Previous studies on relationships between hillslope and gully erosion are mainly concentrated on exploration of water and silt relations, few on quantitative studies of evolution relationships between hillslope and gully landform erosion in small catchments of original scales Quantitative studies on synthetic impact and interactions of hillslope and gully geomorphologic characteristics on catchment dissected extent are still a blank in particular This paper, supported by 3S techniques, based on 1∶5000 digital orthophotomap (DOM), digital elevation model (DEM) and topographic map of the same period and of the same scale, quantitatively analysed the impact and interactions of hillslope and gully geomorphologic characteristics on catchment dissected extent by using orthogonal polynomial regression analysis Research results indicated that gullies play a leading role in the catchment morphologic evolution and ground surface dissected extent When inter gully areas are the same, the 0 1 km 2 gully area is the maximum area affecting erosive evolution intensity of the catchment dissected extent The smaller the catchment area is, the greater the affecting extent of catchment surface fragmentation would be The geomorphologic evolution mechanism of channel slopes and gullies can be explained with synthetic impact of geomorphologic indicator of slope and gully fluvial energy Gullied land plays the leading role in affecting catchment dissected extent indicators of D r and L e , when inter gullied land area ( A p ) is constant, there exists maximum value of the dissected extent indicator L e and critical gully catchment area, the catchment dissected extent is the greatest when gully catchment area is about 0 1 km 2. The smaller the gully catchment area is, the greater the gully density would be. When inter gullied land area increases, the dissected extent indicators D r and L e decrease. When gullied land area ( A g ) keeps constant, the catchment dissected extent indicators D r and L e decrease with the increase of inter gullied land area.Catchment dissected extent is synthetically affected by fluvial erodibility under conditions of varying gradients of inter gullies and gullies and their interactions. The evolution mechanism of slope and gully landforms of gully catchment can be explained via synthetic effect of slope and gully fluvial energy landform indicators and their interactions.According to erosional characteristics of slope and gully landforms, to elevate erosional basement level is the key link for controlling modern gully head advancement and hillslope expansion rate of the catchment basins. Priorities should be given to soil and water conservation management of gully catchment area of 0 1 km 2.

With the support of GIS information, a process-based crop growth model is designed to estimate the spatial pattern of dry matter accumulation, seed yield and evapotranspiration of winter wheat in the Hebei Plain, from October, 1989 to June, 1990. The crop leaf area index in the model is retrieved from NOAA-AVHRR monthly maximum composite NDVI and the daily meteorological variables are scaled up with gradient inverse distance square method. The simulated domain ranges from 113°E to 118°E and 36°N to 41°N with an area of about 60,000 km 2. The grid resolution is 1 km 2 and time step is daily in this paper. The model was tested with field sampled dry matter data of five varieties and the district statistical economic yields. The absolute bias between the simulated and the statistical yields is about 12% in the domain. The simulated results show that the high yields are located in Baoding, Shijiazhuang, the central part of Xingtai and the eastern part of Handan districts from North to South with values of 6000 to 8400 kg hm -2. The low yields are shown at the eastern part of Langfang, Cangzhou, Hengshui and the eastern part of Xingtai with values lower than 3000 kg hm -2. Compared with the simulated potential yield, it is found that the differences between actual yields and potential yields are significant in this region, of which 72% shows a yield gap as large as 5000 kg hm -2. The simulated amounts of evapotranspiration over the growing season are from 310 to 500 mm, and the water use efficiency (WUE) in the irrigated fields is about 10 to 17 kg ha -2 mm -1. Low WUE area (<8 kg hm -2mm -1) occupies 42% of the whole area. The spatial pattern of WUE is similar to that of yield. As suggestion, some water conservancy techniques should be taken to increase the water use efficiency in this area, such as stalk cover, new irrigation projects,etc.

Due to the tremendous soil organic carbon pool and the high carbon content on surface soil, even a trivial disturbance in surface soil can easily induce great changes of the whole soil organic carbon pool. On the other hand, as a universal geological process on earth, wind erosion has strong capacities to entrap, transport and redistribute the surface soil. Naturally, wind erosion then has important influences on the evolution of soil organic carbon pool. In eroded area, surface soil is eroded and the soil organic carbon pool decreases; in transportation process, soil organic carbon is further transformed and carbon dioxide (CO 2) is emitted; in deposition area, the changes of soil organic carbon pool are more complicated and the carbon pool increases at least in a short term. The redistribution of soil organic carbon over landscape and the emission of CO 2 react on the terrestrial ecosystem and finally affect the carbon budget. Such processes can be modeled by a series of equations based on the mass balance principle. Using the Arc/Info GRID data derived from the 2nd Chinese national remote sensing based soil erosion investigation and the 2nd Chinese national soil investigation, the spatial patterns of the top 20cm soil organic carbon content and wind erosion intensity are described in detail firstly. Soil organic loss and corresponding carbon flux are then estimated supported by GIS techniques. The total soil organic carbon loss induced by wind erosion is about 59.76 10 6t C/yr, including creeping materials of 14.34 10 6t C/yr, saltating materials of 44.82 10 6t C/yr and suspending materials of 0.60 10 6t C/yr. The emitted carbon dioxide (CO 2) is about 29.88 10 6t C/yr, ranging from 11.95 10 6t C/yr to 41.83 10 6t C/yr. The affected areas mainly lie in the Northwest China. The uncertainties in our research depend on the estimation of the eroded soil mass, the ratio of different erosion fluxes and the oxidizing ratio of SOC during transportation.

According to different vegetation types and their cover degrees in Qinling-Daba Mountains in Shaanxi, using an improved model of net primary productivity of natural vegetation, regional energy balance, water balance and model of evapo-transpiration, goods produced by different types of vegetation have been calculated. Based on net primary productivity of natural vegetation, using equation of photosynthesis, reforestation cost and industrial method of making O 2, the value of CO 2 fixation and O 2 release by vegetation ecosystem in Qinling-Daba Mountains in Shaanxi can be estimated. The results are as follows:① the total CO 2 fixation and O 2 release is 13.5×10 7 t/a, 9.93×10 7 t/a, respectively. ② Using reforestation cost ,the value of CO 2 fixation is 352.24 billion RMB yuan/a. ③Using reforestation cost and industrial method of making O 2 , the value of O 2 release is 374.19 billion RMB yuan/a. ④The temperate deciduous broad-leaved forest has the highest contribution rate, the second is subtropical deciduous shrub. This study can provide basic data and methods for setting up regional “green eco-account”.

