Explore the vast range of titles available.

Quantifying the responses of the coupled carbon and water cycles to current global warming and rising atmospheric CO 2 concentration is crucial for predicting and adapting to climate changes. Here we show that terrestrial carbon uptake (i.e. gross primary production) increased significantly from 1982 to 2011 using a combination of ground-based and remotely sensed land and atmospheric observations. Importantly, we find that the terrestrial carbon uptake increase is not accompanied by a proportional increase in water use (i.e. evapotranspiration) but is largely (about 90%) driven by increased carbon uptake per unit of water use, i.e. water use efficiency. The increased water use efficiency is positively related to rising CO 2 concentration and increased canopy leaf area index, and negatively influenced by increased vapour pressure deficits. Our findings suggest that rising atmospheric CO 2 concentration has caused a shift in terrestrial water economics of carbon uptake. The response of the coupled carbon and water cycles to anthropogenic climate change is unclear. Here, the authors show that terrestrial carbon uptake increased significantly from 1982 to 2011 and that this increase is largely driven by increased water-use efficiency, rather than an increase in water use.

Aims Co-limitation of ecosystem productivity by nitrogen (N) and phosphorus (P) is gaining increasing recognition, but how co-limitation through N and P interactions differs among different terrestrial ecosystems remains unclear. Methods We performed a meta-analysis of 133 independent studies conducted in four natural terrestrial ecosystems to examine the interactive effects of N and P additions on ten plant growth-related variables. Results Adding N and P individually or in combination significantly increased aboveground biomass (AGB), and the interactions were uniformly synergistic for AGB, and additive for belowground biomass (BGB), but variable for other eight growth-related variables among four different ecosystems. The interaction was synergistic for leaf P and soil NO 3 -N only in tropical forests, and antagonistic for soil available P (AP) in tropical forests, leaf N in grasslands, root P in wetlands, and leaf P and soil NH 4 -N in tundra. The interaction for leaf N: P ratios was additive only in tropical forests, and synergistic in the other three ecosystems. Conclusions Our results highlighted the interactions of N and P additions can promote uptake of both nutrients by plants, and plants tend to maintain the optimal nutrient balance for growth and reproduction through regulating biomass production and tissue nutrient concentrations.

Increases in carbon (C) inputs to soil can replenish soil organic C (SOC) through various mechanisms. However, recent studies have suggested that the increased C input can also stimulate the decomposition of old SOC via priming. Whether the loss of old SOC by priming can override C replenishment has not been rigorously examined. Here we show, through data–model synthesis, that the magnitude of replenishment is greater than that of priming, resulting in a net increase in SOC by a mean of 32% of the added new C. The magnitude of the net increase in SOC is positively correlated with the nitrogen-to-C ratio of the added substrates. Additionally, model evaluation indicates that a two-pool interactive model is a parsimonious model to represent the SOC decomposition with priming and replenishment. Our findings suggest that increasing C input to soils likely promote SOC accumulation despite the enhanced decomposition of old C via priming. The magnitudes of replenishment and priming, two important but opposing fluxes in soil organic carbon (SOC) dynamics, have not been compared. Here the authors show that the magnitude of replenishment is greater than that of priming, resulting in a net SOC accumulation after additional carbon input to soils.

Carbon allocation is one of the most important physiological processes to optimize the plant growth, which exerts a strong influence on ecosystem structure and function, with potentially large implications for the global carbon budget. However, it remains unclear how the carbon allocation pattern has changed at global scale and impacted terrestrial carbon uptake. Based on the Community Atmosphere Biosphere Land Exchange (CABLE) model, this study shows the increasing partitioning ratios to leaf and wood and reducing ratio to root globally from 1979 to 2014. The results imply the plant optimizes carbon allocation and reaches its maximum growth by allocating more newly acquired photosynthate to leaves and wood tissues. Thus, terrestrial vegetation has absorbed 16% more carbon averagely between 1979 and 2014 through adjusting their carbon allocation process. Compared with the fixed carbon allocation simulation, the trend of terrestrial carbon sink from 1979 to 2014 increased by 34% in the adaptive carbon allocation simulation. Our study highlights carbon allocation, associated with climate change, needs to be mapped and incorporated into terrestrial carbon cycle estimates.

