From 1981 to 2010,the effects of climate change on evapotranspiration of the alpine ecosystem and the regional difference of effects in the Tibetan Plateau(TP)were studied based on the Lund-Potsdam-Jena dynamic vegetation model and data from 80 meteorological stations.Changes in actual evapotranspiration(AET)and water balance in TP were analyzed.Over the last 30 years,climate change in TP was characterized by sig- nificantly increased temperature,slightly increased precipitation,and decreased potential evapotranspiration(PET),which was significant before 2000.AET exhibited increasing trends in most parts of TP.The difference between precipitation and AET decreased in the south- eastern plateau and increased in the northwestern plateau.A decrease in atmospheric water demand will lead to a decreased trend in AET.However,AET in most regions increased be- cause of increased precipitation.Increased precipitation was observed in 86%of the areas with increased AET,whereas decreased precipitation was observed in 73%of the areas with decreased AET.

Using the daily temperature data of 95 meteorological stations from Sichuan- Chongqing Region and its surrounding areas, this paper adopted these methods (e.g., linear regression, trend coefficient, geographical statistics, gray relational analysis and spatial analysis functions of GIS) to analyze the relations of temperature variability with topography, latitude and longitude. Moreover, the rank of gray correlation between temperature variability and elevation, longitude, latitude, topographic position and surface roughness also was measured. These results indicated: (1) The elevation affected temperature variability most obviously, followed by latitude, and longitude. The slope of the linear regression between temperature change rate and elevation, latitude and longitude was 0.4142, 0.0293 and -0.3270, respectively. (2) The rank of gray correlation between temperature change rate and geographic factors was elevation > latitude > surface roughness > topographic position > longitude. The gray correlation degree between temperature change rate and elevation was 0.865, followed by latitude with 0.796, and longitude with 0.671. (3) The rate of temperature change enhanced with the increase of elevation. Especially, the warming trend was significant in the plateau and mountain areas of western Sichuan, and mountain and valley areas of southwestern Sichuan (with the warming rate of 0.74℃/10a during the 1990s). However, there was a weak warming trend in Sichuan Basin and its surrounding low mountain and hilly areas. (4) The effects of latitude on temperature change rate presented the specific regulation, which the warming rate of low-latitude areas was more significant than that of high-latitude areas. However, they were consistent with the regulation that the increasing of low temperature controlled most of the warming trend, due to the effects of terrain and elevation on annual mean temperature. (5) Basically, temperature variability along longitude direction resulted from the regular change of elevation along longitude. It was suggested that, in Sichuan-Chongqing Region, special features of temperature variability largely depended on the terrain complexity (e.g., undulations, mutations and roughness). The elevation level controlled only high or low annual mean temperature and the range of temperature change rate in the macro sense.

By decomposing and reconstructing the runoff information from 1965 to 2007 of the hydrologic stations of Tuotuo River and Zhimenda in the source region of the Yangtze River, and Jimai and Tangnaihai in the source region of the Yellow River with db3 wavelet, runoff of different hydrologic stations tends to be declining in the seasons of spring flood, summer flood and dry ones except for that in Tuotuo River. The declining flood/dry seasons series was summer > spring > dry; while runoff of Tuotuo River was always increasing in different stages from 1965 to 2007 with a higher increase rate in summer flood seasons than that in spring ones. Complex Morlet wavelet was selected to detect runoff periodicity of the four hydrologic stations mentioned above. Over all seasons the periodicity was 11-12 years in the source region of the Yellow River. For the source region of the Yangtze River the periodicity was 4-6 years in the spring flood seasons and 13-14 years in the summer flood seasons. The differences of variations of flow periodicity between the upper catchment areas of the Yellow River and the Yangtze River and between seasons were considered in relation to glacial melt and annual snowfall and rainfall as providers of water for runoff.

Ecological compensation is a hot subject in academic studies, and the determination of the spatial allocation of compensation payments is a key point in the research of ecological compensation. There are two kinds of thoughts in the determination of regional spatial allocation at present: “evaluation of ecological construction cost” and “evaluation of ecosystem services value”. This paper analyzes the relationships between social ecological compensation and regional socio-economic development, and establishes two econometric models with the data of 2007 from various provinces in China. Through these models, the impacts of geographical endowments on the regional socio-economic development in various provinces are analyzed from the social justice viewpoint and the concept of “equivalent value of geographical endowments” (EGE for short) is proposed. This paper analyzes the application prospect of EGE in the policy making of regional ecological compensation. The results showed that: (1) the implementation of social ecological compensation is not only an effective guarantee for each region to obtain the equal rights of survival, development and decent environment, but also an essential assurance to the coordinated, balanced and sustainable development among various regions; (2) the regional difference in geographical endowments is an important factor affecting the regional spatial variation of socio-economic development. Therefore, geographical endowments are important bases for the determination of the spatial allocation of compensation payments in social ecological compensation; (3) based on the EGE, the government can determine the spatial allocation of social ecological compensation scientifically, and avoid the “sweeping approach” phenomenon in the policy making process of ecological compensation.

