Geographic System is fundamentally a complex system with properties (e.g. emergence, nonlinearity, feedbacks, self organization, path dependence, adaptation, and multiple scales) that cannot be explained through understanding the components parts individually. Complexity sciences, rising in the 1980s, has brought a new perspective for the paradigm transformation of geography. This paper briefly reviews the development of complexity sciences and the changing paradigm of geography. Then the performance, characteristics, and causes of complexity in geographic system are explained and analyzed thoroughly. Paradigms, including ontology, epistemology and methodology between classical geography and geography from the perspective of complexity sciences are compared. Six methods (i.e. soft computing, simulating, scaling, Geographic Information System, metaphor and meta-synthetic method) are summarized for the study of complexity in geographic system. In the end, the authors conclude that the paradigm transformation of geography from the perspective of complexity sciences lies in the formation of a new and innovative thinking, which is considered a beyond reductionism, holistic and pattern/process based generalized evolutionary thinking.
The impacts of winter extreme climate events in recent years on socio-economy indicated that the importance of winter climate anomalies is the same as its summer counterpart in southwestern China (SWC). The spatio-temporal variations and its possible causes of climate anomalies in SWC were investigated by utilizing observation data from 1961 to 2010. The results indicate that surface air temperature anomalies in SWC have two dominant modes, one is homogenous, the other is dipole in latitudinal direction. The former was caused by the anomalies of East Asian winter monsoon, the latter arose from the anomalies of both subtropical west Pacific high and regional cold air in lower troposphere. The most dominant mode of precipitation anomalies in SWC is homogenous and it has a high correlation with northern hemisphere annular mode (NAM, AO). NAM and ENSO did not have significant impacts on the variation of surface air temperature in SWC. The anomalies of NAM would lead to the anomalies of tropical circulations. When NAM is in positive (negative) phase, the winter precipitation is more (less) than normal in SWC. Precipitation in the whole SWC increased during El Niño winter, but increased in central SWC, and decreased in west and east of SWC during La Niña winter. The severe drought in SWC in the winter of 2010 is more likely caused by anomalies of NAM instead of El Niño.
This paper presents a high-resolution pollen record from a 40.92-m-long sediment core taken from Dalianhai Lake, a terminal lake situated in the Gonghe Basin, northeast Tibetan Plateau, in order to reconstruct the vegetation and climate history in the period from the last deglaciation through the Holocene. The 158000-yr chronology of the sediment core was controlled by ten AMS 14C dates on plant remains. The result of pollen analysis shows that six pollen zones can be partitioned in the whole pollen assemblages, and each zone is mainly characterized by the growth and decline of tree or herb pollen percentage. During the periods of 14.8-12.9 Cal ka BP and 9.4-3.9 Cal ka BP, the arboreal pollen increased, indicating that the subalpine forest developed in the surrounding mountains, and the basin was characterized by the increased coverage of desert steppe or typical steppe, reflecting a moister climate. During the periods of 15.8-14.8 Cal ka BP, 12.9-9.4 Cal ka BP and 3.9-1.4 Cal ka BP, the forest shrank or disappeared due to different degrees of aridity, and the desert steppe degraded to a more arid steppe desert in the basin, showing a dry climate. After 1.4 Cal ka BP, vegetation type around the Dalianhai Lake was mainly dominated by steppe suggested by the increased Artemisia. Our results suggest the climate in this region was dry from 15.8 to 14.8 Cal ka BP, humid from 14.8 to 12.9 Cal ka BP and dry from 12.9 to 9.4 Cal ka BP, and then the climate was humid during 9.4-3.9 Cal ka BP, followed by dry conditions during 3.9-1.4 Cal ka BP and humid conditions in the last 1.4 Cal ka BP. The change of pollen percentage and the evolution of palaeovegetation in the Dalianhai Lake since the Last Deglaciation were similar to those in the Qinghai Lake. The forest expanded in the mountains around the Dalianhai Lake during the Bølling-Allerød period, and it shrank during Young Dryas and early Holocene. Then it developed and reached its maximum in mid-Holocene, after that it began to shrink till disappearance. However, the timing of forest expansion in the Holocene lagged behind that of the Qinghai Lake, and this spatial heterogeneity was probably caused by different forest species composition between these two places. The maximum of forest development was asynchronous with the period of stronger summer monsoon in the early Holocene indicated by stalagmite records, which might be related to the complexity of vegetation in response to long-term climatic change.
