The development of small towns and its strategy are the important part of China’s new urbanization plan. Using the data of designated towns in Chinese counties, the article analyzes the spatial distributions of population and non-agricultural employment of small towns, and tests the impacts of non-agricultural employment opportunities on the population concentration in small towns by utilizing the quantile regression method. Through the analysis, we find that: 1) The population of small towns mainly concentrate on the east side of the Hu’s line, especially in the Harbin-Dalian area, the Chengdu-Chongqing area, the middle and lower reaches of the Changjiang River area and some southeast provinces. From 2009 to 2014, the population density of small towns has increased in general, while the share of population of small towns on both sides of the Hu’s line has kept stable. 2) The distribution of non-agricultural employment of small towns coincides with the distribution of population, while the distribution of employment is more concentrated. 3) Non-agricultural employment of small towns promotes the agglomeration of population. With the population growth in small towns, the influence of non-agricultural employment opportunities has become lower and the impact of employment in the tertiary industry would surpass that of the secondary industry. 4) In terms of the regional disparity, the impact of non-agricultural employment opportunities on the population concentration in small towns is more significant in the eastern region, followed by the central region and the western region.
Northeast China (Liaoning, Jilin and Heilongjiang) occupies 8% of total population in China. However, since the opening up and reforming, frequent population out-migration was on-going in Northeast China. The topic about population loss in Northeast China attracts more and more attentions. According to the census and sampling data after 2000, this research calculates the loss population in Northeast China. Based on the provincial scale and county-level scale data, the spatial pattern evolution of population loss is also figured out. The results are as follows. 1) Northeast China faced a continuous population loss during 2000-2015. And population loss in recent years has aggravated. 2) Northeast China is not the most serious population-losing region in China. 3) Most of counties or cities faced population loss in Northeast China. And population loss area in Northeast China was expanding. 4) The inactive economy development was the key affecting factor for the population loss in Northeast China. 5) The key issues that caused by population loss in Northeast China were population quality and demographic structure, such as brain drain, population aging, and population spatial polarization.This research aims to give some policy implications to the new round development in Northeast China.
This paper selects transportation, storage and postal industries to represent logistics, taking the carbon dioxide emissions as unexpected outputs, introducing the SBM-Undesirable model to measure the logistics industry efficiency of 30 provinces which are restricted by the low carbon (province-level municipality or autonomous regions) in mainland China in 2003-2014. Based on the pattern- process- mechanism framework system, this paper reveals the spatial evolution characteristics of logistics efficiency and its influencing factors: ① Under low carbon constraints, Chinese logistics industry efficiency in general is low, and the spatial distribution varies from zone to zone, characterized as the trend of the East > Central > West. ② Spatial distribution has some path dependency as those with high efficiency concentrate in the eastern coastal areas, which is represented by the evolution from "large agglomeration, small dispersion" to "banded cluster ", While the low efficiency areas focus on the northwest and southwest. ③ The space agglomeration of efficiency is comparatively low, tending to be equilibrium, while the high-efficiency zones are likely to move west and north. ④ There presents a significant spatial matching between the high-efficiency logistics industry and high-output industry. ⑤ The spatial evolution of logistics efficiency is affected by various factors, among which, the economic development, market environment, industrial agglomeration, informationization level and governmental regulation have a significant positive impact on logistics efficiency, while energy intensity has negative influence. By contrast, the level of opening-up and environmental regulation show no obvious effect on increasing the efficiency of logistics industry. All of these can provide reference for regional logistics coordinated development and improve logistics efficiency.
Through reviewing the literature and theory of tourism and trade relations at home and abroad, this article constructs an analytical framework and interactive mechanism model of tourism-trade interaction based on cultural association, explores the interaction mechanism and inducing pathway of trade and inbound tourism between the Ningxia and Arab countries. The results found that: 1) the tourism and trade interaction path hypothesis are verified at 5% confidence level, which has a positive impact on the relationship between the link path of knowledge association; trade association has a positive effect on the path of knowledge association and advertising; dissemination of information has a positive impact on the path of advertising effect. Business relevance, advertising effect and knowledge association have positive influences on trade behavior. 2) The direct path exists mainly between trade behavior and trade association,two indirect paths exist between relation linkage and trade behavior via Knowledge linkage, also between information dissemination and trade behavior via advertising effect; 3) The Interaction mechanism between tourism and trade of Ningxia and Arab countries has been found and verified. Also, the study found and validated the main path of tourism and trade interaction between Ningxia and the Arab countries: cultural and ethnic demand, business information transmission, the path of reducing transaction costs, the buying and selling market expansion, the construction of interpersonal relationship. Conversely path involves in improving the degree of convenience, being closer in perceived distance, eliminating transaction costs, building intermediary associations, and increasing tourism needs. The growth of trade has improved the convenience of tourism, further narrowed the perceived distance, eliminated transaction costs, constructed an intermediary relationship, and increased the demand for more tourism.