The agricultural reclamations in the Xiliao River Valley since the Holocene have led to a huge landscape change from grassland to farmland. In this paper we reconsider the man-land relationship in the Xiliao River Valley by analyzing three major agricultural reclamations in prehistory, the Liao-Jin Dynasty and the period since the Qing Dynasty. We argue that when the demographic pressure appears in this area, especially during the last reclamation, the intraregional migration (second migration) is the major response to relieve such pressure, which also distinguishes two different settlement locations: “the initial area” and “the secondary area”. Due to the environmental differences between these two areas, the cultivation on the latter one has caused more serious disturbance to the local environment. Thus the secondary area has become the key region which needs environmental management seriously.

Karamay City is a typical mining city, relying on oilfield exploration and development. After 60 years of construction and development, Karamay has become the first large oilfield and an important base of the national petroleum and petrochemical industry in China. Based on spatial analysis, and Geographic Information Systems (GIS) grid computing and overlay techniques, whilst considering the effect of oilfield development and aimed at the ecological problems of Karamay City in the Xinjiang Uygur Autonomous Region of China, we conducted research on the spatial characteristics of the comprehensive ecological sensitivity of Karamay. The ecological problems of natural environment evolution include soil erosion, land desertification, soil salinization, and biodiversity reduction. The most significant disturbance factor from the activities of humans in this area is oilfield exploitation. This study carries out an analysis of single factor ecological problem sensitivity and integrated ecological sensitivity. The results of the research are as follows: (1) Soil erosion is relatively sensitive, especially in Karamay district, Dushanzi district, north of Urho district and west of Baijiantan district, which is mainly a result of the vertical dropping slopes, serious rainfall erosion and the distribution of scattered woodland. (2) The main types of land desertification are represented by high and moderate grade sensitivities, and high and extremely high sensitive areas are distributed in the intersection of Karamay and Baijiantan districts. This is due to evaporation exceeding rainfall in these areas, and the soil mainly consists of sand and is seldom covered by vegetation. (3) The soil salinizatiion sensitivity grades are mainly moderate, high and extremely high. The highly sensitive areas are mainly distributed in southeast of Baijiantan district, north and east of Karamay district and east of Urho district. The primary causes are evaporation exceeding rainfall and extreme human activities. (4) The main types of biodiversity sensitivity are light and moderate grade. Highly sensitive areas are located in the east and south of Karamay district, north of the Baiyang River basin and parts of the wetland areas. (5) Oil fields development areas are highly ecologically sensitive, which are located in the northern oilfields of Urho district, western oilfields of Baijiantan district, northwestern oilfields of Karamay district and central oilfields of Dushanzi district. (6) The main types of integrated ecological sensitivity are high and moderate. The high and extremely highly sensitive areas are located in the central and northern parts of Karamay district, and southwest of Baijiantan district. The evaluation results will provide guidance for the future planning and development, the protection of the ecological environment and the realization of harmonious social, economic, and ecological development in Karamay City.

The IGU Regional Conference (UGI 2011) was held on November 14-18, 2011 in Santiago, Chile. It was organized by the Military Geographic Institute (IGM). Nearly 1000 geographers across the world participated in this event. The Geographical Society of China (GSC) sent a delegation consisting of more than 40 members to attend the conference.

Carrying capacity research has been carried out for a long time. However, synthesized carrying capacity researches based on systematic views began only in the 1970s. There is even less work done in China. This paper tries to address both synthesized carrying capacity research and its utilization in China. State spaces method from the systematic science was borrowed to construct the conceptual model of regional carrying capacity. Based on the conceptual model and the surveys in the Bohai Rim area, we construct a representative indicators system for quantifying regional carrying capacity in the Bohai Rim. While employing system dynamic models we simulated the evolving trend of both the regional carrying states and regional carrying capacity from 1999 to 2015. The results proved the statement that Bohai Rim is overall over-capacity for a long time and will be over-capacity in the foreseeable future. Among all the restriction factors, water shortage and environmental pollution stand out to be the two primary obstacles for Bohai Rim’s sustainable development. Regional differentiation analysis further indicates that coastal areas of the Bohai Rim burden more than its overall level. However, Shandong province shows some good signs in addressing the regional carrying capacity issues. The research is successful in addressing the quantification of regional carrying capacity issues, but nonetheless it needs further refinery and more information.

