The climate change and its induced ecosystem change have gotten more and more attentions from scientists and societies.The past researches showed that the temperature and precipitation variations in southwestern mountainous area of China were different from those in the other parts of China.So the climate change and its impacts on ecosystem in southwestern China is still a question to be understood.In this study,the spatial distributions and interannual variations of net primary productivity(NPP)were simulated by the atmosphere-vegetation interaction model(AVIm²)in southwestern China.The responses of forests,shrub lands,grasslands and crop lands to temperature and precipitation change during 1980 to 2000 were discussed.The study indicates that the spatial distribution of vegetation NPP in southwestern China is positively correlated with the pattern of precipitation and negatively correlated with that of elevation.The total vegetation NPP of southwestern part increased in the 20 years period.More detailed analyses show that variation of plant function type's NPP are different due to precipitation in the areas where they are located varies.In forest area,where the mean temperature rise rate is 0.037℃ per year and the precipitation has no obvious trend,the simulated annual NPP does not show any increase or decrease trend.In shrub lands and grasslands area,where the temperature rise rate is 0.040℃ and 0.034℃ per year,individually,and the precipitations increased,both the simulated shrub and grass NPP show significant increase tendency.

This paper mainly analyzes water-heat distribution and soil water variations in grassland area of southern Gansu by applying the EOF(empirical orthogonal function) and wavelet analysis.The results show there were jump-points in the evolvement of monthly rainfall and soil-water decreasing,and monthly temperature rise.The slopes of rainfall and temperature were different.The variation rate of monthly rainfall was-13.6mm/10a-4.3mm/10a and that of temperature,0.883℃/10a-0.108℃/10a.The obvious correlations of rainfall and temperature with soil water during growth periods were observed.Also the variation evolvement of rainfall and temperature corresponded with weak 4-year variation period.The change of soil water had good relations with annual rainfall and inter-decadal temperature variations.The oscillation of soil water responded obviously on short rainfall periods and long temperature periods.

Since the 1980s,especially since the mid 1990s,the climate in China has been warming up,which exerted significant impacts on winter heating conditions and energy require-ments in China.This paper analyzes the impacts of climate warming on winter heating climatic conditions and energy requirements in China during the past 20 years,based on daily mean temperature data from 458 stations throughout China.According to the definition of Code for Design of Heating,Ventilation and Air Conditioning(GB50019-2003),the start/end date for heating and central/intermittent heating region are defined.When we analyze the heating intensity,the degree-day method is selected.Comparing to the referential period(before 1980),during the period of 1985 to 2004 and 1995 to 2004,the borderlines of central heating region and intermittent heating region were shifted northward obviously.Especially in eastern China(east of 110°E),they were shifted northward by 2-3 latitude degrees.The heating length has decreased 5-15d in most parts of northern China and more than 30d in some parts south of the Yangtze River.Heating intensity decreased by more than 200℃ in northern China.Theoretically,the rates of energy saving for heating merely caused by climate warming are 5%-30% in northern China and more than 30% in the middle and lower reaches of the Yangtze River.

The global climate is changing due to constant increase in atmospheric greenhouse gases.The latest climate simulation result indicates that even more drastic change will take place in future global climate,which might exert significant impacts on many production sectors,particularly agriculture.Agriculture is a fundamental production sector for society,as China is an agricultural country with a large population,climate change will bound to exert multiple impacts on Chinese agricultural production.Therefore,using clinmate change projects and crop models to acquire a understanding of the impacts of climate change on Chinese agriculture,especially on winter wheat,is extremely helpful to policy makers and international agencies.CERES-Wheat,a dynamic process crop growth model,has been calibrated and validated for current production at ten sites in the major winter wheat-growing region of Huang-Huai-Hai Plain in China.With the aid of the two Global Climate Models(GISS and Hadley),the present study simulates the production changes under IPCC SRES A2 and B2 climate change scenarios.The simulations consider the impacts on rainfed and irrigated winter wheat with and without CO2 fertilization.The results indicated the possibility of significant impacts of climate change on winter wheat production in this region,with marked differences between rainfed and irrigated production.The conclusion is that an overall reduction of the rainfed wheat yield was observed in the study area,the yield reduction extent is greater in the western part and smaller in the eastern,taking no account of direct CO2 fertilization effect while the irrigated wheat yield keeps the current level with the increase in irrigation water amount but without considering the CO2 fertilization effect.Meantime both the rainfed and irrigated wheat yield increased largely with the consideration of the CO2 fertilization effect,but the increasing extent of rainfed wheat is greater than the irrigated wheat because the CO2 fertilization effect improves significantly water use efficiency and reduces the irrigation water amount.Our simulation results also showed that the selection of GCM could significantly affect final predictions,especially in relation to precipitation signals.By contrast,we found that the selection of emission scenario(A2 vs.B2) was less important in determining final impacts.

