Research on tourism hubs in China and abroad are based on transportation hubs,after which the basic theory about tourism hubs occurred and boosted study on the theoretical and practical development of tourism hubs. Tourism hubs originated from transportation hubs. Based on transportation hubs,tourism hubs provide tourists with tourism-related information,service and infrastructure,as well as well-rounded,seamless and accessible integration of all kind of transports which make tourist transfers and travel more convenient. Tourism hubs bridge tourism markets and destinations,but there are differences between them. The tourism resources are main attractions for tourists while tourism hubs strike to control the local tourism industry through tourist flows. The functions of gathering and scattering are key factors for tourism hubs which help to control tourist flows and the tourism industry. According to different practical functions and various development processes of international tourism hubs,we generalize their practices and divide them into two categories：hub-dominated tourism cities and hub-destination tourism cities. The development of international tourism hubs follows similar laws. Well-constructed hubs,especially the airport hub network will be helpful for tourism hubs to attract tourist flow. Tourism hubs benefit from their hub functions and control of local tourism industries. With the development of the tourism industry,tourist destinations and tourism hubs tend to mix together.
System Integration Research on the interaction of tourist flow and destination contributes to the theoretical framework of tourism system and settles issues on internal element relations,law of development and evolvement,forecasting,regulating supply and demand balance. Taking inbound tourism of Beijing,Shanghai,Guangzhou,Xi’an,Chengdu,and Kunming as research objects,we constructed a coupling evaluation index system for inbound tourist flows and destination. With application of a gray associative model,we conducted a quantitative evaluation of the coupling degree of inbound tourist flow system and destination system in the six cities from 1993 to 2012,and examined the coupling effect degree of system elements. We found that the velocity and quantity of tourist flow are the most important coupling dominant elements in inbound tourist flow system,while tourism service facility,personnel and destination economic environment are the most important coupling dominant elements in destination system. The coupling system between tourist flow and destination in these tourist cities has long been amelioration coupling. The fluctuation of coupling degree between the two systems is an inverted U in Beijing and Shanghai,and in the other cities coupling degree shows a downward trend. In the aspect of the coupling dominant elements in inbound tourist flow system,the differentiation of dominant elements in eastern cities is obvious,but in western cities the dominant elements are similar,showing tourist flow scale as the dominant element and other elements as supplementary. As for coupling dominant elements in the destination system,the natural,economic and social environment have stronger effects on system coupling in eastern cities,while tourism service facility and personnel and infrastructure have stronger effects in western cities. This indicates that enhancing the coupling quality of the systems needs to rely on the support of the overall environment of the destination. Hindered by poor geographical conditions and low levels of economic development,investment in core supply elements and media support elements on the destination system in western cities is still at a stage of increasing marginal returns.
With rapid urbanization in China,large areas of vegetated surfaces have been replaced by impervious built surfaces. The development of urban heat islands （UHIs）has recently become a critical environmental issue in many cities. Fortunately,trees and vegetation in an urban environment can greatly improve microclimates and mitigate UHI development by reducing summer air temperature. Although many recent studies have observed such ecosystem services as temperature reduction and humidity increase by urban green spaces,the relationship between community structure of urban green space and air temperature reduction and humidity increase remains unknown. This study investigated 24 typical green space communities and observed their role in temperature reduction and humidity increases,and the relationship between these roles and canopy density and green biomass. The results showed that green areas in Beijing reduce summer air temperature by 0.2~2.0
Cultivated land carbon sequestration as an effective supplement to the terrestrial ecosystem is recognized; however,research on the carbon sequestration function of cultivated land has been conducted from the perspective of ecology. For example, carbon uptake and carbon release of vegetation and arable soil and carbon balance in agro-ecosystems is often a focus and there is a lack of research into the carbon sequestration of cultivated land from the viewpoint of land science. Here we built a basic research framework for the carbon sequestration function of cultivated land use for the Huang-Huai-Hai Plain based on the carbon cycle process of cultivated land use system theory. Then the carbon sequestration function was evaluated from three aspects of carbon sequestration ability,carbon sequestration efficiency and carbon sequestration dominance. The results suggest that the carbon sequestration function of cultivated land use can be known from four aspects：natural carbon sequestration ability, ideal carbon sequestration ability,practical carbon sequestration ability and regional carbon sequestration ability. The carbon sequestration of cultivated land use systems of the Huang-Huai-Hai Plain is a carbon sink. The carbon sequestration efficiency and carbon sequestration dominance degree are 2.5 and 0.85 respectively. The carbon sequestration function of cultivated land use system plays an irreplaceable role on the Huang-Huai-Hai Plain,which should be a prominent function in this area. This study provides a new way of thinking about ecological function theory research for cultivated land,and support for promoting the ecological benefits of cultivated land,mitigating climate warming,and administering cultivated land ecology interregional compensation.