In this study, a monthly dataset of temperature time series (1961-2010) from 12 meteorological stations across the Three-River Headwater Region of Qinghai Province (THRHR) was used to analyze the climate change. The temperature variation and abrupt change analysis were examined by using moving average, linear regression, Spline interpolation, Mann-Kendall test and so on. Some important conclusions were obtained from this research, which mainly contained four aspects as follows. (1) There were several cold and warm fluctuations for the annual and seasonal average temperature in the THRHR and its three sub-headwater regions, but the temperature in these regions all had an obviously rising trend at the statistical significance level, especially after 2001. The spring, summer, autumn and annual average temperature increased evidently after the 1990s, and the winter average temperature exhibited an obvious upward trend after entering the 21st century. Except the standard value of spring temperature, the annual and seasonal temperature standard value in the THRHR and its three sub-headwater regions increased gradually, and the upward trend for the standard value of winter average temperature indicated significantly. (2) The tendency rate of annual average temperature in the THRHR was 0.36℃10a^-1, while the tendency rates in the Yellow River Headwater Region (YERHR), Lancangjiang River Headwater Region (LARHR) and Yangtze River Headwater Region (YARHR) were 0.37℃10a^-1, 0.37℃10a^-1 and 0.34℃10a^-1 respectively. The temperature increased significantly in the south of Yushu County and the north of Nangqian County. The rising trends of temperature in winter and autumn were higher than the upward trends in spring and summer. (3) The abrupt changes of annual, summer, autumn and winter average temperature were found in the THRHR, LARHR and YARHR, and were detected for the summer and autumn average temperature in the YERHR. The abrupt changes of annual and summer average temperatures were mainly in the late 1990s, while the abrupt changes of autumn and winter average temperatures appeared primarily in the early 1990s and the early 21st century respectively. (4) With the global warming, the diversities of altitude and underlying surface in different parts of the Tibetan Plateau were possibly the main reasons for the high increasing rate of temperature in the THRHR.

Employing DEA model and Malmquist productivity index, this paper probes into the urban efficiencies of 24 typical resources-based cities in China and their changes from 2000 to 2008. The research finds that the overall efficiencies of the resources-based cities are just at a general level, and only a few of them reach the optimal level. The scale efficiency is the major determining factor of the achievement of overall efficiency, the effect of which, nevertheless, is reducing. From the perspective of classification characteristics, the resources- based cities in northeastern region have been in the front rank in terms of overall efficiency, pure technical efficiency and scale efficiency. There is a certain positive correlation between urban population scale and urban efficiency. The analysis of urban efficiency changes shows that the changes in overall efficiency of resources-based cities from 2000 to 2008 had a weak improving tendency. Both the technical change index and productivity change index decreased, indicating that the urban efficiency did not improve during this period, and the tendency of technical recession and productivity decline was obvious. In terms of the classification of urban efficiency changes, the urban overall efficiency improved in each of the four regions from 2000 to 2008, among which western region witnessed the greatest increase. Cities with different resource types have improved their urban overall efficiencies except steel-based cities. The urban overall efficiency increased in resources-based cities of different scales, with greater improvement in small and medium-sized cities than in big cities.

From 2020 to 2030, accelerating the “citizenization” of the migrant population is key to promoting urbanization and achieving common prosperity. The urbanization rate of the registered population in China is roughly 18% lower than that of permanent residents. The pressure of the ageing population and the lack of a labor force have caused big cities to introduce relevant policies to attract talent, and the citizenization process needs to be improved urgently, with a particular focus on megacities. The transformation in the number of registered residents in megacities varies greatly, and there is a lack of research on this topic, which makes it an important academic issue. Using both natural and social perspectives, we selected concise indicators and combined the possibility-satisfiability model to estimate the urbanization transformation gap of annual household registration. Further, we constructed a panel data model to empirically analyze the different factors leading to the gap of household registration in megacities. The main factors affecting the transformation of the registered population in megacities are medical services, as well as educational resources and the urban water supply. It is urgent for urban and rural administrators to change the current passive and rigid institutional mechanisms and to ensure flexible, normal governance.

