2012 Vol. 22, No. 6

Display Method:
Estimation of Storage and Density of Organic Carbon in Peatlands of China
LIU Zigang1, WANG Ming2, 3, MA Xuehui2
2012, 22(6): 637-646.
Based on the results of the National Survey of Peat Resources (1983–1985) and the investigation results on the peatlands of China, the storage and density of the organic carbon in the peatlands of China were estimated. The total organic carbon storage (OCS) of the peatlands in China, including bare peatlands and buried peatlands, are 1.503 × 109 t, unevenly distributed over 30 provincial level administrative units and 16 climatic zones. Peatland organic carbon storage (POCS) in Sichuan (6.45 × 108 t) and Yunnan provinces (2.91 × 108 t) is the highest, accounting for 62.29% of the total POCS. Humid zone of plateau has the highest POCS of 7.14 × 108 t, especially in the Zoigê Plateau, where the POCS is 6.30 × 108 t, accounting for 41.92% of the total POCS of China. The organic carbon density (OCD) of the peatlands in China mostly ranges from 80 kg/m3 to 140 kg/m3, and the range of the maximum is 270–360 kg/m3, and the minimum is less than 80 kg/m3. Divided by the Yanshan Mountain, Taihang Mountains and Hengduan Mountains, the peatland oganic carbon density (POCD) is lower on the northwestern side than that on the southeastern side. Jiangxi Province has the highest POCD due to the ancient buried peatlands. The OCD of the bare peatlands is mostly in the range of 60–150 kg/m3, and that of the buried peatlands is more than 100 kg/m3. In the bare peatlands, the OCD generally increases from the surface layer to the below surface layer, and then decreases with the depth. Although the peatlands area in China is small, the OCS per unit area is far higher than the other soil types, so peatlands protection can effectively mitigate climate change.
Responses of Soil Fauna Structure and Leaf Litter Decomposition to Effective Microorganism Treatments in Da Hinggan Mountains, China
GAO Meixiang, LI Jingke, ZHANG Xueping
2012, 22(6): 647-658.
Microorganisms are nutritious resources for various soil fauna. Although soil fauna grazing affects microorganism composition and decomposition rate, the responses of soil fauna and leaf litter decomposition to added microorganism is little understood. In this study, in the coniferous and broad-leaved mixed forest of Tahe County in the northern Da Hinggan Mountains, China, three sampling sites (each has an area of 10 m2) were selected. The first two sites were sprinkled with 250 times (EM1) and 1000 times (EM2) diluted effective microorganism (EM) preparations evenly, and the third site was sprinkled with the same volume of water as a control site. The responses of soil fauna structure and leaf litter decomposition to EM treatment were conducted during three years. The results revealed that EM treatment resulted in significant increase of soil organic matter. The number of soil fauna in the EM1 and EM2 sites increased by 12.88% and 2.23% compared to the control site, and among them springtails and mites showed the highest increase. However, the groups of soil fauna in the EM1 and EM2 sites decreased by 6 and 9, respectively. And the changes in the diversity and evenness index were relatively complicated. EM treatment slowed the decomposition of broad-leaved litter, but accelerated the decomposition of coniferous litter. However, the decomposition rate of broad-leaved litter was still higher than that of coniferous litter. The results of this study suggested that the added microorganisms could help individual growth of soil fauna, and this method led to a change in the process of leaf litter decomposition. This paper did not analyze the activity of soil microorganisms, thus it is difficult to clearly explain the complex relationships among litter type, soil fauna and soil microorganisms. Further research on this subject is needed.
Discretization Approach in Integrated Hydrologic Model for Surface and Groundwater Interaction
ZHANG Jing, Mark A ROSS, Jeffery GEURINK
2012, 22(6): 659-672.