Quantitative estimation of carbon storage of terrestrial vegetation and its distribution can help to understand the regional carbon balance,and provide scientific basis for the management of emission reduction and sustainable development. According to GF-1 WFV satellite remote sensing images and synchronous field surveys conducted in 2015 in Fengning county,Hebei,China we established single curve regression models and multiple linear regression models of aboveground biomass for forest,shrub and grassland. Optical inversion models were selected to calculate vegetation aboveground biomass,and aboveground carbon density and carbon storage were estimated. Spatial distribution features of the study area were analyzed using GIS. We found that our multiple regression models had good inversion precision,which can be well applied to estimate vegetation aboveground biomass for the forest and grassland （R2 values respectively 0.528 and 0.777）. The exponential equation based on RVI was the best inversion model to estimate shrub aboveground biomass and the R2 value was 0.620. As at August 2015,the aboveground vegetation carbon densities were respectively 55.406tC/hm2,3.304tC/hm2 and 0.533 t C/hm2 for forest,shrub and grassland. Aboveground vegetation carbon storages were respectively 15.714TgC,1.016TgC and 0.080TgC for forest,shrub and grassland. The total aboveground vegetation carbon storage was 16.810TgC except for croplands,indicating that forest vegetation represents the main aboveground carbon pool. The vegetation carbon density in Fengning county increased, then decreased with rising of elevation. The vegetation aboveground carbon storage lies mainly at an altitude of 700~1500m.
In order to determine whether soil fractal dimension affects the growth of steppe plants,we analyzed the correlation between soil fractal dimension and plant biomass. Eighty-eight soil samples were collected in the Xilinhot area in 2012 and we used linear regression,correlation analysis and other statistical methods to analyze the relationship between soil fractal dimension and particle content,soil fractal dimension and plant biomass. We found that soil fractal dimension had a significant negative correlation with coarse sand content,no significant correlation with fine sand content,and an extreme significant correlation with silt and clay. To some extent,soil fractal dimension could reflect the content of soil particles,especially clay content;according to morphological characteristics and the ways adapted to the natural environment,grassland plants were divided into different functional groups,among life-form functional groups the biomass of perennial bunch grasses,semi-shrubs,annuals and biennials were positively correlated with soil fractal dimension （R was respectively 0.345,0.674 and 0.238） and indicates that soil fractal dimension probably impacts the accumulation of biomass in these three functional groups. Among functional groups of water ecological types,xerophytes and intermediate mesophytes had no significant correlation with soil fractal dimension,but xerophytes were positively correlated with clay particle content and intermediate mesophytes biomass was positively correlated with silt content. In view of the relationship between particle content and fractal dimension,the growth of these plants were positively correlated with soil fractal dimension. Perennial rhizome grasses,forbs,intermediate xerophytes and mesophytes had no significant correlation with soil fractal dimension.
As the core area in southern Xinjiang,local residents in the Tarim River Basin will affect its environment evolution. Taking the Tarim River Basin as an example,we investigated payment behavior of 1962 residents using the conditional value method to analyze ecological attitudes,ecological environmental externalities and quasi-public goods. We found that 60.3% of river basin residents in the sample area think the ecological environment has been improved,and 67.3% of residents believe that protective forest can conserve soil,conserve water,regulate climate and increase biodiversity. The cognitive degree of ecosystem service had the greatest impact on residents’ willingness to pay. Differences in family endowment,cognition of environmental value and psychological perception of climate change,cause the heterogeneity factors of residents’ willingness to pay. Downstream residents’ willingness to pay is an average 29.99% higher than that of upstream residents. Income level does not affect residents’ objective and rational cognition of ecological value. Residents with zero willingness were 11.9%,psychological ‘free rider’ and ‘lack trust in government to governance environment’ account for 61.9%. River downstream residents act as the most direct beneficiaries of environment improvement,the proportion of zero willingness to ecological environment protection is only 5.3%. Considering the heterogeneity of residents,local economic and social conditions,environmental evolution trends and resource allocation play an important role in improving the validity and reliability of CVM theory when assessing environmental value.