Accumulated temperature is an important heat resource and one of the key factors for crop growth. Accumulated temperature is of significance in guiding agricultural production. Usually, accumulated temperature data from meteorological stations can only reflect heat regimes of areas close to meteorological stations. In areas far from meteorological stations, it is by interpolation that accumulated temperature can be calculated. Rasterizing is one of the means for interpolating accumulated temperature data. Accumulated temperature is influenced by longitude, latitude and altitude to a great extent. There is a close linear relationship between accumulated temperature and longitude, latitude and altitude. By analyzing data from more than four hundred national meteorological stations in China, it was found that the ≥0℃ accumulated temperature and ≥10℃ accumulated temperature in 1995 had correlation coefficients of r 2= 0.9656 and r 2= 0.9402 with longitude, latitude and altitude respectively. In order to explore ways to process rasterized accumulated temperature data products, the ≥0℃ accumulated temperature was taken as an example. China was divided into seven different accumulated temperature regions by means of cluster analysis, seven models suitable for each region were established respectively, and the method of "model based computation result plus spatialized residues "was used to rasterize accumulated temperature data in China. Data from 436 of 481 meteorological stations were used to establish rasterizing models, and accumulated temperature data in whole China were calculated. 45 meteorological stations, which were distributed countrywide evenly and were not used to establish the models and to calculate accumulated temperature, were selected to test and verify precision of the rasterizing method. The result showed that there was a close relationship of r 2 = 0.9889 between actual observed accumulated temperatures and calculated temperature by rasterizing with mean relative deviation equal to 3.56%, and the meteorological stations with deviation less than 5% occupied 86% of the total meteorological stations used for testing and verifying. It was demonstrated that the rasterizing method used in the study is more accurate and it can be used for rasterizing of accumulated temperature data at large scale.

Occurrence of sand dust storms is a process that accelerates land desertification, and can also be considered as an indicator of land desertification at a certain stage Thus, it is of significance both in theory and practice to reveal the interaction between these two phenomena Based on the data from the Erdos Plateau and its surrounding areas, a study has been made of the effect of land desertification on sand dust storms A non linear relationship has been established between sand dust storm frequency and the index of land desertification (I ld ), which is defined as the percentage of the area of desertified land of the total This relationship indicates a threshold at I ld = 30% When I ld < 30%, the sand dust storm frequency did not change with an increasing I ld ; however, when I ld > 30%, the sand dust storm frequency increased rapidly This threshold means that the sand dust storm frequency would increase abruptly when the man induced I ld exceeds 30% This study also deals with sand dust storm frequency in response to the change in the area of cultivated land The time series of annual number of sand dust storm days in the neighboring area has been related with the time series in the annual number of strong wind days and the time series in the area of cultivated land. As a result, a multi regression equation has been established, based on which the relative contributions of the changes in land use and in number of strong wind have been estimated as 59 7% and 40 3%, respectively This result indicates that the frequency of sand dust storm may be effectively decreased by reducing the area of cultivated land and restoring steppe ecosystem in the ecologically fragile areas in arid and semi arid climates

It is well known that the Yellow River is the river with the highest sediment contents of all rivers in the world Several hundred million tons of sediments are transported to the coast and to the sea nearby annually, so the Yellow River Estuary area has witnessed the fastest coastline changes in the world This paper describes the spatio temporal features of the coastline dynamics in the estuary area using remote sensing images since the course of the Yellow River was changed to Qingshuigou channel artificially in 1976 Trying to anatomize the spatio temporal features of coastline evolution, 20 sheets of Landsat images were used as the data source The multi temporal satellite images were rectificated precisely and registered each other, and all the images have the same coordinate system After supervised classification the coastlines were extracted automatically from remote sensing images The result shows that a new land of 330 km 2 was formed during 1976 to 2000 by GIS overlay analysis Finally, combined with the hydrologic data from Lijin station, the relation between coastline change and the runoff and sand transportation was analyzed, and the evolution trend was forecasted The results are as follows: (1) The method in the paper is viable to monitor the coastline change (2) Generally, the land forming speed is faster at the initial stage after course change, and the range of the spit shows a strong linear positive correlation with the net epirogenetic area But the coastline begins to erode after the sediment source is broken off absolutely (3) The evolution process during 1976 to 2000 is divided into four stages based on the spatio temporal features of the coastline (4)There is a consanguineous correlation between the ranges of the spit and the runoff and sand transportation, and the speed of the coastline change will become slow in the future according to the present condition of the runoff and sand transportation

With rapid development of tourism, the environmental degradation in Wulingyuan Scenic Spot, especially the degradation of the air and water quality, has attracted some scholarly and governmental attention. To quantitatively evaluate the environmental quality, this paper developed an evaluation model based on the field work and a Delphi methodology. The main findings show that although there exist advantageous ecological environment and tourism resources, the rapid development of tourism has laid more pressure on the environment capacity which further leads to a series of environmental problems. In this sense, this paper brought about some suggestions on the tourism resources exploitation, optimum determination of the tourism planning and tourism environmental management and suggested that the local government should strength the monitoring of environmental quality, promote the assessment programs of environmental impacts, strengthen the systematic reforms to internalize the external effects of environment and develop the industries of environmental resources to guarantee the rational exploitation of environmental resources.