Although China was one of the countries with the fastest-growing aging population in the world, limited scholarly attention has been paid to migration among older adults in China. The full picture of their migration in the entire country over time remains unknown. This study examines the spatial patterns of older interprovincial migration flows and their drivers in China over the period 1995 to 2015, using four waves of census data and intercensal population sample survey data. Results from eigenvector spatial filtering negative binomial regressions indicate that older adults tend to migrate away from low cost-of-living rural areas to high cost-of-living urban and rural areas, moving away from areas with extreme temperature differences. The location of their grandchildren is among the most important attractions. Our findings suggest that family-oriented migration is more common than amenity-led migration among retired Chinese older adults, and the cost-of-living is an indicator of economic opportunities for adult children and the quality of senior care services.

Household structure is an important aspect of family change during China’s modernization process. Existing literature has demonstrated significant associations between various factors and household structure, but the spatial variation in these relationships has not been examined. Using the 2010 Chinese population census data and geographically weighted regression (GWR) model, this study explored the spatial patterns of three-generation lineal households, a functionally important household type in China, and its influencing factors. There was significant heterogeneity in the distribution of three-generation lineal households. Socioeconomic, demographic, and cultural factors were all significantly related to the proportion of three-generation lineal households, but the relationships are place-specific in terms of direction and magnitude. These results suggest that the distribution of Chinese household structures cannot be explained by a single framework of family modernization theory but is determined by the interplay of various local characteristics. Especially, population migration plays an equally important role in affecting household structure than socioeconomic development in China. This work contributes to the family literature by highlighting the spatial heterogeneity in the impact of varying factors on household structure. Beyond the classic modernization theory, it sets a contextualized framework for understanding how Chinese household change in response to the rapid social transformation.

This paper examines the process and internal mechanisms of rural ecommerce industry agglomeration and space reconstruction in metropolitan fringe areas, employing Lirendong village in Guangzhou, China, as a case study. Questionnaire surveys and in-depth interviews were utilized and interpreted through the perspective of the actor-network theory. The results show that, in Lirendong village, local government, processing enterprises, rural collectives, e-commerce entrepreneurial talent, and other key actors participate in the pursuit and realization of suburban land value according to their action logic. Actors jointly evolved and constructed the phased industrial processes and space value accumulation process of the e-commerce industry. The reconstruction process experienced three stages, including the government-led agricultural decentralization stage, the market-oriented industrialization stage, and the Internet+ stage dominated by the social network of fellow villagers. The development process has evolved from the dominance of exogenous forces to that of endogenous forces, and, as a result, the types and structures of rural land use are diversified. The spatial texture and rural environment of the traditional country gradually disappeared, forming a diversified mixed form of urban-rural land and mixed-use landscape of industrial, commercial, and residential land in vertical space. At the same time, the social network changed from a single and homogeneous social network of acquaintances to a multiple network of strangers.

Cultivated land protection (CLP) entered the new era of macro administration in 1999 in China. This paper presents a holistic analysis of cultivated land use change concerning the three goals of the CLP, i.e., grain security, ecological security and harmonizing regional development. Farmers’ willingness to grow grain has been the key factor in safeguarding grain security. Grain-for-green policy has contributed to improving ecological state especially in the western provinces. Effects of the land macro-control of the CLP on harmonizing regional development were significant. Moreover, cultivated land use change in 1999-2007 points out the way of the evolving policy in the future. From the viewpoint of normative concept of multifunctionality, we discuss development of the three land functions, i.e., production function, environmental function and carrier function. Finally, we propose to emphasize multifunctional land management based on regional differences to promote transition of the CLP.

