In recent decades, the idea of "health" as an appropriate paradigm to assess the condition of ecosystems has been raised. Ecosystem health is the watchword of contemporary ecosystem management, it is also a controversial topic in ecology because there is still no explicit definition, which makes it difficult to assess ecosystem health. As there are too many uncertain factors accompanied with complexity, the qualitative and semi-qualitative methods have become the main approaches to assess ecosystem health. In this study, based on GIS and remote sensing technique we take China's forest ecosystems as a case study and assess the health status of forests. Vigor (V), Organization (O), and Resilience (R) are taken as the indicators to evaluate large-scale forest ecosystem health. As this model is applied to assess forest ecosystems, NPP, Gleason index of biodiversity, and resistance to forest pest-disease disaster are selected as concrete indicators to assess forest ecosystem health in China. The spatial pattern of forest ecosystem health shows a decreasing trend along latitude gradient and longitude gradient. According to the zonation of forest in China, the healthy forests are mainly distributed in natural forest, tropical rain forest and seasonal rain forest distributed areas, as well as northeast national forest zone. Whereas the unhealthy forests are mainly distributed in warm temperate zone and Xinjiang-Mongolia forest zone. Many catastrophic events such as forest fire, acid deposition, pest-disease disasters affect forest health. The health status relates to landform, climate condition, forest species structure, exotic forest pest invasion, human activities disturbance, national law and policy and so on. We measure the correlation coefficient by spatial correlation analysis. The coefficient of correction between FEHI and annual average precipitation is 0.58 (p < 0.01), while the coefficient of correlation between FEHI and annual mean temperature is 0.49 (p < 0.01), which means that the precipitation and temperature affect the pattern of FEHI, and the precipitation's effect is stronger than the temperature's. We also measure the correlation coefficient between FEHI and NPP, biodiversity and resistance, the coefficient of correlation is 0.64, 0.76 and 0.81 (p < 0.01) respectively. The order of effect on forest ecosystem health is vigor, organization and resistance.
Based on a distributed model for calculating astronomical solar radiation (ASR), monthly ASR with a resolution of 1 km×1 km for the rugged topography of the Yellow River Basin is calculated, with DEM data as the general characterization of terrain. This model gives an all-sided consideration on factors that influence the ASR. Results suggest that (1) the annual ASR has a progressive decreasing trend from south to north; (2) the order of seasonal ASR is summer>spring>autumn>winter; (3) the geographical and topographical factors have robust effects on the spatial distribution of ASR, particularly in winter where a lower sun elevation angle exists; (4) the ASR magnitude for slopes with a sunny exposure is generally 2 or 3 times that of slopes with a shading exposure in January and the extreme difference of ASR for different terrains is over 10 times; (5) the spatial differences of ASR are relatively small in summer where a higher sun elevation angle exists and the extreme difference of ASR for different terrains is only 16% in July; and (6) the sequence of influence strength for topography is winter>autumn>spring>summer.
A radar survey on permafrost changes has been conducted in Xidatan, the northern limit of permafrost on the Qinghai-Tibet Plateau (QTP). Comparison with the survey result of 1975 in the same region shows that, in the last 30 years, permafrost degradation has occurred on a relatively large scale in the northern limit of permafrost on the QTP. Permafrost area in the region of interest has been shrunk to 141.0 km2 from original 160.5 km2 in 1975, or permafrost reduction rate estimated being about 12%. The lowest altitude with permafrost coverage is 4385 m exposed in this survey, 25 m higher than that of 1975. Climate change during the past 3 decades in the permafrost northern limit mostly contributes to the reduction. However, under the same climate scenario, no significant degradation was found in the scale of 30 years in the continuous permafrost zone, despite distinct ground temperature rising there. The survey result shows a fact to tell how and how much permafrost responses to climate change, and provides a reference to identify interaction models between permafrost and climate system.
