The terrestrial biosphere is a dynamic system that interacts with the atmosphere and climate principally through the exchanges of energy, water and elements. Because of the limitations of equilibrium terrestrial biosphere models, the new generation models - dynamic biosphere models, are critically needed for assessing and predicting the primary production and biogeochemical cycles of the terrestrial biosphere in changing global environments. The goal of dynamic biosphere modeling is to model dynamics of terrestrial ecosystems induced by natural and anthropogenic disturbances, as well as the interactions of energy, water and carbon cycles within the terrestrial biosphere and between the terrestrial biosphere and the atmosphere. The critical gaps in developing such a terrestrial biosphere model are not our inability to construct model code but instead the poorly developed links between empiricism and the concepts we used to construct our models, especially: a lack of data that would help to make our models mechanistic, an incomplete fundamental knowledge about how complex terrestrial ecosystems work, a poor understanding of how to scale up what we do know and of how to validate such a model. We have watched many models put forth as hypotheses, criticized, and fail to predict--but then over time become more and more useful, more mechanistic, and genuinely predictive.
As the main topic of global environmental change, researches on land use/land cover change (LUCC) have been extensively carried out. Effects of land use/land cover changes on regional ecological environment were one of the top concerns recently. By affecting regional material cycling and energy flows, LUCC has great impact on regional climate, soil, rainfall, and water quality. The study of the influences of LUCC on regional environment, especially on process and flux of nutrient elements and heavy metals in catchment scale, is significant to raise and draw up land use polices in accordance with sustainable development strategies. In this study, five typical land covers in West Tiaoxi catchment were studied on nitrogen loss in artificial rainstorm runoff. Triple duplication experiments have been carried out under the artificial rain condition with an intensity of 2 mmin-1 and lasting 32 minutes in a 3 m2 field. Transportation and flux of various species of nitrogen in runoff and sediment were investigated. The results show that nitrogen loss amount and rate are quite different among five kinds of land covers. The loss of total nitrogen in runoff of mulberry is the largest and that of paddy field is the smallest. Particle nitrogen accounts for 70%~90% of total nitrogen in runoff of various kinds of land covers. Loss of dissolved nitrogen in pine trees is much higher than the other kinds of land covers, which are similar among them. More detailed species of dissolved nitrogen show their respective features among various land covers. Total amounts of nitrogen loss from top 10 cm layer of 5 kinds of soils are estimated as high as 4.66-9.40 gm-2, of which nitrogen loss through sediment of runoff accounts for more than 90%. The rate of total nitrogen loss ranges in 2.68-14.48 mgm-2min-1 in runoff, which is much lower than that of 100.01-172.67 mgm-2min-1 in sediment of runoff.
Adsorption of phosphate (PO4-P) on sediments taken from the Yangtze estuarine and coastal tidal flats were determined in laboratory. The results indicate that the process of phosphorus adsorption onto sediments mainly occurs within 0-10 h, and then attends to a dynamic equilibrium. Maximum adsorption rates occurred within 0-0.5 h, ranging from 10.40 to 56.40 mg/kgh. The adsorption rates were obviously influenced by the concentration levels of fine particles. Adsorption isotherm curves were fitted to modified Langmuir's equation. Adsorption capacities varied from 26.32 to 204.08 mg/kg, showing good affinities for Fe3+ and total organic carbon (TOC) concentrations. The adsorption efficiency of phosphate on sediments ranged from 21.55 to 248.30 L/kg, showing close correlation with TOC concentrations. Furthermore, the correlation between environmental factors and phosphate adsorption was presented in this experiment, indicating that temperature, pH and salinity have obvious effects on phosphate adsorption.
In 1998-1999, contents of inorganic nitrogen (NH4-N, NO3-N and NO2-N) in water and sediment of intertidal flats of the Shanghai coast were investigated at three stations (CY, DH and LY). Results show that the main form of inorganic nitrogen in water of intertidal flats is of NO3-N with a wide range (37.2~226.1 mol-1); most of exchangeable N in surface intertidal sediments is of NH4-N, accounting for 70%~85%; NH4-N and NO3-N are the main form of inorganic N in pore water of surface sediments. Content distributions of NH4-N, NO3-N and NO2-N in water and sediment of intertidal flats vary seasonally. The basic factors affecting the seasonal variation of inorganic N were discussed. Moreover, the diffusion fluxes of NH4-N, NO3-N and NO2-N between water and intertidal sediment interface were estimated, indicating that NH4-N in sediments may play an important role in the Yangtze estuarine and coastal environment.