Water resources in the arid land of Northwest China mainly derive from snow and glacier melt water in mountainous areas. So the study on onset, cessation, length, temperature and precipitation of snowmelt period is of great significance for allocating limited water resources reasonably and taking scientific water resources management measures. Using daily mean temperature and precipitation from 8 mountainous weather stations over the period 1960?2010 in the arid land of Northwest China, this paper analyzes climate change of snowmelt period and its spatial variations and explores the sensitivity of runoff to length, temperature and precipitation of snowmelt period. The results show that mean onset of snowmelt period has shifted 15.33 days earlier while mean ending date has moved 9.19 days later. Onset of snowmelt period in southern Tianshan Mountains moved 20.01 days earlier while that in northern Qilian Mountains moved only 10.16 days earlier. Mean precipitation and air temperature increased by 47.3 mm and 0.857℃ in the mountainous areas of Northwest China, respectively. The precipitation of snowmelt period increased the fastest, which is observed in southern Tianshan Mountains, up to 65 mm, and the precipitation and temperature in northern Kunlun Mountains increased the slowest, an increase of 25 mm and 0.617℃, respectively, while the temperature in northern Qilian Mountains increased the fastest, increasing by 1.05℃. The annual runoff is also sensitive to the variations of precipitation and temperature of snowmelt period, because variation of precipitation induces annual runoff change by 7.69% while change of snowmelt period temperature results in annual runoff change by 14.15%.

Runoff at the three time scales (non-flooding season, flooding season and annual period) was simulated and tested from 1958 to 2005 at Tangnaihai (Yellow River Source Region: YeSR), Zhimenda (Yangtze River Source Region: YaSR) and Changdu (Lancang River Source Region: LcSR) by hydrological modeling, trend detection and comparative analysis. Also, future runoff variations from 2010 to 2039 at the three outlets were analyzed in A1B and B1 scenarios of CSIRO and NCAR climate model and the impact of climate change was tested. The results showed that the annual and non-flooding season runoff decreased significantly in YeSR, which decreased the water discharge to the midstream and downstream of the Yellow River, and intensified the water shortage in the Yellow River Basin, but the other two regions were not statistically significant in the last 48 years. Compared with the runoff in baseline (1990s), the runoff in YeSR would decrease in the following 30 years (2010-2039), especially in the non-flooding season. Thus the water shortage in the midstream and downstream of the Yellow River Basin would be serious continuously. The runoff in YaSR would increase, especially in the flooding season, thus the flood control situation would be severe. The runoff in LcSR would also be greater than the current runoff, and the annual and flooding season runoff would not change significantly, while the runoff variation in the non-flooding season is uncertain. It would increase significantly in the B1 scenario of CSIRO model but decrease significantly in B1 scenario of NCAR model. Furthermore, the most sensitive region to climate change is YaSR, followed by YeSR and LcSR.

The expansion of agriculture is posited as one of the main dynamics of forest landscape change globally, and the robust modeling of these processes is important for policy as well as academic concern. This paper concerns a relatively small area of Yiluo River catchment where considerable attention has been paid to slow down the process of the expansion of agriculture into the remaining natural forests. In the present study, we reconstructed the former forest landscape structure and elucidated the landscape change during a period of about 15 years. Three sets (1987, 1996 and 2002) of maps derived from Landsat-5 images were used for analyses. The result showed that there was a decrease in the area of the forest landscape from 995.60 km² in 1987 to 650.50 km² in 2002. Then we examined the degree to which forest landscape conversion could be attributed to a set of factors identified as significant at broader scales, namely topography, distribution of the village clusters (centroids), distance from villages (centroids), and distance from forest edge (1987). By using “spatial analysis” in Arc/gis 8.3, the correlation between forest landscape change and driving factors was constructed. This study found that forest landscape conversion in this region was largely explained by elevation, slope and proximity to village.

The mouth bar in the Yangtze estuarine waterways has a significant influence on navigational transport within the estuary,flood discharge and construction of the Shanghai Port.In this paper the morphological evolution and mechanisms of mouth bar formation of the Yangtze estuarine waterways are studied by analyzing hundreds of years of historical data and the latest profile maps of some or the main mouth bar channels in the Yangtze Estuary. The results are shown as follows:The mouth bars in the North Branch have moved gradually from outside the mouth to the inside and formed a huge sand bar.In the North Channel,the head of the mouth bar has migrated about 30 kilometers downstream,and a channel bar has been developing since 2001.Two mouth bar tops,which always existed in the North Passage, disappeared in 2010.The head of the mouth bar in the South Passage has migrated downstream about 14 km and the number of tops increased at first but is reduced to only one now. According to the results,we can conclude that the evolution of the mouth bars differs depending on their location.In the North Branch it is directly related to large-scale reclamation in Chongming Island,but in the North Passage it has a close relationship with regulation of the Yangtze Estuary Deepwater Channel.However,the evolution of mouth bars in the North Channel and South Passage is not only connected with the Yangtze Estuary Deepwater Channel Regulation Project,but also with the reclamation in the East Hengsha Shoal and the closure of the Qingcaosha Reservoir.

