Based on the road network data of 1990 and 2009 in the Zhujiang River Delta (ZJRD), this article explores the spatio-temporal evolution of the road network accessibility and quantitatively analyzes its influences on urban potential change of ZJRD region with the support of space syntax model, GIS technology and statistical analysis method. The basic conclusions are obtained as follows: 1) The grade-layer difference of the topological connection of the road network has decreased, and the whole accessibility of the road network have been improved significantly from 1990 to 2009. However, the road network development gap between inner and out the core region of ZJRD has been enlarged. 2) The road network accessibility shows an obvious core-periphery structure as a whole, and the core area has been gradually expanded. In 2009, the road network accessibility of Guangzhou-Foshan metropolitan region and Shenzhen-Dongguan-Huizhou metropolitan region was the highest, gradually decreasing from those two regions to the surroundings, which results in the “∧-shaped” form of high integration axes and spatial pattern of the entire road axes stretching radially. There are obvious differences of the spatial distribution change of different grade road axes, and the imbalance of the topological connection of the road network is more significant. The road accessibility in the middle zone is the highest and has been improved quickly, and the east zone ranks the second highest and the disparity between the eastern zone and the middle zone has decreased. Whereas, the road accessibility in the western zone is the lowest, and the disparity between the western zone and the middle and eastern zones has been on a trend of expanding. 3) The spatial intelligibility of the layout of the road network as a whole has improved significantly, but most roads out the core region have still low spatial intelligibility and poor convenience. 4) There is a positive correlation between the road accessibility and city potential of ZJRD region, and the correlative degree has strengthened, indicating that the influence of road traffic on urban potential change is more significant. But it still remained a moderate correlation in 2009.
The development of processing trade in China is the result of labor-intensive manufacturing link transfer to Chinese mainland since opening-up and reform. Therefore, the imbalance development of processing trade in different provinces of China reflects the location selection rules of the export-oriented manufacturing activities. Based on the location factors analysis, using processing trade data in 2008 and 2001, this article is intended to analyze the basic location selection rules of the processing manufacturing activities. The result shows that comprehensive advantages of endowments and transaction cost saving determine the location of export-oriented manufacturing activities. That is also the reason for east coastal areas of China taking the lead in processing trade. With the formation of China's multi-directional opening-up pattern and improvement of the infrastructure conditions, transaction costs in Midwest China are rapidly reducing. It creates favorable conditions for processing manufacturing activities to transfer to Midwest areas. In this context, east coastal areas of China need to promote the transformation and upgrading of the manufacturing industry through cultivating advanced elements urgently. For the Midwest areas, paying more attention to better the introduction pattern of processing manufacture is also very important. That is the key for the optimization of spatial structure of processing manufacture in China.
By the methods of ESDA, Markov Chains, and based on the data of crime rates at province evel in China from 1993 to 2008, the spatio-temporal pattern change of crime rates were discussed. The results are shown as follows. First, on the overall distribution of space, the higher criminal rates gradually transferred to coastal areas. Second, The crime rates showed a strong trend of spatial correlation, the similar units cluster in space, the higher level spatial units were concentrated in the provinces of eastern China, and the lower level spatial unites were mainly in the provinces of middle China. There was an obvious trend in the “Polarization” of crime rates development level. Third, there exited a phenomenon of “Club Convergence” in crime rates development level in the study area, spatial discrepancy of crime rates development level has become greater. Referring to the previous studies, the relationship among income inequality, floating population and crime rates. In order to improve the overall predicting ability for crime rates at province level, the “spatial effect” is incorporated into the panel econometric model. The panel econometric model includes two effects, fix effect and random effect. Generally speaking, the fixed effect model is favored when the regression analysis is applied to a precise set of regions; random effect, instead, is an appropriate specification if a certain number of individuals are randomly drawn from a large region of reference. For this reason, the fixed effect panel model is chosen, which is extender to include spatial error autocorrelation or a spatially lagged dependent variable autocorrelation. This article uses spatial lag fixed effect panel regression model to analyze the relationship between macro factors and crime rates. The regression results show that considering the effect of time and spatial heterogeneity of conditions, there is no significant correlation between floating population and crime rates; but under the common role of the industry and the income gap, the floating population and the crime rates has significantly correlation. The correlation between industry income inequality and crime rates is much bigger than the correlation between urban-rural income inequality and regional income inequality and crime rates, and, the result is robust in a series of sensitivity tests, it means that industry income inequality has a leading effect on crime rate. The neighborhood spatial effect is the most important factor when explain crime. The construction of transportation infrastructure leads to time-space compression, and the time-space compression has a profound influence on neighborhood spatial effect.