The CC1 core, with a length of 216 cm, was drilled in the western part of Chen Co Lake in Tibetan Plateau. The 210Pb and 137Cs test indicated that it was a continuous sedimentary sequence since ca. 1400 years. A total of 15 species of ostracodes belonging to 7 genera in the core sediments had been identified. The ostracoda assemblages and their ecological features, together with the sediments dating decision were used to infer the past ca. 1400 years environmental changes as follows: (1) from the end of the 6th century to the 1370s Chen Co was a deeper water lake. The replenished water that flew into the lake increased obviously and the lake water deepened during ca. 708-780 AD; (2) from the 1370s to the 1890s Chen Co gradually became a shallow water lake. However, the lake level still experienced intensive fluctuation in this period. The lake water impetus was stronger in two stages from ca. 1454 to 1525 AD and from ca. 1803 to 1891 AD, during which sediments were subjected to disturbance, transportation and redeposition. The lake shrank and became a shallow water environment. During the stage of ca. 1645-1670 AD the lake environment deteriorated, which led ostracoda fauna not to be able to live. The lake level rose while the depth of the lake increased relatively during ca. 1731-1803 AD; and (3) from the 1890s to the present Chen Co had evolved from a deeper water lake before the mid-1960s to a shallow one at present. The lake had been shrinking since the mid-1960s and became a shallow water lake environment.
Seven Water Control Zones in Hong Kong's coastal waters with sampling data of 17 parameters collected at 37 monitoring stations from 1988 to 1999 were selected to analyze the spatio-temporal variations of chlorophyll-a concentration. The results suggest that frequent red tides occurred in eastern Hong Kong's coastal waters, and less red tides occurred in an estuarine environment in the west. In all coastal waters, the organic contents indicator, BOD5, was a common significant influential factor of the chlorophyll-a level. Nitrogen and light penetration condition related to turbility, total volatile solids and suspended solids had greater influence on the cholophyll-a level in the east than in the west, while phosphorus and oceanographic condition associated with salinity, temperature, dissolved oxygen and pH was more important in west than in east. Generally, there was a higher average chlorophyll-a level in the late winter and early spring, and late summer and early autumn in a year. The chlorophyll-a level was higher in the east than in the west among all seasons in general. The chlorophyll-a concentration has a fluctuation period of 8-10 years generally in the whole region.
This paper aims to summarize and illustrate a variety of human-induced hydrologic and geomorphic changes in the Pearl River Delta (PRD) and to analyse the causes and effects.The hydrologic characteristics of the river network have been altered in the following three main aspects. First, stage has become higher or lower over the past decades in an uneven manner in the delta. From the early 1950s to the 1980s, scattered and small embankments were enlarged and combined to expand land mass and reduce flood hazards in the PRD. However, reduction of water surface area and concentration of flow into major channels generally caused stage to go up slightly. Secondly, corresponding to the stage changes, the stage-discharge relationship has been substantially modified, as evidenced by over 2 m drop of stage for the same amount of discharge. Thirdly, the ratio of flow partition into two channels at several river bifurcation points has continuously changed over the past decade. Closely associated with the hydrologic changes are alterations of river channel and estuarine morphologies. Such geomorphic changes primarily include noticeable or even alarmingly severe modification of river channel bed, extension of river mouth and contraction of estuary in the study region. It was found that the hydrologic and geomorphic changes that have occurred within a relatively short period of time are mainly consequences of a wide variety of human activities, coupled with influences of natural events, including (a) channel dredging of sand for construction usage, (b) combination of embankments and construction of dams, (c) channel constriction and reduction or complete loss of floodplain, (d) sea level rise, and (e) channel bed erosion by record floods.
Based on the available original duststorms data from 60 meteorological observation stations, the paper constructed a quite complete series of severe group duststorms in the eastern part of Northwest China in 1954-2001. As a result, 99 severe group dust-storms have been found and confirmed in the eastern part of Northwest China in 1954-2001. Based on these 99 cases, the temporal and spatial distribution characteristics, especially inter-decade change of severe group duststorms were analyzed in the eastern part of Northwest China, and the following viewpoints were noted: (1) Alasan Plateau, most parts of Erdos Plateau and most parts of Hexi Corridor were the main area influenced by severe group duststorms, where there were generally more than 10 severe duststorms at some places and more than 20 events in some stations such as Minqin in Gansu Province in recent 48 years. (2) The major number of severe group duststorms is in spring, and the figure was 78.8%, especially in April there were 41 events and the figure was 41.4%. (3) The number of severe group dust-storms during the 1990s was 15, which is less than other decades. At the same time, the life cycle and the influencing area of severe group duststorms during the 1990s are shorter and smaller too. (4) In 2000 and 2001, there are 4 severe group duststroms broke out separately in the eastern part of Northwest China. It is the maximum after 1983.