The vegetation coverage dynamics and its relationship with climate factors on different spatial and temporal scales in Inner Mongolia during 2001–2010 were analyzed based on MODIS-NDVI data and climate data.The results indicated that vegetation coverage in Inner Mongolia showed obvious longitudinal zonality,increasing from west to east across the region with a change rate of 0.2/10°N.During 2001–2010,the mean vegetation coverage was 0.57,0.4 and 0.16 in forest,grassland and desert biome,respectively,exhibiting evident spatial heterogeneities.Totally,vegetation coverage had a slight increasing trend during the study period.Across Inner Mongolia,the area of which the vegetation coverage showed extremely significant and significant increase accounted for 11.25%and 29.13%of the area of whole region,respectively,while the area of which the vegetation coverage showed extremely significant and significant decrease accounted for 7.65%and 26.61%,respectively. On inter-annual time scale,precipitation was the dominant driving force of vegetation coverage for the whole region.On inter-monthly scale,the change of vegetation coverage was consistent with both the change of temperature and precipitation,implying that the vegetation growth within a year is more sensitive to the combined effects of water and heat rather than either single climate factor.The vegetation coverage in forest biome was mainly driven by temperature on both inter-annual and inter-monthly scales,while that in desert biome was mainly influenced by precipitation on both the two temporal scales.In grassland biome,the yearly vegetation coverage had a better correlation with precipitation,while the monthly vegetation coverage was influenced by both temperature and precipitation.In grassland biome,the impacts of precipitation on monthly vegetation coverage showed time-delay effects.

As important mechanisms of regional strategy and policy,prefecture-level regions have played an increasingly significant role in the development of China's economy.However, little research has grasped the essence of the economic development stage and the spatio-temporal evolution process at the prefecture level;this may lead to biased policies and their ineffective implementations.Based on Chenery's economic development theory,this paper identifies China's economic development stages at both national and prefectural levels. Both the Global Moran I index and the Getis–Ord Gi*index are employed to investigate the spatio-temporal evolution of China's economic development from 1990 to 2010.Major conclusions can be drawn as follows.(1)China's economic development is generally in the state of agglomeration.It entered the Primary Production Stage in 1990,and the Middle Industrialized Stage in 2010,with a‘balanced–unbalanced–gradually rebalanced' pattern in the process.(2)China's rapid economic growth experienced a spatial shift from the coastal areas to the the inland areas.Most advanced cities in mid-western China can be roughly categorized into regional hub cities and resource-dependent cities.(3)Hot spots in China's economy moved northward and westward.The interactions between cities and prefectures became weaker in Eastern China,while cities and prefectures in Central and Western China were still at the stage of individual development,with limited effect on the surrounding cities.(4)While the overall growth rate of China's economy has gradually slowed down during the past two decades,the growth rate of cities and prefectures in Central and Western China was much faster than those in coastal areas.(5)Areas rich in resources,such as Xinjiang and Inner Mongolia,have become the new hot spots of economic growth in recent years.For these regions,however,more attention needs to be paid to their unbalanced industrial structures and the lagging social development against the backdrop of the rapid economic growth, driven predominantly by the exploitation of resources.

Environments in arid and semiarid regions are extremely sensitive to climate changes.High wind activity in these regions has resulted in an extensively developed arid geomorphology,but past environmental changes are poorly understood because of the absence of relatively high-resolution proxies.The accumulation characteristics of nebkhas, which have developed extensively in these regions,can be used as a method of reconstructing environmental changes.Here we summarized recent advances in research on the formation,development,and sediment characteristics of nebkhas and their significance to environmental changes in arid and semiarid regions.Based on the studies of our colleagues, we suggested that research on nebkha formation can provide distinct clues about environmental changes in arid and semiarid regions;however,continued studies are needed.

Actual evapotranspiration is a key process of hydrological cycle and a sole term that links land surface water balance and land surface energy balance.Evapotranspiration plays a key role in simulating hydrological effect of climate change,and a review of evapotranspiration estimation methods in hydrological models is of vital importance.This paper firstly summarizes the evapotranspiration estimation methods applied in hydrological models and then classifies them into the integrated converting methods and the classification gathering methods by their mechanism.Integrated converting methods are usually used in hydrological models and two differences exist among them:one is in the potential evaporation estimation methods,while the other in the function for defining relationship between potential evaporation and actual evapotranspiration.Due to the higher information requirements of the Penman-Monteith method and the existing data uncertainty,simplified empirical methods for calculating potential and actual evapotranspiration are widely used in hydrological models. Different evapotranspiration calculation methods are used depending on the complexity of the hydrological model,and importance and difficulty in the selection of the most suitable evapotranspiration methods is discussed.Finally,this paper points out the prospective development trends of the evapotranspiration estimating methods in hydrological modeling.