Slope is one of crucial terrain variables in spatial analysis and land use planning, especially in the Loess Plateau area of China where rugged terrains enhance serious soil erosion. DEM based on slope extracting method has been widely accepted and applied in practice. However slope accuracy derived from this method usually does not match with their popularity. A quantitative simulation to slope data uncertainty is important not only theoretically but also necessarily to applications. This paper focuses on how resolution and terrain complexity impact the accuracy of mean slope extracted from DEMs of different resolutions in the Loess Plateau. Six typical geomorphologic areas are selected as test areas, representing different terrain types from smooth to rough. Their DEMs are produced from digitizing contours of 1:10000 scale topographical maps. Field survey results show that 5 m should be the most suitable grid size for representing slope in loess area. Comparative and math-simulation methodology was employed for data processing and analysis. A linear correlativity between mean slope and DEM resolution was found at all test areas, but their regression coefficients were closely related with the terrain complexity of the test areas. If stream channel density was taken to represent terrain complexity, mean slope error could be regressed against DEM resolution (X) and stream channel density (S) at 8 resolution levels could be expressed as (0.0015S2 + 0.031S - 0.0325)X - 0.0045S2 - 0.155S + 0.1625, with a R2 value of over 0.98. Practical tests also show an effective result of this model in applications.
The paper chooses the industrial city-Shuicheng basin in Guizhou province-as research site because the karst water quality around the city has become deteriorated with land use and land cover change. The natural susceptibility of karst water system is the important factor leading to karst water pollution. But the change of land use and land cover is the main factor according to the changing data of the water quality analysis and land use change. So it is a good way to protect karst water through rational planning and managing land use and land cover.
Diversity indices and abundance distribution models are statistical tools which ecologists have applied for decades for analyzing the intrinsic regularities of various ecological entities. In this work, similar techniques are used to analyze pedodiversity of some soil properties, and discussions are conducted on the basis of the SOTER digital databases in Hainan Island of China. Through calculation of indices of richness (S), indices of diversity (H') and indices of evenness (E) of soil profile depth types, soil horizon number types and soil (surface) bulk density types of different landforms, and establishment and application of the model of multi-distribution of soil profile depth types, soil horizon number types and soil (surface) bulk density types of the landforms, the analysis of pedodiversity of some soil properties of different landforms in Hainan under the GIS environment can be expressed digitally.
In 2000 and 2001, the water content and salinity of soil, groundwater table and salt concentration were investigated in Sangonghe basin. Using the land use maps of 1987 and 1998, the dynamics of land use and the influence of spatio-temporal dynamics of water and salinity on land use are analyzed. In old oasis of the upper reaches of the rivers, farmland area increased gradually, and water used in old oasis also increased, acccounting for over 90% of the total runoff. Compared with 1988, 1998 witnessed a drop of groundwater table in old oasis but a rise in all investigation spots of new oasis in the lower reaches. In the new oasis of lower reaches of Songonghe, from oasis, ecotone to sand dune, soil salinity has not changed much, and no significant differences among these ecosystems have been found. Soil water content has decreased much from oasis, ecotone to sand dune. In ecotone, influenced by irrigation of the adjoining oasis, groundwater table has been raised and soil water content also increased compared with sand dune nearby, vegetation developed well, ecotone has been very stable and border of oasis has not changed for decades. From oasis to abandoned land and desert grassland, soil salinity changes much with significant difference in spatial variations. In abandoned land and peripheral desert of oasis, influenced by irrigation of oasis, groundwater table has been raised above the critical depth.Because the soil salt cannot be eluviated by irrigation water and precipitation, salt brought to the upper layers of soils by strong evaporation is especially concentrated on soil surface.
Sampling and testing are conducted on the salt content of the groundwater in the 3 408 km2 of Weigan watershed and semi-variograms function analysis is made afterwards based on the available data by using the geo-statistical method. Results showed that the variance curves of the groundwater salt content in the years 1998 and 1999 display a spherical model, while the curves in 1997 and 2000 exhibit a linear model. Analysis of water samples obtained from 1997 to 2000 indicates that the salt content varies both temporally and spatially in this area. The salinity increases, in the spatial scale, from northwest to southeast of the research area, with east and south higher than west and north separately, and southeast higher than northwest. And the groundwater salinity in the southeast is aggravating with the elapse of time. Geopack and Surfer 7.0 softwares are used to work out a spatio-temporal variation map of salt content, thus providing basis for the decision-making on water-soil management and salinization prevention in this area.