The study on 82 surface soil pollen samples from different types of cultivated vegetations in central and southern parts of Hebei Province indicates that the pollen assemblages from farmlands on the plain have not only their own plant types, but also the pollen components from the nearby mountains. Arboreal pollen percentages and concentrations (dominated by Pinus) of samples from the farmlands in the mountains are higher than those on the plains, and it reduces gradually with the increasing distance away from the mountains. Taking Pinus in Taihang Mountains for example, its content is 20%-30%, 10%-20%, 20%-30% and below 16% respectively for the samples from the area of 0-50, 50-100, 100-150 and more than 150 km away from the east of Taihang mountains. The increase of Pinus proportion in the central plains is probably related to the fohn effect. The spatial variation of AP from mountains to plains in Hebei Province may be similar to the historical change of forests clearance by human activities in early period. Shrubby pollen proportion is small both in mountains and in plains, but their major components are different. Elaeagnaceae, Corylus, Ostryopsis and Oleaceae are common in mountain farmlands, while there are relatively high contents of Rosaceae and Vitaceae in plains, Herb content in plains (about 60%) is 15% higher than that in mountains, among which the Cereals and Cruciferae pollen percentages are 5% and 2% higher respectively. Artemisia pollen percentage on the plains is lower than that in the mountains. Since the human activities are weaker in mountains compared with that on the plains, the general trend is that Chenopodiaceae pollen increases from mountains to plains gradually, reflecting the raising intensity of human activities. The fern spores of Selaginella sinensis in mountains are higher than that on the plains, which is about 7%. The fern spores of Selaginella sinensis are not prone to be spread by wind, indicating that those in the surface soil of the plains may be carried by currents from mountains during the deposition of the plains.
Weather data of 8 meteorologic stations in the Lancang River Basin from the 1950s to 2007 and current cropping pattern, field water moisture management, etc., were collected and used to investigate changes in humidity and crop irrigation water requirements using Mann-Kendall and the Rescaled Range Analysis methods. The results show that in the whole basin, annual and dry-season average temperatures significantly increased, and dry-season rainfall increased while wet-season rainfall decreased. Evaportranspiration (ET0) increased during both dry and wet seasons at all the stations except Dali, Jianchuan and Gengma, and the aridity-humidity index decreased at most stations. The turning points of weather factors, ET0, the aridity-humidity index, paddy irrigation requirements and total agricultural water requirements occurred from the 1960s to the 1990s. The spatial changing tendency of paddy irrigation quota increased with the increase of altitude and latitude, and the coorelation coefficients are 0.513 and 0.610, respectively. The maximum value inWeixi, while the minimum in Mengla.
Evapotranspiration is one of the key components of hydrological processes. Assessing the impact of climate factors on reference evapotranspiration (RET) is helpful in understanding the impact of climate change on hydrological processes. In this paper, based on the daily meteorological data from 1960 to 2007 within and around Aksu River basin, RET was estimated with the FAO Penman-Monteith Method. The temporal and spatial variations of PET were analyzed by using ARCGIS. Multiple Regression Analysis was employed to differentiate the effects of the variations of air temperature, solar radiation, relative humidity, vapor pressure and wind speed on PET. The results showed that RET in the eastern plain area of Aksu River Basin was about 1100 mm, which was nearly twice as much as that in the western mountain area.
Palaeoflood hydrological studies were carried out in the middle reach gorges of the Yellow River. Palaeoflood slackwater deposit was found at the MFT site in the Hukou gorges of the mainstream of the river. Analysis of the grain-size distribution indicates that these SWD consist of sandy silt, sourced from the suspended sediment load of the floodwater. The low magnetic susceptibility indicates they are fresh deposit without weathering and pedogenic alteration. Stratigraphic correlation with the chronological framework established in the middle reaches of the Yellow River and OSL dating shows that these extreme floods occurred in two periods, that is, at the turn from early to middle Holocene, and at the end of the mid-Holocene Climatic Optimum. The reconstructed peak discharges of the palaeoflood range from 27,490 m3/ s to 40,920 m3/s which is much larger than those of gauged floods. These results were further tested and proved to be reliable in reconstruction of the modern floods at the same reach. This research is of great importance to hydrological engineering and flood mitigation. And it is also very important in the establishment of the relationships between extreme flood events and global climate change.
Glacial Lake Outburst Flood (GLOF) hazards have been paid more attention in Himalayan region. The accurate calculation of reservoir capacity of glacial lake is very important for estimating outburst flood peak discharge and simulating flood evolution. The Longbasaba Lake, located in Dingjie County of Tibet, is a potential dangerous moraine-dammed lake. Its depth was measured by HydroboxTM high resolution echo sounder and 6916 samples were collected in field investigation held in September 2009. The maximum depth and average depth of Longbasaba Lake were found to be up to 101.94 m and 47.50 m, respectively. Based on the same time Landsat Thematic Mapper (TM) image interpretation, lake basin shape was simulated by constructing Triangulated Irregular Network (TIN) and the reservoir capacity was 0.64 × 108 m3. Furthermore, multi-source remote sensing images from 1977 to 2008, such as Landsat MSS, topographic map, Landsat TM and ASTER, were interpreted and digitalized by a GIS software. The result showed that the length and area of Longbasaba Lake were increasing in the last 32 years and the tendency was more significant since 2000. The empirical formula of volume-area of moraine-dammed lake was built by analyzing the volume and area in different periods, which could be used to calculate the reservoir capacity of other moraine-dammed lakes in the Himalayan region. Finally, based on the analysis of the interdecadal variations in temperature and precipitation from five weather stations in this region, and the same direction of lake expansion with the glacier recession, it could be demonstrated that the area increase of Longbasaba Lake was due to climate warming, glacier ablation and retreat.