Set pair analysis (SPA) is to study the certain and uncertain relationship among different things and is introduced to assess the economic system vulnerability (ESV) of tourism city through the approximate degree of ESV to the optimal set, which is calculated to describe the vulnerability level of the economic system by combining multiple indices. Based on a detailed discussion about the conception of ESV, the article establishes an economic system vulnerability assessment model of tourist city from the aspects of sensitivity and response capacity by using the SPA. Then it uses entropy method to evaluate the indicators and to calculate their weights for the assessment of ESV. Taking islands city— Zhoushan as an example, this article analyses the evolution characteristics and the major influencing factors of the ESV in 1995-2010. The results indicate that firstly the ESV of Zhoushan City shows a declining trend, the sensitivity to adverse disturbance takes on a declining trend, and response capacity presents a fluctuation rise. The evolution of ESV can be divided into two stages: the economic vulnerability of Zhoushan City declined with fluctuation in 1995-2002; the ESV steadily decreased in 2003-2010. Secondly, the influence of sensitivity on Zhoushan’s economic system vulnerability is more evident than that of response capacity. The evolution of sensitivity to adverse disturbance presents a fluctuation decline which can be divided into three stages: decreased with obvious fluctuation in 1995-1999; declined slowly in 2000-2004; increased firstly and then descended rapidly in 2005-2010. While the evolution of response capacity changed slightly after 1995, declined with fluctuation in 1995-1999 and then went up steadily in 2000-2010. Thirdly, the growth rate of the total number of tourists, the proportion of foreign exchange earnings to the total tourism income, the self-sufficiency rate of local finance to concentration of tourist source market are the leading factors influencing the ESV of Zhoushan City. Finally, the results of obstacle degree of regional response capacity indicate that the low self-sufficiency rate of local finance, unreasonable industrial structure and insufficient education input are the most important obstacle factors to enhance the response capacity.
As the most important human factor to impact the environment, the farmer’s livelihood strategy decides the intervention measure and the intervention intensity to environment. Thus, understanding the impact of farmer’s livelihood on the environment and identifying the relationship between human livelihood and environment is the key to solve the environmental problem. In recent years, the relationship between farmer’s livelihood and environment has been the research focus of the sustainable development domain. Through stratified random sampling survey, participatory rural appraisal and investigation of plots, 217 households are investigated and sampled. Farmers are divided into 3 types: the households earning from farming, the off-farming, and both. From the farmer’s household energy consumption and ecological footprint, the article employs the investigation data to analyze the environmental impact of the farmers with different livelihood strategies in the Gannan Plateau. The results show: 1) The diversification level of farmers’ livelihood in the Gannan Plateau is low, and the farmer’s livelihood diversity index is only 1.84. The livelihood diversity index of the farmers in the farming-pastoral area reaches 2.10, but that of the farmers in the pure pasturing area is 1.54. Moreover, the non-agricultural level in the farming-pastoral area is higher than that of the other areas; 2) With the non-agricultural level improving, the farmer’s household energy consumption in the Gannan Plateau will decline. Among the farmers of different livelihood strategies, the energy consumption of the farmer household is 738.08 kgce, but those of the household with combined occupation and the off-farming household are 368.34 kgce and 260.49 kgce respectively. Furthermore, following the non-agricultural level increasing, the proportion of biomass energy consumption will reduce, but that of commercial energy consumption proportion will increase; 3) The farmer’s per capita ecological footprint in the Gannan Plateau will decline with the non-agricultural level improving. Among the farmers of different livelihood strategies, the per capita ecological footprint of the farmer household is 1.644 gha, but those of the household with combined occupation and the off farming household are 1.488 gha and 1.225 gha respectively. Except that the proportion of per capita grassland footprint will decrease, those of per capita forest footprint, building land footprint, water area and fossil energy land proportion will increase; 4) The farmers’ livelihood mode has remarkable influences on their ecological footprint, and increasing non-agricultural level will decrease the impact on the environment. Meanwhile, increasing the labour/householder education level will also cut down the impact on the environment, but improving family size and earning level will aggravate the impact on the environment. However, within the range of calculated data, the analysis result supports the environmental Kuznets curve hypothesis.
