| 1. |
- Wang, Chunyu, et al.
(författare)
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Modelling water and energy fluxes with an explicit representation of irrigation under mulch in a maize field
- 2022
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Ingår i: Agricultural and Forest Meteorology. - : Elsevier BV. - 0168-1923 .- 1873-2240. ; 326
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Tidskriftsartikel (refereegranskat)abstract
- Globally, water-saving irrigation plays a vital role in agricultural ecosystems to achieve sustainable food pro-duction under climate change. Irrigation under mulch (IUM) system has been widely used in modern agricultural ecosystems due to its high water use efficiency, but it remains unclear how each component of the water and energy processes responds to this agricultural management practice. Current modeling approaches are inade-quate in investigating the impacts of IUM management on water-energy balance, which have shown more complicated than non-mulched management. Therefore, this study provided an explicit simulation of water and energy fluxes in IUM system using a process-oriented ecosystem model-CoupModel and the three years of the eddy covariance (EC) measurements. Based on Monte Carlo and the multiple model performance evaluation criteria, most of the model sensitive parameters were well constrained and 32 potentially important parameters, e.g., iscovevap, the fraction of mulch coverage, were identified to characterize the impacts of plastic mulching on energy balance and water transport. After proper calibration, the coefficient of determination (R2) for measured and simulated soil temperature (T) and soil water content (SWC) was 0.79 and 0.60, respectively, and the R2 for T and SWC during the validation period were 0.91 and 0.71, respectively. Furthermore, we found that there was a strong coupling between the parameters of the water and energy processes, which would restrict the simulation results due to the correlation between the parameters and the evaluation indices. This study presented a sys-tematic model parameters calibration in the agricultural ecosystem implemented with IUM and provided with a more comprehensive understanding of the water and energy balance in cropland. These results would help agricultural model development with more detailed considerations of the water-saving management.
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| 2. |
- Fu, Ziteng, et al.
(författare)
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Water Migration and Segregated Ice Formation in Frozen Ground : Current Advances and Future Perspectives
- 2022
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Ingår i: Frontiers in Earth Science. - : Frontiers Media SA. - 2296-6463. ; 10
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Forskningsöversikt (refereegranskat)abstract
- A characteristic of frozen ground is a tendency to form banded sequences of particle-free ice lenses separated by layers of ice-infiltrated soil, which produce frost heave. In permafrost, the deformation of the ground surface caused by segregated ice harms engineering facilities and has considerable influences on regional hydrology, ecology, and climate changes. For predicting the impacts of permafrost degradation under global warming and segregated ice transformation on engineering and environmental, establishing appropriate mathematical models to describe water migration and ice behavior in frozen soil is necessary. This requires an essential understanding of water migration and segregated ice formation in frozen ground. This article reviewed mechanisms of water migration and ice formation in frozen soils and their model construction and introduced the effects of segregated ice on the permafrost environment included landforms, regional hydrological patterns, and ecosystems. Currently, the soil water potential has been widely accepted to characterize the energy state of liquid water, to further study the direction and water flux of water moisture migration. Models aimed to describe the dynamics of ice formation have successfully predicted the macroscopic processes of segregated ice, such as the rigid ice model and segregation potential model, which has been widely used and further developed. However, some difficulties to describe their theoretical basis of microscope physics still need further study. Besides, how to describe the ice lens in the landscape models is another interesting challenge that helps to understand the interaction between soil ice segregation and the permafrost environment. In the final of this review, some concerns overlooked by current research have been summarized which should be the central focus in future study.
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| 3. |
- Gao, Hongkai, et al.
