Age Structure and Change Trend of Tobacco Farmers:A Case Study of Shashi Town,Liuyang City,Hunan Province

Taking the tobacco-growing area of Shashi Town,Liuyang City as the object,the number of registered,newly added and resigned tobacco farmers in each year,average age,number and proportion of tobacco farmers of different ages,number and proportion of tobacco farmers born in different eras,as well as planting scale and planting history of flue-cured tobacco in the last 10 years were analyzed statistically.The results showed that the number of tobacco farmers in Shashi Town showed a rapid decline trend from 2012 to 2018,while the average age continuously increased,and the average planting scale rose in a wave like way.From 2019 to 2021,the decline rate of the number of tobacco farmers slowed down,and the average planting scale continuously increased,while the aging of tobacco farmers accelerated.Meantime,the birth years of tobacco farmers were further concentrated in the 1960s,and they were mainly at the age of 50-59.The tobacco industry in Shashi Town of Liuyang City is facing the crisis of aging tobacco farmers and no successor of flue-cured tobacco planting,and it is predicted that the next 5-10 years will continue the change trend from 2019 to 2021.

Climate change trend and its effects on reference evapotranspiration at Linhe Station, Hetao Irrigation District

Linhe National Meteorological Station, a representative weather station in the Hetao Irrigation District of China, was selected as the research site for the present study. Changes in climatic variables and reference evapotranspiration （ET0 ） （estimated by the Penman-Monteith method） were detected using Mann-Kendall tests and Sen＇s slope estimator, respectively. The authors analyzed the relationship between the ET0 change and each climatic variable＇s change. From 1954 to 2012, the air temperature showed a significant increasing trend, whereas relative humidity and wind speed decreased dramatically. These changes resulted in a slight increase in ETo. The radiative component of total ET0 increased from 50% to 57%, indicating that this component made a greater contribution to the increase in total ETo than the aerodynamic component, especially during the crop growing season （from April to October）. The sensitivity analysis showed that ETo in Hetao is most sensitive to mean daily air temperature （11.8%）, followed by wind speed （-7.3%） and relative humidity （4.8%）. Changes in sunshine duration had only a minor effect on ET0 over the past 59 years.

Change Trends of Accumulated Temperature and Effects on Agricultural Production in Shenyang during Recent 58 Years

[Objective] The aim was to study the change trend of accumulated temperature in Shenyang in recent 58 years, as well as its effect on agricultural production. [Method] Based on the surface temperature data in Shenyang, the change trends of ≥0 ℃ and ≥10 ℃ accumulated temperature in Shenyang in recent 58 years were analyzed by means of climatic statistics method, and the effects of accumulated temperature variation on agricultural production were discussed. [Result] In recent 58 years, the first day with temperature ≥0 ℃ advanced 10 d, and the last day put off slightly, while sustained days prolonged 13 d, and ≥0 ℃ accumulated temperature increased by 343 ℃·d; meanwhile, the first day with temperature ≥10 ℃ advanced 9 d, and the last day put off 8 d, while sustained days prolonged 16 d, and ≥10 ℃ accumulated temperature increased by 370 ℃·d; compared with the first 20 years, sustained days with temperature ≥0 ℃ and ≥10 ℃ prolonged 9 d in the last 20 years, and ≥0 ℃ and ≥10 ℃ accumulated temperature increased by 196 and 202 ℃·d, respectively. In addition, the increase of heat resources affected agricultural production in Shenyang. [Conclusion] The study could provide theoretical foundation for grasping heat resources variation and adjusting agriculture distribution.