The commercial area is one of the most important study topics of urban geography. This article mainly studies on the spatial evolution characteristics and mechanism of super markets in Changchun by use of GIS spatial analysis and measurement statistics, which is based on the data of supermarkets in central district of Changchun from 1998 to 2011. The development of markets in Changchun started from 1994. The first supermarket was emerged in 1998, which named Yatai Supermarket. And then, the supermarkets are developed very rapidly, especially in quantity. At the end of 2011, there are 48 supermarkets in Changchun, and the total business area of supermarkets reaches 478 000 m2. According to the changes of supermarket number and distribution, the development of supermarkets in Changchun is divided into three stages: 1998-2001, 2002-2006 and 2007-2011. From 1998 to 2001, the location choice of supermarkets was random and disorderly. From 2002 to 2006, the distribution of supermarkets began to appear the phenomenon of dispersion. From 2003 to 2011, the new town trend of the distribution of supermarkets was very obviously. This study reaches some important and novel conclusions. First the spatial distribution change of supermarkets in Changchun follows the rules of “random-cluster-disperse”. The main evolution characteristics of super markets are as follows: The space directivity is very significant, and the distribution of super markets is mainly concentrated in dominant area. The Chongqing Road, Damalu Road, Dongsheng Street, Chuncheng Street and Hongqi Street, which are the hot zones of the spatial distribution of supermarkets. There is unevenly distribution in the different areas: the number of supermarkets in Nanguan District, Chaoyang District and Luyuan District is more than others areas. With the passage of time, the number of supermarkets in Changchun are more and more equal to each other in each ring road, but the distribution of change trend in north-south direction is more invariable than in west-east direction. The change trend of mean center of super markets is the same as the direction of urban development in past years and the distribution of Chain Supermarkets is more and more inclined to the whole strategy. Lastly, the research indicates that some factors are obviously affect the space evolution of supermarkets, such as the density and purchasing power of consumer, enterprise factors, market factors, the development of urban and so on.
The relationship of new-approach urbanization, new-approach industrialization and service industry modernization is coupling interaction, intercoordination and mutual promotion. Their benign resonating is one of the essential conditions on urban sustainable development. On the base of elaboration the coupling coordinated implication about new-approach urbanization, new-approach industrialization and service industry modernization, a set of indicator system was constructed. Then all-around principle component analysis method was used to count the indexes of new-approach urbanization, new-approach industrialization and service industry modernization. Then the coupling degree model was put forward. Lastly the empirical analysis of space-time coordination rules about Chinese ten cities in 2004-2010 was carried on. The findings is that: 1) the levels of new-approach urbanization, new-approach industrialization and service industry modernization in the first-tier cities were higher than those of the second-tier urban, especially Beijing, Shanghai and Guangzhou being the top 3; 2) the couplings of cities with various tiers were at the resisting stage, basically belong to the extensive level; 3) on the succession, various urban coupling coordination degrees were in the trend of escalation, but the coupling degree change was not steady but fluctuating. The escalation speed of the second-tier urban coordination was quickly than those of first-tier ones. 4) Speaking of spatial differentiation, various urban coupling coordination had spatial correspondence with their synthetical development level in the some degree, and the level of urban coupling coordination degree in first-tier urban were higher than those of the second-tier ones.