Climate is a basic factor that controls the directions and intensities of soil-forming process, which affects the levels of weathering, the composition and decomposition of soil organic matter (SOM), the migration of soil materials and changes of their forms,and soil geographic distribution around the world and so on. Although many scholars have done a lot of work about the influence of precipitation on components and properties of regional soils, yet the main concern of their work is average precipitation or the moist indexes influencing soil individual component and properties, and the influence of rainstorm on components and properties of regional soils has not been discussed thoroughly yet. Taking the central area of rainstorm in Biyang county as an example, the influence of rainstorm on soil components and properties was discussed on the basis of field works and laboratory experiments in this paper. In comparison with the soils of other areas that are less affected by rainstorm, the soils in the central area of rainstorm in Biyang have the following characteristics: (1) Eluviation ratios of base (β) are less than 1.00, silica-sesquioxide ratios (Saf) are less than 7.00, and the soil reaction is feeble acid in the central area of rainstorm, which indicate that the processes of desilicification and allitization in soils are obvious, and that the weathering of soil is stronger. (2) Soil thickness is thinner.The amount of horizons in each soil is less, no more than two, and the patterns of soils profiles are simple. Content of gravels (>1 mm) is higher, and that of physical clay (<0.01mm) is lower. The texture of soil belongs to sandy type, most of them have some gravel. (3) Iron-manganese nodules that could be seen by unaided eye could not be found in all soils located, which indicates that soil-forming conditions are unstable in this area. (4) The content of soil organic matter (SOM) and alkali-hydrolyzable nitrogen is higher, and readily available potassium is lower in the central area of rainstorm. Because much soil organic matter (SOM) migrated from up to down, the content of soil organic matter in second soil horizon is higher too. Soils around the central area of rainstorm have different components and properties from these in the central area of rainstorm obviously, which indicates that rainstorm can influence components and properties of soils strongly.

Using the static chamber method, the fluxes of nitrous oxide from the undisturbed community and soil layer were measured through the continuous experiment in situ from 2001 to 2003 in Leymus Chinense grassland in Xilin river basin of Inner Mongolia, China.The seasonal variation, characteristics of sources and sinks, and the effects of main environmental factors on N 2O fluxes were analyzed. The regression models between the N 2O fluxes and the environmental factors were also established using the statistical method, at the same time, the annual total emission flux of N 2O was estimated. The main results are as follows:(1) The seasonal variations of N 2O fluxes in undisturbed community and soil layer were very obvious with higher emissions in spring and summer, then autumn but maintaining a relatively low emissions level in winter, furthermore, negative fluxes were found sometimes in winter. (2) The annual mean N 2O flux of undisturbed community ranged from 3.91 μgm -2h -1 to 4.71 μgm -2h -1 and that of soil layer ranged from 5.49 to 10.03 μgm -2h -1.The average N 2O flux of undisturbed community was lower than that of soil layer in the same statistical period, the relative thick litter layer obviously reduced the emission of N 2O to a certain degree. (3) To compare the N 2O fluxes of the whole year, the N 2O fluxes from undisturbed community and soil layer were significantly positive correlated with the air temperature and surface soil temperature at non-growing season, whereas they had a weak correlation with the soil moisture. The changes of air temperature and the other closely relative temperature factors could account for 72%～88% of the variation of undisturbed community and soil layer N 2O fluxes in non-growing season. What’s more, the correlations between N 2O flux and the soil temperature at 5cm and 10cm depth were higher than that between N 2O flux and surface soil temperature. But in growing season, negative correlations were found between N 2O flux and the air temperature and the soil temperature at 0cm, 5cm and 10cm depth, especially the correlations between N 2O flux and air temperature reached the significance level of 0.05. The results of multi-variable stepwise regression indicated that the change of 0～10cm and 10～20cm soil moisture could account for 72～85% of the variation of undisturbed community and soil layer N 2O fluxes in growing season.

We have worked out quite a few pollens and spores from the commonly sporopollen poor loess, and plotted some concentration sporopollen diagrams of the loess strata for the first time. The evolution of vegetation and corresponding climate in time and space in the region has been brought to light by an analysis of the variation of sporopollen assemblages in many sections. There are three interstadials, warmer than present and two cooler stadials in the last interglaciation. They are correlated with the substages 5a, 5b, 5c, 5d and 5e of the deep sea oxygen isotopic curves. The climate in the stadials was severely cold, with a mean annual temperature 14℃ lower than the present. The climate in the interstadials was relatively warmer, with a mean annual temperature 3-9℃ lower than the present. The temperature in the stadials of the last interglaciation was the same as that in the interstadials of the last glaciation. The temperature in the interstadials was 1-3℃ higher than the present. It is known by comparing the sporopollen dliagrams from ten sections in the Loess Plateau that the changes of vegetation in time are very similar, implying that they were controlled by the same global climatic change. But the vegetation may vary from place to place due to changes of local natural environment. Vegetation during the late Pleistocene in the Loess Plateau is familiar with vegetation types of the warm-belt generally. When in the case of stadials of the interglaciation and interstadials of the glaciation, the alpine vegetation was descended to the land level, and in the stadials of the last glaciation, steppe or desert steppe landscapes were commonly seen.

Land consolidation (LC) in rural residential areas is one of the important measurements or techniques of readjusting rural land use structure and of keeping the balance of arable land The characters of land use for rural residential areas in hilly and mountainous regions of Southwest China are greatly different from that in other regions of China. A survey of hilly and mountainous regions in Chongqing shows the following features of the land use system of rural residential spots: (1) the scale of residential plots is very small, mostly, only one to three families reside in one residential plot; (2) the average density is 30 plots per square kilometers in the Three Gorges region, such as Fengdu county of Chongqing ; (3) the residential plots are greatly scattered and the mean distance of plots is from tens to hundreds meters, and usually no more than 500 meters; (4) land use is so extensive that near 12% of the residential areas is unused This paper presents two feasible models of land consolidation for villages in hilly and mountainous regions of Southwest China, which could be used in various regions according to local characters One is the constructing of new hamlet and the other is the multiple development of agriculture and forestry The former is suitable for the mountainous regions and the latter is feasible in hilly regions where the economy is relatively developed Case study of Xinchun village in Chongqing shows, that the intensive target of land use can be realized through the planning and constructing of new hamlets After the land consolidation, the density of residential plots becomes lower and the area is decreased, and the net area of arable land increases 7 06 hm 2 which is 6 31% of the total area of Xinchun village Conclusions have been drawn as follows: (1) it is necessary that the effects of environment, economy and society are concerned synthetically when the model of LC in rural residential area; (2) it is very important to choose the model of LC of rural residential areas according to local physical conditions and social economic development level in the hilly and mountainous region of Southwest China; and (3) the policy guidelines of local governments and the investment of collective economic organizations play the key roles in the operating of land consolidation project (LCP) for rural residential areas