Simulation of Change Trend of Drought in Shaanxi Province in Future Based on PRECIS Model

[Objective] The aim was to predict the change trend of drought in Shaanxi Province in future. [Method] Based on the regional climate model PRECIS from Hadley Climate Center, British Meteorological Bureau, taking precipitation anomaly percentage as assessment index, the change trend of drought in Shaanxi Province in reference years (1971-1990) was simulated, and the change trend of drought in Shaanxi Province from 2071 to 2100 was predicted. [Result] The simulated value of drought frequency in reference years could simulate the distribution of drought well, namely drought frequency was high in the north and low in the south; annual mean frequency of drought above second grade decreased gradually from north to south in future, and it was the highest in northern Shaanxi (above 4 times) and lowest in southern Shaanxi (below 2.5 times); drought frequency in future went down in northern Shaanxi from southern Yulin to Yan’an, eastern Guanzhong (including Weibei) and the west of southern Shaanxi, while it went up in the north of northern Shaanxi, Qinling Mountains and Shangluo region in western Guanzhong. [Conclusion] The study could provide theoretical references for the research on the change trend of drought in Shaanxi Province in future.

Analysis on Temporal-spatial Distribution and Change Trend of the Temperature in Beibei District

[ Objective] The research aimed to analyze temporal-spatial distribution and change trend of the temperature in Beibei District. [ Method] Based on temperature observation data at 6 ground meteorological observatories of Beibei District from 1951 to 2010, EOF and linear trend method were used to analyze temporal-spatial distribution and change characteristics of the temperature in Beibei District in recent 60 years. [ Result] Tem- perature in Beibei District in recent 60 years overall presented rise trend, and average rise velocity was 0.045 ~C/10 a. Temperature rise in autumn was the most obvious, while summer temperature presented decline trend. Average temperature presented gradual rise trend from January to July and gradual decrease trend from August to December. Seen from spatial distribution, temperature in the whole district was higher in the west and lower in the middle. Abnormal spatial distribution of the average temperature in the whole district mainly had consistent higher （lower） type, south- north reverse type and east-west reverse type. [ Condusionl The research provided theoretical basis for effective disaster prevention and reduction in the zone.

Analysis on Change Trend and Influencing Factors of Natural Resource Utilization of Community Farmers around the Habitat of Giant Pandas

The habitat of giant pandas borders the living areas of farmers in surrounding communities. Due to the low level of economic development and resource used method, the life of community farmers depends on the natural resources of the habitat of giant pandas. Analyzing the natural resource utilization of farmers in communities around the habitat of giant pandas is conducive to formulating more reasonable management policies and protecting the habitat of giant pandas more effectively. Based on the field survey data, this paper classifies the main ways of community farmers using the natural resources of the habitat of giant pandas, counts the quantity of resources used and analyzes their change trends. On this basis, this paper selects indicators, constructs a model and analyzes the main influencing factors affecting the natural resources utilization of community farmers from three aspects: the individual characteristics of household heads, the family characteristics of community farmers and the residence characteristics of community farmers.

Preliminary Studies on Evaluation and Change Trends of Dominant Components in New Types of Tobacco Sheets by Thick Pulp Process

[Objectives]This study was conducted to deeply understand the effects of production process on the quality of new types of tobacco sheets with different flavors.[Methods]Based on the pilot production process of thick pulp method,four different flavors of tobacco sheets were sampled at several links in the production process,for the detection of the contents of the main components in the samples,including propylene glycol,glycerol,menthol and glyceryl triacetate,so as to explore the change trends of various components in the thick pulp process.[Results]The change laws of propylene glycol and glycerol contents had a very high similarity,showing a trend of first decreasing and increasing then.The changes of menthol content and glyceryl triacetate content were greatly affected by the specific flavor formula.As one of the indexes of the new tobacco evaluation system,the alcohol-to-ester ratio data need to be further improved in the actual production and application process.[Conclusions]This study provides basic data support for improving the quality of tobacco sheets.

Changes of coastline and tidal flat and its implication for ecological protection under human activities: Take China’s Bohai Bay as an example

The change processes and trends of shoreline and tidal flat forced by human activities are essential issues for the sustainability of coastal area,which is also of great significance for understanding coastal ecological environment changes and even global changes.Based on field measurements,combined with Linear Regression(LR)model and Inverse Distance Weighing(IDW)method,this paper presents detailed analysis on the change history and trend of the shoreline and tidal flat in Bohai Bay.The shoreline faces a high erosion chance under the action of natural factors,while the tidal flat faces a different erosion and deposition patterns in Bohai Bay due to the impact of human activities.The implication of change rule for ecological protection and recovery is also discussed.Measures should be taken to protect the coastal ecological environment.The models used in this paper show a high correlation coefficient between observed and modeling data,which means that this method can be used to predict the changing trend of shoreline and tidal flat.The research results of present study can provide scientific supports for future coastal protection and management.