The recognition of factors affecting high seas fisheries development in China has very important meaning to the exploration of development pathways. The influences on high seas fisheries development in China are diverse and complex. On the basis of a great deal of relevant materials and expert-level discussion,17 factors affecting the development of Chinese high seas fisheries are detailed here and include aspects of the resource,market,technology,policy and external security. By building interpretative structural modeling （ISM）,the factors above were analyzed and the structure and inherent links among factors were determined using a hierarchical structure diagram. The results showed that these 17 factors were correlative and they established interpretative structural modeling along four layers. In the hierarchical structure,the surface direct influencing factors were the market distribution and the demand of catches,the market prices of catches and the improvement level of fish market circulation system. The middle indirect influencing factors were the technical level of fishing vessels and supporting facilities,the professional technical standard and abilities of fishermen,capability of product processing and development,working environment of fishing grounds,and exploring potential of new fish species. The root and basic influencing factors were high seas fishery resources,capacity of ocean fisheries resources investigation and evaluation,international system of high seas fishery resources management,national and local support policies of pelagic fisheries and the degree and level of high seas fisheries management countries’ participation.
In order to study the main influencing factors of farmers' behavior of straw treatment, so as to put forward the reasonable policy suggestions for the comprehensive utilization of straw, we constructed a system of farmer straw processing behavior using 473 surveys across Jiangsu, Zhejiang and Anhui provinces and Logit model, based on the theory of rational hypothesis of small peasant economy system. According to the results, straw burning behavior is mainly affected by the age of farmers, prohibition subsidy and farmer cognition of straw burning. Returning straw to fields is mainly affected by prohibition of policy enforcement, energy situation of family life, willingness and technical guidance of straw returning to fields. Straw selling is mainly affected by farmer willingness to sell and whether straw purchase sites are nearby. In order to improve the comprehensive utilization efficiency of straw, we should proceed from the following three points. First, we should continue to implement the prohibition policy of straw burning conducive to curb farmer straw burning behavior, and the government should strengthen communications to farmers about straw comprehensive utilization to help farmers better understand the comprehensive utilization of straw. Second, we should increase the development and promotion of straw comprehensive utilization technology to promote the comprehensive utilization of straw with the help of technical reform, and improve the support of corresponding policy. Finally, we should establish a sound system of straw storage and transport with the help of government, enterprise and three party organization so as to promote the industrialization and market development of comprehensive utilization of straw.
Resource-based regions have unique spatial characteristics because of mining development and excessive dependence on resource industries in regional economic development. Due to trends in regional economic spatial structure,logical organization and distribution of production cannot be configured in accordance with new resource disposition. Due to unbalanced development,regional economic differences become more apparent. It will inevitably lead to the formation and evolution of regional economic spatial differentiation. Here we analyzed the role of resource endowment,factor input,regional development strategy and policy,geographical location,industrialization,urbanization and information in economic spatial structure formation in the Central Plains Economic Region of China. Using ordinary least squares and geographic weighted regression we looked at county economic growth and influencing factors on spatial structure to determine dominant factors in the Central Plains Economic Region. The driving force of economic growth spatial differentiation is determined by the coefficient of variation method. We found that regional county economic growth has spatial association and strong spillovers. For example, the main driving forces of economic growth spatial differentiation are mining （18.78）,agriculture （13.43）and transport （7.79）. Mineral resource development and utilization promote formation around Zhengzhou as regional economic core circles. Mainly relying on agriculture to enhance the total economy as east Henan is poor. Transportation infrastructure strengthens the regional economic space and accelerates the pace of economic spatial agglomeration in the Central Plains Economic Region. This study provides scientific guidance when transforming regional economic spatial differentiation.
According to monthly precipitation data from 1960 to 2010 for 24 meteorological stations distributed in Kazakhstan in the Balkhash Lake Basin,average annual precipitation and precipitation using Kriging difference technology and SPI,Z and PDECI （aridity-wetness indexes）were used to study inter annual aridity-wetness change,aridity-wetness event frequency,aridity-wetness duration and aridity-wetness spatial distribution. The results showed that inter annual aridity-wetness events happened across the Basin,and under a time scale of three months as partial drought events usually occurred in February to April and partial moist events occurred from June to August. The duration of the moist event increased gradually after the 1970s; since entering 21st century the frequency of moist events has increased significantly. Currently,statistical results according to the three kinds of aridity-wetness indexes proved that the Basin is in a moist period. In a moist year in 1998,the Basin was “Southeast drought and west moist”; in a normal year in 2000 the Basin was “Northeast drought and southeast moist”;and in a drought year in 1978 the Basin was “South drought and west moist”. These research results reveal distribution changes in climate and environment in the area and provide references for protecting aquatic and land ecological environments of Balkhash Lake.