Global warming will lead to changes in many environmental factors and disturbance regimes (e g fire, drought, insect outbreak etc ) As a consequence, changes in characteristics of existing ecosystems, such as species composition and competition, stability and productivity, ecosystem health, ecological safety and ecosystem services, are to be expected Palaeoecological evidence and palaeoclimatic records pointed out plant pole ward migration in latitude and upward shift in elevation with increased temperature after the last glaciation Ecological observations also showed that the elevation of the alpine timberline moved upward worldwide with increasing global temperatures during the last 100 years Current global warming could mean that the plants currently growing at lower elevations or at lower latitudes might progressively migrate to higher elevations and latitudes However, it does not mean that all plants of an ecosystem move upward or pole ward with the same velocity Many species may re adapt to the changed and changing environmental conditions and survive for generations at their present location Many species will shift their ranges to track climate change As climate may change faster than plants are able to migrate from one region to another, species will become extinct An extinction of a plant species will also harm the animals depending on this specific species On the other hand, global warming and new disturbance regimes could favour the invasion of non native species due to the reduced stability and resistance of ecosystems Biological invasions will lead to massive losses of biological diversity on local, regional and global scales Global warming during the past 20 30 years has already had a severe impact on sensitive biological systems As a continued warming has to be expected, the global warming issue should be addressed by conservation planners and policy makers, as one of the most serious and immediate threats to biodiversity

The features of pollen assemblages are dealt with in this paper using the methods of DCA and correlation analysis. Altogether 23 samples taken from topsoils at 8 sites in the east of Qaidam Basin are studied. In this study area, pollen taxa are mainly shrubs and herbs, whose total percentage is 92.77%～100%. Pteridophyta pollen is found in 5 samples, but the percentage is quite low, only less than 0.38%. This pollen assemblage clearly shows the characteristics of obvious desert and steppe desert area without trees. In the pollens of shrubs and herbs, Artemisia and Chenopodiaceae dominate in desert area, being respectively about 40% and 70% in general and 66.38% and 74.54% at maximum. Comparatively, Ephedra is also commonly seen, whose percentage is usually less than 5%, but in 6 samples the percentage is more than 10% and 49.27% at maximum. Gramineae and Compositae also occupy a certain percentage, the maximum may reach 10.6% and 6.82%. Results of DCA and correlation analysis appear that the features of topsoil pollens in different vegetations are not the same. Different assemblages of pollens can be distinguished and are in accordance with corresponding vegetations and environments. According to the aridity, the vegetation communities are divided into four groups: severe drought group, moderate drought group, slight drought group and slight-drought-and-slight-wetness group and it is found that A/C (Artemisia/ Chenopodiaceae) in the desert can indicate the aridity. A/C value is less 0.2 in the severe drought group, 0.2～0.5 in the moderate drought group, 1.63 in the slight drought group and 5.72 in the slight-drought-and-slight-wetness group with aridities being 8.96, 3.00, 2.98 and 2.82 respectively.

Nonpoint sources of nitrogen (N) in agricultural soils have been identified as one of the main causes of freshwater eutrophication. Studies have showed that decades of N fertilization at rates exceeding the amount removed by crops have resulted in widespread accumulation of N in agricultural soils in Taihu Lake basin, and the accumulation of N will increase the potential of soil N loss to surface and ground waters. Therefore studying the spatial variability of soil N at large scale will be helpful to develop optimal management practices for controlling agricultural nonpoint N pollution. Geostatistics has proven to be useful for characterizing and mapping spatial variability of soil properties. In this paper, a geostatistics method, combined with Geographic Information System (GIS), was applied to analyze the spatial variability of total soil N in topsoil in the typical area of Taihu Lake basin. The results showed that the spatial variability of total soil N was apparent in isotropy within the maximum lag extent of 40km, beyond which the anisotropy of spatial variability was increasing due to the change of soil parent materials in the direction of NE34°. The isotropic semivariograms showed that the ratio of nugget to sill of the total soil N was about 0.5,indicating that the total soil N had a relatively good spatial autocorrelation in the study area, and the range of autocorrelation extended to about 16km. The map of the total soil N interpolated through Block Kriging based on the fitted exponential model depicted that the soils in Jiangyin and Yixing counties generally had much more N than that in the other counties,which was mainly contributed to the different application levels of N fertilizers;and the "hot spots" of high soil N content were apparent in low-lying polderland, which probably was the results of interaction of topography and human factors such as fertilization.

Using the static chamber method, the diurnal variation of CH 4 fluxes of the undisturbed community and soil were studied through the experiment in situ at different phenologies of Leymus Chinense grassland in Xilin river basin of Inner Mongolia. According to the results of field experiment, we analyzed the characteristics of diurnal variation of undisturbed community and soil CH 4 flux and the statistic relationship between CH 4 fluxes and environmental factors (e.g. air temperature, surface soil temperature, soil moisture) together with the ecological factors(e.g. aboveground biomass, underground biomass, litter biomass)by correlation analysis and multiple stepwise regression method. The main research results were as follows: The fluxes of undisturbed community and soil CH 4 were all negative and the Leymus Chinense grassland was the sink of air CH 4. There was great difference among diurnal variation patterns of CH 4 flux in different phenologies and the effect of temperature condition on diurnal variation of CH 4 flux wasn't remarkable except the post-fruiting vegetative stage. The difference between undisturbed community CH 4 fluxes and corresponding soil CH 4 fluxes wasn't significant except in post-fruit vegetative stage of 2002 and in flowering stage. And for the difference of undisturbed community CH 4 flux among different phenologies, the difference between flowering stage and post grain-filling stage, flowering stage and post-fruiting vegetative stage of 2001, post grain-filling stage and post-fruiting vegetative stage of 2002 reached the significance of 0.01 or 0.05, but the differences of undisturbed community CH 4 flux between any other two phenologies and the differences of soil CH 4 flux between any two phenologies were all not significant. The results of multiple regression analysis indicated that the changes of underground biomass at 0-20cm depth could account for 95.0% of the variance of the community CH 4 flux and 99.0% of the change of soil CH 4 flux of different phenologies. The change of the ratio of soil CH 4 diurnal uptake flux and the total community diurnal uptake flux was affected markedly by the change of litterfall biomass.