(författare)
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Assessing glacier retreat and its impact on water resources in a headwater of Yangtze River based on CMIP6 projections
- 2021
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697. ; 765
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Tidskriftsartikel (refereegranskat)abstract
- Glacier retreat caused by global warming alters the hydrological regime and poses far-reaching challenges to water resources and nature conservation of the headwater of Yangtze River, and its vast downstream regions with dense population. However, there is still lack of a robust modeling framework of the “climate-glacier-streamflow” in this water tower region, to project the future changes of glacier mass balance, glacier geometry, and the consequent impacts on runoff. Moreover, it is imperative to use the state-of-the-art sixth phase Coupled Model Intercomparison Project (CMIP6) to assess glacio-hydrology variations in future. In this study, we coupled a glacio-hydrological model (FLEXG) with a glacier retreat method (Δh-parameterization) to simulate glacio-hydrological processes in the Dongkemadi Glacier (over 5155 m.a.s.l), which has the longest continuous glacio-hydrology observation on the headwater of Yangtze River. The FLEXG-Δh model was forced with in-situ observed meteorological data, radar ice thickness, remote sensing topography and land cover data, and validated by measured runoff. The results showed that the model was capable to simulate hydrological processes in this glacierized basin, with Kling-Gupta efficiency (IKGE) of daily runoff simulation 0.88 in calibration and 0.70 in validation. Then, forcing by the bias-corrected meteorological forcing from the eight latest CMIP6 Earth system models under two climate scenarios (RCP2.6 and RCP8.5), we assessed the impact of future climate change on glacier response and its hydrological effects. The results showed that, to the end of simulation in 2100, the volume of the Dongkemadi Glacier would continuously retreat. For the RCP2.6 and RCP8.5 scenarios, the glacier volume will decrease by 8.7 × 108 m3 (74%) and 10.8 × 108 m3 (92%) respectively in 2100. The glacier runoff will increase and reach to peak water around 2060 to 2085, after this tipping point water resources will likely decrease.
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| 4. |
- He, Lei, et al.
(författare)
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Non-symmetric responses of leaf onset date to natural warming and cooling in northern ecosystems
- 2023
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Ingår i: PNAS Nexus. - 2752-6542. ; 2:9
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Tidskriftsartikel (refereegranskat)abstract
- The northern hemisphere has experienced regional cooling, especially during the global warming hiatus (1998-2012) due to ocean energy redistribution. However, the lack of studies about the natural cooling effects hampers our understanding of vegetation responses to climate change. Using 15,125 ground phenological time series at 3,620 sites since the 1950s and 31-year satellite greenness observations (1982-2012) covering the warming hiatus period, we show a stronger response of leaf onset date (LOD) to natural cooling than to warming, i.e. the delay of LOD caused by 1°C cooling is larger than the advance of LOD with 1°C warming. This might be because cooling leads to larger chilling accumulation and heating requirements for leaf onset, but this non-symmetric LOD response is partially offset by warming-related drying. Moreover, spring greening magnitude, in terms of satellite-based greenness and productivity, is more sensitive to LOD changes in the warming area than in the cooling. These results highlight the importance of considering non-symmetric responses of spring greening to warming and cooling when predicting vegetation-climate feedbacks.
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| 5. |
- Kasimir, Åsa, 1956, et al.
(författare)
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Lower greenhouse gas flux and better economy with wetter peat soil use
- 2019
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Ingår i: Geophysical Research AbstractsVol. 21, EGU2019-14821, 2019.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We have used the CoupModel to investigate effects of 80 years of peatland use on greenhouse gas (GHG) emissions for four scenarios (1) business as usual - Norway spruce with average soil water table depth (WTD) of -40 cm; (2) willow plantation with WTD at -20 cm; (3) reed canary grass production with WTD at -10 cm; and (4) a fully rewetted peatland with no harvested product. Total soil GHG emissions for the scenarios were (including litter and peat respiration CO2 emissions as well as N2O and CH4) on average 33, 19, 15, and 11 Mg CO2eq ha-1year-1. No peat was lost for the wet peatland. At WTD -10 cm GHG emissions were at a minimum. Economy was analyzed by a cost–benefit analysis (CBA) where scenario (1) with spruce included gain from sold products like timber, pulpwood and energy biomass, and scenarios (2) and (3) harvests were for bioenergy purpose. Stored C in biomass and litter was included as gains, as well as biodiversity gains for the rewetted scenario. Costs included management and soil emissions. The CBA showed on average the best result for the rewetted peatland (4) and next were willow (2) together with reed canary grass (3), while spruce (1) production economic benefit was the lowest. This showed wetter condition to be a gain for the climate as well as for the economy. Questions to resolve are influences of fluctuating water tables and vegetation types on CH4 and N2O emission as well as DOC/DON loss etc. Continuation Clear-cut of forest followed by either continued forest or wetland restoration. We are now to clear-cut the mature spruce forest at Skogaryd research station, on which the model was calibrated. Half the area will then still be drained and planted with spruce and the other half rewetted to a wet meadow by building a dam. Collection of ecosystem and flux data will continue. We will now use the model to investigate the two scenarios, where we are most interested in effects on GHG and water DOC/DON losses, results presented here.We will also gain further knowledge on GHG and other losses from agricultural peat soils in the project Climate Smart Use of Norwegian organic soils (MYR). We will calibrate the CoupModel on data generated from the project and use it for investigating alternative land use options (wetter soil and lower management intensity at cultivated peatlands). In this later step, we want co-operate with research groups using other models.