According to years of synchronous observations of growth spectrum of Dongzhiyuan main crops(e.g.winter wheat) and main fruit trees(e.g.apple,pear) and climatic change,this paper analyzes the ecological response of crop growth spectrum to the climatic change in Loess Plateau of east Gansu province.The result indicates that the mean annual temperature has presented an increasing trend notably in the last 35 years in Dongzhiyuan,and dominated by winter and spring warming(winter wheat over-wintering period temperature increase linear trend reaches 0.067 2℃/a),basically identical with the warming trend of global climate.It reaches 0.050 7℃/a,which is much higher than the mean national temperature increase range since the 1960s and also higher than the Loess Plateau in east Gansu province(0.034 8℃/a) in the last 35 years.It is also the central area in temperature increase in the study area.This further confirms that the eastern part of Northwest China is one of the regions witnessing greater temperature increase range.The impact of climate warming on ecology of winter wheat and fruit tree ia mainly reflected in advance in growth stage generally in spring in Dongzhiyuan and winter wheat over-wintering stage shortens notably(the shortened linear trend reaching 0.674d/a).However,winter wheat and fruit tree growth intervals at various phases do not present shortening trend.And because the locally plant winter wheat variety is strong winter enduring and long sunshine tolerate variety,the advancement in growth period causes the shortening of sunshine time,restricts crop or plant growth to a certain degree and offsets partly,the temperature increase effect.Therefore,the linear trend of fruit tree puberty in advance in spring is more obvious than the winter wheat.With regard to fruit tree,the linear trend of puberty of pear tree in advance is more obvious than the apple tree in spring.The conclusion is that the impact of climatic change is both advantageous and disadvantageous to agriculture.So the relevant agricultural administrative department should follow the local climatic change characteristics to adjust the cropping pattern in time,optimize the mode of planting,go after profits and advoid disadvantages,fully excavate the resource potentiality of the climate and improve the agricultural economic benefits.

Foshan city is the third biggest city in Guangdong province and typically one of the fast developing cities of Pearl River Delta,which has been one of the most prosperous economic zones but meanwhile one of the areas characterized with serious ecological degradation within China's coastal economic regions since the late 1970s.Therefore,Foshan was selected as a case for the study on ecological security situation during the recent rapid urbanization process.Based on statistical methodology,Landsat 7 ETM+ interpretation by remote sensing software and GIS based integrated assessment,the local ecological capacity assessment,which was calculated with REP(Relative Ecological Pressure)and RREC(Relative Residual Ecological Capacity),and the ecological risk assessment,which was calculated with RERI(Relative Ecological Risk Index),were performed to demonstrate the total environmental situation,ecological consequences and causes for Foshan regional development.Results show that among the various districts of Foshan the REP levels rank in decreasing order as Chanchen>Nanhai>Shunde>Gaoming>Sanshui,whereas the RREC levels rank in decreasing order as Chanchen