Chen Co lake is located at northern slope of the Himalayas. The geographical location of Chen Co lake is 28°53′～28°59′N,90°28′～90°35′E . The maximums of length and width are 11km and 7.8km respectively. The area of lake is about 37km 2. The maximum of depth is 31m. In lacustrine delta of Chen Co lake, 2 boreholes were drilled. In addition, using piston sampling method, 2.16m sedimentary core was gathered at 8m of the lake water depth. In laboratory, the time scale was established by 14C and ESR dating. On the basis of core description, grain size distribution, and CaCO 3 content analysis, the sedimentary environments and facies of lacustrine delta were explained. The 36.70m longer drilling core on the lacustrine delta plain recorded the sedimentary history since about 55000 aBP. The mean sedimentary rate of the whole borehole is about 0.667mm/a. Since 16920 aBP, the sedimentary rate rose and reached up to 1.27mm/a or so. The sediments of Chen Co delta indicate a complex of depositional processes. The main body of sediment consists of debris deposition of land-origin. The sedimentary strata sequence and sub-environment of deposition were recognized according to the colour, lithology, grain size, sedimentary structure, etc. Due to the multi-provenance of sediment material, the CaCO 3 content of lacustrine sediment showed ruleless change on profile. But, the grain size and sedimentary sequence indicated that the total sediment consisted of alluvial fan, subaquatic alluvial fan (fan delta) and delta sediment from bottom to upper. The sedimentary environment of delta also changed among delta front, delta plain and prodelta. Up to now, it presented the nature of delta plain environment. During 17500aBP～14000aBP, Chen Co lake witnessed the greatest lake period. In addition, the sedimentary sequence recorded the Last Glacial Maximum (LGM) and Younger Dryas cold event. The sedimentary characteristics and sedimentary environment were controlled by lake-level fluctuations.The authors suggested the driving factor of lake-level fluctuation is climate, especially the change of summer monsoon.

Agriculture is the basic industry in mountainous area, it is also the economic mainstay in most mountainous regions Meanwhile, mountain agricultural ecosystem is much more sensitive to global change and fragile in global change process Any types of mountain agricultural resources development will lead to change of original ecosystem and its material retention The past violent agricultural development based on changing landscape, increasing material and energy consumption has weakened the basis of agricultural sustainable development, affected stability of mountain ecosystem and biological biodiversity seriously, at the same time, it has also brought harmful effects on the surroundings Therefore, sustainable development of mountain agriculture is facing the severe challenges from both global change and mountain environment protection In order to reply the challenges above, we have to adjust the structure of mountainous agricultural economy, and establish the agricultural ecosystem that will not cause environmental deterioration, suitable in technique, feasible in economic, accepted by society, which will assure sustainable development of mountain agriculture This paper analyzes the problems that China mountain agricultural sustainable development is facing under the conditions of market economy, puts forwards the conception of designing model for mountain land agricultural use It has concluded that it is the physical geographical factors, market and land system that affect the model of mountain agricultural land use, especially market and land system are much more conspicuous in the new historic period This paper also stresses that the design of mountain agricultural land use model should obey the rule of physical variation in different regions, combination of biodiversity and size management of agricultural economy, and widening the market of agricultural products Finally we take Luoning county, located in western part of Henan province, as an example to explain the technique routine for designing mountain agricultural land use model on the basis of analysis of its present situation of agricultural land use in details But there are 3 questions remained to discuss, i e , how to play market's role to adjust and revise mountain agricultural land use model, how to organize and arrange agricultural land management in size, and how to coordinate the relationship between ecologic conservation and economic development in the process of mountain agricultural land use

As no single interpolation method is optimal for all regions and data, it is important to compare the results obtained using alternative methods applied to each data set In this study, two methods for spatial interpolation of climatic data from sparse weather station networks were compared Forty year monthly mean temperature and precipitation data from regions in Gansu province were interpolated using a deterministic estimation method termed "Inverse distance weighted" (IDS) and a statistical method termed "Gradient plus Inverse Distance Squared"(GIDS) By design, their power parameters were optimized on the basis of minimum root mean square error (RMSE) Corresponding cross validation tests show that optimal inverse distance had consistently better results than usual: As for temperature, the value of MAE decreases by 6 77% and 9 95% in the method of IDW and GIDW respectively; as for precipitation, the value of MAE decreases by 28 19% and 6 25% in the two methods correspondingly Summary statistics were used to determine if one method was significantly better than the other on the basis of mean absolute error (MAE), mean relative error (MRE) and root mean squared error(RMSE) Based on the mean absolute errors from cross validation tests, the methods were ranked GIDS>IDW for interpolating monthly precipitation and temperature, being average by 0 73℃ for monthly temperature and 4 90 mm for monthly precipitation Based on the mean relative errors from cross validation tests, the methods were also ranked GIDW>IDW for interpolating monthly precipitation and temperature, being averagely 9 02% for monthly temperature and 17 82% for monthly precipitation In addition, GIDW yields more accurate predictions than IDW when the correlation between rainfall and elevation is high (less than 0 80 in the case study) For Gansu province, except January and December, the remaining months in the year see the correlation between elevation and rainfall higher than 0 80,while these two months are not very important for us to study soil water balance, so we prefer GIDW method to our study Furthermore, before the interpolation of precipitation, we try to analyse the data, and the results show it is very important to analyse the character and distribution of data before interpolation In our study area, a cubic transformation improves the accuracy well