With the development of the thoughts of “cultural turn” and “spatial turn”, geographic space has been subjectivized and has participated in the construction of social ideology. Its research perspective, from macroscopic to microscopic, focuses more on “offbeat groups” who are excluded and marginalized by the mainstream society in a micro-scale domain. It has been a long time since the interaction and the intermarriage between the nationals across the Sino-Vietnam border due to their geographical proximity and ethnic and cultural similarities. The number of the transnational marriages in this area has increases annually since China and Vietnam successively carried out the “Reform and Opening-up” policy, especially after the normalization of the Sino-Vietnam relations in 1991. The Vietnamese brides, due to the lack of legal status, are often excluded from the mainstream society in the everyday life. The Social Exclusion Theory, developed in Europe in the 1990s, originated in the study of social inequality and now has become a core concept of interpreting various social problems. This article, with the Qiaotou administrative village of Hekou County, Yunnan Province as the location for case study and with a qualitative research method, in a micro-spatial scale explores the social exclusion suffered by the Vietnamese brides. The researchers investigated in January 2012 and August 2012 respectively 10 Vietnamese brides on the spots of 7 villages. The research findings are shown as follows: 1) Without legal status, the Vietnamese brides have no access to buying train tickets and to checking in at hotels, which make their activities restricted in the terms of public space; 2) The Vietnamese brides and the indigenous villagers, being “Others” and “Subjects” respectively in “place”, form two opposed “spaces”. The Vietnamese brides, without citizenship and excluded from the village’s public space, have no access to the village’s political affairs and social activities. Even worse, the Vietnamese brides are monitored by the indigenous villagers who try to prevent them from escaping, which makes them live in a situation somewhat similar to “Panopticon” proposed by Jerome Bentham and developed by Michel Foucault. 3) The inferior spatial position of the Vietnamese brides’ houses worsens the social exclusion of the Vietnamese brides. The spatial analysis of a house owned by an indigenous villager who married a Vietnamese bride reveals that the spatial marginalization caused by the house being on the edge of the village—an inferior spatial position, hinders the communications between the Vietnamese brides and the indigenous villagers. This study reveals that the spatial exclusion of the Vietnamese brides are due to their lack of legal status, economic inferiority and stigmatization imposed by the public opinions. This study enriches, in terms of the micro-space, both the Social Exclusion Theory and its related empirical research.
Drought is a disaster which occurs in the broadest area most frequently and has the most severe impact among natural disasters. It was very popular in other disaster research especially in earthquake and geologic disaster field to study the relationship between frequency and magnitude. This article could get quantitative results about the occurrence frequency on a certain scale and the risk assessment (risk acceptable or unacceptable) of the disaster. This article aims to build the relationship between frequency and magnitude of droughts on the basis of analyzing the droughts change in China in 1950-2000 and accordingly divide the risky area to risk acceptable and unacceptable area. The main results included: 1) In general, grain lost, affected and damaged area of farmland increased during the past 60 years. The annual grain lost, affected area and damaged area were 161.18×108kg, 21 599.54×103ha and 9 613.41×103ha, respectively. The increase rates of the grain lost, affected and damaged area were 5.39×108kg/a, 219.66×103ha/a and 178.82×103ha/a, respectively. 2) Similar to famous Gutenberg-Richard relationship, relationship between cumulative frequency and grain lost showed a good power-law relation. The formula was: LnN(>G)=4.26-0.006G(R2=0.996, P<0.05). Cumulative frequency with damaged and affected area showed good linear relation. The formulas were: N(>DA)=65.869-0.001DA(R2=0.971, P<0.05),N(>IA)=62.105-0.003 IA(R2=0.992,P<0.05), respectively. 3) The principle “Acceptable level of risk is inversely proportional to the damaging effect” is a common principle during the risk control process in engineering. When the principle was used to divide the acceptable level of risk of life loss, F(frequency)-N(number of casualty) rule was appropriate. As a result, the boundary between acceptable and unacceptable risk on annual grain lost, affected and damaged area was drawn. More work need undergoing.
