At present, the scale of landscaping projects continues to expand, and lawn is a common construction project. The planting and maintenance of cold season lawn is crucial, which has great influence on the effect of lan...At present, the scale of landscaping projects continues to expand, and lawn is a common construction project. The planting and maintenance of cold season lawn is crucial, which has great influence on the effect of landscaping projects. The paper expounds the planting methods of cold season lawn, then puts forward maintenance strategies from the aspects of timely pruning, reasonable irrigation, watering, pest control, etc., and finally summarizes the content of the full text.展开更多
An outbreak of powerful tornadoes tore through multiple states in the central and southern United States from 10 to 11 December 2021.It is claimed the deadliest tornado outbreak that has taken place on December days.T...An outbreak of powerful tornadoes tore through multiple states in the central and southern United States from 10 to 11 December 2021.It is claimed the deadliest tornado outbreak that has taken place on December days.The National Oceanic and Atmospheric Administration had confirmed 66 tornadoes as of 21 December,producing at least 90 fatalities.Most tornadoes occurred at night and thus they were difficult to be visually located,which directly increases the risk for local residents.Two violent nighttime tornadoes were rated category 4 on the enhanced Fujita scale(EF4).Although a high death toll was caused during this event,the operational service actually presented an excellent performance.This tornado outbreak has aroused extensive discussion from both the public and the research community in China.This paper presents a brief discussion on the formation environment and warning services of the tornado outbreak.Recall the deadliest violent tornado in the past 45 years in China,the radar-based tornadic vortex signatures at the locations with EF4 damages show a comparable strength with those in the current cases.Some views on the tornado warning issuance and receiving and damage surveys in China are also presented.展开更多
A wave-tide-circulation coupled model based on the Princeton Ocean Model is established to explore the seasonal variation of the cold water mass in the Beibu Gulf and its mechanisms. The results show that the cold wat...A wave-tide-circulation coupled model based on the Princeton Ocean Model is established to explore the seasonal variation of the cold water mass in the Beibu Gulf and its mechanisms. The results show that the cold water mass starts forming in March, reaches the maximum strength during June and July, and fades away since October. Strong mixing in winter transports the cold water from sea surface to bottom. The cold water mass remains in the bottom layer as the thermocline strengthens during spring, except for the shallow water where the themocline is broken by strong tidal mixing, which gradually separate the cold water mass from its surrounding warm water. Further analysis on the ocean current and stream function confirms that the cold water mass in the Beibu Gulf is locally developed, with an anticlockwise circulation caused by a strong temperature gradient. Sensitivity experiments reveal that the cold water mass is controlled by the sea surface heat flux, while the terrain and tidal mixing also play important roles.展开更多
The cold vortex is a major high impact weather system in northeast China during the warm season, its frequent activities also affect the short-term climate throughout eastern China. How to objectively and quantitative...The cold vortex is a major high impact weather system in northeast China during the warm season, its frequent activities also affect the short-term climate throughout eastern China. How to objectively and quantitatively predict the intensity trend of the cold vortex is an urgent and difficult problem for current short-term climate prediction. Based on the dynamical-statistical combining principle, the predicted results of the Beijing Climate Center＇s global atmosphereocean coupled model and rich historical data are used for dynamic-statistical extra-seasonal prediction testing and actual prediction of the summer 500-hPa geopotential height over the cold vortex activity area. The results show that this method can significantly reduce the model＇s prediction error over the cold vortex activity area, and improve the prediction skills. Furthermore, the results of the sensitivity test reveal that the predicted results are highly dependent on the quantity of similar factors and the number of similar years.展开更多
Potassium antimonite was used to localize Ca2+ in the apical bud cells of spruce from July 1999 to May 2000. During the period of active growth (July 14), Calcium precipitates, an indication of Ca2+ localization, were...Potassium antimonite was used to localize Ca2+ in the apical bud cells of spruce from July 1999 to May 2000. During the period of active growth (July 14), Calcium precipitates, an indication of Ca2+ localization, were mainly distributed in vacuoles, intercellular spaces and cell walls. Few Ca2+ deposits localized in the cytosol and nucleus, showing a low level of the cytosolic and nuclear Ca2+ concentration in the warm summer. In August, some Ca2+ deposits appeared in the cytosol and nuclei, indicating that Ca2+ influx occurred in the cytosol and nucleus as the day length became shorter. From September to November, high levels of the cytosolic and nuclear Ca2+ remained. During the mid-winter (December and January), the distribution of Ca2+ deposits and the ultrastructures in the cells were altered dramatically. Plasmolysis occurred in many cells due to the protoplasmic dehydration. In addition plasmalemma invagination and nuclear chromatin aggregation also occurred. A large number of Ca2+ deposits appeared in the space between the plasmalemma and the cell wall. And also some Ca2+ deposits were distributed in the plastids. However, few Ca2+ deposits were observed in the cytosol and nuclei. By spring of the next year (May), when plants were de-acclimated and resumed active growth, Ca2+ subcellular localization essentially restored to that observed in July of the last year, i.e., the cells contained low cytosolic and nuclear Ca2+ concentrations; Ca2+ deposits were mainly distributed in the vacuoles, cell walls and intercellular spaces. The relationships between the seasonal changes of intracellular Ca2+ concentration and the development of dormancy/cold acclimation, as well as plasmolysis associated with dormancy and cold hardiness were discussed.展开更多