The 2012 Annual Meeting of the Geographical Society of China(GSC)was held on October 12-14 in Henan University,Kaifeng,Henan Province.The meeting was co-sponsored by the GSC and Henan Association of Science and Technology,and co-hosted by Henan University with a history of 100 years and Henan University of Economics and Law.A total of around 1300 geographers throughout China participated in this meeting and more than 800 papers including 560 oral presentations were submitted and discussed.During the meeting,20 young scholars were prized for their excellent papers presented to this annual meeting.

Land cover change has presented clear spatial differences in the New Eurasian Continental Bridge Economic Corridor (NECBEC) region in the 21st century. A spatiotemporal dynamic probability model and a driving force analysis model of land cover change were developed to analyze explicitly the dynamics and driving forces of land cover change in the NECBEC region. The results show that the areas of grassland, cropland and built-up land increased by 114.57 million ha, 8.41 million ha and 3.96 million ha, and the areas of woodland, other land, and water bodies and wetlands decreased by 74.09 million ha, 6.26 million ha, and 46.59 million ha in the NECBEC region between 2001 and 2017, respectively. Woodland and other land were mainly transformed to grassland, and grassland was mainly transformed to woodland and cropland. Built-up land had the largest annual rate of increase and 50% of this originated from cropland. Moreover, since the Belt and Road Initiative (BRI) commenced in 2013, there has been a greater change in the dynamics of land cover change, and the gaps in the socio-economic development level have gradually decreased. The index of socio-economic development was the highest in western Europe, and the lowest in northern Central Asia. The impacts of socio-economic development on cropland and built-up land were greater than those for other land cover types. In general, in the context of rapid socio-economic development, the rate of land cover change in the NECBEC has clearly shown an accelerating trend since 2001, especially after the launch of the BRI in 2013.

The study of mountain vertical natural belts is an important component in the study of regional differentiation. These areas are especially sensitive to climate change and have indicative function, which is the core of three-dimensional zonality research. Thus, based on high precision land cover and digital elevation model (DEM) data, and supported by MATLAB and ArcGIS analyses, this paper aimed to study the present situation and changes of the land cover vertical belts between 1990 and 2015 on the northern and southern slopes of the Koshi River Basin (KRB). Results showed that the vertical belts on both slopes were markedly different from one another. The vertical belts on the southern slope were mainly dominated by cropland, forest, bare land, and glacier and snow cover. In contrast, grassland, bare land, sparse vegetation, glacier and snow cover dominated the northern slope. Study found that the main vertical belts across the KRB within this region have not changed substantially over the past 25 years. In contrast, on the southern slope, the upper limits of cropland and bare land have moved to higher elevation, while the lower limits of forest and glacier and snow cover have moved to higher elevation. The upper limit of alpine grassland on the northern slope retreated and moved to higher elevation, while the lower limits of glacier and snow cover and vegetation moved northward to higher elevations. Changes in the vertical belt were influenced by climate change and human activities over time. Cropland was mainly controlled by human activities and climate warming, and the reduced precipitation also led to the abandonment of cropland, at least to a certain extent. Changes in grassland and forest ecosystems were predominantly influenced by both human activities and climate change. At the same time, glacier and snow cover far away from human activities was also mainly influenced by climate warming.

