In the context of 1951-2001 NCEP daily re-analyses and the 1957-2000 daily precipitation from 366 stations over eastern China, a quantitative index is proposed to study the interdecadal variation of the northerly advancement of East Asian Summer Monsoon (EASM). The results show that drawing the isoline of standardized rainfall index of 1.5 that is better indicative of the meridional shifting of the summer rainband in eastern China, and its phased and abrupt change in its northward march. The northerly march of EASM displays conspicuous interdecadal variations. The position indices of the EASM jump in the mid-1960s, however the jump of the intensity indices occurs in the end of the 1970s. Before the mid-1960s, the onset of the South China Sea monsoon is later, but the northward advance is quicker, the time of arrival in North China is earlier, which maintains a longer time in North China, its north edge lies north to the normal position, and thus the North China rainy season and Huaihe River Valley (HRV) Mei-yu are distinct. In recent 20 years, the onset is earlier, the intensity is obviously weaker, and therefore precipitation mainly concentrates in the Yangtze River Valley (YRV) and areas south of the Yangtze River, and the North China rainy season is not evident.
Using annual mean, maximum, minimum air temperature and monthly mean precipitation data from 5 weather stations in Mt. Qomolangma region from 1971 to 2004, climatic linear trend, moving mean, low-pass filter and accumulated variance analysis methods, the spatial and temporal patterns of the climatic change in this region were analyzed. The main findings can be summarized as follows: (1) There is an obvious ascending trend for the interannual variation of air temperature in Mt. Qomolangma region and the ascending trend of the highest station, Tingri, is most significant. The rate of increasing air temperature is 0.0234 oCa-1 in Mt. Qomolangma region and 0.0302 oCa-1 in Tingri. The air temperature increases more strongly in non-growing season. (2) Compared with China and the global mean, the warming of Mt. Qomolangma region occurred early. The linear rates of temperature increase in Mt. Qomolangma region exceed those for China and the global mean in the same period. This is attributed to the sensitivity of mountain regions to climate change. (3) The southern and northern parts of Mt. Qomolangma region are quite different in precipitation changes. Stations in the northern part show increasing trends but are not statistically significant. Nyalam in the southern part shows a decreasing trend and the sudden decrease of precipitation occurred in the early 1990s. (4) Compared with the previous studies, we find that the warming of Mt. Qomolangma high-elevation region is most significant in China in the same period. The highest automatic meteorological comprehensive observation station in the world that was set up at the base camp of Mt. Qomolangma with an elevation of 5032 m above sea level will play an important role in monitoring the global climate change.
Based on Digital Elevation Model with a spatial resolution of 1 km×1 km, the data of annual precipitation obtained from 12 meteorological and 2 hydrological stations (1961-2000) in the Aksu river catchment was filtered using Empirical Orthogonal Function (EOF). Through regression analysis, an interpolation model between the main characteristic vectors of EOF and geographical parameters was established. The annual areal precipitation was calculated from this model, and it is proved to be an efficient scheme to establish areal mean series of climate element. As a result, the annual areal precipitation and its spatial distribution are calculated on the grids that covered the basin. Point estimates were verified against meteorological or hydrological station data. The ratio (R/P) of the runoff of the Aksu river and calculated areal precipitation is 0.43 on average, the maximum is 0.69 (1997) and the minimum 0.30 (1963). The rates of changing trends of calculated areal precipitation and the observed runoff of Aksu river were 5.79×108 m3/10a and 4.29×108 m3/10a respectively, and both of them presented an increasing trend. The annual changing trend and extent of the areal precipitation are higher than those of the runoff. Both of their coefficients of variation (Cv) are 0.17 and 0.13, respectively. There is a close relationship between the annual runoff and annual areal precipitation and 0oC level height in summer. So the climate change after the 1990s in Xinjiang was the main cause for stable runoff increase in the Aksu river basin.
Based on year by year examination and correction of files-dominated historical documents and verification of various kinds of data, the later or earlier rainy seasons in Yunnan from 1711 to 1911 has been reconstructed. The analysis indicates that there are obvious interannual and interdecadal fluctuations in the starting date of rainy seasons in Yunnan, as well as long-term fluctuations exceeding the interdecadal scale. It comes earlier from the beginning of the 18th century, later in the 19th century and earlier again in the 20th century. This reflects to a certain degree the gradual change of the summer monsoon in Yunnan. There exist obvious quasi-3 years and 11.3 years cycles for starting date of raining seasons in Yunnan, the quasi-3 years might be related to the El Nino's quasi-3 years cycle while the 11.3 years being visiblely related to the 11 years cycle of solar activity. Meanwhile, the dissertation finds that the El Nino plays a very important role in the starting date of rainy seasons in Yunnan. The starting date of rainy seasons in Yunnan often comes later or normally in the year of El Nino. However, in the period when such influence weakens obviously, this means that ENSO may exert certain impact on Asian summer monsoon.