China’s photovoltaic (PV) industry has experienced rapid growth in recent years, gaining significant competitive advantage in the global market. This article investigated the global-local linkages in the photovoltaic industry in Wuxi, which facilitates the localization of imported technology to achieve economy of scale for production. Various firms along the value chain were interviewed, such as polysilicon producers, cell processers, module assemblers, production equipment suppliers, operation and maintenance service providers, as well as distributed PV users, to characterize the interactions between the global market and local actors. Conclusions point out that: 1) the development of Wuxi photovoltaic industry represents new form of technology transfer and industrial shift in emerging technology, in which the local learning in developing countries has a significant impact on the trajectory of the new technology. 2) The local industrial base enables the upscaling of production, which not only reduces the cost of photovoltaic technology dramatically, but also shapes the technological choice in world PV development. 3) While breaking through the bottleneck of production in the photovoltaic industry, Wuxi is now confronting the regime conflicts between distributed PV generation and traditional energy system. It calls for wider technological transition at the demands side.
Urban informality is a one of important research agendas in Global South, it is also considered as a new urban theory in 21st. The informal sector has been focused by scholars since 1973, and three broads approaches have been founded, that the dualism approach, Neo-Marxism approach and neoliberalism approach.This paper used the critical governance approach, which founded in 21st and emphasized on state power and institution at determining informality. Based on this approach, Chang’an Town of Dongguan City in the Pearl River Delta was choose, to research the prevailing informal phenomenon in cities of China— the informal land use practice, its emergence roots, pattern of manifestation and the relationship with institutional innovation since 1978 with qualitative methods. Our research findings include that at the period of lack of national land institution, the state and government actively supports and promotes the informal land practice when it produces new strategic knowledge. At the period of national land institution be founded, the local government utilizes and tolerates the informal land practice when it serves development. At the period of institutional innovation driven by local government, the informal land practice was overcame by government and the informal land be formalization when important economic and political interests are prevailing and more legal certainty is needed. The informal land practice and informal land institution are the seeds of formal land institution in PRD, when it produces new strategic knowledge, and serves urban development, the state and local government would make it formalization, and become institutional innovation.The mode of land institutional change in PRD has been turned form above to below. Some informal practice may be prohibited, and the informal institution would be fade, but we should pay more attention on informal practice and informal institution from below in the future.
In the context of economic globalization, connections between different cities and regions become much closer, which calls for intensive regional cooperation on the increasing-intersected regional affairs. Based on the framework of political-economy analysis, this article sorts out the changing context and the structure of major administrative bodies at horizontal and vertical levels in the Yangtze Economic Belt, and it evaluates the development levels of regional cooperation in the whole economic belt, lower, middle and upper reaches, respectively, in terms of cooperation structures, cooperative subjects and cooperative forms. In general, there are several regional cooperation patterns emerging in the Yangtze Economic Belt because of the huge regional differences of economic development and marketization levels, as well as the complicated Yangtze water-related governance affairs. The most developed subjects of regional cooperation among the 11 province-level units are located in the flood control, customs clearance policies, and quarantine. However the necessitated regional cooperation in the water resources and environment management, waterfront and port management, infrastructure construction and management, and ecological compensation and relevant platform of information-sharing are still under developed and lag behind the needs of integrated social and economic development in the economic belt. Comparatively, regional cooperation is at the highest level of development among Shanghai, Jiangsu and Zhejiang in the lower reaches, and multi-level coordination mechanisms have been established to fulfill their agreements on many subjects, such as tourism and transpiration building, etc. The development level of regional cooperation in the upper reaches is higher than that in the middle reaches. In the upper reaches, regional cooperation is concentrated between Chongqing and Sichuan and several regional projects have been co-built because of their rooted similarities in cultural and historical background, as well as the promotion of central government. Lastly, regional cooperation is hampered among the four provinces in the middle reaches because there is lack of a strong economic center to drive the cooperation as that in the lower reaches, and they also have more incentives to compete for attracting industrial transfer from Eastern China than to cooperate for regional govenance affairs.