With the development of climate change research, the oxygen concentration in the atmosphere has attracted more and more attentions. This study attempts to estimate and compare regional oxygen production using the ratio of the net ecosystem productivity and oxygen mass according to the principles of the plant photosynthesis and respiration. The total amount and spatial distribution of the century dynamics of the vegetation oxygen production in Heilongjiang Province are estimated by employing the C-FIX model and spatial analysis function in ArcGIS based on the vegetation spatial distribution of Heilongjiang Province, in 1900 and 2009. The results show that: 1) the total amount of the vegetation oxygen production of Heilongjiang Province in 1900 is 338.05 million tons. The total amount of the vegetation oxygen production in 2009 is 210.23 million tons. The vegetation oxygen production decreased about 37.8% with the vegetation deductions in the past one hundred years. 2) The spatial distribution trend of the oxygen production in Heilongjiang Province, 1900 and 2009 are pretty similar. However, they have significant spatial distribution variability. The western and southwestern part of Heilongjiang Province shifted from high oxygen production region in 1900 to low oxygen production region in 2009. The oxygen production in the eastern part, the Sanjiang Plain, has also decreased significantly. 3) The oxygen production trends to decrease at county level in Heilongjiang Province, and the average decrease rate are over 50%. In contrast, Yichun, Heihe and Tahe show increasing trend, but not significantly, and the average decrease rate is less than 5%. The most significantly decreased cities are Harbin, Shuangcheng, Suihua, Suibin, Lanxi, Baiquan, Hulan, and Yi’an, and the average decrease rate is over 90%. 4) The results of control experiments show that, the century vegetation deduction caused about 162.10 million tons decrease of the oxygen production. The oxygen production increased about 34.28 million tons due to the climate change. The amount of the oxygen production decreased by vegetation change is about 4.728 times of the oxygen production increment caused by climate change. In summary, the vegetation deduction is the main reason for the regional oxygen production decrement.
Using SPOTNDVI data, the multiple cropping indexes were inversed by remote sensing in 2000, 2004 and 2008 around Bohai in China. Meanwhile, the influencing factors for the changes of the multiple cropping indexes were detected by geographical detection method. The results showed: 1) The Spatial differences of the multiple cropping index were significant. The latitude zonal laws were obvious for the multiple cropping index spatial distribution, which was changed from 280% in the south plain to 70% in the north mountainous region. It was lower to 40%-50% in hills and the plateau mountain region than in the plain of the same latitude, showed a certain vertical zones law. The multiple cropping index was higher than 150% in traditional agricultural areas of plains, including the southern of Hebei Province, the southwest and north of Shandong Province. The lower value regions of the multiple cropping index were located at Shandong Hilly Areas, Bashang Plateau in Hebei Province and Changbai Mountains in Liaoning Province. 2) The regional differences of the dynamic change for the multiple cropping index were obvious in 2000-2008. The multiple cropping index was increased in the traditional agricultural areas of the plains. The regions where the dynamic degree was more than 10% were located in the southwest, northwest and east in Shandong Province, Haihe river plain in Hebei Province. On the contrary, the negative value regions of the dynamic degree were located in the Hilly Areas of Shandong Province, Bashang Plateau of Hebei Province and the Liaohe River plain in Liaoning Province in 2000-2004. There were rebound in declined areas, and remained stable in increase areas in 2004-2008. 3) The level of grain production was an important factor affecting changes of the multiple cropping indexes. There were many factors affecting changes of the multiple cropping index, including the per capita cultivated land area, transfer degree for rural labor force, the basic conditions of agricultural production, the level of agricultural modernization, location conditions etc. In order to improve cultivated land use efficiency and agriculture development, a reasonable and order land transfer should be actively pursued in the plain. Meanwhile, large of new agricultural cooperative organizations should be developed, so that the regional agricultural modernization is improved. On the other hand, the comprehensive consolidation of land should be actively implemented including cultivated land, water, roads, forests, and villages, which promoted the construction of high-standard farmland, to protect regional food security and rural-urban development transition healthily. Developing specialized agriculture in the hills and mountains and highland areas, the quality fruits are developed to enhance industrial competitiveness of specialty agriculture.