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| 6. |
- Liu, Shenhai, et al.
(författare)
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The Glucagon-Like Peptide-1 Analogue Liraglutide Reduces Seizures Susceptibility, Cognition Dysfunction and Neuronal Apoptosis in a Mouse Model of Dravet Syndrome
- 2020
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Ingår i: Frontiers in Pharmacology. - : Frontiers Media SA. - 1663-9812. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Dravet syndrome (DS) is a refractory epilepsy typically caused by heterozygous mutations of the Scn1a gene, which encodes the voltage-gated sodium channel Nav1.1. Glucagon-like peptide-1 (GLP-1) analogues, effective therapeutic agents for the treatment of diabetes, have recently become attractive treatment modalities for patients with nervous system disease; however, the impact of GLP-1 analogues on DS remains unknown. This study aimed to determine the neuroprotective role of liraglutide in mouse and cell models of Scn1a KO-induced epilepsy. Epileptic susceptibility, behavioral changes, and behavioral seizures were assessed using electroencephalography (EEG), IntelliCage (TSE Systems, Bad Homburg, Germany), and the open field task. Morphological changes in brain tissues were observed using hematoxylin and eosin (HE) and Nissl staining. Expression of apoptosis-related proteins and the mammalian target of rapamycin (mTOR) signaling pathway were determined using immunofluorescence and western blotting in Scn1a KO-induced epileptic mice in vitro. Scn1a KO model cell proliferation was evaluated using the Cell Counting Kit-8 assay, and the effect of liraglutide on cellular apoptosis levels was examined using Annexin V-FITC/PI flow cytometry. Apoptotic signal proteins and mTOR were assessed using reverse transcription - quantitative polymerase chain reaction (RT-qPCR) and western blotting. Our results showed that liraglutide significantly increased mRNA ((0.31 ± 0.04) *10-3 vs. (1.07 ± 0.08) * 10-3, P = 0.0004) and protein (0.10 ± 0.02 vs. 0.27 ± 0.02, P = 0.0006) expression of Scn1a in Scn1a KO-induced epileptic mice. In addition, liraglutide significantly alleviated electroencephalographic seizures, the severity of responses to epileptic seizures (96.53 ± 0.45 % vs. 85.98 ± 1.24 %, P = 0.0003), cognitive dysfunction, and epileptic-related necrotic neurons (9.76 ± 0.91 % vs. 19.65 ± 2.64 %, P = 0.0005) in Scn1a KO-induced epileptic mice. Moreover, liraglutide protected against Scn1a KO-induced apoptosis, which was manifested in the phosphorylation of mTOR (KO+NS: 1.99 ± 0.31 vs. KO+Lira: 0.97 ± 0.18, P = 0.0004), as well as the downregulation of cleaved caspase-3 (KO+NS: 0.49 ± 0.04 vs. KO+Lira: 0.30 ± 0.01, P = 0.0003) and restoration of the imbalance between BAX (KO+NS: 0.90 ± 0.02 vs. KO+Lira: 0.75 ± 0.04, P = 0.0005) and BCL-2 (KO+NS: 0.46 ± 0.02 vs. KO+Lira: 0.61 ± 0.02, P = 0.0006). Collectively, these results show that liraglutide reduces seizure susceptibility and cognitive dysfunction in the mouse model of Dravet syndrome, and exerts anti-apoptotic and neuroprotective effects in Scn1a KO mice and cells.
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| 7. |
- Ni, Jingwen, et al.