Taking 336 cities across China as research subject, this study employs Kernel Density Estimation (KDE) and Exploratory Spatial Data Analysis (ESDA) to analyze and discuss the spatial-temporal evolution and influencing factors of urban land economic density disparity in prefecture-level cities of China from 2001 to 2014. The results show that: ① Urban land economic density in prefecture-level cities of China increases, the average value increased from RMB 47.69 million per km2 in 2001 to RMB 1.5375 billion per km2 in 2014, with increasing regional disparity. ② Urban land economic density in prefecture-level cities of China displays significant global positive spatial autocorrelation, and neighboring cities interrelate, showing the spatial agglomeration of "high- high" or "low-low". From the LISA map, the spatial cluster of urban land economic density can be divided into high level and equally regional type, type of collapse, type of polarization and lower level and equally regional type, while the stability of the spatial distribution of various clubs are differ. ③ Cold spots and hot spots of the urban land economic density in prefecture-level cities of China distribute stably, showing the pattern of "hot east and cold west" on the whole, hot spots mainly lie in Beijing-Tianjin-Hebei region, the Yangtze River delta and the Pearl River delta; While most middle and west regions locate in the low value cluster, belonging to the cold spots or second cold spots of urban land economic density. ④ Natural conditions determines the supply ability and development potential of urban land, which is the basic factor for the disparity of urban land economic density in prefecture-level cities of China. Additionally, the level of regional economic development, the policies of regional economic development and land use management also have a certain influence on the disparity of urban land economic density.
Jiangsu is the first province to enter the aging society, and aging system has become one of the important topics for scholars in various fields to explore the aging system in China. Based on township-scale data in the 2000 and 2010 censuses, this study analyzed the spatial variation characteristics of population aging. The results are as follows. Firstly, the population aging of Jiangsu Province was characterized by “E” shaped structure. In the 10 years, the elderly population in the north of Jiangsu was growing rapidly, aging phenomenon has become increasingly prominent, the population aging in the south of Jiangsu has slight change and grow slowly, in the middle of Jiangsu was growing at a high speed. The differences of regional aging types change significantly, south of Jiangsu change from the early stage of the elderly to the late stage of the elderly, the middle of Jiangsu change from the middle stage of the elderly to the super aging stage, the north of Jiangsu change from not aging to the middle stage of the elderly. “Township-Street” inverse dual structure become prominent, the level of street is lower than the level of township. Secondly, the effect of spatial agglomeration is further strengthened, spatial development is not balanced. Nantong is the hottest zone which expand to northwest, and the cold zone evolve toward to Southeast then meet in the Nanjing metropolitan area and Suzhou Wuxi Changzhou metropolitan area. The degree of spatial variation is enhanced. The structural factors are the main reasons of spatial variability. The random factors are enhanced. Thirdly, the not aging, early stage of the elderly showed the opposite of the center of gravity migration trajectory to the middle stage of the elderly, the late stage of the elderly. The not aging, middle stage of the elderly, late stage of the elderly have the diffusion phenomenon, the early stage of the elderly has the polarization phenomenon. The formation mechanism is mainly due to natural factors, economic factors and social factors.
Taking Jiangsu Province as the research object, based on the geographic data of banks on the network platform, using the methods of nearest neighbor index, Ripley's K function and multiple linear regression analysis, this article respectively studies the spatial distribution characteristics of the 5 major commercial banks, agricultural financial institutions, small and medium commercial banks, local banks of Jiangsu and foreign banks, and reveals the influencing factors of location choices of banks. The results show that, the spatial distribution of banks in Jiangsu Province is obviously denser in the south than in the north on the whole. The spatial clustering is characterized by "dense in urban areas and scattered on periphery". Different types of banks are different in terms of functional orientation and market positioning. Thus in addition to the common characteristics in urban area, the density and service range are different in the peripheral area. The proportion of urban built-up area, population size, regional per capita GDP, the number of industrial enterprises above designated size, the urbanization rate and the proportion of the output value of the secondary and tertiary industries are the main factors influencing the location selection of the bank, but their influences vary depending on the nature of different banks. The 5 major commercial banks tend to be located in large-populated, highly urbanized cities, while the agricultural financial institutions are more dependent on agricultural population factors. Small and medium-sized commercial banks prefer to be located in developed areas where the secondary and tertiary thrive. The number of industrial enterprises above designated size has a significant impact on the layout of Jiangsu local banks, while foreign banks are mainly distributed in open cities that are rich in foreign capital. The influence of institutional factors, such as the administrative level and the nature of cities, on the location selection of banks is not prominent.