This study constructed growing season NDVI in 1982-2011 based on GIMMS and MODIS data in Inner Mongolia. The spatial and temporal characteristics of inter-annual NDVI changes were analyzed and natural and human influence factors were investigated in different eco-geographical regions. The results show that, linear regression equation is a good method to modify NDVI in GIMMS and MODIS remote images. The growing season NDVI increased on the whole and the increase rate was 0.265% and displayed significant inter-annual fluctuations in the past 30 years. NDVI decreased significantly in 1982-1986, then increase significantly during 1997-2002, and relative steady phases were in 1986-1997 and in 2002-2011. NDVI that increased most significantly were located in the northern of Inner Mongolia. However, there were 5.075% regions decreased which mainly distributed on typical steppe in Hulun Buir and Xilin Gol. NDVI change rates of different vegetations from eco-geographical region were in the following order: farm and shrub > forest > farm and typical steppe > meadow and meadow steppe > typical steppe and farm > typical steppe > desert steppe > desert. NDVI change rate was fastest in IIC2 eco-geographical region which was 0.277 and slowest in IID2 eco-geographical region which was 0.001. NDVI was significantly correlated with precipitation in most regions and presented obvious strap regularity from east to west, which was negative correlation in the eastern region, positive correlation in center region and no correlation in the western region. However, great differences existed in different eco-geographical region of Inner Mongolia. Eco-geographical region of IIA3, IA1 had biggest correlation which more than 0.5 but significant negative correlate between NDVI and precipitation in all regions. NDVI had little significantly positive correlations with temperature in Inner Mongolia whose correlations were less than 0.2 in most eco-geographical regions. However, NDVI exhibited significant positive correlations with temperature in highland desert steppe region of Western Inner Mongolia and highland steppe region of Eastern Inner Mongolia. Vegetation that influenced by human activities was gradually increased with the increase of vegetation complex degree in the last 30 years. There are most effects by human activities in IIC1, IIC2, IIIB3 eco-geographical region which located on the south of the Da Hinggan Mountains and least effects in IA1, IIB2, IIA3 eco-geographical region which distributed in the northeastern of the mountains. In the areas where human activities heavily restrained NDVI increased by 41.165%, and they were located in IIC3, IIC4 and IID2 eco-geographical region, in the other eco-geographical regions NDVI were promoted about 58.835% obviously. In IIC1, IIC2, IIIB3 eco-geographical region human activities promote NDVI most significantly. NDVI was promoted by national policies such as the natural forest protection project, conversion of cropland to forest and grassland project, desertification treatment and so on. However, over grazing, excessive reclamation, rapid urbanization etc could lead NDVI decrease.