Based on ERA-Interim reanalysis data and Universal Thermal Climate Index （UTCI）,the spatial pattern and temporal variation in thermal comfort in China from 1979-2014 was investigated. The results show that annual UTCI decreases with increasing latitude for most of China and exhibits a circular distribution on the Qinghai-Tibetan Plateau. “No thermal stress” covers maximum area in summer,and minimum area in winter. From 1979 to 2014,the frequency of “no thermal stress” was highest over southern Yungui Plateau （>70%）and lowest for the Qinghai-Tibet Plateau（<10%）. Most regions to the north of the Yangtze River have seen extremely strong cold stress,especially over eastern Inner Mongolia,northern Northeast China（14%~32%）,and the Qinghai-Tibet Plateau（16%~40%）. Extremely strong heat stress has occurred over central and eastern China and the basin area in Xinjiang province,among which the eastern Tarim Basin has the highest frequency of more than 4%. From 1979 to 2014,annual UTCI show positive trends in northeastern China and negative trends in southwestern China,with the largest increase and decrease in the Yangtze River Delta（（0.6~0.8）°C/10y）and western Qinghai-Tibet Plateau（（-0.8~ -0.6）°C/10y）respectively. Summer UTCI has consistently increased across China,whereas the contrary is the case for winter UTCI. “No thermal stress” has become more frequent in northern China,and less frequent in southern China,with the largest frequency increase and decrease occurring over regions near the border between the eastern Qinghai-Tibet Plateau and Loess Plateau（（0.8~1.5）percent/10y）and southern Yungui Plateau（（1.5~2.8）percent/10y）. Extremely strong cold and heat stress have become increasingly frequent across the majority China.
Evapotranspiration is a key processes in water cycles and energy balance. In this study,evapotranspiration was estimated based on water-energy balance theory using hydrological and meteorological data from 71 typical catchments in China from 1960 to 2000. Sensitivities for evapotranspiration to precipitation,potential evapotranspiration and characterizations of the underlying surface （represented by parameter α）are further investigated in catchments classified by four groups：under all conditions without parameter α （group 1）,under all conditions with one parameter α （group 2）,under different climate zones （group 3）and different predominant land covers （group 4）. The results show that α at group 2 is 2.202,and smaller in humid catchments than arid catchments in group 3. α at forest catchments in group 4 are the smallest,followed by grass catchments and mixed catchments. The NSE of evapotranspiration estimation by the original Budyko equation is only 0.64 at group 1,which can be improved effectively by adding parameter α. The NSE of evapotranspiration estimation are 0.80,0.81 and 0.83 in group 2,group 3 and group 4,respectively. In particular, the NSE at forest catchments is 0.88. Evapotranspiration in group 3 is most sensitive to precipitation in arid catchments,followed by α and potential evapotranspiration,while it is most sensitive to α in humid catchments,followed by potential evapotranspiration and precipitation. In group 4,evapotranspiration is most sensitive to α in forest and mixed catchments,while it is most sensitive to precipitation in grass catchments. The results are helpful for water-energy balance modeling,hydrological predictions in ungauged basins and water management decision-making.
The hydrologic variability of the international river and its transboundary influences have become a worldwide concern. Analyzing the variation characteristics of runoff and its impacting factors could provide the basis for the reasonable utilization and management of transboundary water resources. Based on the discharge data of 6 hydrological stations and temperature and precipitation data at 64 meteorological stations in the Red River Basin,we analyzed multi-temporal scale changes of runoff,and the influences of climate change and human activities on runoff were discussed. We found that the intra-annual distribution of runoff was uneven and 80% of runoff was concentrated in the wet season （June to November）. Intra-annual distribution of runoff for tributaries was more uneven than in the main stream. Furthermore,the concentration period of runoff at all stations showed an advance trend. Especially,Manhao,Yen Bai and Ghen Ga station had advanced trends. Inter-annual variation was acute,with significant differences between wet and dry years. This shows that low water periods appeared from the mid-1950s to mid-1960s,high water period from the mid-1960s to mid-1970s,flat partial dry period from mid-1970s to mid-1990s,flat partial wet period from mid-1970s to 2002,and low water period after 2002. Mean annual runoff decreased in the past 50 years. Lixianjiang station showed a significantly decreasing trend. According to the results of R/S analysis,annual runoff will increase in the future. Wavelet analysis showed that annual runoff at Manhao and Lixianjiang stations had change periodicities of 4a,6~9a and 21~22a. Similarly,Son Tay station had a change periodicity of 8~10a and 21~22a. Significant change periodicities of 21~22a were found at the three stations. The most important factor causing decline of discharge in the Red River was precipitation. Human activity was also an important factor which influenced the intra-annual distribution of runoff; however,the impact of human activity on runoff was limited at an annual scale.