Urbanization is closely related to transportation infrastructure development. On the basis of depth analysis of the internal transmission mechanism, using the data of social economy and actual road network in Yunnan Province from 2000 to 2014, by means of ArcGIS spatial analysis, transportation superiority model and coupling coordination model, the coupling coordination degree between county urbanization and transportation superiority in Yunnan Province was measured from time and space dimensions, and the changing situation and the characteristics of spatio-temporal cooperative evolution were analyzed. The results show that: 1) There are both positive and negative feedback relationship between urbanization and transportation infrastructure, both of them promote each other, but also restrict each other; The lag of infrastructure construction, the dualistic structure system of urban and rural areas and the sprawl of urban space are the main factors that lead to the spatial difference of coupling and coordination. 2) The overall level of urbanization in Yunnan Province is generally low from 2000 to 2014, although the region has been improved to varying degrees, about 90% counties are in the initial stage of urbanization. County urbanization pattern is basically stable, and the high value of urbanization is still dotted in some counties in Kunming, Dali, Xishuangbanna, Dehong, Red River and other cities, and the rest of the counties are at a lower level of urbanization. 3) The overall level of transportation superiority in Yunnan Province is increasing year by year, and the spatial heterogeneity is significant. From the “Yunling mountains-Yuanjiang Valley” as the boundary, transportation superiority of Eastern Yunnan Plateau is significantly higher than that of the Hengduan Mountains in western area, and the most obvious characteristic of gradient is in the Yuanjiang valley; The transportation superiority in Central Yunnan Province is generally higher than that in the periphery region, and both the high and the low value areas show strong spatial agglomeration. 4) During the study period, although the level of coupling coordination between county urbanization and transportation superiority in Yunnan Province has been greatly improved, the overall coordination degree is low, and the spatial differentiation phenomenon is still prominent. The coordination degree of the middle and eastern counties in Yunnan is higher than that in the northwest plateau, and the spatial coupling coordination degree shows a decreasing gradient trend from east to west; Among them, The high values of the coupling coordination degree are mainly distributed in the central Yunnan Urban Agglomeration and the sporadic counties (cities and districts) in the northeast of Yunnan Province, and the coupling coordination degree of the low value areas are concentrated in the northwest of Yunnan plateau mountain and Diqing Tibetan etc; The spatial distribution characteristics of the middle and high value counties (cities, districts) in the coupling coordination degree are basically identical with the layout of the highway skeleton network in Yunnan Province.
In this study, twenty seven sets of the <63 μm fine-grained subsamples from fluvial sand, floodplain muddy silt, sandy paleosoil and aeolian sand, respectively, in Dumeng Sandy Land, were collected and analyzed for major, trace elements and REE as well as Sr-Nd isotopic compositions to evaluate their source-area chemical weathering and sediment recycling, and to infer their contribution to aeolian dust. It can be concluded, based on low values of chemical index of alteration (CIA=48 to 56, mean value of 52), combined with A-CN-K and A-CNK-FM diagrams, that Dumeng Sandy Land was subjected to weak degree of chemical weathering. The relatively high values of index of compositional variability (ICV=0.95 to 1.2, mean value of 1.05) suggest an immature source. It follows from Zr/Sc vs. Th/Sc plot, integrated with CIA vs. WIP and MFW plots that the majority of fluvial sediments are characterized by first-cycle sediment, sourced from weathering-eroding products of intermediate to felsic rocks in eastern Great Xingan Mountains by transportation of NenJiang River and its tributaries. The paleosoils have the identical first-cycle fingerprints to fluvial sediments, suggestive of their soil parent material being fluvial sediments, consistent with field observation. The good sediment recycled signature, however, characterizes aeolian sands, suggesting that these aeolian sands were derived in situ from fluvial sediments. The integrated provenance tracing plots, involving the ratio of immobile elements, REE and Sr-Nd isotopic composition, in combination with vegetation and geomorphy feature, consistently suggest that Dumen Sandy Land bears a poor geochemical affinity with aeolian dust, indicative of its very little contribution to atmospheric dust to the eastern and central NE Plain.