Through the analysis of historical natural settings in the farming and grazing interlocked zone along the Great Wall in northern Shaanxi Province of China, this study has ascertained that its land degradation is both natural and anthropogenic. The overlay of desertification severity layers interpreted from multi-temporal remotely sensed materials in a GIS, in conjunction with field investigation, has revealed that the spatial extent of desertified land in the area has drastically expanded during the 13-year period in certain localities. Both natural and anthropogenic factors in this study are realistically considered to assess land degradation severity. It is found that desertified area of most of the counties in the study area has exceeded 50% of each county's total area. The percentage is even higher in a few counties. The overall severity of land degradation has worsened during the last 13 years with extremely serious and serious degraded areas accounting for 88.5% of the total study area in 1998. The spatial distribution of the desertified land is uneven in terms of degrees. A comparison of the recent satellite image with historical aerial photographs reveals that the extent of degraded land in the study area has expanded while the overall severity of land degradation has worsened. Confirmed by the field investigation, the desert front in the vicinity of Xincheng, Jingbian County has encroached by over 10 km. In the worst affected region between Yulin and Hengshan, the encroachment is as far as over 40 km. Because of the expansion of the Mu Us Desert and the impact of sandstorms, the Great Wall is no longer the divide between sandy land and loessial area. The worsened desertification is attributed to the intensified conflicts among mounting population pressure, limited land resources, and the fragile ecosystem. Inappropriate human activities such as excessive exploitation of natural resources and malmanagement of land, to a certain extent, have inevitably resulted in the destruction of the environment. Mining activities have been identified as the sole cause of rapid spread of desertification in the vicinities of coalfields. The findings in this study have profound implications on how to reduce the severity of desertification hazard in the study area. As the cause of this problem is both natural and anthropogenic in origin, any measure must deal with problems of rural economic development, especially development of agriculture and animal husbandry for increasing farmer's income. A mechanism should be established to compensate for farmers whose income has dropped as a consequence of diminished land productivity caused by mining-induced degradation in the vicinity. Secondly, environmental laws aimed at controlling desertification and protecting environment should be formulated to mitigate the detrimental influence of human economic activities on land. For instance, in severely degraded, poverty-stricken regions the scattered small villages must be shifted to areas with relatively richer water resources so as to enable natural vegetation to recover, thus reversing the trend of desertification.
On the basis of relative superiority assessment, this paper achieves regionalization of sustainable agricultural development of China.Firstly, an index system of sustainable agricultural development of China is built, including 5 supporting subsystems of agricultural resources, agricultural development, environment and ecosystem, rural society, and science-education management, and 95 factors at provincial level are selected as basic indicators. Secondly, a relative assets/debt assessing method is used to gain relative net assets values (relative superiority) of every province or municipality directly under the Central Government at the 5 supporting subsystems and the total capability. Then the assessment results are graded and shown as distribution maps by GIS. Thirdly, according to the assessment result of sustainable agricultural developing capability, the whole nation is divided into 9 agricultural developing regions (first level) and 22 sub-regions (second level). The first level reflects each region's direction for sustainable agricultural development and issues' management. The second level reflects whether or not each sub-region reaches sustainable agricultural development and its degree. Thereby regionalization of sustainable agricultural development of China is set up. Based on the above-mentioned assessment and regionalization, this paper puts forward the target of sustainable agricultural development in China: (1) The eastern area of China must enhance its level of sustainable agricultural development, increase its science input, modulate its inner structure; and focus on intensive, commercial and green agriculture. (2) The central and western parts of China must change their situation firstly, and then improve their sustainable developmental level. (3) In western China development, the key policies are focused on ecological construction, producing input, social and scientific management in rural area.
