoscale, yet these structures are often short-lived (hours to days), due to both soil drying processes and the impact of new storms. Here, we use satellite observations over the Sahel to examine how the strong, locally negative, SM-precipitation feedback there impacts rainfall patterns over subsequent days. The memory of an initial storm pattern decays rapidly over the first 3-4 days, but a weak signature is still detected in surface observations 10-20 days later. The wet soil suppresses rainfall over the storm track for the first 2-8 days, depending on aridity regime. Whilst the negative SM feedback initially enhances mesoscale rainfall predictability, the transient nature of SM likely limits forecast skill on sub-seasonal time scales. Early warning of severe weather is particularly important in Africa, where resilience to storm hazards such as flash flooding is weak. Given large-scale atmospheric conditions favorable for convective activity, understanding where storms will occur is challenging for conventional weather prediction models. In semi-arid regions such as the Sahel, the spatial distribution of SM provides additional predictability of convective rain, via its impact on heating and moistening of the atmosphere. Given that convection is favored over drier soils and that storms create new SM patterns every few days during the wet season, the extent to which knowledge of today's SM aids rainfall prediction in future days is unclear. Here we use 17 years of satellite observations to document how surface properties evolve over 20 days after a storm, and how the surface influences subsequent rainfall patterns. We find that even in regions of West Africa where storms are frequent, the suppression of rain over recently-wetted soils is evident out to 2 days. In climatologically drier regions, this predictability extends out to 8 days. Overall, the feedback between SM and rainfall enhances rainfall predictability in the short-term (days), but effectively degrades the skill of longer-term (weeks) forecasts. Satellite observations over the Sahel reveal how the land surface evolves in the 20 days after a Mesoscale Convective System (MCS) After an MCS, rainfall is suppressed over wet soils for 2 days in humid regions and up to 8 days in drier areas Initially soil moisture enhances rainfall predictability, but the strong land feedback degrades skill at longer lead times

Since the 5th Assessment Report of the Intergovernmental Panel on Climate Change (AR5) an extended concept of the energetic analysis of climate change including forcings, feedbacks and adjustment processes has become widely adopted. Adjustments are defined as processes that occur in response to the introduction of a climate forcing agent, but that are independent of global-mean surface temperature changes. Most considered are the adjustments that impact the Earth energy budget and strengthen or weaken the instantaneous radiative forcing due to the forcing agent. Some adjustment mechanisms also impact other aspects of climate not related to the Earth radiation budget. Since AR5 and a following description by Sherwood et al. (2015, ), much research on adjustments has been performed and is reviewed here. We classify the adjustment mechanisms into six main categories, and discuss methods of quantifying these adjustments in terms of their potentials, shortcomings and practicality. We furthermore describe aspects of adjustments that act beyond the energetic framework, and we propose new ideas to observe adjustments or to make use of observations to constrain their representation in models. Altogether, the problem of adjustments is now on a robust scientific footing, and better quantification and observational constraint is possible. This allows for improvements in understanding and quantifying climate change. Climate change is driven by perturbations to the atmospheric composition, to land use, or by changes of incoming solar radiation. It can be understood energetically by quantifying the perturbation to the Earth energy budget-the instantaneous radiative forcing-and the response of the climate system to this perturbation. This response can be split into feedbacks-mechanisms that act in response to global-mean surface temperature changes-and other processes that act independently of the global-mean surface temperature change. These latter processes are called adjustments. There is also a category of climate-relevant adjustments that is not directly related to the energy budget. This review documents the improved classification, understanding, constraint, and quantification of adjustments. A clearer picture of adjustments allows to better understand and quantify climate change. Adjustments impact the Earth energy budget, but also circulation, precipitation and atmospheric structure Adjustments are classified into six different mechanisms and act at time scales ranging from seconds to multiple years Observational constraints can inform on some aspects of adjustments