Interest in the dynamics of soil respiration(R_(S))in subalpine forest ecosystems is increasing due to their high soil carbon density and potential sensitivity to environmental changes.However,as a principal silvicult...Interest in the dynamics of soil respiration(R_(S))in subalpine forest ecosystems is increasing due to their high soil carbon density and potential sensitivity to environmental changes.However,as a principal silvicultural practice,the long-term impacts of thinning on R_(S) and its heterotrophic and autotrophic respiration components(R_(h) and Ra,respectively)in subalpine plantations are poorly understood,espe-cially in winter.A 3-year field observation was carried out with consideration of winter CO_(2) efflux in middle-aged sub-alpine spruce plantations in northwestern China.A trench-ing method was used to explore the long-term impacts of thinning on Rs,Rn and R_(a).Seventeen years after thinning,mean annual Rs,Rn and R_(a) increased,while the contribu-tion of R_(h) to R_(s) decreased with thinning intensity.Thinning significantly decreased winter R,because of the reduction in R_(n) but had no significant effect on Ra.The temperature sensitivity(Q_(10))of R_(h) and R_(a) also increased with thinning intensity,with lower Q_(10) values for R_(h)(2.1-2.6)than for Ra(2.4-2.8).The results revealed the explanatory variables and pathways related to R_(n) and R_(a) dynamics.Thinning increased soil moisture and nitrate nitrogen(NO_(3)^(-)-N),and the enhanced nitrogen and water availability promoted R_(h) and R_(a) by improving fine root biomass and microbial activity.Our results highlight the positive roles of NO_(3)^(-)-N in stimulating R_(s) components following long-term thinning.Therefore,applications of nitrogen fertilizer are not recommended while thinning subalpine spruce plantations from the perspective of reducing soil CO_(2) emissions.The increased Q_(10) values of R_(s) components indicate that a large increase in soil CO_(2) emissions would be expected following thinning because of more pronounced climate warming in alpineregions.展开更多
文摘At present, the scale of landscaping projects continues to expand, and lawn is a common construction project. The planting and maintenance of cold season lawn is crucial, which has great influence on the effect of landscaping projects. The paper expounds the planting methods of cold season lawn, then puts forward maintenance strategies from the aspects of timely pruning, reasonable irrigation, watering, pest control, etc., and finally summarizes the content of the full text.
基金Radar Application and Short-term Severe-weather Predictions and Warnings Technology Program(GRMCTD202002)Foshan Innovation Driving and Assistance Project(2021002)+1 种基金Science and Technology Planning Project of Guangdong Province(2019B020208015)Foshan Science and Technology Project in Social Field(2120001008761)。
文摘An outbreak of powerful tornadoes tore through multiple states in the central and southern United States from 10 to 11 December 2021.It is claimed the deadliest tornado outbreak that has taken place on December days.The National Oceanic and Atmospheric Administration had confirmed 66 tornadoes as of 21 December,producing at least 90 fatalities.Most tornadoes occurred at night and thus they were difficult to be visually located,which directly increases the risk for local residents.Two violent nighttime tornadoes were rated category 4 on the enhanced Fujita scale(EF4).Although a high death toll was caused during this event,the operational service actually presented an excellent performance.This tornado outbreak has aroused extensive discussion from both the public and the research community in China.This paper presents a brief discussion on the formation environment and warning services of the tornado outbreak.Recall the deadliest violent tornado in the past 45 years in China,the radar-based tornadic vortex signatures at the locations with EF4 damages show a comparable strength with those in the current cases.Some views on the tornado warning issuance and receiving and damage surveys in China are also presented.
基金The National Natural Science Foundation of China under contract No.U1406404the National Basic Research Program(973 Program)of China under contract No.2014CB745004
文摘A wave-tide-circulation coupled model based on the Princeton Ocean Model is established to explore the seasonal variation of the cold water mass in the Beibu Gulf and its mechanisms. The results show that the cold water mass starts forming in March, reaches the maximum strength during June and July, and fades away since October. Strong mixing in winter transports the cold water from sea surface to bottom. The cold water mass remains in the bottom layer as the thermocline strengthens during spring, except for the shallow water where the themocline is broken by strong tidal mixing, which gradually separate the cold water mass from its surrounding warm water. Further analysis on the ocean current and stream function confirms that the cold water mass in the Beibu Gulf is locally developed, with an anticlockwise circulation caused by a strong temperature gradient. Sensitivity experiments reveal that the cold water mass is controlled by the sea surface heat flux, while the terrain and tidal mixing also play important roles.
