scholarly journals Cold Wave-Induced Reductions in NDII and ChlRE for North-Western Pacific Mangroves Varies with Latitude and Climate History

2021 ◽  
Vol 13 (14) ◽  
pp. 2732
Author(s):  
Jonathan Peereman ◽  
J. Aaron Hogan ◽  
Teng-Chiu Lin
Keyword(s):  
Water Content ◽  
Geographic Distribution ◽  
Low Temperatures ◽  
Forest Canopy ◽  
Cold Wave ◽  
Mangrove Forests ◽  
Climate History ◽  
Wave Effects ◽  
Northern Pacific ◽  
Wave Induced

Mangrove forests growing at the poleward edges of their geographic distribution are occasionally subject to freezing (<0 °C) and cold wave (>0 °C) events. Cold wave effects on mangrove trees are well documented and adaptation to cold stress has been reported for local mangrove populations in the North Atlantic. However, there is less understanding of effects of cold waves on mangroves in the northern Pacific, especially at the regional scale. Moreover, it is unclear if cold tolerant mangrove species of North Asia display variation in resistance to cold temperatures across their geographic distribution. Using a cold wave event that occurred in January 2021, we evaluated the effects of low temperatures on vegetation index (VI) change (relative to a recent five-year baseline) for mangrove forests dominated by Kandelia obovata (Rhizophoraceae) and Avicennia marina (Acanthaceaee) at the northern edge of their geographical range. We used two VIs derived from Sentinel-2 imagery as indicators for canopy health: the normalized difference infrared index (NDII) and the chlorophyll red-edge index (ChlRE), which reflect forest canopy water content and chlorophyll concentration, respectively. We isolated the cold wave effects on the forest canopy from phenology (i.e., cold wave induced deviation from a five-year baseline) and used multiple linear regression to identify significant climatic predictors for the response of mangrove forest canopy VI change to low temperatures. For areas where the cold wave resulted in temperatures <10 °C, immediate decreases in both VIs were observed, and the VI difference relative to the baseline was generally greater at 30-days after the cold wave than when temperatures initially recovered to baseline values, showing a slight delay in VI response to cold wave-induced canopy damage. Furthermore, the two VIs did not respond consistently suggesting that cold-temperature induced changes in mangrove canopy chlorophyll and water content are affected independently or subject to differing physiological controls. Our results confirm that local baseline (i.e., recent past) climate predicts canopy resistance to cold wave damage across K. obovata stands in the northern Pacific, and in congruence with findings from New World mangroves, they imply geographic variation in mangrove leaf physiological resistance to cold for Northern Pacific mangroves.

scholarly journals Water-Use Characteristics and Physiological Response of Moso Bamboo to Flash Droughts

2019 ◽  
Vol 16 (12) ◽  
pp. 2174 ◽  
Author(s):  
Minxia Zhang ◽  
Shulin Chen ◽  
Hong Jiang ◽  
Yong Lin ◽  
Jinmeng Zhang ◽  
...  
Keyword(s):  
Water Content ◽  
Water Use ◽  
Forest Canopy ◽  
Stand Density ◽  
Water Shortage ◽  
Volumetric Water Content ◽  
Moso Bamboo ◽  
Extreme Drought ◽  
Soil Volumetric Water Content ◽  
The Stability

Frequent flash droughts can rapidly lead to water shortage, which affects the stability of ecosystems. This study determines the water-use characteristics and physiological mechanisms underlying Moso bamboo response to flash-drought events, and estimates changes to water budgets caused by extreme drought. We analyzed the variability in forest canopy transpiration versus precipitation from 2011–2013. Evapotranspiration reached 730 mm during flash drought years. When the vapor pressure deficit > 2 kPa and evapotranspiration > 4.27 mm·day−1, evapotranspiration was mainly controlled through stomatal opening and closing to reduce water loss. However, water exchange mainly occurred in the upper 0–50 cm of the soil. When soil volumetric water content of 50 cm was lower than 0.17 m3·m−3, physiological dehydration occurred in Moso bamboo to reduce transpiration by defoliation, which leads to water-use efficiency decrease. When mean stand density was <3500 trees·ha−1, the bamboo forest can safely survive the flash drought. Therefore, we recommend thinning Moso bamboo as a management strategy to reduce transpiration in response to future extreme drought events. Additionally, the response function of soil volumetric water content should be used to better simulate evapotranspiration, especially when soil water is limited.