Mu Us Sandy Land lies in the farming-pastoral ecotone of northern China, whose ecological environment shows great sensitivity and vulnerability. In this article, temporal series of MOD13Q1 productions, which derived from moderate resolution imaging spectroradiometer (MODIS) sensor in 2000-2011, were used to establish temporal sequence of annual enhanced vegetation index (EVI) maximum. Departure, slope, standard deviation and coefficient of variance of EVI were calculated to study the spatial and temporal characteristics of vegetation growth status in Mu Us Sandy Land. Results show that: 1) in 2000-2011, annual maximum of EVI value mainly fluctuates slightly in Mu Us Sandy Land and area whose EVI departure range is -0.1≤ΔEEVI≤0.1, occupies more than 98.467% of the total area. Area with -0.2≤ΔEEVI<-0.1 is the largest in 2001 (1.341%) and the smallest is in 2009 (0.074%). Area with 0.1<ΔEEVI≤0.2 is the largest in 2002 (1.050%) and is the smallest in 2001 (0.138%). In the whole region, the average EVI departure values in 2000, 2001, 2003, 2005 and 2006 are negative while the values in 2002, 2004, 2007, 2008, 2009, 2010 and 2011 are positive. Vegetation growth status is the worst in 2001 and the second worst is in 2000. Conversely, the best vegetation growth status is in 2010 and the second best in 2002. 2) Annual maximum of EVI in the whole region increases by 0.002 5/a. Area with increasing trend occupies 81.916% of the whole area, which mainly distributes in the middle, eastern and southern parts of Sandy Land. Area with decreasing trend occupies 18.084% of the whole area, which mainly distributes in the northern, western, southern and middle parts of Mu Us Sandy Land. 3) Vegetation grow status mainly improves with slight and moderate fluctuations, whose areas occupie 35.878% and 34.697% of the total area respectively, which locate in the southwest, middle and eastern parts of Mu Us Sandy Land. Area of vegetation with severe fluctuated improving growth status occupies 8.381%. Moreover, areas with slight and moderate fluctuated degraded growth status occupies 7.876% and 7.174% of the whole area, respectively. Vegetation with severe fluctuated improving growth status mainly locates in the southwest and southeast parts of Sandy Land while slight and moderate fluctuated degraded growth status locate in the southwest, western, central and southern parts of Mu Us Sandy Land.
The change trend of vegetation cover in Mongolian plateau and its response to seasonal temperature and precipitation were analyzed by employing MODIS NDVI in 2001-2010, composed by 16 day maximum value synchronous climate variables and MODIS land cover product MCD12Q1. The result indicated that the area of vegetation cover increased which was similar to that of vegetation cover decreased, reaching 43.75% and 42.22% of the total area of Mongolian plateau, respectively. In recent 10 years, the vegetation cover decreased in spring and summer, while increased in autumn. The correlation analysis between seasonal NDVI and corresponding seasonal climate factors showed that the correlativity between NDVI and precipitation was significant in spring and summer (P=0.02 in spring, P=0.003 in summer), and the correlation coefficient between NDVI and precipitation in autumn also reached 90% confidence level, indicating that precipitation was a main factor of influencing vegetation cover changes in Mongolian plateau. It was found that five different vegetation types experienced increasing trend in autumn, vegetation changes in Gobi-desert experienced increasing trend in all 3 seasons.NDVI of forest, grassland and shrub decreased in spring and summer, while farmland decreased in spring and increased in summer.
Gully density is used to describe the intensity of regional soil erosion and landform development, which is significant to understand the spatial pattern and formation mechanism of loess landforms by analyzing the spatial distribution. According to the principal of quadrat analysis, this article represent a series of maps revealing the spatial distribution of gully density in the Loess Plateau through digital terrain analysis method and Kriging interpolation model, as well as 5 m×5 m DEM data sets. The spatial variation characteristics of gully in the Loess Plateau were investigated. Moreover, some controlling factors on gully development were explored, and relationship between gully density and soil erosion was revealed. Results showed that the spatial variation feature of gully density was obvious, and gully density reached the peak in region of Suide-Mizhi in northern Shaanxi, then, it decreased from north to south in the Loess Plateau. On the macroscopic, the distribution trend of gully was controlled by geological structure so that it was classified into three parts. To the west of the Liupan Mountains as the first part, its value was low with smooth changes. The second part located in the middle and southern parts of the Loess Plateau to the east of the Liupan Mountains, the west of the Luliang Mountains, and its value decreased in gradient from north to south. To the east of the Luliang Mountains as the third part, its value ranged from 1.7 to 6.4 km/km2 with fluctuant change. Rainfall intensity was rather significant for spatial variability of gully erosion, which was coupled with the diversification of gully density in space. In addition, vegetation condition and composition of ground material in the Loess Plateau varied from northwest to southeast, which influenced gully development. Gully density was positively and strongly correlated with the sediment transport modulus in the soil erosion in spatial, especially for regions of the middle Loess Plateau, indicating it is an important factor reflecting the capacity of gully erosion. In conclusion, gully density was significantly indicative on understanding the spatial pattern of loess landform.