The commonly used discretization approaches for distributed hydrological models can be broadly categorized into four types, based on the nature of the discrete components: Regular Mesh, Triangular Irregular Networks (TINs), Representative Elementary Watershed (REWs) and Hydrologic Response Units (HRUs). In this paper, a new discretization approach for landforms that have similar hydrologic properties is developed and discussed here for the Integrated Hydrologic Model (IHM), a combining simulation of surface and groundwater processes, accounting for the interaction between the systems. The approach used in the IHM is to disaggregate basin parameters into discrete landforms that have similar hydrologic properties. These landforms may be impervious areas, related areas, areas with high or low clay or organic fractions, areas with significantly different depths-to-water-table, and areas with different types of land cover or different land uses. Incorporating discrete landforms within basins allows significant distributed parameter analysis, but requires an efficient computational structure. The IHM integration represents a new approach interpreting fluxes across the model interface and storages near the interface for transfer to the appropriate model component, accounting for the disparate discretization while rigidly maintaining mass conservation. The discretization approaches employed in IHM will provide some ideas and insights which are helpful to those researchers who have been working on the integrated models for surface-groundwater interaction.
Relationship Between Changes of River-lake Networks and Water Levels in Typical Regions of Taihu Lake Basin, China
YIN Yixing, XU Youpeng, CHEN Ying
2012, 22(6): 673-682.
The typical regions of the Taihu Lake basin, China, were selected to analyze the variation characteristics of river-lake networks under intensive human activities. The characteristics of the fractal dimension of river networks and lakes for different periods were investigated and the influences of river system evolution on water level changes were further explored through the comparison of their fractal characters. The results are as follows: 1) River network development of the study area is becoming more monotonous and more simple; the number of lakes is reducing significantly, and the water surface ratio has dropped significantly since the 1980s. 2) The box dimension of the river networks in all the cities of the study area decreased slowly from the 1960s to the 1980s, while the decrease was significant from the 1980s to the 2000s. The variations of lake correlation dimension are similar to those of the river network box dimensions. This is unfavorable for the storage capacity of the river networks and lakes. 3) The Hurst exponents of water levels were all between 0.5 and 1.0 from the 1960s to the 1980s, while decreased in the 2000s, indicating the decline in persistence and increase in the complexity of water level series. The paper draws a conclusion that the relationship between the fractal dimension of river-lake networks and the Hurst exponents of the water level series can reveal the impacts of river system changes on flood disasters to some extent: the disappearance of river networks and lakes will increase the possibility of flood occurrence.
A Novel Dynamic Stretching Solution to Eliminate Saturation Effect in NDVI and Its Application in Drought Monitoring
LIU Fang, QIN Qiming, ZHAN Zhiming
2012, 22(6): 683-694.
The normalized difference vegetation index (NDVI) is one of the key input variables for developing drought indices. However, the NDVI quickly saturates in high vegetation surfaces, and thus, the generalization of a drought index over different ecosystems becomes a challenge. This paper presents a novel, dynamic stretching algorithm to overcome the saturation effect in NDVI. A scaling transformation function to eliminate saturation effects when the vegetation fraction (VF) is large is proposed. Dynamic range adjustment is conducted using three coefficients, namely, the normalization factor (a), the stretching range controlling factor (m), and the stretching size controlling factor (e). The results show that the stretched NDVI (S-NDVI) is more sensitive to vegetation fraction than NDVI when the VF is large, ranging from 0.75 to 1.00. Moreover, the saturation effect in NDVI is effectively removed by using the S-NDVI. Further analysis suggests that there is a good linear correlation between the S-NDVI and the leaf area index (LAI). At the same time, the proposed S-NDVI significantly reduces or even eliminates the saturation effect over high biomass. A comparative analysis is performed between drought indices derived from NDVI and S-NDVI, respectively. In the experiment, reflectance data from the moderate resolution imaging spectroradiometer (MODIS) products and in-situ observation data from the meteorological sites at a regional scale are used. In this study, the coefficient of determination (R2) of the stretched drought index (S-DI) is above 0.5, indicating the reliability of the proposed algorithm with surface soil moisture content. Thus, the S-DI is suggested to be used as a drought index in extended regions, thus regional heterogeneity should be taken into account when applying stretching method.