In this paper, we firstly introduce the concept of virtual water, discuss its role in managing water resources and its social, economic, and political implications. Virtual water strategy means countries or regions whose water is scarce achieve their water security and food security by importing water-intensive products from those whose water is abundant, which expands the solution of water resource scarcity to the political-economic system. The particular linkage of population, food, and trade has been the masterstroke of virtual water strategy research. Secondly, we present the methodology to assess the virtual water content in crop and livestock products, and take Gansu as a case to analyse the virtual water content in product and circulating field. Owing to lack of rigorous statistical data of trade among provinces, the above results are then combined with the index of consumption amount of product to get a picture of virtual water circulation in social-economic system of the province. The calculation results show that the total product-related and consumption-related virtual water amount is estimated to be 222.02×108 m3 and 183.75×108 m3 respectively. Thirdly, we discuss the political implications and potential applicability of virtual water associated with water security, economic benefit and consumption structure in Gansu, and examine the advantage and disadvantage of virtual water strategy. The results show that virtual water trade is an instrument to achieve water security and efficient water use. A linkage between consumption patterns and the impacts on water is made.
Historically China was a country with high epidemic frequency which was as high as 25% during 770BC-AD1911. The changes of the epidemic frequency in historical China had closely corresponded with temperature variations climatically. The high frequency periods of epidemics often occurred in the cold spells whereas the sparse periods usually dropped into the warm spells; the colder the climate was, the more frequent the epidemic was, and the longer the cold spell of climate went on, the longer the climax period of the epidemic lasted. For example, the cold era of the Wei, Jin and Southern & Northern dynasties from the 3rd century through the 6th century was the first epidemic climax, the "little ice age" of the Ming and Qing dynasties from the 14th century through the 19th century formed the second epidemic climax. For the past 3000 years China's epidemic frequency had a long-term increasing tendency due to the increasing older climate trend. The general characters of China's epidemic distribution showed that epidemic prevalence in the cities was more severe than in the countryside, and there were more frequent epidemic disasters in the capital city and its environs, densely populated areas, natural epidemic foci, or frequent natural disaster affected areas. The process of regional development and earth-surface humanization had significant impact on the changes of epidemic geographical distribution, the distributional area of epidemics in China during 770BC-AD1911 was radiated gradually from the middle and lower Yellow River, and the core of epidemics showed a shifting trend both from north to south and from east to west.
In this paper, tree ring chronologies were used to reconstruct early-spring temperature in the Qinling Mountains of China. The reconstructed series and the instrument data are well correlated, which the maximum correlation coefficient is up to 0.7 at Zhen'an meteorological station, and that of other stations are above 0.6. So the early-spring temperature changes are well reflected by the reconstructed series in this region. Three warm periods, which are from 1715 to 1740, from 1773 to 1804 and from 1893 to 1958, with 26-year, 32-year and 66-year durations respectively, could be detected in the last 300 years, and three cool periods, which are from 1741 to 1772, from 1805 to 1892 and from 1959 to 1992, with 32-year, 88-year and 34-year durations respectively, could also be detected. It is showed that the early-spring temperature in the region increases quickly and decreases slowly, with changes being consistent with the consequences of other researches. Neither the reconstructed series nor the instrument data has significant warming trend before 1992 in the latter part of the 20th century. For the extent of warm or cool period, the early-spring temperature of the west Qinling Mountains is larger than that of the east. The 100-year, 50 to 60-year, 7 to 8-year and 2 to 3-year period cycles can be detected in the reconstructed early-spring temperature series.
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This paper presented compounded night light index (CNLI) derived from DMSP/OLS data which were pre-processed by Japan National Institute of Environmental Studies for regional urbanization level estimation considering the light spatial distribution and intensity. The correlation analyses between light indices and composite urbanization indices were carried out at provincial level and county level. They can also be carried out in other scales if appropriate census data are available. The results show that there were significant relationships between the two kinds of indices. The regression models at provincial scale and county scale for composite urbanization index estimation using CNLI were also developed. It suggests that CNLI is an effective and applicable index for regional urbanization analysis and monitoring. Analysis of the changes of CNLI, S and I in China during the period 1992-1998 showed that the imbalance of urbanization level in China was obvious. It was higher in the east and lower in the west. Urbanization level was improved largely during 1992-1998, but the speed and the type of development were different.
Using the latest data of the fifth census, the authors try to find some laws of the growth and distribution of population in Beijing Metropolitan Area from 1982 to 2000. First of all, the characteristics of population growth in Beijing Metropolitan Area are analyzed and the spatial models of population growth of different periods are drawn. The authors find that suburbanization happened in the 1980s, and quickened its step in the 1990s. The progress of population growth in the 1980s is homogeneous, because types of spatial change of population are less and similarity is more than difference, while that in the 1990s is heterogeneous, because there are more types and difference is more than similarity. Then regression of mathematical models is used to study the distribution of population and the evolution of spatial structure of Beijing Metropolitan Area. In Beijing, the model of Clark can describe population densities of urban areas well, while the model of Smeed can describe those of metropolitan area well. The changes of some parameters indicate that suburbanization in Beijing is still in the primary phase, and that the main way of suburbanization is not the outer one but the inner one. Based on the regression of multi-nuclear model, the authors find that a multi-nuclear spatial structure of Beijing Metropolitan Area did not exist in 1982, that a two-nuclear one appeared in 1990, and that a multi-nuclear one developed in 2000, which was not ripe compared with that in the western cities.
