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The adaptability of marine organisms to changes in salinity has been a significant research area under global climate change. However, the underlying mechanisms of this adaptability remain a debated subject. We hypothesize that neglecting salinity fluctuation properties is a key contributing factor to the controversy. The ciliate Euplotes vannus was used as the model organism, with two salinity fluctuation period sets: acute (24 h) and chronic (336 h). We examined its population growth dynamics and energy metabolism parameters following exposure to salinity levels from 15‰ to 50‰. The carrying capacity (K) decreased with increasing salinity under both acute and chronic stresses. The intrinsic growth rate (r) decreased with increasing salinity under acute stress. Under chronic stress, the r initially increased with stress intensity before decreasing when salinity exceeded 40‰. Overall, glycogen and lipid content decreased with stress increasing and were significantly higher in the acute stress set compared to the chronic one. Both hypotonic and hypertonic stresses enhanced the activities of metabolic enzymes. A trade-off between survival and reproduction was observed, prioritizing survival under acute stress. Under chronic stress, the weight on reproduction increased in significance. In conclusion, the tested ciliates adopted an r-strategy in response to salinity stress. The trade-off between reproduction and survival is a significant biological response mechanism varying with salinity fluctuation properties. [ABSTRACT FROM AUTHOR]

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Vegetation changes have a significant impact on the underlying surface of a watershed and alter hydrological processes. To clarify the synergistic evolution relationship between climate, vegetation, and hydrology, this study aims to reveal how vegetation restoration influences streamflow decline. This study first applied the trend-free pre-whitening Mann–Kendall (TFPW-MK) method to identify variation trends of various elements at Baihe and Shayang hydrologic stations from 1982 to 2015. Secondly, an extended Budyko equation was improved by fitting the linear relationship between annual NDVI and Budyko parameter (ω). Finally, based on the extended Budyko formula, the elastic coefficient method was applied to identify the influence of vegetation changes on runoff changes of the Baihe and Shayang stations from 1982 to 2015. The results displayed that (1) the annual NDVI of Baihe and Shayang hydrologic stations both presented an increasing trend, and streamflow presented an insignificant decrease trend. The mutation year of the annual runoff depth of Baihe and Shayang stations both occurred in 1990. (2) The annual NDVI had a significant and positive linear relationship with ω. (3) The streamflow decline of Baihe and Shayang stations is mainly influenced by precipitation variation and human activities. (4) Vegetation growth had a positive effect on the streamflow decline of Baihe and Shayang stations, with a contribution rate of 14.06% and 17.87%. This effect of vegetation growth on discharge attenuation should be given high priority. [ABSTRACT FROM AUTHOR]

As global warming continues, extreme precipitation events occur frequently in inland areas, seriously affecting human security and the ecological environment. Spatiotemporal evolution of extreme precipitation as well as response of extreme precipitation to climatic warming and its mechanism were investigated by considering the Weihe river basin in a monsoon transition zone of China as a research object. The results indicate that while the annual average temperature of the Weihe river basin increased with fluctuations from 1966 to 2017, except for the consecutive dry days (CDD) and simple daily intensity index that increased slightly, the other extreme precipitation indices (consecutive wet days, R25, and Rx5day) tended to decrease. Moreover, except for the CDD, the other four indices gradually increased from the northwest to the southeast, showing a similar trend to the temperature. The relationship between the 95th percentile threshold and temperature (hereinafter referred to as the P 95d–T relationship) in the Weihe river basin demonstrates the hook structure and its strength in terms of response is mainly dominated by the super-Clausius–Clapeyron (C–C) and C–C scaling. Furthermore, the peak temperature rises gradually from the northwest to the southeast. The results can provide important reference for the prediction of climate change and future studies of disaster risk in the Weihe river basin.