Metropolitan resources efficiencies,change trends and causes in China under the goal to build an international metropolis

The metropolitan resources comprehensive efficiencies （also called comprehensive technical efficiency, short for CTE, thereafter）, change trends and causes are investigated using DEA and Malmquist index models, respectively, in China during the period 1990–2006. Firstly, the DEA model results show that the metropolitan CTE was just fair to middling with the characteristics of almost declining from the Eastern Coastal to Western China, and only few metropolises were DEA efficient. Secondly, the results also show that the PTE was correlated with the urban population sizes of metropolises negatively, and the SE correlated positively with the urban population sizes of metropolises in 1990, 2000 and 2006, that is, with urban population sizes getting larger the corresponding PTE was decreasing accordingly, and the SE was increasing consequently and the increasing rate was smaller with the scale increase. Thirdly, the influencing factors of metropolitan efficiency were SE and PTE in 1990 and 2000, respectively. But the PTE became the predominant influencing factor with the rapid expansions of built-up areas and population scales of metropolises in 2006. Fourthly, the Malmquist index results show that the CTE change trends were increasing weakly, the technological change trends were declining, and the TFP change trends were declining obviously during 1990–2006, in which they were all increasing during the sub-period 1990–2000, and all decreasing during the sub-period 2000–2006. Fifthly, the Malmquist index results also demonstrate that the CTE change trend was increasing weakly in the Eastern Coastal China, declining in Central China, and declining evidently in Western China. And with the urban population size increasing the increasing trends of SE became weaker and weaker. And the main causes for the CTE being not too high and its change trends and TFP change trends being increasing weakly lie mainly in the technological degeneracy and PTE change trends declining significantly during 2000–2006. Finally, the analyses show that the China’s metropolitan population boom and the rapid spread of built-up area had really caused their resources efficiency losses.

Trend of Salt Lake Changes in the Background of Global Warming and Tactics for Adaptation to the Changes

Salt lakes are a mirror of climatic changes and provide holographic records of environmental changes of lakes. According to a study of geological hazards in typical salt lake areas in China and other regions, the authors explain how geological hazards in salt lake areas are caused by natural agents and how humans can seek benefits, avoid hazards and reduce losses on the premise that they have monitored and mastered the trend of salt lake changes in advance and even can store flood and recharge water in lakes and extract saline resources. The climate in western China is probably turning from warm-dry to warm-moist. The authors analyze the change trend of salt lakes sensu lato (with salinity≥0.3 wt% (NaCl)eq) and salt lakes sensu stricto (with salinity ≥3.5 wt% (NaCl)eq) in China in such climatic conditions and distinguish three types of salt lake areas (i.e. lake water rising type, lake water falling type and lake water rising and unstable type) according to the characteristics of lake water rising and shrinking. In order to conform to the climatic and lake changes in China's salt lake areas, the authors propose to add and improve hydrological and meteorological observation stations and integrate observations with remote sensing monitoring in important salt lake areas and set up multidisciplinary and interdepartmental basic projects to monitor and study recent climatic and environmental changes in salt lake areas of western China. Moreover, it is necessary to build additional flood-control and drought-preventing water conservancy facilities in key salt lake areas and work out measures for ecological protection in salt lake areas. Full consideration should be given to the influence of flooding when building saltfields and implementing capital projects.