Soil organic carbon is the main part of terrestrial carbon pool. It plays an important role in terrestrial carbon cycle and is one of the important components in the research of global change, so it is important for soil carbon cycle to ascertain soil organic carbon reserves and spatial distribution in soil carbon cycle research. This paper adopted the soil distribution areas, sampling data and soil organic contents from 84 samples and 50 profiles to estimate soil carbon pool in Xingguo county of Jiangxi province. The calculation results show that parent material has influence on contents of soil organic carbon, soil derived from lime rock has higher levels of organic carbon (17.92 g/kg) in surface layer(0-20 cm),soil derived from red sandstone has lower levels of organic carbon (6.11 g/kg); and contents of soil organic carbon increased in turn from red clay,red sandstone, granitic, phyllite to lime rock. The contents of soil organic carbon vary greatly under different vegetation types.Soil under pin (Pinus massonniana) has lower levels of organic carbon, but soil under fir(Cunninghamia lanceolata) or broad-leaved forest has higher levels of organic carbon. The total amount of soil organic carbon is about 559.38×10 4t and organic carbon density is about 2.47 kgC/m 2 in depth of 20cm, the total amount of soil organic carbon is about 1437.19 10 4t and organic carbon density is about 6.36 kgC/m2 in depth of 100cm. The distribution of soil organic carbon density is high in the northwest and northeast but low in the middle and southwest in Xingguo county. Soil organic carbon and topographic variables have correlations. In topsoil(0-20cm), the correlations of aspect and the content of soil organic carbon is positively significant while that of elevation and the content of soil organic carbon is highly significant. In profile(0-100cm), the correlation of elevation and the content of soil organic carbon is significant while the content of soil organic carbon and aspect and slope grade have no obvious correlations.

By analyzing the forming process of the cave landscape the authors think that the change of the CO 2 solubility in the water entering into the cave is vital to the formation of the cave landscape.And the temperature and partial pressure of CO 2 are the key elements to play the role on it. Calculation indicates that when the cave air CO 2 concentration is within 1800ppm the latter is the most important element to the landscape formation. The soil CO 2 is the major source of CO 2 in the cave water: Firstly it facilitates the formation of the soil water into carbonic acid water and when the water contacts with the carbonate rock above the cave the solution chemical reaction will happen. This action will provide the Ca 2+ for the cave sediments. Secondly the soil CO 2 concentration will affect the CO 2 concentration directly in the cave water. From the experts' views the soil CO 2 mainly comes from the respiration of the vegetation the amount of the microorganism and the atmosphere outside the cave. Our field work also indicates that vegetation is one of the most important elements that control the soil CO 2 concentration and its distribution. We do the research in the Yaolin cave by comparing the effect of different CO 2 concentrations to simulate the different CO 2 concentrations under different types of vegetation dealing with the cave landscape. The conclusion is that when the soil CO 2 concentration is higher it will be good to the cave landscape protection and development.That is to say the cave landscape covered by the vegetation is much better than the one covered poorly. But if the CO 2 concentration is too high the soil CO 2 can filter into the cave through rock slot and make the cave water keep the acid character to dissolve the old landscape sediments and the dissolved views are formed.

This paper analzyes the temporal and spatial distribution characteristics of the second greatest flood occurrence ever since 1954 in Huaihe river basin during the summer of 2003. Comparison is conducted with the previous data for the same period. The results show that 7 weather processes occurred with the total precipitation and water level and flux more than 1991 and less than 1954; that stable rain belt, intensive and explosive heavy rain are the main reason for the whole Huaihe river above the guaranteed water level. At the same time, by use of NCEP reanalysis data, large-scale atmospheric circulation and its formation reasons are discussed, which indicate that one of the important reasons for subtropical high noncontinually moving northward as a rule is that between the end of June and the beginning of July, the mid-high latitudes(60～180°E,30～50°S) of southern hemisphere experienced circulation change from low index(longitudinal pattern) to high index(latitudinal pattern) which lasted to the mid July with the cold masses and cross-equatorial flow at 110° E weaker than the normal. The other reasons are that between the third dekad of June and the second dekad of July, ITCZ was rather weak and further southward shifted than the normal, and shear between the west and the east wind is not obvious, and tropical cyclones formed at the western North Pacific Oceans and South China Sea; that high-level jet was southward shifted by 2 more degrees than the normal, whose coordination and coupling with low-level jet is the main reason for continuous torrential rain; that the secondary circulation caused by high and low jets played an important role in maintaining stable sub-tropical high and large-scale circulations in mid-high latitudes; and that the polar vortex in Asia is stronger than the normal.

Analysis on the changes of the characteristics of runoff and sediment in the upper reaches of the Yangtze River is necessary to the operation and management of the Three Gorges Project. Zhutuo and Cuntan hydro-stations are the major water and sediment reference points for the Yangtze River and the Three Gorges Reservoir. Through analyzing the field data of the annual runoff and the pebble bed load (the PBL) across Zhutuo hydro-station from 1975 to 2001 and Cuntan hydro-station from 1966 to 2001,we concluded that the characteristics of the PBL of the upper reaches of Yangtze River change markedly. First of all, the mean annual transportation amount decreased distinctly: the transportation amount at Zhutuo station from 1992 to 2001 decreased by 46.9% compared with that from 1975 to 1991;and the transportation amount at Cuntan station from 1982 to 2001 decreased by 40.6% compared with that from 1966 to 1981. Secondly, the grading sizes of the PBL became smaller: the median granule diameter decreases 11 mm. Thirdly, the relationship between bed load rate and hydraulic factors changed obviously: the parameters B decreased by 47.5% at Zhutuo hydro-station and 41.1% at Cuntan hydro-station. Finally, the sediment discharge imbalance increased: the calculated abrasion parameter between Zhutuo and Cuntan hydro-stations increased by about 70%. Based on the fore study, the driving causes for the changes of the characteristics of the PBL in the upper reaches of the Yangtze River were analyzed. Firstly, the measures adopted such as soil and water conservation are the direct reason. Next, because the runoff keeps the same during different periods, the runoff has nothing to do with the above changes. Thirdly, it was concluded that the main causes are that more sediments which are being used as timbering are excavated from the watercourse and soil and water conservation prevent sediments from entering the main channel of the Yangtze River. Based on the above analysis,it is pointed out that soil and water conservation should be strengthened.And it is important for us to investigate the current conditions and the patterns of siltation and silt movement in tributaries of the upper reaches of the Yangtze River. Finally, it is suggested that the sands excavation should be confined strictly according to the capacity of sand that can be excavated.