Mountainous runoff is very important to the inland river basin in Northwest China, because it is related to the oasis ecological environment security and the social and economic sustainable development in the middle and lower reaches of the basin. Therefore, more and more studies are focused on the changes of mountainous runoff under the climate change in this region. The Shule River is one of the three largest inland river in Hexi Corridor, Gansu Province, Northwest China. Based on the runoff data at Changmabu hydrological station and the meteorological data of the Shule River Basin during the period 1958-2015, this article analyzed the characteristics of mountainous runoff of the Shule River Basin and its response to the climate change. The trend of mountainous runoff is analyzed by the line trend method. The mutation of mountainous runoff is analyzed by the Cumulative departure method. Morerover, the evapotranspiration is calculated by the Takahashi formula, and the relationships between mountainous runoff and climate factors are analyzed by the Correlation and Sliding correlation method. The main results were obtained as follows: In general, the mountainous runoff of the Shule River Basin presents an increasing trend in the research periods, and this trend was more obvious since the late 1990s, however, it is declined slowly in recent years. Moreover, the runoff series appears an obvious mutation in 1997. Finally, the correlation analysis shows that precipitation was the main control factor for the mountainous runoff changes. At the same time, the increased snow and ice melt caused by the rising temperature was the main reason for the changes of mountainous run off in recent years. In a word, the variability of runoff depends on the comprehensive impact of the climate factors for the effect of each factor is inconsistent in different stage.
The frequency of extreme climatic events is increasing under the background of climate change, which leads to a significant impact on production and livelihood. Temporal and spatial distribution characteristics of extreme temperature and precipitation indices had been analyzed using Mann-Kendall test and Kriging interpolation, and the relationships between trend magnitudes of climate extremes and elevations were also discussed based on daily temperature and precipitation data from 33 meteorological stations over the Huaihe River Basin from 1960 to 2014. The results showed that: 1) the cold indices (FD0, ID0, TN10p, TX10p and CSDI) showed significantly decreasing trends; FD0 and TN10p decreased by -4.14 and -1.76 days per decade respectively. The warm indices (TN90p, TX90p, SU25, TR20 and WSDI) exhibited increasing trends; TN90p, TR20 and SU25 increased significantly by 3.01, 1.99 and 3.18 days per decade, respectively. Diurnal temperature range (DTR) showed a significant downward trend because of the minimum temperature increases larger than the maximum temperature. 2) No significant changes for extreme precipitation indices were observed over the past 55 years. PRCPTOT, R10 and R20 showed a slow downward trend, while RX1day, RX5day, as well as the SDII showed a slowly rising trend. 3) From the spatial distribution characteristics of temperature indices, FD0, TN10p, TR20 and TN90p showed significant variations over the most area of the basin; FD0 and TN10p decreased from the center region to the northeastern and southwestern region of the basin; TR20 and TN90p showed the largest increasing rate in the center part of the basin. Considering the extreme precipitation indices, no indices exhibited significant changes over the whole basin. 4) No significant relationships were observed between temperature, precipitation extremes and elevation based on the data captured from current meteorological stations. This indicated that the elevation dependency is deficiency in the Huaihe River Basin, China. 5) The variation trends of extreme temperature and precipitation indices in the Huaihe River Basin are approximately between the Yellow River Valley and the Pearl River, which showed the characteristics of the North-South transition zone. This study is of great significance to the sustainable development of water resources in the Huaihe River Basin, the construction of the South-to-North Water Transfer Project and the disaster prevention and reduction.