Lake organic matter is one of the important forms of terrestrial carbon, and its sedimentary evolution is affected by many factors such as climate and sources. However, few studies have been conducted on the feedback mechanism of the sedimentary evolution of organic matter to climate change in cold and arid lakes. Historical variations and compositions of sources of the sediment organic matter (SOM) of Hulun Lake, a typical lake in the cold and arid region of China, were studied by multiple methods. The interactions and fee7dback mechanisms between the sedimentary evolution of SOM and climate change, and compositions of SOM source change, were also discussed. Overall, the characteristic indexes of the SOM, including total organic carbon (TOC), carbon stable isotope (δ13C), carbon to nitrogen ratio (C/N), and fluorescence intensity (FI) of the protein-like component in water extractable organic matter (WEOM), showed obvious and uniform characteristics of periodical changes. The indexes were relatively stable before 1920, and fluctuated from 1920 to 1979. Since the 1980s, values of TOC, δ13C, and FI of the protein-like component in WEOM has increased, while C/N decreased. The absolute dominant contribution of terrestrial source to the SOM had changed, and the relative average contribution rate of autochthonous source increased from 17.6% before 1920 to 36.9% after 2000. The increase of temperature, strong evaporation concentration effect, and change of compositions of SOM sources are the important driving factors of the sedimentary evolution of organic matter in Hulun Lake. [ABSTRACT FROM AUTHOR]

Climate change will likely increase the total streamflow in most headwaters on the Tibetan Plateau in the next decades, yet the response of runoff components to climate change and permafrost thaw remain largely uncertain. Here, we investigate the changes in runoff components under a changing climate, based on a high‐resolution cryosphere‐hydrology model (Spatial Processes in Hydrology model, SPHY) and multi‐decadal streamflow observations at the upstream (Jimai) and downstream stations (Maqu and Tangnaihai) in the source‐region of the Yellow River (SYR). We find that rainfall flow dominates the runoff regime in SYR (contributions of 48%–56%), followed by snowmelt flow (contributions of 26%/23% at Maqu/Tangnaihai). Baseflow is more important at Jimai (32%) than at the the downstream stations (21%–23%). Glacier meltwater from the Anyê Maqên and Bayankala Mountains contributes negligibly to the downstream total runoff. With increasing temperature and precipitation, the increase in total runoff is smaller in the warm and wet downstream stations than in the cold and dry upstream station. This is because of a higher increase in evapotranspiration and a larger reduction in snowmelt flow in the downstream region in response to a warming climate. With temperature increase, there is less increase in rainfall flow in the downstream region due to increased water loss through evapotranspiration. Meanwhile, the decline in snowmelt flow is larger further downstream, which can negatively impact the spring irrigation for the whole Yellow River basin that supports the livelihoods of 140 million people. Importantly, we find that baseflow plays an increasingly important role in the permafrost‐dominated upstream region with atmospheric warming and permafrost thaw, accompanied by decreased surface flow. These findings improve our current understanding of how different hydrological processes respond to climate change and provide insights for optimizing hydropower and irrigation systems in the entire Yellow River basin under a rapidly changing climate. [ABSTRACT FROM AUTHOR]

Investigating the interrelation between snow and vegetation is essential to explain the response of alpine ecosystems to climate change. Based on the MOD10A1 daily cloud-free snow product and MOD13A1 NDVI (normalized difference vegetation index) data, this study analysed the spatial and temporal patterns of snow phenology including snow onset date, snow end date, snow cover days, and vegetation phenology including the start of growing season, the end of growing season and the length of growing season in the Chinese Tianshan Mountainous Region (CTMR) from 2002 to 2018, and then investigated the snow phenological effects on the vegetation phenology among different ecogeographic zones and diverse vegetation types. The results indicated that snow onset date was earlier at higher elevations and later at lower elevations, while snow end date showed opposite spatial distribution characteristics. The end of growing season occurred later on the northwest slope of the CTMR and the Yili Valley. The earliest end of growing season was in the middle part of the CTMR. A long growing season was mainly distributed along the northern slope and the Yili Valley, while a short growing season was concentrated in the middle part of the CTMR. The response of vegetation phenology to changes in snow phenology varied among vegetation types and ecogeographic zones. The effect of snow phenology on vegetation phenology was more significant in IID5 (Yili Valley) than in the other ecogeographic zones. A negative correlation was observed between the start of growing season and snow end date in nearly 54.78% of the study area, while a positive correlation was observed between the start of growing season and the snow end date in 66.85% of the study area. The sensitivity of vegetation phenology to changes in snow cover varied among different vegetation types. Snow onset date had the greatest effect on the start of growing season in the four vegetation cover types (alpine meadows, alpine steppes, shrubs, and alpine sparse vegetation), whereas the snow cover days had the least impact. Snow end date had the greatest impact on the end of growing season in the alpine steppes and shrub areas. The study results are helpful for understanding the vegetation dynamics under ongoing climate change, and can benefit vegetation management and pasture development in the CTMR. [ABSTRACT FROM AUTHOR]