Based on the tree ring width chronologies developed in Delingha region, Qinghai province, the annual precipitation variations for the last 1000 years has been reconstructed recently. In this study, we investigate the abrupt changes of precipitation for the last 1000 years. Smoothing t-test and smoothing F-test methods were used to search for possible abrupt changes in the mean value and the standard deviations of 30-year climatic average precipitation. Significant abrupt changes were found during the last 1000 years and we suggested that solar activity played an important role in influencing these changes. It is evident that the precipitation decreased significantly during the periods of the Wolf, Spoerer, Maunder and Dalton minima of solar activity, and the t-test verified the existence of statistically significant differences within these periods. The time and the direction of abrupt changes of precipitation coincided well with the abnormal variations of solar activity. The abrupt changes of precipitation in Delingha may link with the interdecadal changes of East Asian Summer Monsoon for the last century. The time of abrupt changes in Delingha was ahead the time of abrupt changes in eastern China, which may be an important indicator for long-term change forecast of precipitation.
The alpine meadow ecosystem is one of the important grassland resources for grazing on the Tibetan Plateau. High-resolution sampling, measurement of roots contents and organic carbon contents of selected soil in Haibei Station were made in an attempt to detect the soil organic carbon storage and vertical distribution of the alpine meadow in the northeast Tibetan Plateau. The results show that considerable magnitude roots biomass (23544.60 kg ha-1-27947 kg ha-1) and organic carbon (21.52 GtC) have been stored in soils of the alpine meadow. Some 30% of total soil organic carbon of natural soil profiles has been stored in the upper horizons (upper 10 cm). Comparison suggests that soil organic carbon storage (23.17×104 kg C ha-1) (0-60 cm) is 2-6 folds of that of forest soil, shrub soil and pasture soil in the Tropics. Soil organic carbon pool of the alpine meadow is ignorable in the carbon budget both of the globe and China. With the global warming, it is important to protect flimsy alpine meadow ecosystem on the Tibetan Plateau, not to disturb the soil cover of alpine meadow, and to introduce feasibly deep-rooted plants for storing much more soil organic carbon, for decreasing CO2 emitting from the soils, for slowing down CO2 concentration rising rate of the atmosphere, and for sustainable developing ecotype services of the alpine meadow.
Based on the data of inorganic nitrogen fluxes at the sediment-water interface of eleven typical sectional sites in tidal wetland of the Yangtze estuary from 2002 to 2004, we established the inorganic nitrogen fluxes interpolation model and calculating model. Using these models, we studied the spatio-temporal distributing characteristics of inorganic nitrogen fluxes, and calculated the total fluxes in different sectional tidal wetlands and different seasons. The results show: (1) compared to IDS and Ordinary Kriging, the forecast precision of fluxes interpolation is better using revising GIDS interpolation model; (2) the sediment-water exchanges of inorganic nitrogen showed complicated spatial differences and seasonal variations; (3) when using revising GIDS model to interpolate, in order to improve calculating precision of fluxes, the spatial scale should adopt 1.2' ×1.2'; (4) the Yangtze estuary tidal wetland releases inorganic nitrogen fluxes into water in spring, and the releasing quantity is 1.33×104 t. In summer, autumn and winter, Yangtze estuary tidal wetland purifies inorganic nitrogen fluxes from water, and the purifying quantity is 4.36×104 t, 6.81×104 t and 2.24×104 t, separately. All the year round, the Yangtze estuary tidal wetland purifies inorganic nitrogen fluxes from water, tand he purifying quantity is 12.1×104 t; and (5) the purifying ratio is about 23.0%.