Under global climate warming, the frequent occurrence of extreme weather events has caused great economic losses, thus, as a scientific issue, researching on regional extreme climate change has remarkable significance. In this study, based on the daily temperature data of 11 meteorological stations from 1971 to 2014 in Inner Mongolia Daxing’anling forest region, analyzed the spatio-temporal characteristics of extreme hot weather, extreme cold weather and the biological growth season in recent 50 years, using the methods of Linear trend, Morlet wavelet, Mann-Kendall and Kriging interpolation. The results are as follows: In the last 44 years, the extreme hot temperature days and biological growth season were on the rise significantly(P<0.001), the rates of change were 7.6 d/10a and 3.1 d/10a respectively, especially increased with larger scales after the middle of 1980s. However, the extreme cold temperature days showed a downward trend(-5.4 d/10a), and after the mid 1990s, the trend became weaker. From the perspective of spatial distribution, the extreme hot weather days and biological growth season showed an upward trend at all sites, while the extreme cold weather days showed a downward trend, but the spatial difference was obvious. The extreme minimum temperature has 27 a, 18 a,11 a, 7 a periodic changes, that played a major role in the extreme low temperature weather, of these, 27 a cycle time scale was considered the first main period. The extreme maximum temperature contained the cyclical in a number of different time scales, the 28 years periodic oscillation was most strongly, was considered the first main period, and played the most significant effect on the extreme maximum temperature, over the next 8 years (2019-2026) extreme hot weather may be more frequent. The growth season mainly was affected by 28 a cycle time scale, and in 2015-2022 with a higher growth period. This result will provide a powerful scientific basis for revealing extreme climatic changes in high latitudes in China, and provide reference for forestry production, agricultural production and disaster prevention and reduction in Inner Mongolia Daxing’anling forest region.
Impervious surface is considered as an indicator of urban ecological environment and impervious surface area data, which is important to urban planning and environmental and resources management. The reconciliation between the V-I-S model and LSMA provided a continuum field model, which offered an alternative, effective approach for characterizing and quantifying the spatial and temporal changes of impervious surface. In this article, we extracted the impervious surface information from Landsat images of 2002, 2009 and 2015 within the metropolitan area of Wuhan by a fully constrained linear spectral mixture model based on the vegetation-impervious surface-soil (V-I-S) model. Here, gradient analysis was adopted to analyze spatial distribution and four different landscape indicators were chosen to analysis landscape patterns dynamics of impervious surface from 2002 to 2015. Rusults of this study were as follows: The average impervious surface coverage of Wuhan was respectively 27.53% in 2002, 34.65% in 2009 and 40.51% in 2015, which showed a trend of rising. The areas of high impervious surface coverage value of Wuhan are mainly distributed along the Yangtze River and Han River as well as in some secondary centers such as Jiangxia and Hannan and that of low value are mainly distributed in suburban counties. For the period 2002 to 2009, areas of new impervious surfaces mainly formed around existing urban areas and mostly concentrated in circumjacent areas of Wuhan Economy and Technology Development Zone and Donghu New Technology Development Zone as well. After 2009, it was observed that the distribution of new impervious surfaces was scattered. The impervious surface coverage of main urban area is obviously higher than new urban district, but the impervious surface coverage of new urban district increase rapidly. With the increase of the distance to downtown, impervious surface coverage tended to be stable after progressive decrease. The range of 10km outside the third-ring road and 4 km within it was the area of largest increment of average impervious surface coverage. Landscape pattern analysis results showed that natural surface and area of very high density impervious surface had a low degree of fragmentation, strong spatial continuity and a very simple shape. Conversely, low density and medium density impervious surface area had a high degree of fragmentation, weakest spatial continuity and a very complex shape. The patches shape shows that natural surface had a high dominant position in 2002, but after that changed to high density impervious surface after 2015.
Modern pollen assemblages in the arid regions and consequently the fossil ones, considerably differ from the modern vegetation and palaeo-vegetation caused by various dispersal agents, depending on the sampled location and the geographical conditions. Fluvial flow and wind are the main agents to influence the pollen transportation in the arid regions. Exotic pollen carried by these two dispersal agents could interrupt the relationship between the pollen and vegetation. Therefore, the influences of these two dispersal agents on the pollen transportation must be taken into account as reconstructing the palaeo-vegetation and the palaeo-environment via fossil pollen data. Moreover, a distinction should be made between the local pollen, which indicate the conditions around the sapling sites; and the exotic pollen, that rather represent far away vegetation, together with the energy and possibilities of the dispersal agents. To do this, we collected 8 riverbed samples and 7 surface soil samples for pollen analysis across the middle reach of Heihe River, located in the Hexi Corridor. The results showed that wind affects the pollen transportation relatively weak, percentages of exotic pollen transported by wind are usually under 10%. The surface soil pollen assemblages can reflect the distribution of local vegetation. While fluvial flow could carry more pollen from the upland to the study area and strongly affect the pollen transportation. Notably, the percentages of exotic pollen transported by fluvial flow reach up to 39.4%, and exotic pollen becomes the dominance of the pollen assemblages, leading an inaccurate relationship between the pollen assemblages and the local vegetation. The pollen assemblages of fluvial sediments mirror the distribution of upland vegetation and local vegetation.