The Influence of the Changes in Social Trends of Thought in Japan

The social trend of thought is the trend of thought that is of extensive influence formed in a certain period of time in a given society. It o-riginates from the changes in international environment and domestic social situation, reflecting the interests and demands of a given group of people and producing a great influence on the foreign and domestic policies and the future trend of the society. One prominent feature of

Variation Trend of Total Solar Radiation in Nujiang Basin in Recent 30 Years

Based on the data of sunshine duration,cloud cover and relative humidity from 9 stations in 1981-2008,the spatial and temporal distribution and change trend of total solar radiation in river valley basin of Nujiang were analyzed,as well as its impact factors.The results showed that annual solar radiation decreased obviously in Nujiang basin from 1981 to 1997,with the rate of-161.1 MJ/(m2·10 a),while it went up after 1997 at the rate of 111.3 MJ/(m2·10 a).Annual total cloud cover showed significant decrease trend with the rate of 1.8%/10 a,but annual low cloud cover increased at the rate of 3.2%/10 a.Contrary to the change trend of annual solar radiation,relative humidity rose at the increase of 3.1%/10 a from 1981 to 1997 and decreased significantly at the rate of 5.6%/10 a in 1997-2008.The change of water vapor pressure was consistent with relative humility change.Low cloud cover was the main impact factor of total solar radiation and had a negative correlation with total solar radiation.

气候变化对青藏高原河流源区径流的影响

The Tibetan Plateau(TP)is the headwater of the Yangtze,Yellow,and the transboundary Yarlung Zangbo,Lancang,and Nujiang Rivers,providing essential and pristine freshwater to around 1.6 billion people in Southeast and South Asia.However,the temperature rise TP has experienced is almost three times that of the global warming rate.The rising temperature has resulted in glacier retreat,snow cover reduction,permafrost layer thawing,and so forth.Here we show,based on the longest observed streamflow data available for the region so far,that changing climatic conditions in the TP already had significant impacts on the streamflow in the headwater basins in the area.Our analysis indicated that the annual average temperature in the headwater basins of these five major rivers has been rising on a trend averaging 0.38℃-decade^(-1) since 1998,almost triple the rate before 1998,and the change of streamflow has been predominantly impacted by precipitation in these headwater basins.As a result,streamflow in the Yangtze,Yarlung Zangbo,Lancang,and Nujiang River headwater areas is on a decreasing trend with a reduction of flow ranging from 3.0-10^(9)-5.9-10^(9) m^(3)·decade^(-1)(-9.12%to-16.89%per decade)since 1998.The increased precipitation in the Tangnahai(TNH)and Lanzhou(LZ)Basins contributed to the increase of their streamflows at 8.04%and 14.29%per decade,respectively.Although the increased streamflow in the headwater basins of the Yellow River may ease some of the water resources concerns,the decreasing trend of streamflow in the headwater areas of the southeastern TP region since 1998 could lead to a water crisis in transboundary river basins for billions of people in Southeast and South Asia.

Water quality changing trends of the Miyun Reservoir

In order to simulate changes in the water quality of the Miyun Reservoir dueto continuous descent of surface water level, a 3-D ecological hydrodynamic model was developedthrough coupling the water quality analysis simulation program (WASP) with the environmental fluiddynamics code (EFDC). The model was then calibrated and verified. Four scenarios (S1, S21, S22 andS23) were simulated using the model. Results show that the water quality of the Miyun Reservoirunder conditions of low surface water level is apparently affected by different amounts of inflowand different total phosphorus (TP) loadings. The chlorophyll-a concentration might exceed 10 μg/Lin many areas of the Miyun Reservoir (This limitative value is seen as a critical value ofeutrophication) when large loadings of TP enter due to the amount of inflow increasing. Results ofscenario S23 indicate that control of TP loadings can decrease chlorophyll-a concentrationeffectively, and the water quality of the Miyun Reservoir will improve or retain its status quo.