Systematic investigations in various forms of P and SiO3-Si in the Yangtze mainstream and major tributaries and lakes from the Jinshajiang River (a section in the upper Yangtze River) to the mouth were carried out from November to December, 1997 (dry season), and in August and October, 1998 (flood season). In the dry and flood seasons in the Yangtze mainstream, the variations in particulate P and total P concentrations were almost synchronous, which increased speedily in the upper reaches and then decreased with less variations in the middle and lower reaches, and the variations in dissolved P and SiO3-Si concentrations were little. The fluxes of various forms of P and SiO3-Si gradually increased from the river's upper reaches to the lower reaches. The fluxes of various forms of P and SiO3-Si in the dry season came mainly from the middle and lower reaches and over half of them were contributed by tributaries and lakes. Various forms of P and SiO3-Si in the flood season were mainly contributed by the mainstream except for tributaries in the upper reaches which contributed over half of the particulate P. The ratios of TPP in TP in the mainstream and tributaries were higher in the upper reaches than in the middle and lower, higher in the flood season than in the dry season and higher in the mainstream than in the tributaries, which were clearly relative with suspended matter content. The particulate P was the main contributor of P in the Yangtze River. In transport fluxes of dissolved P, DOP was slightly in dominance in the mainstream in the dry season, while organic P and inorganic P was 50% each in the tributaries. The transport fluxes of various forms of P and SiO3-Si and export fluxes of TP and PO4-P were mainly controlled by runoff, especially, it was more obvious than P that SiO3-Si flux increased with runoff. The transport equations of various forms of P and SiO3-Si and export fluxes equations of TP and PO4-P are suggested in this paper.
The rising of urban complex ecosystem has built a bridge for the infiltration from ecologic theories to sociology and urban planning. Niche, as one of the most important theories of ecology, has the profound directive meaning in the study of human ecosystem, and preferably interprets the phenomenon such as competition, evolvement in different urban functional modules. This paper tries to introduce niche theory into the studies on the development of different urban functional modules, discusses the rules of niche pattern change of different functional modules in the city of Kaifeng in recent 10 years and analyses the reason for its changes. The results showed that: (1) The atmospheric niche and urban virescence niche increased, but the water niche and sound niche had a decreasing trend from 1994 to 2003 in the natural environmental system of Kaifeng. (2) The tertiary industrial niche went up, and secondary industrial niche came down, but primary industrial niche had a little change from 1994 to 2003 in the economic system of Kaifeng. (3) Social basic establishment suitable niche, social resource distribution suitable niche and social production and insurance suitable niche increased, but only population suitable niche went down from 1994 to 2003 in the social system of Kaifeng. (4) The reform of policy system was the direct and basic reason for niche pattern changes of different functional modules in Kaifeng in the last decade. The present study has not only concrete directing meaning in macroscopic planning, economic development and environmental protection of different urban functional modules, but also important theoretical and realistic meaning in developing urban ecologic theory and studying the inherent action mechanism of the complex ecosystem.
Although water has the central function of the bloodstream in the biosphere, especially in arid or semi-arid regions such as Yan'an region in Northwest China, yet very limited attention is paid to the role of the water-related processes in ecosystem. In this research, based on continuous 30-year weather condition report data and 10-year soil water content data in Yan'an region, using experiment models and field tests combined with GIS spatial analysis, a comparatively accurate method for measuring the minimum, moderate and maximum eco-water requirements of plant-soil compound ecosystem has been put forward. Additionally, the changing characters of eco-water requirement or scarcity have been addressed from spatio-temporal dimensions. The results show that: (1) The minimum eco-water requirement of plant-soil compound ecosystem in the study area is 21.6185 billion m3, and the corresponding scarcity is 2.3556 billion m3. (2) The landscapes presenting severe eco-water scarcity are conifer and broad-leaved mixed forest-loam, conifer-loam as well as deciduous and broad-leaved mixed forest-cohesive loam etc. The landscapes presenting eco-water budget balance are shrubby grass-cohesive loam, shrub-cohesive soil as well as grassland-sandy loam; and the landscapes presenting slight eco-water surplus are crop-cohesive loam, crop-sandy loam as well as crop-sand and gravel loam. (3) The areas with relative serious eco-water scarce problem are mainly located in the southwestern and central parts of Yan'an region on the hilly-gullied Loess Plateau, concentrating in summer or early autumn of the year.
After the field trip in Japan and communicating with the planning experts from regional development department of the UN, ministry of communication of Japan, local planning bureau of Kyushu, and some local Japanese specialists, we summarized Japan's trend in national land-use planning, urban planning management and rural planning. Advanced experiences in environmental protection, construction of public transportation and tourism development in Japan are studied. We also analyzed the measures taken in the execution of Japan's national land-use planning, such as building law system, dispatching scientists and specialists to remote areas for directing and functioning the peasantry association etc. These methods that can be learned and used for reference for China are proposed finally.