Man-land relationship research, as the core of geographical research, runs through each development stage of Geography. Based on extensive literature review, this paper systematically generalizes the connotations, research development and contents of man-land relationship in China. (1) It explores the connotations and evolvement rules of man-land relationship in different social development stages in China, and finds that the core role of man-land relationship in geographical research has been strengthened continuously. Changing with times, its connotations have been considerably enriched by sustainable development and other notions, and so does its theoretical system. (2) It applies the bibliometric method to sketch out the basic research status of man-land relationship in China. Specifically, it quantitatively identifies the funding sources, major research teams and journals for publication. It finds that the funding sources show a diversification trend with national funding being the primary source of research grants. The most competitive research teams are mainly concentrated in the Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences (CAS) and normal universities. Journals sponsored by The Geographical Society of China are most influential in publishing man-land relationship research. (3) As resources and environment are the fundamental carriers of man-land relationship, this study focuses further on the research on resource-environmental base of man-land relationship, and finds that the resource-environmental base research in China has gone through an evolution process from single factor perspective research to comprehensive multiple perspective research gradually. Research themes have also experienced similar changes from land, water, energy minerals or other single factor research to comprehensive factor research of resources and environment. Empirical study on national and regional development strategies is the feature of man-land relationship in China. More emphasis should be put on considering and following the changes in features of “man” and “land” and research on the impacts of new factors on man-land relationship in a developing and dynamic manner in the future. Particularly, we should pay more attention to research on the impacts of spatio-temporal changes in resource-environment absolute location on modes of man-land interaction, and to strengthening interdisciplinary research and systematic research on comprehensive techniques so as to advance the development of application of man-land relationship theories and practices.

The karst critical zone is an essential component of the carbon (C) pool, constituting the global C cycle. It is referred to as one of the “residual land sink” that remains largely indeterminate. Karst area (2.2×10⁷ km²) comprises 15% of the world’s land area, and karst area comprises 3.44×10⁶ km² of area in China. Due to the complexity of karst structure and its considerable heterogeneity, C sequestration rate estimations contain large inaccuracies, especially in relation to the different methods used in calculations. Therefore, we reevaluated rock weathering-related C sink estimations in China (approximately 4.74 Tg C yr^-1), which we calibrated from previous studies. Additionally, we stipulated that more comprehensive research on rock-soil-biology-atmosphere continuum C migration is essential to better understand C conversion mechanisms based on uncertainty analyses of C sink estimations. Moreover, we stressed that a collective confirmation of chemical methods and simulated models through a combined research effort could at least partially eliminate such uncertainty. Furthermore, integrated C cycling research need a long-term observation of the carbon flux of multi-interfaces. The enhanced capacity of ecosystem C and soil C pools remains an effective way of increasing C sink. Karst ecosystem health and security is crucial to human social development, accordingly, it is critical that we understand thresholds or potential C sink capacities in karst critical zones now and in the future.

Soil organic carbon (SOC) stocks in terrestrial ecosystems vary considerably with land use types. Grassland, forest, and cropland coexist in the agro-pastoral ecotone of Inner Mongolia, China. Using SOC data compiled from literature and field investigations, this study compared SOC stocks and their vertical distributions among three types of ecosystems. The results indicate that grassland had the largest SOC stock, which was 1.5- and 1.8-folds more than stocks in forest and cropland, respectively. Relative to the stock in 0-100 cm depth, grassland held more than 40% of its SOC stock in the upper 20 cm soil layer; forest and cropland both held over 30% of their respective SOC stocks in the upper 20 cm soil layer. SOC stocks in grazed grasslands were remarkably promoted after ≥20 years of grazing exclusion. Conservational cultivation substantially increased the SOC stocks in cropland, especially in the 0-40 cm depth. Stand ages, tree species, and forest types did not have obvious impacts on forest SOC stocks in the study area likely due to the younger stand ages. Our study implies that soil carbon loss should be taken into account during the implementation of ecological projects, such as reclamation and afforestation, in the arid and semi-arid regions of China.

This research examines the distribution features of 4960 caves across Guizhou Province, while probing the relationship between the caves’ spatial patterns and geographic elements. This study is based on hydrogeological and topographic maps of Guizhou. ArcGIS software was used to process the adjacent index, spatial analysis, and coupling analysis of the caves altitude and longitude, as well as the rock properties, lithology, drainage and tectonic division of almost 5000 caves. Based on a point pattern analysis of Guizhou caves, the adjacent index is 0.53, and the coefficient of variation verified by Tyson polygon reached 72.469%. This figure reflects the clustered distribution pattern of the caves. Across the entire province, caves are divided into four concentrated areas and one weakly affected area. The four concentrated areas are Zunyi-Tongren, Bijie, Qianxinan-Liupanshui, and Guiyang-Anshun-Qinan. The one weakly affected zone is Qiandongnan. The most concentrated among them is the Guiyang-Anshun-Qiannan area, which covers 24.67% of the total province area, and accounts for 36.63% of the total province’s caves. Cave distribution in Guizhou is characterized as dense in the western part and sparse in the eastern part. Under this study background, the natural elements of formation, including lithology, structure, climate, hydrology, and altitude, and their effects on the distribution, number, and spatial pattern of cave development is analyzed.