The urban reforms in China in 1984 introduced an urban land market and a housing market to Chinese cities and had profound impacts on urban structures. Using data from a 1998 survey and other sources in Beijing at the subdistrict level, this research found that differentiations of social areas were taking place in Beijing. Unlike western cities with the socioeconomic status and the family status as dominant forces in forming social areas, Beijing just began to experience the impact of differentiation of socioeconomic status, and the family structure factor was ineffective in Beijing due to decades of family planning. Factor analysis revealed four factors that underlay the social spatial structure in Beijing: (1) land use intensity as the dominant factor displaying a concentric zonal pattern; (2) neighborhood dynamics, mainly composed of the floating population ratio, featuring a sectoral pattern; (3) socioeconomic status exhibiting a combination of sectoral and zonal patterns, and (4) ethnicity resembling a multiple nuclei pattern. Superimposing the four factors generated a complex urban mosaic in Beijing.
Beijing has become one of the most important hi-tech industrial agglomeration areas of China now. Beijing's hi-tech industrial agglomeration has its particular developing process and characteristics. Based on the European and American industrial agglomeration theories, using statistics data, and through questionnaire investigation and enterprise interview, this paper summarizes the process and characteristics of Beijing's hi-tech industrial agglomeration, and also analyzes its industrial types, spatial evolvement process, driving power, driving factors of the cluster, supporting system, developing performance and other important influencing factors. Besides, based on the Diamond Theory of Michael Porter, the paper summarizes the factors influencing Beijing's hi-tech industrial agglomeration and analyses the interaction among them. The particular historic background and original status decides the formation of Beijing's hi-tech industrial agglomeration in some way. While, during the development of Beijing's hi-tech industrial agglomeration, policies and foreign investment play key roles. Policies helping build cooperative network among the government, enterprises and research institutes and regional innovation environment accelerate the development of Beijing's hi-tech industrial agglomeration greatly. And MNCs have also been the most important driving power of Beijing's hi-tech industrial agglomeration these years. Finally, the paper puts forward that the formation of Beijing's hi-tech industrial agglomeration must be analyzed with a comprehensive view, and we should analyze the composition and specific functions of the influencing factors combined with Beijing's peculiarities.
Based on the 5th census data and the China's Statistical Yearbook 2000, the accuracy and reliability of the industrialization levels at the national and provincial levels respectively calculated from the census and statistical data are firstly compared and checked. While analyzing the relationship between industrialization and urbanization at the national and provincial levels in China, this paper finds that it is applicable to use the census data rather than the statistical data to calculate the industrialization level although the industrialization levels calculated from the two types of data sources are both inaccurate. Secondly, the provincial disparities of the relationship between industrialization and urbanization in 1982-2000 are explored in detail, based on the 3rd, 4th and 5th census data in China. Four characteristics have been summarized: (1) The relationships between industrialization and urbanization at provincial level in China are of various types with great differences. Thus, an identical urbanization policy nationwide is inapplicable in China. (2) After the reform and opening up policy was launched in the 1980s, the growth rate of urbanization level greatly exceeds that of industrialization level in most provinces of China, which results in a sharp decrease in the number of provinces with urbanization lagged behind and a rapid increase in the number of provinces with industrialization lagged behind. (3) In those provinces with rather high urbanization level and rapid growth rate, such as Shanghai, Zhejiang, Jiangsu, Fujian, Guangdong and Beijing, their urbanization levels are still lower than their respective industrialization levels; while in those provinces with rather lower urbanization level and slow growth rate, such as Heilongjiang, Liaoning, Jilin, Qinghai, Guizhou, Guangxi, Hubei, Chongqing, Hainan etc., their urbanization levels are, however, higher than their respective industrialization levels. (4) The provincial disparities of the relationship between industrialization and urbanization in China are primarily caused by various growth rates of industrialization among provinces, in particular the sluggish growth of industrialization in the central and western regions.