Based on precipitation and temperature data for the upper reaches of the Kaidu River Basin from 1958 to 2013 and MODIS （Moderate-resolution Imaging Spectroradiometer）snow product data MOD10A2 from 2001 to 2013,we investigated snow coverage dynamics and trends in different seasons and regions using linear regression analysis and non-parametric Mann-Kendall tests from 2001 to 2013. Trends in climate change between precipitation and temperature were analyzed over the past 50 years and correlation analysis between precipitation,temperature and snow coverage data was conducted. We found that all elevation zones show decreasing trends,except for B （2000~2900 m）for which the increasing trend was the main focus. In the whole study zone and all elevation zones except for D （3800~4794m）,changes in snow coverage are common single-peak curves in the whole year. The maximum value for snow coverage occurred in winter and the minimum in summer. However,D shows a double-peak curve. Its peak occurred in November and April,and the valley occurred in February. The increasing trend is significant and obvious for annual snow coverage of B in autumn. For other elevation zones,a decreasing trend is dominant. There is a central trend from A （1098~2000m）,C （2900~3800m）and D to B. Obvious correlations between snow coverage and precipitation in winter and temperature in spring are clear. There may be an increasing run-off and flood frequency in spring.
According to the theoretical framework of population-environment relationships,the dynamic stability of relationships between population size and waste water emissions was analyzed qualitatively. This data can help our understanding of future trends in water environments in China. Panel data of waste water,population size and other socioeconomic factors from the National Bureau of Statistics and five province-level panel regression models,in which the year interaction and slope-dummy interactions were constructed,were employed to decompose fixed effects and tempo effects from dynamic relationships between population size and the amount of waster water from 2003 to 2012. The slope-dummy interactions enable models to determine whether a national-level relationships between population and waste water emissions have remained stable,declined,or intensified in recent years. Results indicate that the population size has a large and stable positive association with the amount of waste water,which means that population size is one of the major pressures on water environments among several social drivers. The negative tempo effects reflect that the impact of population size on the amount of waste water is decreasing while the scale effect of population on waste water emissions was gradually substituted by structural effects. This dynamic analysis indicates that the tempo effects are decreasing annually. While the stable phase of relationships between population size and waste water emissions is approaching,population in tandem with other social drivers,remains an important consideration for research that addresses the human dimensions of changes on water environment. Policy making should take into account the dynamic impacts of population size on waste water emissions.
Chongling catchment is located in the northeast of Taihang Mountains. Based on precipitation event data from six observation points from 2005 to 2014 （April to October）in the Chongling catchment,temporal（annual,monthly,daily and hourly）and spatial characteristics of precipitation and other factors were analyzed using linear regression and Mann-Kendall trend tests. A significant uneven distribution was found in temporal and spatial analysis of precipitation data. Precipitation amount from April to October in different years changed sharply without any significant increase or decrease tendency. Precipitation from June to September contributed more than 70% of the whole year. Precipitation amount under monthly time scale showed only precipitation in May had a significant decrease tendency. Precipitation days decreased with a slope of 1.22 days/year over the last 10 years. Light rain （less than 10 mm/day）is the main type of precipitation in the catchment which contributed more than 50% of total precipitation resources. However,the frequency of heavy rain significantly increased with a slope of 0.19 days/yr which certified a potential threat of extreme precipitation still exists. For spatial analysis of precipitation,the observation points on downstream have more precipitation amounts than points on upstream. Combined with the method of control variable,it can be concluded that vegetation cover played an important role in rainfall distribution in the Chongling catchment and hilly area of Taihang Mountains. Pine, Arborvitae and Acacia can significantly increase reginal precipitation amount.