A high-resolution oxygen isotope profile of the past 500 years was established with an average resolution of approximately one year, based on 7 high-precision 230Th dates and 438 stable oxygen isotope ratios (δ18O) which were obtained from a stalagmite (NSM03) collected from Shuiming Cave, Chongqing City. So the variation of summer monsoon precipitation in the Three-Gorges reservoir area during the period of 1250-1750 A.D. was reconstructed. The δ18O value of the stalagmite NSM03 became heavier rapidly from 1280 A.D., and reached to the heaviest around 1300 A.D. During the past 500 years, the Asian monsoon became weak rapidly, implying the Little Ice Age (LIA) starts. The trend of δ18O record from stalagmite NSM03 coincides with the other stalagmite records of the Asian monsoon region within the limits of dating error. Results showed that there were obvious interdecadal wet and dry fluctuations in LIA, especially during 1400-1650A.D. δ18O value of the stalagmite fluctuated dramatically indicating that monsoon precipitation was in frequently fluctuate period. Spectral analysis showed NSM03 δ18O sequence had significant cycle of 98, 26, 5, 4, and 3 years (above the 99% confidence level). Similar periodicities of 98 and 26 years were proved by the δ18O record, further supporting the idea that solar changes were mainly responsible for Asian monsoon intensity changes in LIA; and 5, 4 and 3 years were consistent with the 2-7 years standard cycle of El Nino-Southern Oscillation (ENSO), which implied that LIA climate variation had a close relation with ENSO.
Permafrost on the Qinghai-Tibet Plateau (QTP) is elevational, where the permafrost accounts for approximately 75% of the elevational permafrost in the Northrn hemisphere. Located in the transition zone from the Qinghai-Tibet Plateau higher than 4 500 m a. s. l. to the Loess Plateau at less than 2 000 m a. s. l., the Bayan Har Mountains (BHM) have typical alpine permafrost. The intensive uplifts of the BHM have resulted in a great variety in climate, permafrost and landscapes on the north and south slopes. Based on field investigations and ground temperature measurements between 2008-2012, the distributive features and controlling/influencing factors of permafrost in the BHM are revealed in detail in this paper. Most permafrost in the BHM is warm (>-1℃), except that at some mountain tops such as Chalaping and the Bayan Har Mountain Pass. The ground temperature in the BHM is principally controlled by elevations. The lowest MAGT of -1.8℃ and the thickest permafrost of 74 m are found at Chalaping higher than 4 700 m a. s. l. The lapse rate of MAGT with rising elevation is 6℃/km on the north slopes and 4℃/km on the south slopes, respectively. The MAGTs are -0.2℃ in Borehole YNG-1 at the north-slope toes, and +0.3℃ in Borehole QSH-1 at the south-slope toes. Permafrost thins rapidly downwards at both slope toes. The MAGTs are lower than -0.5℃ at elevations above 4 570 m a. s. l. on the south slopes and above 4 527 m a. s. l. on the north slopes. The MAGTs are lower than -1℃ at elevations above 4 670 m a. s. l. on the south slopes and above 4 615 m a. s. l. on the north slopes. The zone boundaries of -0.5℃ in mean annual ground temperatures largely coincide with the lower limits of sporadic (discontinuous) permafrost, and zone boundaries of -1℃ correspond to the lower limits of continuous permafrost. The active layer thickness, which usually affected by the lithology (soil types) and moisture conditions, is about 1 m at the Bayan Har Mountain Pass and Chalaping on the north slopes. It increases with declining elevation. However, on the south slopes, it is greatly influenced by some local factors, such as vegetative coverage and soil moisture contents. For example, the active layer is more than 4 m deep in Borehole CLQ-1 at 4 642 m a. s. l., where the surface vegetation coverage is low, and soils and alpine meadows are broken by rodent and insect activities.