Land is one of the most important natural resources for human existence Although the development of modern technology has greatly promoted the economic level and improved people's standard of living, the dependence of human beings on land has not been decreased at all As a result of the rapid growth of population and the acceleration of industrialization and urbanization, the land problems have become more and more acute Keeping certain amount of farmland is the fundamental condition for human living and the key issue of affecting regional sustainable development Yet, owing to the ever increasing demand of the socioeconomic development, oasis population and town construction for farmland, the contradictions between population and food supplies, and between population and farmland are becoming more and more severe. Therefore, to intensify dynamic research on changes of farmland, find out its distribution rules and driving factors for the changes are of great significance to the proper utilization and conservation of the farmland resources According to the detailed statistical data and general survey data from 1950 to 2000, this paper analyzed farmland changes in recent 5 decades and regional differences such as the relative changes of cultivated land in each county, irrigated land and paddy field , the per capita cultivated land ,the multiple crop index in the delta oases of Weigan and Kuqa rivers, discussed the driving factors accountable for the farmland dynamic changes in the delta oases of Weigan and Kuqa rivers Results showed that the cultivated land of delta oases of Weigan and Kuqa rivers has undergone three growth times and two falling times The author pointed out the driving factors causing cultivated land dynamic changes are related to such problems as the five times of drastic changes in politics, the ever increasing demand for farmland, the degrading soil fertility, desertification, saline land and identified some feasible countermeasures

Qilian juniper ( Sabina przewalskii Kom ) growing in the mountainous area of the easterm part of Qaidam Basin is sensitive to climate change It can reach one millennial years old and the tree ring width chronology can be used to reconstruct climate change over the past 1000 years Power spectrum analysis, Singular Spectrum Analysis (SSA) and wavelet analysis were utilized to trace the variations recorded in two standard tree ring width chronologies (WL3 and WL4) of Qilian juniper in Shalike Mountain, Qinghai, China The power spectrum of the series showed low frequency periodicity of 200 years are most statistically significant at the 95% confidence level for both chronologies Analysis of the power spectrum of both series also showed evidently that low frequency variations of century scale are present in the chronologies It was found that the most important cycle was 200 years for both chronologies by SSA, cycle of 133 years for WL3 and 100 years for WL4 are also identified by this method The reconstructed components of paired eigenvectors of SSA showed that different scale cycles had different behaviors over the past 1000 years Wavelet analysis can provide information on the amplitude of periodic signals and their variations with time The Morlet wavelet coefficient distributions indicated that the 200 years cycle was most prevailing from the 15th to the 17th century for both chronologies, the century scale cycles were pronounced since the 18th century The prominent low value of the ring width in the second half of 15th century is affected by the cycle of 200 years, the high value in the late 20th century is the contribution of century scale periodicities One possible explanation of the low frequencies in the ring width data might be related to the fluctuations of the solar activity Narrow ring width seems to occur during quiet solar periods such as the Wolf, Sprer, Maunder and Dalton solar minima, suggesting that the low variation of the climate indicated by tree ring width may be affected by the long term change in solar activity

Based on an analysis of fieldwork data collected by the authors from 80 households in the Shapo Village of Shuicheng County in Guizhou Province, the phenomenon of differentiation between behaviors of households who own different resources has been found. The differentiation is adaptable to resources, environment and structure of society and economy up against households. The paper has revealed the main characteristics of employment structure, employment behaviors in both agricultural and nonagricultural sectors and has explained the causes. The results show that factors such as household registration system, low economic accumulation, limited knowledge and simple technology restrict the farmers to be employed by nonagricultural sectors; and household registration constitutes the greatest institutional barrier constraining the migration of rural workers. Because of the low input and output agricultural production mode, households have few accumulation generally, helping the households break out the greatest institutional barrier of registration system to migrate. But owing to the limited knowledge and simple technology, the farmers can not get stable job and incomes, which pull them back home, most of the farmers cannot but choose part time work in nonagricultural sectors. Part time work in nonagricultural sectors can improve the farmers' living standard to a certain degree, which however can contribute little to the optimization of the rural resources, as well as the rural social and economic development. Finally some feasible suggestions are put forwards, i.e.,control the amount of population and increase investment of education; to establish uniform system of social security; and to strengthen rural infrastructure construcion.

The evolution of Lake Dongting is determined by three main factors, which are tectonic subsidence, siltation and human impacts. "The Dongting Basin" and "the basin of Lake Dongting" are two different spatial concepts. "The basin of Lake Dongting" is only one of the components of "the Dongting Basin". The basin of Lake Dongting, the levees and the farmlands synchronously keep subsiding and relatively actionless due to the tectonic subsidence of the whole Dongting Basin. At present, the mean sedimentation rate of Lake East Dongting,Lake South Dongting and Lake Muping is 9.43, 19.11, 12.46mm/a, respectively. The rate of tectonic subsidence of the lake is low (3～10mm/a), but the capacity of tectonic subsidence still counteract a certain capacity of siltation, which restrains the shrinkage of Lake Dongting. The sedimentation rate is bigger than the rate of tectonic subsidence in Lake Dongting. Sandbars will continue to grow and expand, and Lake Dongting will still keep the trend of siltation and shrinkage. At present, the whole Dongting Basin is subsiding and expanding due to tectonic subsidence, which has no influence on the change of the capacity of storing flood of Lake Dongting, and siltation is playing a main role. The capacity of storing flood of Lake Dongting will continue to decrease as siltation goes on. During the 80 years after the Three Gorge Dam is completed with the completion of "the 4350 Project", the sedimentation rate of Lake Dongting will reduce to 1.79 mm/a. Then, the trend of siltation of Lake Dongting will be restrained.