Cerium Tetrafluoride. I. Preparation and reactions

1965 ◽  
Vol 18 (7) ◽  
pp. 959 ◽  
Author(s):  
WJ Asker ◽  
AW Wylie
Keyword(s):  
Aqueous Solution ◽  
Water Content ◽  
Water Vapour ◽  
Hydrogen Fluoride ◽  
Low Temperatures ◽  
Cerium Dioxide ◽  
Lattice Parameters ◽  
Refractive Indices ◽  
Dissociation Pressure ◽  
Cerium Trifluoride

Pure anhydrous cerium tetrafluoride is best prepared by fluorinating cerium dioxide at 350-500�. A monohydrate can be obtained from aqueous solution in a variety of ways, but it cannot be dehydrated without decomposition. It loses water "zeolitically" in vacuum, showing relatively small changes in lattice parameters for loss of 70% of its water content. Thereafter the lattice collapses, forming well-crystallized cerium trifluoride and poorly crystallized "anhydrous" cerium tetrafluoride. The refractive indices of anhydrous monoclinic cerium tetrafluoride have been measured and its fluorine dissociation pressure at 500� shown to be less than 0.5 mm. At higher temperatures the tetrafluoride sublimes incongruently, and at 835-841� it melts with extensive decomposition into a fluorine-poor liquid and a fluorine-rich vapour. Cerium tetrafluoride is easily reduced to the trifluoride by ammonia and by water vapour at low temperatures. At higher temperatures it is quantitatively converted by water vapour to cerium dioxide and hydrogen fluoride. When heated with cerium dioxide it is reduced to the trifluoride with liberation of oxygen.

Wave Effects on the Storm Surge Simulation: A Case Study of Typhoon Khanun

2016 ◽  
Vol 11 (5) ◽  
pp. 964-972 ◽  
Author(s):  
Fuchun Lai ◽  
◽  
Luying Liu ◽  
Haijiang Liu ◽  
◽  
...  
Keyword(s):  
Storm Surge ◽  
Flow Model ◽  
Coupled Model ◽  
Wave Model ◽  
Model Tests ◽  
Storm Events ◽  
Wave Effects ◽  
Near Shore ◽  
Wave Induced ◽  
Surge Height

To study wave effects on storm surge, a depth-averaged 2D numerical model based on the Delft3D-FLOW model was utilized to simulate near-shore hydrodynamic responses to Typhoon Khanun. The Delft3D-WAVE model is coupled dynamically with the FLOW model and the enhanced vertical mixing, mass flux and wave set-up were considered as wave-current interaction in the coupled model. After verifying storm surge wind and pressure formulae of storm surge and optimizing calibration parameters, three numerical tests with different control variables were conducted. Model tests show that wave effects must be considered in numerical simulation. Simulating the flow-wave coupled model showed that wave-induced surge height could be as large as 0.4 m in near-shore areas for Typhoon Khanun. Comparing to its contribution to the peak surge height, wave-induced surge plays a more significant role to total surge height with respect to the time-averaged surge height in storm events. Wave-induced surge (wave setup) is in advance of typhoon propagation and becomes significant even before the typhoon landfall. Model tests demonstrate that the wave effects are driven predominantly by the storm wave, while the boundary wave contribution is rather limited.

Artificial Cold Wave-Induced Cerebral Infarction in Rats with Carotid Atherosclerosis

2012 ◽  
Vol 47 (2) ◽  
pp. 278-285 ◽  
Author(s):  
Zhen-Yu Tang ◽  
Qiu-Yan Zhu ◽  
Li-Jun Xu ◽  
Li-Ying Deng ◽  
Ying Zeng ◽  
...  
Keyword(s):  
Cerebral Infarction ◽  
Carotid Atherosclerosis ◽  
Cold Wave ◽  
Wave Induced

scholarly journals EXPANSION OF THE ARCTOGEIC ELEMENT OF FLORA INTO THE BOREAL REGION (ON THE EXAMPLE OF OKHOTIA)