Errors Prediction for Vector-to-Raster Conversion Based on Map Load and Cell Size
LIAO Shunbao, BAI Zhongqiang, BAI Yan
2012, 22(6): 695-704.
Vector-to-raster conversion is a process accompanied with errors. The errors are classified into predicted errors before rasterization and actual errors after that. Accurate prediction of the errors is beneficial to developing reasonable rasterization technical schemes and to making products of high quality. Analyzing and establishing a quantitative relationship between the error and its affecting factors is the key to error prediction. In this study, land cover data of China at a scale of 1∶250 000 were taken as an example for analyzing the relationship between rasterization errors and the density of arc length (DA), the density of polygon (DP) and the size of grid cells (SG). Significant correlations were found between the errors and DA, DP and SG. The correlation coefficient (R2) of a model established based on samples collected in a small region (Beijing) reaches 0.95, and the value of R2 is equal to 0.91 while the model was validated with samples from the whole nation. On the other hand, the R2 of a model established based on nationwide samples reaches 0.96, and R2 is equal to 0.91 while it was validated with the samples in Beijing. These models depict well the relationships between rasterization errors and their affecting factors (DA, DP and SG). The analyzing method established in this study can be applied to effectively predicting rasterization errors in other cases as well.
A New Approach to Measurement of Regional Inequality in Particular Directions
WANG Yang, FANG Chuanglin, XIU Chunliang, LIU Daqian
2012, 22(6): 705-717.
Regional inequality is a core issue in geography, and it can be measured by several approaches and indexes. However, the global inequality measures can not reflect regional characteristics in terms of spatiality and non-mobility, as well as correctly explore regional inequality in particular directions. Although conventional between-group inequality indexes can measure the inequality in particular directions, they can not reflect the reversals of regional patterns and changes of within-group patterns. Therefore, we set forth a new approach to measure regional inequality in particular directions, which is applicable to geographic field. Based on grouping, we established a new index to measure regional inequality in particular directions named Particular Direction Inequality index (PDI index), which is comprised of between-group inequality of all data and between-group average gap. It can reflect regional spatiality and non-mobility, judge the main direction of regional inequality, and capture the changes and reversals of regional patterns. We used the PDI index to measure the changes of regional inequality from 1952 to 2009 in China. The results show that: 1) the main direction of China′s regional inequality was between coastal areas and inland areas; the increasing extent of inequality between coastal areas and inland areas was higher than the global inequality; 2) the PDI index can measure the between-region average gap, and is more sensitive to evolution of within-region patterns; 3) the inequality between the northern China and the southern China has been decreasing from 1952 to 2009 and was reversed in 1994 and 1995.
Changing Spatial and Structural Patterns of Non-agricultural Activities in Outward-moving Beijing Urban Fringe
CAO Guangzhong, LIU Tao, LIU Hui, MIAO Yangbing
2012, 22(6): 718-729.
As responses to metropolitan suburbanization and rural urbanization, the formation and evolution of urban fringes should be understood against the background of overall economic development and spatial reconstruction of entire metropolises. At the same time, however, endogenous interactions between industrial structure and spatial patterns of non-agricultural activities are also worthy of scholarly attention. Since the 1980s, studies on urban fringes in China have been restricted by the lack of micro-level data. This paper investigates the spatial expansion and structural evolution of the urban fringe by taking the case of Beijing and uses systematic firm-level data in 1996 and 2001 from the National Census of Basic Units. The diversity of distribution patterns across industrial sectors brings about two interrelated results. On the one hand, structural adjustment of non-agricultural industries promotes the expansion and spatial evolution of the urban fringe. On the other hand, the stability and dynamics of industrial structure coexist in the moving urban fringe. This study also reveals that the outward-moving urban fringe is the optimal location for manufacturing, especially heavy manufacturing, as well as traditional producer and consumer services. However, industries with spatial stickiness such as tourism and sports have not moved with the fringe. Most advanced services remain concentrated in the city center. The authors argue that it is essential for understanding and managing urban fringes to take into account spatial evolution and industrial structural adjustment together with their interaction with each other.