This paper takes Geographical Information System (GIS) as a platform, gains altitude values (range of 1 km×1 km ), 3D map and basic data of evaluation in the studied area of the city of Panjin, based on the 1∶100,000 scale relief map and land use map as well as socio-economic statistic data. Submerged land area and potential loss are assessed for the case of no defence,different sea-level rise and high water level, respectively. The concrete conclusion is as follows. First of all, the potential effects on land include: Firstly, for no defence(the same as hereinafter) and average high water level, submerged land composing mostly of coastal villages and towns extends along coastline, and submerged area is 869-949km 2 or 21% to 24%. Secondly, for the historic highest water level,submerged area is 2,444-3,259km 2 or 61% to 84% with Dawa county submerged almost. Thirdly, the submerged area in Liaohe River Delta (Panjin) is 23%, but Zhujiang River is 7%, Changjiang River 18% and Huanghe River 5%. Next, potential population affected by sea-level rise contains: Firstly, for the average high water level, population affected in 1998 is 4 to 6 (if considered increasing, then 7 in 2030 and 14 in 2100)ten thousand or 3% to 5%. Secondly, for the historic highest water level, population affected in 1998 is 65-106(97 in 2030 and 267 in 2100)ten thousand or 55% to 90%. Again, potential economic losses by sea-level rise have: Firstly, for the average high water level, economic loss in 1998 is 8-9( if considered increasing, then 40 in 2030 and 1,328 in 2100)hundred million yuan or 7% to 9%. Secondly, for the historic highest water level, economic loss in 1998 is 62-93(297 in 2030 and 13,256 in 2100)hundred million yuan or 58% to 87%. Finally, potential environment loss of wetland by sea-level rise includes: Firstly, for the average high water level, environment loss in 1998 is 179(if considered increasing, then 872 in 2050 and 924 in 2100)hundred million yuan or 45% to 49%. Secondly, for historic highest water level, environment loss is 328(4,235 in 2050 and 4,665 in 2100) hundred million yuan or 83% to 93%. Relevant preventive measures such as sea wall defence reinforcement, adjusting and renewal wetland environment, establisment of flood insurance system, and formulation of integrated coastal management plan are put forward. And scientific basis for constituting regional strategies to mitigate and prevent disasters are provided.

Exploration and summarization of the laws of migration is one of the important topics in the historical migration study. Long history and complexity of migrating movements which happened in ancient China provides abundant sources for our research. Chinese scholars paid more attention to case studies of migration and have published a lot of papers and works (e.g. Chinese History of Migration, 1997), but little progress has been made on presentation of migration theories. As an tentative work, using the foreign scholars' successful experience (e. g. Ravenstein's laws of migration) for reference, basing on many other Chinese scholars' achievement in this field, the author of this paper deduces five categories of migration laws from Chinese history: 1. Political dominance . Political factors usually play the most important role in many mass migrations. It is easily found that in many dynasties forced migration and free migration made the capital the most populous region. Chaos in transition of dynasties produced a large numbers of refugees and forced them leave their homeland to find shelters. Forced current inevitably produced a compensating countercurrent. 2. Density of population and carrying capacity . Carrying capacity is the key factor for the quantity of population who lived in a certain place. People tend to move to those regions of low population density. On the other hand, overcrowding would force some inhabitants to move to other places. 3. Impelling of disaster and famine .Chinese people were subject to repeated natural disasters in long history. Fierce disaster would damage agriculture badly and lack of food often threatened peoples' lives. Fleeing to other places to seek food gave people a way of saving their lives. The more fierce famine emerged, the more residents left their hometown. 4. Migration of ethnic groups . The basic distribution pattern of ethnic groups in ancient China was formed from pre-Qin period. The Han people gathered in the Central Plain and other ethnic groups scattered the frontiers and border regions. As a moving trend, people of other ethnic groups tried to move into the Central Plain, while the Han people escaped to border regions to avoid heavy taxation and corvee. 5. Migrant and regional characteristics of culture . Migrants are the most important carrier of culture and customs. The cultural characteristics of migrant region were determined by the selection of migrants. Most migrants liked to accept the elegant culture achievement of the Han people while they kept their original customs and dialects.

Based on the monitoring of the results of atmospheric pollutants from 1981 to 1997 and the climatic data from similar years in Guangzhou city, the distribution regularity of the air pollution in this city is researched The results are described as follows: 1) There was clear cut seasonal changes of the atmospheric pollution in Guangzhou, the highest concentration of contaminants was monitored in winter and the lowest one in summer 2) During the past 15 years, the pollutant load rates of NOx and CO were on the rise while those of the SO 2 and DF ware on the decline each year,which showed that optical chemical pollution had been strengthening year after year since the late 1980s in Guangzhou 3) The pollutant load rate of each atmospheric contamination changed as the function and administration of the areas studied changed. The highest values of SO 2 and DF always appeared in the Industrial Area while CO and NOx in the Heavy Traffic Area In terms of Pollutant Synthetical Index, the Heavy Traffic Area was the maximum and Industrial Area took second place for the functional area. Liwan district was the maximum, Yuexiu and Fangcun took second place and Baiyun was the minimum for administration district, which showed that both Industrial pollution and Traffic pollution were equally heavy and that the atmospheric pollution was gradually aggravated from east and north to west and south in Guangzhou 4) Acid rain was very serious especially in spring 5) The distribution characteristics of atmospheric pollutants in Guangzhou both in time and in space are closely related to the weather factors (wind speed and wind direction, air temperature and so on) and the source of pollutants In order to reach the goal of protecting urban environment from being atmospherically polluted, the author thinks rational urban planning measures should be adopted so as to improve urban atmospheric environment, and specific countermeasures are put forward.