2021 ◽  
Vol 24 (2-3) ◽  
pp. 148-151
Author(s):  
S.D. Shlotgauer
Keyword(s):  
Water Content ◽  
Low Temperatures ◽  
High Water ◽  
High Water Content ◽  
Species Dispersal ◽  
Ecological Adaptations ◽  
Boreal Region ◽  
Element Species ◽  
Alpine Species ◽  
Mountain Systems

On the example of arctic and arctoalpine species of the sedge family (Cyperaceae Juss.), willow family (Salicaea Mirb.), saxifrage family (Saxifragaceae Juss.), buttercup family (Ranunculaceae Juss.) and rose family (Rosaceae Juss.) new points of their settlement in the subarctic mountain structures of Priokhotye are shown. The ecological adaptations of arctogenic element species to existence in mountainous conditions of low temperatures and high water content of habitats (nival lawns, the outskirts of ice crust fields, key bogs, etc.) are considered. This made it possible to clarify the main ways of arctic and arctic-alpine species dispersal in the subarctic mountain systems of the Boreal region.

scholarly journals Investigations of internal structure and transformational processes from firn to ice in a perennial snow patch

1993 ◽  
Vol 18 ◽  
pp. 117-122 ◽  
Author(s):  
Katsuhisa Kawashima ◽  
Tomomi Yamada ◽  
Gorow Wakahama
Keyword(s):  
Water Content ◽  
Internal Structure ◽  
Formation Mechanism ◽  
Free Water ◽  
Ice Cores ◽  
Cold Wave ◽  
Mass Budget ◽  
Free Water Content ◽  
Water Saturated

To investigate the internal structure and transformational processes from firn to ice of the Hisago snow patch on Daisetsu Mountain, Hokkaido, Japan, many drillings were made during the ablation period in 1986 and 1987. The ice cores were analyzed for stratigraphy, density and free water content. The internal structure of the snow patch was characterized by a wet firn layer with abundant ice layers and ice glands overlying a 4.3 m-thick ice body. The thickness of the firn layer varied from 12.7 m in June to 1.3 m in October. A water-saturated firn layer about 1 m thick existed just above the firn-ice transition. The annual layers were identified by dirt layers which showed that 1–2 m of ice was formed each year when the mass budget was positive. Although the densification of the water-saturated firn layer proceeded rapidly, the transformation from firn to ice could not be recognized during the ablation period. It was concluded that the formation mechanism of the ice body comprised three processes: the formation of superimposed ice, the densification of a water-saturated firn layer and the freezing of wet and/or water-saturated firn by cold wave penetration.

scholarly journals Effects of pruning a temperate mangrove forest on the associated assemblages of macroinvertebrates

2003 ◽  
Vol 54 (5) ◽  
pp. 683 ◽  
Author(s):  
William Gladstone ◽  
Maria J. Schreider
Keyword(s):  
Mangrove Forest ◽  
Forest Canopy ◽  
Sampling Period ◽  
Mangrove Forests ◽  
Short Term ◽  
Macrobenthic Assemblages ◽  
Highly Correlated ◽  
Taxonomic Groups ◽  
Macroinvertebrate Fauna ◽  
Similarity Matrices

Mangrove forests around the world are being impacted by development in adjacent land and water areas. An after-control-impact study was undertaken to assess the effects of mangrove forest pruning on the associated benthic macroinvertebrate fauna. Pruning, undertaken 5 years before our sampling period, reduced the height of the forest canopy from 5 m to 1 m. Macrobenthic assemblages were sampled in September 2000 and January 2001 from two randomly selected sites within the pruned section of forest, and two sites in each of two control locations in the same forest. Assemblage composition in the pruned and undisturbed mangrove forests was not significantly different, nor were there significant differences in variability between the two areas. Similarity matrices for assemblages based on higher taxonomic groups and molluscs were highly correlated with similarity matrices for all taxa, indicating the utility of more rapid forms of assessment in this habitat. The results suggest that although short-term impacts may have occurred, no impact on macroinvertebrate assemblages was evident 5 years after the pruning.

scholarly journals Wave-induced mixing and transport of buoyant particles: application to the Statfjord A oil spill