There exists lake-land breeze that wind blowing onshore from lake to land during the day and offshore in the evening around lake area, due to differences in air pressure mainly caused by different heat capacities between lake and land. Generally speaking, the closer to the lake, the more remarkable the lake climate effects. For studying the lake climate effects, it is not only important for understanding the characteristics of local climate and atmospheric circulation, but also helpful for analyzing and forecasting meso-and micro-scale weather processes. Miyun Reservoir (MYR), which located at 15 km north of Miyun District of Beijing city, is the largest artificial lake in North China. Up to now, there are seldom reports on the influence of MYR on local weather and climate. Based on hourly observation data obtained by 77 automatic weather stations surrounding MYR from 2011 to 2015, local climate effects of MYR were explored and discussed in the present work. The results showed that: 1) comparing with peripheral plains, climate effects of MYR were characterized by the facts that lower air temperature, higher humidity, slightly weaker wind speed and larger rainfall. As far as regional climate was concerned, the MYR had a modulate effect on the local climate and the spatial extent of the effect is about 10 km. The closer to the MYR, the more notable the MYR climate effects. 2) The MYR climate effects were mainly occurred in the summer, especially for temperature and rainfall. In detail, averaged air temperature was lower of 0.96℃ and averaged rainfall amount was higher of 13.3% in MYR than in the adjacent plains, where has the same elevation with MYR away from 10km. In addition, there were significant differences in diurnal variations of meteorological factors between the south and north regions of the MYR. 3) Excluding the impact of the large-scale background wind field, local wind presented the characteristics of monthly variation, i.e., mountain breeze was dominant from April to September, especially in summer; while in other months, valley breeze was more prevailing, especially in the wintertime. In general, annual averaged local wind speed was about 0.14 m/s in the east-west direction, which was slightly larger than that of 0.10 m/s in the north-south direction around the MYR. 4) In summer, there existed significant differences in wind vectors at the south and north regions of the MYR, due to the influence of local circulation. In most time of the whole day, component anomalies were usually in the same phase, while component anomalies presented out of phase at the south and north regions of the MYR. Lake-land breeze and mountain-valley breeze had the same/opposite directions at the north/south regions of the MYR, and thus these correspondingly formed the overlaying/counteractive effects. Due to lake-land differences in heat capacities and topography effects, lake-land breeze and mountain-valley breeze in the areas around MYR usually existed at the same time, which mainly caused the differences in seasonal and diurnal variations of meteorological elements at different locations around the MYR region.
Total factor productivity (TFP) is key for sustainable agriculture, the higher growth of TFP, the more output of agriculture sector. TFP index is often employed to measure growth in the total factor productivity and the source attributed to its growth, which theoretically is defined as the ratio of an aggregate output index to an aggregate input index. In previous literature, the agricultural TFP index has been widely used in different spatial scales of China, such as province regions scale and county regions scale, however, the analysis of agricultural TFP index in Chongqing is scarce. In addition, although the analysis of agricultural TFP index under constraint of resources and environment have been conducted in many studies, our knowledge about the impact of climate change on agricultural TFP growth is still limited, correspondingly the adaptation measures to climate change are also rarely discussed in previous studies. The aim of this study is to detect the spatial and temporal changes of total factor productivity in Chongqing agriculture, and explore the influence of climate change on TFP growth in Chongqing agriculture. The results show that: 1) Under the constraints of climatic factors, the value of TFP growth is relative lower but with more significant spatial heterogeneity, and the change of TFP growth can reflect the influence of climate change and technical change on agricultural production. 2) The drivers of TFP growth come from technical improvement, but negative factor of TFP growth come from mix efficiency change. 3) The high value of TFP growth focused on the western region of Chongqing, however, the lower value focused on the main city of Chongqing. 4) The extreme drought in 2006 led to a lower TFP growth of Chongqing agriculture, so agricultural adaptation measures to climate change should be taken for different regions of Chongqing. Our results can help policy makers identify where agricultural productivity growth is strongest and weakest, and thereby assist in illuminating specific policies and practices on supply-side reform of agricultural structure.