It is well known that global ecosystem water-use efficiency (EWUE) has noticeably increased over the last several decades. However, it remains unclear how individual environmental drivers contribute to EWUE changes, particularly from CO2 fertilization and stomatal suppression effects. Using a satellite-driven water–carbon coupling model—Penman–Monteith–Leuning version 2 (PML-V2), we quantified individual contributions from the observational drivers (atmospheric CO2, climate forcing, leaf area index (LAI), albedo and emissivity) across the globe over 1982–2014. The PML-V2 was well-calibrated and showed a good performance for simulating EWUE (with a determination coefficient (R2) of 0.56) compared to observational annual EWUE over 1982–2014 derived from global 95 eddy flux sites from the FLUXNET2015 dataset. Our results showed that global EWUE increasing trend (0.04 ± 0.004 gC mm−1 H2O decade−1) was largely contributed by increasing CO2 (51%) and LAI (20%), but counteracted by climate forcing (−26%). Globally, the CO2 fertilization effect on photosynthesis (23%) was similar to the CO2 suppression effect on stomatal conductance (28%). Spatially, the fertilization effect dominated EWUE trend over semi-arid regions while the stomatal suppression effect controlled over tropical forests. These findings improve understanding of how environmental factors affect the long-term change of EWUE, and can help policymakers for water use planning and ecosystem management.

Objectives Based on previous reports that ginsenosides have been shown to exert better preventive effects on cisplatin‐induced kidney injury, the present work aims to evaluate the protective effects of ginsenoside Rb3 (G‐Rb3) on cisplatin‐induced renal damage and underlying mechanisms in vivo and in vitro. Materials and methods The protective effect of G‐Rb3 on cisplatin‐induced acute renal failure in ICR mouse model and HEK293 cell model was investigated, and the underlying possible mechanisms were also explored. For animal experiment, renal function, kidney histology, inflammation, oxidative stress, relative protein molecules involved in apoptosis and autophagy signalling pathways were assessed. In addition, rapamycin (a specific inhibitor of mTOR), compound C (a specific inhibitor of AMPK) and acetylcysteine (NAC, a specific ROS scavenger) were employed to testify the effects of AMPK/mTOR signal pathway on the protective effects of G‐Rb3 in HEK293 cells. Results Pre‐treatment with G‐Rb3 at doses of 10 and 20 mg/kg for ten days significantly reversed the increases in serum creatinine (CRE), blood urea nitrogen (BUN) and malondialdehyde (MDA), and decrease in glutathione (GSH) content and superoxide dismutase (SOD) activity. Histopathological examination further revealed that G‐Rb3 inhibited cisplatin‐induced nephrotoxicity. G‐Rb3 diminished cisplatin‐induced increase in protein expression levels of p62, Atg3, Atg5 and Atg7, and decrease in protein expression level of p‐mTOR and the ratio of LC3‐I/LC3‐II, indicating that G‐Rb3 suppressed cisplatin‐induced activation of autophagy. Inhibition of autophagy induced inactivation of apoptosis, which suggested that autophagy played an adverse effect on cisplatin‐evoked renal damage. Further, we found that G‐Rb3 might potentially modulate the expressions of AMPK‐related signal pathways. Conclusions These findings clearly suggested that G‐Rb3‐mediated alleviation of cisplatin‐induced nephrotoxicity was in part due to regulation of AMPK‐/mTOR‐mediated autophagy and inhibition of apoptosis in vitro and in vivo.