(författare)
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天山典型流域水文多要素模拟与气候变化影响预估
- 2023
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Ingår i: Journal of Glaciology and Geocryology. - 1000-0240. ; 45:6, s. 1875-1886
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Tidskriftsartikel (refereegranskat)abstract
- Because of varied topography and landscape heterogeneity，Tianshan Mountain has extremely complex hydrological processes. Considering that the climate change poses a great threat to the water security，it’s necessary to simulate the change of water elements quantitatively and systematically along with elevation. In this study，we applied the modified FLEXG-Δh model to four classic river basins in Tianshan Mountain in consideration of glacier area changes. The results suggested that：（1）FLEXG-Δh model has high simulation accuracy for the historical runoff process because the average Kling-Gupta coefficient（IKGE）in calibration is 0. 75 and IKGE in validation is 0. 60. （2）Precipitation increases along with elevation while runoff and evaporation increase first but then decreased，with the maximum values at 4 000 m and 2 000 m respectively. The height zone with the greatest runoff is mainly affected by the glacier cover，while it is the distribution of forest for the greatest evaporation. （3）By 2100，the glaciers at low altitudes will melt significantly，while there will be a little melting above 4 500 m. Under SSP1-RCP2. 6 and SSP5-RCP8. 5 scenarios，145 and 222 glaciers will completely melt and the volume of glaciers will decrease 1. 81×104 km3（54% of the existing glaciers）and 2. 44×104 km3（73% of the existing glaciers），respectively. In the SSP5-RCP8. 5 scenario，the rise of temperature will increase the evap⁃ oration but lead to the fact that the runoff depth will decrease 0. 16~1. 40 mm·a-1 below 4 000 m and increase 0. 20~0. 67 mm·a-1 above 4 000 m ，causing the height of peak value will go up by about 500 m. Under SSP1-RCP2. 6 scenario，there will be few obvious changes. This study presented the vertical zonal law of hydrology and vegetation，and predicted the impact of global changes on the Tianshan Mountains，which provided theoreti⁃ cal support for water utilization and sustainable development.
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| 8. |
- Wang, Chunyu, et al.
(författare)
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Water use efficiency control for a maize field under mulched drip irrigation
- 2023
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697. ; 857
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Tidskriftsartikel (refereegranskat)abstract
- Agricultural ecosystem water use efficiency (WUE) is an important indicator reflecting carbon-water coupling, but its control mechanisms in managed fields remain unclear. In order to reveal the influencing factors of WUE in the agricultural field under mulched drip irrigation (DM), we carried out the 8-year continuous observations in a maize field from Northwestern China. The structural equation model, relative importance analysis and principal component analysis were used to quantify the regulation effects of environmental and biological factors on WUE at different time scales, in different growth stages and under different hydrothermal conditions. The results showed that annual WUE varied between 2.18 g C Kg−1 H2O and 3.60 g C Kg−1 H2O, with a multi-year mean of 2.91 g C Kg−1 H2O. The total effects of air temperature on the daily WUE in the whole growth period, the vegetative growth stage, the warm and dry years, the cold and wet years, and the warm and wet years were the largest, with values of 0.61, 0.80, 0.70, 0.70 and 0.91 respectively. However, vapor pressure deficit and net radiation had the largest total effect in the cold and dry years (−0.63) and the reproductive growth stage (−0.49), respectively. Leaf biomass played a leading role in regulating the daily and interannual WUE, and the relative importance of leaf biomass to WUE in the vegetative growth stage was up to 75 %. In the warm and wet years, the relative importance of root biomass to WUE was 33 %, slightly higher than that of leaf biomass (31 %). At the same time, we found that Ta has the potential to increase WUE under future climate warming. Our results improve the understanding of carbon-water coupling mechanisms and provide important enlightenment on how crop ecosystems should adapt to future climate change.
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| 9. |
- Xing, Xiuli, et al.
(författare)
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Modeling China's terrestrial ecosystem gross primary productivity with BEPS model : Parameter sensitivity analysis and model calibration
- 2023
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Ingår i: Agricultural and Forest Meteorology. - 0168-1923. ; 343
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Tidskriftsartikel (refereegranskat)abstract
- Terrestrial ecosystems are the largest sink for carbon, and their ecosystem gross primary productivity (GPP) regulates variations in atmospheric carbon dioxide (CO2) concentrations. Current process-based ecosystem models used for estimating GPP are subject to large uncertainties due to poorly constrained parameter values. In this study, we implemented a global sensitivity analysis (GSA) on parameters in the Boreal Ecosystem Productivity Simulator (BEPS) considering the parameters’ second-order impacts. We also applied the generalized likelihood estimation (GLUE) method, which is flexible for a multi-parameter calibration, to optimize the GPP simulation by BEPS for 10 sites covering 7 plant functional types (PFT) over China. Our optimized results significantly reduced the uncertainty of the simulated GPP over all the sites by 17 % to 82 % and showed that the GPP is sensitive to not only the photosynthesis-related parameters but also the parameters related to the soil water uptake as well as to the energy balance. The optimized GPP across South China showed that the mix forest, shrub, and grass have a higher GPP and are more controlled by the soil water availability. This study showed that the GLUE method together with the GSA scheme could constrain the ecosystem model well when simulating GPP across multiple ecosystems and provide a reasonable estimate of the spatial and temporal distribution of the ecosystem GPP over China. We call for more observations from more sites, as well as data on plant traits, to be collected in China in order to better constrain ecosystem carbon cycle modeling and understand its response to climate change.
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