The Marine Dynamics and Changing Trend off the Modern Yellow River Mouth

Topography around the Yellow River mouth has changed greatly in recent years, but studies on the current state of ma- rine dynamics off the Yellow River mouth are relatively scarce. This paper uses a two-dimension numerical model （MIKE 21） to reveal the tidal and wave dynamics in 2012, and conducts comparative analysis of the changes from 1996 to 2012. The results show that M2 amphidromic point moved southeastward by 11 kin. It further reveals that the tides around the Yellow River mouth are relatively stable due to the small variations in the tidal constituents. Over the study period, there is no noticeable change in the distribution of tidal types and tidal range, and the mean tidal range off the river mouth during the period studied is 0.5-1.1 m. However, the tidal currents changed greatly due to large change in topography. It is observed that the area with strong tidal currents shifted from the old river mouth （1976-1996） to the modem river mouth （1996-present）. While the tidal current speeds decreased continually off the old river mouth, they increased off the modem river mouth. The Maximum Tidal Current Speed （MTCS） reached 1.4 m s-1, and the maximum current speed of 50-year return period reached 2.8 m s-1. Waves also changed greatly due to change in topography. The significant wave height （H1/3） of 50-year return period changed proportionately with the water depth, and the ratio of Hi/3 to depth being 0.4-0.6. H1/3 of the 50-year return period in erosion zone increased continually with increasing water depth, and the rate of change varied between 0.06 and 0.07myr-1. Based on the results of this study, we infer that in the future, the modem river mouth will protrude gradually northward, while the erosion zone, comprising the old river mouth and area between the modern river mouth and the old river mouth （Intermediate region） will continue to erode. As the modem river mouth protrudes towards the sea, there will be a gradual increase in the current speed and decrease in wave height. Conversely, the old river mouth will retreat, with gradual decrease in current speed and increase in wave height. As more coastal constructions spring up around the Yellow River mouth in the future, we recommend that variation in hydrodynamics over time should be taken into consideration when designing such coastal constructions.

Spatial-temporal Changes of Vegetation Cover in Guizhou Province, Southern China

Guizhou Province is an important karst area in the world and a fragile ecological area in China. Ecological risk assessment is very necessary to be conducted in this region. This study investigates different characteristics of the spatial-temporal changes of vegetation cover in Guizhou Province of Southern China using the data set of SPOT VEGETATION(1999–2015) at spatial resolution of 1-km and temporal resolution of 10-day. The coefficient of variation, the Theil-Sen median trend analysis, and the Mann-Kendall test are used to investigate the spatial-temporal change of vegetation cover and its future trend. Results show that: 1) the spatial distribution pattern of vegetation cover in Guizhou Plateau is high in the east whereas low in the west. The average annual normalized difference vegetation index(NDVI) from west to east is higher than that from south to north. 2) Average annual NDVI improved obviously in the past 17 years. The growth rate of average annual NDVI is 0.028/10 yr, which is slower than that of vegetation in the country(0.048/10 yr) from 1998 to 2007. Average annual NDVI in karst area is lower than that in non-karst area. However, the growing rate of average annual NDVI in karst area(0.030/10 yr) is faster than that in non-karst area(0.023/10 yr), indicating that vegetation coverage increases more rapidly in karst area. 3) Vegetation coverage in the study area is stable overall, but fluctuates in the local scales. 4) Vegetation coverage presents a continuous increasing trend. The Hurst exponent of NDVI in different vegetation types has an obvious threshold in various elevations. 5) The proportion of vegetation cover with sustainable increase is higher than that of vegetation cover with sustainable decrease. The improvement in vegetation cover may expand to most parts of the study area.

Analysis of Season Change in Jiyang from Meteorological Standpoint

[Objective] The aim was to analyze changing characters of four seasons in Jiyang, providing references for farming and disaster prevention in the area. [Methed] Changing characters of initial time and lasting periods of four seasons in Jiyang for 30 years were analyzed from meteorological standpoint with weather information from 1981 to 2010 observed in surface meteorological observation in Jiyang. [Result] Recent 30 years, initial time of spring and winter in Jiyang were earlier than before, especially for spring. In contrast, initial time of summer and autumn were later, especially for autumn. In addition, periods of spring and winter declined and the latter changed more significantly. Meanwhile, periods of summer and autumn extended and rate of linear trend for summer period was 0.042 hou/year. [Conclusion] The research indicated that lasting days of summer extended significantly and of spring and winter shortened under the background of global warming.