Microbial carbon use efficiency (CUE) affects the fate and storage of carbon in terrestrial ecosystems, but its global importance remains uncertain. Accurately modeling and predicting CUE on a global scale is challenging due to inconsistencies in measurement techniques and the complex interactions of climatic, edaphic, and biological factors across scales. The link between microbial CUE and soil organic carbon relies on the stabilization of microbial necromass within soil aggregates or its association with minerals, necessitating an integration of microbial and stabilization processes in modeling approaches. In this perspective, we propose a comprehensive framework that integrates diverse data sources, ranging from genomic information to traditional soil carbon assessments, to refine carbon cycle models by incorporating variations in CUE, thereby enhancing our understanding of the microbial contribution to carbon cycling. Microbial carbon use efficiency (CUE) is crucial for carbon storage, but its variability is difficult to capture due to inconsistent measurements and complex interactions. This perspective proposes integrating diverse data and models to improve CUE in carbon cycle models

Aim: To investigate how ecosystem water-use efficiency (WUE) varies spatially under different climate conditions, and how spatial variations in WUE differ from those of transpiration-based water-use efficiency (WUEt) and transpiration-based inherent water-use efficiency (IWUEt). Location: Global terrestrial ecosystems. Methods: We investigated spatial patterns of WUE using two datasets of gross primary productivity (GPP) and evapotranspiration (ET) and four biosphere model estimates of GPP and ET. Spatial relationships between WUE and climate variables were further explored through regression analyses. Results: Global WUE estimated by two satellite-based datasets is 1.9 ± 0.1 and 1.8 ± 0.6 g C m⁻² mm⁻¹ lower than the simulations from four process-based models (2.0 ± 0.3 g C m⁻² mm⁻¹) but comparable within the uncertainty of both approaches. In both satellite-based datasets and process models, precipitation is more strongly associated with spatial gradients of WUE for temperate and tropical regions, but temperature dominates north of 50° N. WUE also increases with increasing solar radiation at high latitudes. The values of WUE from datasets and process-based models are systematically higher in wet regions (with higher GPP) than in dry regions. WUEt shows a lower precipitation sensitivity than WUE, which is contrary to leaf- and plant-level observations. IWUEt, the product of WUEt and water vapour deficit, is found to be rather conservative with spatially increasing precipitation, in agreement with leaf- and plant-level measurements. Main conclusions: WUE, WUEt and IWUEt produce different spatial relationships with climate variables. In dry ecosystems, water losses from evaporation from bare soil, uncorrelated with productivity, tend to make WUE lower than in wetter regions. Yet canopy conductance is intrinsically efficient in those ecosystems and maintains a higher IWUEt. This suggests that the responses of each component flux of evapotranspiration should be analysed separately when investigating regional gradients in WUE, its temporal variability and its trends.

Global terrestrial models currently predict that the Amazon rainforest will continue to act as a carbon sink in the future, primarily owing to the rising atmospheric carbon dioxide (CO2) concentration. Soil phosphorus impoverishment in parts of the Amazon basin largely controls its functioning, but the role of phosphorus availability has not been considered in global model ensembles—for example, during the Fifth Climate Model Intercomparison Project. Here we simulate the planned free-air CO2 enrichment experiment AmazonFACE with an ensemble of 14 terrestrial ecosystem models. We show that phosphorus availability reduces the projected CO2-induced biomass carbon growth by about 50% to 79 ± 63 g C m−2 yr−1 over 15 years compared to estimates from carbon and carbon–nitrogen models. Our results suggest that the resilience of the region to climate change may be much less than previously assumed. Variation in the biomass carbon response among the phosphorus-enabled models is considerable, ranging from 5 to 140 g C m−2 yr−1, owing to the contrasting plant phosphorus use and acquisition strategies considered among the models. The Amazon forest response thus depends on the interactions and relative contributions of the phosphorus acquisition and use strategies across individuals, and to what extent these processes can be upregulated under elevated CO2.

Carbon‐climate feedback has been identified as one of the key areas of synthesis for the next Inter‐governmental Panel on Climate Change (IPCC); however, most of the models on which the IPCC will rely are yet to consider vital interactions between nitrogen (N) and carbon (C) cycles. A major impediment to including N limitation in model predictions has been the lack of constraint to rates of N fixation worldwide. Here we use a theoretical framework that considers interactions of C and nutrients to estimate rates of terrestrial N fixation, and thereby examining how the constraints of N on land C uptake and global warming. We show that most global models without nutrient limitations significantly overestimated land C uptake, thus underestimating both the pace and magnitude of the predicted global warming. We suggest that the next IPCC assessment should consider nutrient constraints on carbon‐climate feedback and the pace of global warming.