Ocean Science ◽  
2014 ◽  
Vol 10 (6) ◽  
pp. 977-991 ◽  
Author(s):  
M. Drivdal ◽  
G. Broström ◽  
K. H. Christensen
Keyword(s):  
Oil Spill ◽  
Wave Spectrum ◽  
Wave Model ◽  
Stokes Drift ◽  
Ocean Turbulence ◽  
Wave Effects ◽  
Ekman Theory ◽  
Energy And Momentum ◽  
Drift Models ◽  
Wave Induced

Abstract. This study focuses on how wave–current and wave–turbulence interactions modify the transport of buoyant particles in the ocean. Here the particles can represent oil droplets, plastic particles, or plankton such as fish eggs and larvae. Using the General Ocean Turbulence Model (GOTM), modified to take surface wave effects into account, we investigate how the increased mixing by wave breaking and Stokes shear production, as well as the stronger veering by the Coriolis–Stokes force, affects the drift of the particles. The energy and momentum fluxes, as well as the Stokes drift, depend on the directional wave spectrum obtained from a wave model. As a first test, the depth and velocity scales from the model are compared with analytical solutions based on a constant eddy viscosity (i.e., classical Ekman theory). Secondly, the model is applied to a case in which we investigate the oil drift after an oil spill off the west coast of Norway in 2007. During this accident the average net drift of oil was observed to be both slower and more deflected away from the wind direction than predicted by oil-drift models. In this case, using wind and wave forcing from the ERA Interim archive it is shown that the wave effects are important for the resultant drift and have the potential to improve drift forecasting.

Deglacial and postglacial climate history in east-central Isla Grande De Chiloé, Southern Chile (43°S)

2004 ◽  
Vol 62 (1) ◽  
pp. 49-59 ◽  
Author(s):  
Ana M. Abarzúa ◽  
Carolina Villagrán ◽  
Patricio I. Moreno
Keyword(s):  
Climate Variability ◽  
Geographic Distribution ◽  
Fine Scale ◽  
Southern Chile ◽  
Lake Levels ◽  
Climate History ◽  
East Central ◽  
Cool Temperate ◽  
Paleoclimate Records ◽  
Temperate Rainforests

Palynologic and stratigraphic data from Laguna Tahui (42°50′S, 73°30′W) indicate cool–temperate and humid conditions there between 14,000 and 10,000 14C yr B.P., followed by warmer and drier-than-present conditions between 10,000 and 7000 14C yr B.P., and subsequent cooling and rise in precipitation over the last 5800 14C yr. The thermophilous Valdivian trees Eucryphia cordifolia and Caldcluvia paniculata reached their maximum abundance during the early Holocene warm–dry phase (10,000–7000 14C yr B.P.), followed by a rise in lake levels and reexpansion of North Patagonian conifers starting at 7000 and 5800 14C yr B.P., respectively. Variations in the stratigraphic and geographic distribution of temperate rainforests in southern Chile suggest multimillennial trends in temperature and westerly activity, which are spatially and temporally coherent with paleoclimate records from neighboring regions. Climate variability at millennial and submillennial time scales may account for the establishment and persistence of fine-scale mosaics of Valdivian and North Patagonian rainforest species in low- to mid-elevation communities since ∼5800 14C yr B.P.

THE PHYSIOLOGY OF DORMANCY IN THE SWEETCLOVER WEEVIL

1956 ◽  
Vol 34 (2) ◽  
pp. 86-98 ◽  
Author(s):  
K. G. Davey
Keyword(s):  
Oxygen Consumption ◽  
Water Content ◽  
Low Temperatures ◽  
Adult Stage ◽  
Reproductive Organs ◽  
Fat Content ◽  
Low Level ◽  
Slight Rise

The physiology of the overwintering adult stage of Sitona cylindricollis (Fahr.), the sweetclover weevil, has been examined. It has been shown that the dormancy is characterized by a drop in oxygen consumption, a cessation of development in the reproductive organs, and a slight rise in fat content; and that the termination of dormancy is characterized by a reversal of these conditions. The water content does not change. Although the total respiration exhibited the characteristic U-shaped curve from entry into dormancy until its cessation, the CO-insensitive respiration remained at a low level throughout. Termination of the dormancy requires a period of exposure to low temperatures. It is concluded that this dormancy is not essentially different from diapause in immature insects.

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