Analysis on Change Tendency of the Precipitation Resource during Growth Period of the Conventional Crops in Plain Area before Taihang Mountains

[Objective] The aim was to study change tendency of the precipitation resource during growth period of the conventional crops in plain area before Taihang Mountains. [ Method] Based on daily precipitation data at Shijiazhuang meteorological station in recent 51 years, average rainfall dudng growth periods of the 9 kinds of conventional crops was obtained. Precipitation tendency dudng growth periods of the 9 kinds of conventional crops in plain area before Taihang Mountains was analyzed by Mann-Kendall nonparametric test. [ Result] Seen from rainfall during growth pedods of the different crops, rainfall was the least during the growth period of winter wheat, followed by summer corn. Rainfall during growth peri- ods of the cotton, oil plant, vegetable, fruit tree, potato, rice and legumes was more. Under different guaranteed rates, precipitation change also had difference. Rainfall change during growth periods of the wheat and corn was bigger, and rainfall change during growth period of the rice was smaller. Change degree of the precipitation during growth periods of the cotton, oil plant, vegetable, fruit tree and legumes was equivalent, while precipitation change during growth period of the potato was the biggest. Seen from change tendency of the precipitation during growth periods of the different crops, precipitation in the growth period of winter wheat was increasing at a speed of 0.62 mm/a. However, precipitation in growth periods of the other crops had a decreasing tendency. Precipitation in the growth periods of summer corn and legumes decreased at the same speed which was 2.11 mm/a, while precipitation in growth periods of the cotton, oil plant, vegetable, fruit tree, potato and rice decreased insignificantly. [ Con dusion] The study laid foundation for determination of the agricultural irrigation water and provided theoretical reference for regional agricultural water-saving.

Trends in extreme high temperature at different altitudes of Southwest China during 1961–2014

This study analyzed the trends in extreme high temperature in Southwest China based on the observed daily maximum temperature and average temperature data from 410 Chinese stations recently released by the China Meteorological Administration.The authors found that the trends in extreme high temperature at different altitudes of Southwest China exhibit staged variations during a recent 50-year period(1961–2014).The trends in mean temperature and maximum temperature also exhibit phase variation.All temperature-related variables increase gently during the period 1975–94,whereas they increase dramatically during the recent period of 1995–2014,with a rate that is approximately two to ten times more than that during 1975–94.In addition,the trends in mean temperature,maximum temperature,and the frequency of extreme high temperature in the low altitudes transit from negative to positive in the two periods,while they increase dramatically in the mid-and high-altitude areas during 1995–2014,the well-known global warming hiatus period.In particular,the maximum temperature increases much faster than that of average temperature.This result implies that the regional temperature trend could be apparently different from the global mean temperature change.

Child Malnutrition In China-Present Status and Changing Trend

Halving the malnutrition of under five of years has been set as one of the goals to be achieved by the year of 2000 by Chinese government. So it is important to know the present status of child malnutrition and its trend of changing, in order to predict the possible outcome of the achievement of the goal. According to the Child Survey carried out by the State Statistic Bureau (SSB) in 26 provinces and autonmous regions and 3 municipalities in 1992, the prevalence of malnutrition of under five was: moderate and severe underweight, stunting and wasting were 17.9%, 34.7% and 4.7% respectively. But there are significant differences among urban and rural children and between different provinces. The highest prevalence rate usually occurred in the second year of life of the children, and this may be the result of inadequate weaning food provided to the children. As compared with the data collected in 1987 by SSB in 9 provinces and autonomous regions, an impressive improvement in underweight has occurred within these 5 years. The average declined prevalence was 20.5%. It is specially true for urban children. To stunting, there was also improvement for urban children but not in the rural, resulting and over all increasing of prevalence by 5.9%. To wasting, the prevalence for urban children was low and remained at the same level while there was some what increase in the rural. So, according to these results, with constant economic development and more attempt made in areas and groups at risk, the goal to decrease malnutrition in half in terms of underweight could be reached by the year of 2000