Spatial Disparity and Efficiency of Science and Technology Resources in China
WANG Bei, LIU Weidong, LU Dadao, ZHANG Jianbo
2012, 22(6): 730-741.
In the knowledge economy era, science and technology (S&T) resources are getting more and more important in shaping regional competiveness and building regional innovation capacity. As such, the spatial distribution of S&T resources is a key to understanding regional development and disparities. By designing an input-output indicator system, this paper develops an evaluation model to examine the spatial distribution of S&T resources in China and assess their spatial efficiency. Moreover, the paper tries to explain spatial differences in the efficiency of S&T resources in China. Major findings are: 1) the input and output of S&T resources in China shows a clear T-shaped spatial structure, i.e., concentrated mainly in the coastal region and along the Changjiang (Yangtze) River; 2) the efficiency of S&T resources in China displays strong spatial disparities, with the level of efficiency descending from the east to the west while high efficiency appearing in only several clusters; 3) the utilization rates of S&T resources in most provinces are quite low, resulting in low efficiency of S&T resources allocation. The paper suggests that the utilization rate of S&T resources should be raised and the commercialization of S&T outputs should be enhanced to improve the efficiency of S&T resources in China.
Impact of Tourists′ Perceived Value on Behavioral Intention for Mega Events: Analysis of Inbound and Domestic Tourists
at Shanghai World Expo
WANG Chaohui, LU Lin, XIA Qiaoyun
2012, 22(6): 742-754.

Based on the survey data for 2120 inbound and domestic tourists at the Shanghai World Expo, a structural equation model was constructed for the relationship among tourists′ perceived value dimensions, behavioral intention and revisit intention. Additionally, the influence of tourists′ perceived value dimensions on the behavioral intention and revisit intention was explored. The results show that the utilitarian value and enjoyment value significantly affect the inbound and domestic tourists′ behavioral intention, while the convenience value and aesthetic value have no significant influence. The service value only significantly affects the domestic tourists′ behavioral intention, and the aesthetic value only significantly affects the inbound tourists′ behavioral intention. The utilitarian value, service value and enjoyment value significantly affect the inbound and domestic tourists′ revisit intention, while the convenience value only significantly affects the domestic tourists′ revisit intention. The utilitarian value is the primary factor affecting the inbound tourists′ behavioral intention and revisit intention, and the perceived price has no significant effect on either inbound or domestic tourists′ behavioral intention or revisit intention. The study explores the relationships between tourists′ perceived value, behavioral intention and revisit intention, analyzes the divergence and causation, theoretically enriches the research field of tourism geography and behavioral geography, and has great practical significance to the sustainable development of mega events in China, including the further development of the Shanghai World Expo.  

Roles and Functions of Tourism Destinations in Tourism Region of South Anhui: A Tourist Flow Network Perspective
LIU Fajian, ZHANG Jinhe, ZHANG Jie, CHEN Dongdong, LIU Zehua, LU Song
2012, 22(6): 755-764.
Theoretic and practical significance has been highlighted in the research of the roles and functions of destinations, as destinations are restricted by the spatial structure based on tourist flow network from the perspective of relationship. This article conducted an empirical analysis for Tourism Region of South Anhui (TRSA) and revealed the necessity and feasibility of studying the roles and functions of destinations from tourist flow network′s perspective. The automorphic equivalence analysis and centrality analysis were used to classify 16 destinations in TRSA into six role types: tourist flow distribution center, hub of tourist flows, passageway destination, common touring destination, attached touring destination, and nearly isolated destination. Some suggestions were given on suitable infrastructure construction and destinations service designs according to their functions in network. This destination role positioning was based on tourist flow network structure in integral and macroscopic way. It provided an important reference for the balanced and harmonious development of all the destinations of TRSA. In addition, this article verified the applicability of social network analysis on tourist flow research in local scale, and expanded this method to destination role and function positioning.