The optimal allocation of land use in Guangzhou city was carried out by a linear planning model with multi-objective under the restriction of economic and ecological efficiency. The results indicated that optimal land-use pattern could meet the demands of land use for different departments while the plan to be implemented up to 2020. Currently, the quantitative limitation of land resources exerts tremendous stress on regional land use. The key problem lies in the contradiction between built-up land and agricultural land, especially farmland, in Guangzhou. Potential appraisal model of land use was used to assess the land-use system. The results showed that land-use system tends to be in a highly harmonious status, indicating that the potential of regional development could be lower. On the other hand, the urban land-use system would have no enough space for further development, but it could be improved by optimizing structure allocation. The optimal land-use pattern is the basis for regional sustainable development, and the integrated development among urban areas, suburban areas and industries is the major way to obtain a high regional land-use efficiency.
This study examines land use types and input level of every plot of sample farmers in three typical villages in Chongqing. Through stratified random sampling survey, participatory rural appraisal and investigation of plots, 227 households and 2250 plots are investigated and sampled. Farmers are divided into four types: pure agriculture households, agriculture-dependent households, off-farm dependent households and off-farm households. The results show: (1) Apart from 6.17% of off-farm households, who leave land uncultivated, abandoned or rent, land use types of pure agriculture households, agriculture-dependent households and off-farm dependent households are mainly intensive. Some 48.95% of arable land of pure agriculture households are relatively extensive due to the aging. The proportions of relatively extensive arable land of agriculture-dependent and off-farm dependent households are 71.08% and 67.20% , respectively. (2) Land inputs are different among the four farmer types. Off-farm household have no land input. Pure agriculture households have low agricultural labor input due to aging, and less agricultural machinery and labor-saving inputs due to lack of funds, so they prefer to choose manure, phosphate fertilizer, ammonium bicarbonate and other cheap fertilizers.
Gannan pasturing area, located in the eastern edge of the Tibetan Plateau, is a typical ecological sensitive area. We discern the impact of various human factors on the environment in order to find the measures to solve the complex environment problems. In this paper, the ecological footprint is taken as the index of the environmental impact. First of all, we calculate the ecological footprint from 1980 to 2007, distinguish the key human factors and analyze their characteristics. Then, we use the STIRPAT model to simulate the impact of the different human factors on the environment, such as population, affluence level, grassland utilization intensity, livelihood strategy and urbanization level. The results are obtained as follows: (1) The ecological footprint and per capita ecological footprint show an upward tendency from 1980 to 2007 in this area, which is consistent with the ecological footprint of biological resource, and its correlation coefficient reaches 0.996; (2) The intensity of ecological footprint shows a downward tendency, which coincides with the intensity of the ecological footprint of biological resource, and its correlation coefficient is 0.978; (3) Population and the intensity of grassland utilization are the two main drivers influencing the environment and the changing rate of the environment caused by them goes farther ahead of the changes of these two factors. The affluence level also exerts impact on the environment, but the changing rate of the environment is lower than that of the affluence level. Meanwhile, improving the livelihood strategy and enhancing the urbanization level will lower the impact on the environment; (4) The analytical result supports the environmental Kuznets curve hypothesis within the range of data. Finally, this paper points out the problems which should be focused in the research of the impact of human factors on the environment.
With the method of emergy analysis, the energy storage and flow of different types in natural, social and economic systems of Fujian was transformed through the emergy transformation into a unified standard - emergy. And it reached the result of ratio of emergy consumption gross and GDP, namely emergy/money ratio. Then with that ratio, this paper converted the resource consumption and environment loss into currency value and deducted it from the traditional GDP, therefore obtained the green GDP. Also the condition of sustainable development of Fujian Province was analyzed by using some emergy evaluation indices, and the results showed that the traditional GDP increased rapidly from 2001 to 2006, but the green GDP increased relatively slowly. Fujian Province was characterized by fast-developing economy, high living standard, and export-oriented foreign trade. However, under the huge population and environment pressures, its sustainable development ability dropped. In addition, Fujian was short of internal resources and relied on the external environment. So the economy was encountering increasing risk and the competitiveness of economic activities tended to be weakening. There was still some unsustainable economic growth in the development of Fujian Province, which was in relevance to its level of industrialization.
Landscape health was produced after ecosystem health and became a new research direction. The difference between landscape health and ecosystem health is their scales of study. The criterion of landscape health is to judge the maintenance of landscape. As the urban wetland park, it is important to keep sustainability of socio-economy and ecological protection. So the model of landscape health was established according to the coordination of social economy and ecological protection. The results showed that: (1) The maps clearly showed that the spatial differences obviously existed between socio-economy and ecological sustainability. Socio-economic sustainability and ecological sustainability with better grade covered 2.18% and 39.50% of the whole study area respectively. (2) Better landscape health area was distributed in the inner park and covered 25.06% of the park. (3) In this analysis, we found landscape health was closely related with landscape function and spatial distribution of the landscape.