To reveal molecular mechanisms underlying photosynthesis responses of Dahurian larch (Larix gmelinii) to environmental changes, we used the high-throughput sequencing technology to sequence the transcriptome of larch leaves from four latitudinal sites with different environmental conditions, and compared differential expression genes (DEGs). The four sites from high- to low-latitude were Tahe (52°52'N), Songling (50°72'N), Heihe (49°22'N), and Dailing (47°08'N). A total of 282428811 clean reads were sequenced out, among which the abundace of DEGs were 16915, 18812, 28536, 20635, 29957 and 23617 for the Tahe-Songling, Tahe-Heihe, Tahe-Dailing, Songling-Heihe, Songling-Dailing, and Heihe-Dailing comparisons, respectively. The expression of nine Psb genes family (i.e., PsbB, PsbK, PsbO, PsbP, PsbQ, PsbS, PsbW, Psb21, and />s628) encoding Photo-system E and that of three genes (ATPFIA, atpA, ATPFIG, atpG, and ATP FID, atpH) encoding F-type ATPase, which were involved in photosynthesis pathway, were significantly up-regulated with increasing environmental differences among the sites. A similar up-regulation pattern occurred for the expression of genes encoding glutamine synthetase (glnA, GLUL), nitrate reductase (NR), and carbonic anhydrase (cynT, can) that were involved in nitrogen metabolism pathway. The numbers of DEGs and up-regulated genes increased with the increases in environmental changes among the sites, resulting in inter-site divergence of photosynthetic capacity of larch trees. [ABSTRACT FROM AUTHOR]

Saccharina japonica is an important large brown alga and a major component of productive beds on the northwest coast of the Pacific Ocean. Abiotic stress response mechanisms are receiving considerable attention because global climate change is increasing their abiotic stress levels. However, our knowledge of how S. japonica broadly responds to stress is limited. In this study, we investigated the S. japonica responsive genes underlying acclimation to diverse stressors of acidification, high light, high temperature, hypersalinity, and hyposalinity and identified 408 core genes constantly and differentially expressed in response to all stressors. Our results confirm that stressors had strong effects on genes participating in photosynthesis, amino acid metabolism, carbohydrate metabolism, halogen metabolism, and reactive oxygen species defense. These findings will improve our understanding of brown algal response mechanisms linked to environmental stress and provide a list of candidate genes for improving algal stress tolerance in light of environmental stress in future studies. [ABSTRACT FROM AUTHOR]

Global climate change has resulted in increasingly harsh environments that have become the restriction factors for plants growth and development. Calcium-dependent protein kinases (CDPKs) in plants play critical roles in resisting various abiotic stresses, such as heat and cold stresses. Using the expression pattern analysis of foxtail millet CDPK family members under heat- and cold-treatments, respectively, and the SiCDPK7 was found to respond to extreme temperature stress and was selected for further study. The results suggested that overexpression of SiCDPK7 in Arabidopsis conferred tolerance to heat stress by increasing seedling survival rates and hypocotyl elongation compared with wild type (WT) plants, and also can enhance heat stress tolerance in foxtail millet. Analysis of physiological and biochemical indexes showed that SiCDPK7 transgenic plant lines had the markedly higher catalase (CAT) activity and the significantly lower malonaldehyde (MDA) content than WT plants. In addition, qRT-PCR analysis showed that the transcription levels of heat and cold stress-responsive genes were significantly increased in SiCDPK7 transgenic Arabidopsis and foxtail millet under stress conditions. This supporting evidence suggests that SiCDPK7 facilitated the extreme temperature tolerance capabilities in plants • Our study suggests that SiCDPK7 facilitated the extreme temperature tolerance capabilities in plants. • We verified the function of SiCDPK7 by transgenic techniques in Arabidopsis thaliana and foxtail millet. • Further study showed that some heat- and cold-regulated genes were up-regulated in transgenic plants, which revealed that plant CDPKs play important roles in plants for responding to extreme temperature stress. • Our results possible to provide a great candidate gene and important theoretical evidences for breeding temperature-resistant varieties. [ABSTRACT FROM AUTHOR]