基金supported by the National Natural Science Foundation of China(Grant No.41375078)the National Basic Research Program of China(Grant Nos.2012CB955902 and 2013CB430204)the Special Scientific Research Fund of Public Welfare Profession of China(Grant No.GYHY201306021)
文摘The cold vortex is a major high impact weather system in northeast China during the warm season, its frequent activities also affect the short-term climate throughout eastern China. How to objectively and quantitatively predict the intensity trend of the cold vortex is an urgent and difficult problem for current short-term climate prediction. Based on the dynamical-statistical combining principle, the predicted results of the Beijing Climate Center＇s global atmosphereocean coupled model and rich historical data are used for dynamic-statistical extra-seasonal prediction testing and actual prediction of the summer 500-hPa geopotential height over the cold vortex activity area. The results show that this method can significantly reduce the model＇s prediction error over the cold vortex activity area, and improve the prediction skills. Furthermore, the results of the sensitivity test reveal that the predicted results are highly dependent on the quantity of similar factors and the number of similar years.
基金Partly supported by the National Natural Science Foundation of China (Grant No.60050003)
文摘Potassium antimonite was used to localize Ca2+ in the apical bud cells of spruce from July 1999 to May 2000. During the period of active growth (July 14), Calcium precipitates, an indication of Ca2+ localization, were mainly distributed in vacuoles, intercellular spaces and cell walls. Few Ca2+ deposits localized in the cytosol and nucleus, showing a low level of the cytosolic and nuclear Ca2+ concentration in the warm summer. In August, some Ca2+ deposits appeared in the cytosol and nuclei, indicating that Ca2+ influx occurred in the cytosol and nucleus as the day length became shorter. From September to November, high levels of the cytosolic and nuclear Ca2+ remained. During the mid-winter (December and January), the distribution of Ca2+ deposits and the ultrastructures in the cells were altered dramatically. Plasmolysis occurred in many cells due to the protoplasmic dehydration. In addition plasmalemma invagination and nuclear chromatin aggregation also occurred. A large number of Ca2+ deposits appeared in the space between the plasmalemma and the cell wall. And also some Ca2+ deposits were distributed in the plastids. However, few Ca2+ deposits were observed in the cytosol and nuclei. By spring of the next year (May), when plants were de-acclimated and resumed active growth, Ca2+ subcellular localization essentially restored to that observed in July of the last year, i.e., the cells contained low cytosolic and nuclear Ca2+ concentrations; Ca2+ deposits were mainly distributed in the vacuoles, cell walls and intercellular spaces. The relationships between the seasonal changes of intracellular Ca2+ concentration and the development of dormancy/cold acclimation, as well as plasmolysis associated with dormancy and cold hardiness were discussed.
基金supported by the National Natural Science Foundation of China (Grant Nos.41701296 and 42277481)the Natural Science Foundation of Gansu Province (GrantNo.22JR5RA058)the Youth Science and Technology Fund Program of Gansu Province (Grant No.22JR5RA087).
文摘Interest in the dynamics of soil respiration(R_(S))in subalpine forest ecosystems is increasing due to their high soil carbon density and potential sensitivity to environmental changes.However,as a principal silvicultural practice,the long-term impacts of thinning on R_(S) and its heterotrophic and autotrophic respiration components(R_(h) and Ra,respectively)in subalpine plantations are poorly understood,espe-cially in winter.A 3-year field observation was carried out with consideration of winter CO_(2) efflux in middle-aged sub-alpine spruce plantations in northwestern China.A trench-ing method was used to explore the long-term impacts of thinning on Rs,Rn and R_(a).Seventeen years after thinning,mean annual Rs,Rn and R_(a) increased,while the contribu-tion of R_(h) to R_(s) decreased with thinning intensity.Thinning significantly decreased winter R,because of the reduction in R_(n) but had no significant effect on Ra.The temperature sensitivity(Q_(10))of R_(h) and R_(a) also increased with thinning intensity,with lower Q_(10) values for R_(h)(2.1-2.6)than for Ra(2.4-2.8).The results revealed the explanatory variables and pathways related to R_(n) and R_(a) dynamics.Thinning increased soil moisture and nitrate nitrogen(NO_(3)^(-)-N),and the enhanced nitrogen and water availability promoted R_(h) and R_(a) by improving fine root biomass and microbial activity.Our results highlight the positive roles of NO_(3)^(-)-N in stimulating R_(s) components following long-term thinning.Therefore,applications of nitrogen fertilizer are not recommended while thinning subalpine spruce plantations from the perspective of reducing soil CO_(2) emissions.The increased Q_(10) values of R_(s) components indicate that a large increase in soil CO_(2) emissions would be expected following thinning because of more pronounced climate warming in alpineregions.