A survey was conducted in 1995 and 2000 among 332 rural households purposively selected from 10 counties and county-level cities in western Henan mountainous and hilly region. Analysis on the data brings out several important findings in the relationship between household behavior and regional development. The negative side of household behavior was deeply related to farmer's embededness in traditional agricultural society and the long lasting of isolated inland culture. (1) The information of production, technology and marketing in agriculture, horticulture, stockbreeding and other family business, was narrowly limited. (2) The income of household dominantly relied on physical conditions and natural resources. (3) The surplus labor, existing at large amount, was difficult in transferring to other economic sectors, largely because farmers were reluctant to leave their land for other non-agricultural business or for working in town and village enterprises. (4) Farmers were not active in seeking bank loans and did not feel comfortable in borrowing money for business. Most of their loans were for urgent home needs, such as paying hospital bills and building houses. (5) The increase of house income was expected to be used in improving their family living conditions, instead of developing family business. The quantitative modeling analysis further indicates the variation of impact on household income by production factors among living environment of mountains, hills and river basins. The households with different ratios of commercial production -- wholly self consuming, partly for market, and mostly for market -- played rather different roles in regional economic development. In the conclusion part, the suggestions on development strategies in the study region are proposed. Finally, a new approach is applied to discussion on the roles of households so that regional economic development in less developed rural region can be further studied.
Old industrial areas first appeared in Britain and some other Western developed countries more than a century ago. In China, because of some problems existing in the industrial structure and the dominant industry, several provinces that had been prosperous now are declining. In those provinces, the speed of the economic development is slowing down, and many social problems are getting more and more serious. In fact, those regions have become old industrial areas. In this paper, considering the foreign researches on old industrial areas and the realities of China, the authors put forward four characters of the old industrial areas of China. They are as follows: uncoordinated in industrial structure, the dominant industries are at the end of the regional life cycle, the regions had been prosperous for a long time but now are declining, the living standard of the people is low and the social problems are serious. Considering the data's acquirability, the authors put forward four criterions and twelve indexes which are used to plot out the old industrial areas of China, and set up a suit of estimation system correspondingly. Based on those criterions, indexes and estimation system, the authors make an analysis of China in the unit of province. In the end, the provinces of China are classified into five elementary types: old industrial areas, quasi-old industrial areas, industrializing areas, regular development areas and rapid development areas. Heilongjiang, Shanxi, Liaoning and Jilin are presently the old industrial areas of China in this paper.
The container transportation is a revolution for the grocery transportation in the transportation system. The container transportation makes it impossible for the goods to be transported from door to door in the world. At the same time, the container transportation improves the efficiency of transportation. Based on analyzing the development of container transportation and network in the world, the paper points out not only the formation of container load center and lateral port but alsothe CFS is the result of the development of container transportation. The paper conducts an intensive discussion on the formation and evolvement mechanism and development mode of container load centers in the world. The formation of the network of container transportation is the tendency of container transportation and the necessary result. With economic development and rapid expansion of container transportation in China, it is necessary for China to establish rational network of container transportation. Based on GIS, the paper puts forward the mode of container ports and CFS and container transportation channels. finally a mode of judgement about container transportation channels is proposed through researching Nanchang container transportation system.
Technology flow is a concept widely used yet poorly discussed academically. Based on several cases in the Pearl River Delta, empirical study is done to probe into the conceptual system of technology flow, its dynamism and channels, and the models. First, technology flow is defined as the moving process of technological capacity. Second, the dynamism of technology flow is examined. The authors declare that besides science and market driving forces, the governmental force exists in most parts of China as the third one. However, the technology flow in Shenzhen is principally promoted by the push-pull influences exerted by the government and the market. Third, it is found that the Shenzhen High-tech fairs is typical of the complex interlinked platform structure. Fourth, three models of inter-enterprise technology flow are observed including the dual-circulation model, the Y pattern model and two linear models, represented by HYT, Jinpeng Group, Hualing Group and TCL Group respectively. Fifth, three spatial models are observed in light of the technology source and the level of technology obtained or diffused.
Be seasoned with globalization, some economists in Western countries have new interests in Geography in recent years. A new branch of Economics, "new economic geography" or geographical economics, emerges as the times require. This paper shows the real meaning and main contents of "new economic geography", and introduces approaches and theories of Krugman's "new economic geography". The paper introduces in detail the two major themes of "the new economic geography": the spatial agglomeration of economic activity and the dynamics of regional growth convergence. The paper also gives some appraisements on it from Geographies. In the end the paper emphasizes that geography and economics should construct their new alliance based on the same goal and philosophical foundation.