Based on county-level statistic data in 2000-2003,this article reveals new regional distribution and difference of supply-demand of grain in China in the early 21st century.According to per capita grain available,four types of grain supply-demand are given in this study.Regional pattern of grain supply-demand in China shows a dominant rule of east-west differentiation,and then the rule of south-north differentiation.At present,the main grain-surplus regions are most extensively distributed to the east borderline of the second ladder of topography in China,being about 1/4 of the whole country.At nearly the same quantity,the food-shortage regions in average year are mostly distributed in the region west to the sideline of population geography from Heihe city in Heilongjiang province to Tengchong city in Yunnan province,namely Huhuanyong sideline in China.The potential food-shortage regions are located between the above two geographic boundaries,which have the largest numbers of the four types of grain supply-demand regions,about 1/3 of the whole country.According to the above regional pattern of grain supply-demand,this article divided the whole country into six regions to analyze regional difference in grain production with some key indices.Northeast China and North China Plain produced nearly 70% of the surplus grains of the whole country,and the southern region of the middle and lower reaches of the Yangtze River ranks the third.Northeast China has the least number of food-shortage regions,and supplied about 40% of the surplus grains in China.The southern region of the middle and lower reaches of the Yangtze River has the greatest number of food-shortage regions in China,followed by the interlock area of farming and pasturing in the region east to the borderline of the second ladder of topography.This region is also the most fragile region in food security in China,where the level of grain production and economic development is very low.Most of the above areas are located on the regions sensitive to environmental changes,which have the highest natural risk of grain production.It is necessary to improve human acclimatization and strengthen the studies on impact of environmental changes on China's food security.

Drought and water shortage are the major influencing factors to sustainable agricultural development in northern China,as most of it is located in arid and semi-arid areas.Meanwhile,northern China is also an important grain producing base of the country.Exploiting the major crops potential productivity in macro-scale could provide consultative information and priority regions for the formulation of development strategy.Considering the water shortage situation and its key role in grain production in northern China,CERES-maize is used to simulate rainfall potential productivity of maize in dryland farming areas of northern China,and analyse the temporal and spatial distribution of potential productivity.The results show that average potential productivity of maize in semi-humid area is about 11 000kg/ha,while in arid area is about 5 000kg/ha.As a whole,the rainfall potential productivity of maize is in the order of sub-humid area >semiarid area >arid area.Moreover,the inter-annual fluctuation of potential productivity in sub-humid area is also significant,and that of arid area is relatively stable.The potential productivity in eastern part of northern dryland area is higher than that in the western,but there is no significant difference from north to south in the northern dryland area.

The "Pig-Raising,Methane-Generating and Fruit-Growing" eco-agricultural system is a pattern of recycling economy.The system structure and work mechanism are analyzed and results of scientific experiment are summarized for the development of recycling economy in this paper.The system integrates a series of complex biological and chemical reactive process based on the methane-generating.This leads to simultaneous accomplishment of upgrading structural hierarchy for traditional cultivation pattern,making full use of material in multiple hierarchies,making effective conversion of energy,and bringing economic,social and ecological benefits.Some 103.87 million methanegenerating pits and 250 big methane-generating projects have been constructed in Jiangxi Province.Because firewood gathering has been replaced by methane,more than 6×106 m3 of woods are saved every year,and 74×103 ha of forest has been projected.The residues in methane-generating can be returned to farmland,so that fertilizer use efficiency increased by 20% in contrast to the traditional pattern and the soil quality can be improved,for example the organic materials increased by three times and the dissolve nitrogen increased by more than one times.The "Pig-Raising,Methane-Generating and Fruit-Growing" eco-agricultural system has been widely used in tackling small catchment in a comprehensive way,reducing environmental pollution by area source in rural areas,predicting the pollution-free foods and controlling schistosomiais.The results of the theoretical research and scientific experiment show that development of recycling economy should maintain the direction in the theory and methodology of the system science,take the motive force of science and technology as a guidence and laws and policies as a support.

Using air temperature and precipitation data in 1962-2004 of 14 meteorological stations over "Sanjiangyuan"(head waters of three rivers) region,the changing trend of climate factors and its abrupt changes in evaporation and precipitation as well as air temperature are analyzed.The results show that the seasonal mean air temperature and annual mean over "Sanjiangyuan" region has been rising in recent 43 years,the rising of annual mean air tempera-ture is caused by the rising mean air temperature in summer and autumn;the variation of precipitation in a year,summer and autumn has been slightly decreasing,while the precipitation in winter,and spring has been increasing,and the warming and wet variation is featured in different seasons;the annual and seasonal variations of evaporation have been increasing under the condition of air temperature's rising,and precipitation is regarded as the main material resource of evaporation.Its variation trend,to some extents,causes the variation characteristics of evaporation.The climate change shows significant regional difference,the orographic factor of latitude,longitude and sea level has a significant influence upon the climate change,and annual mean temperature presented abrupt change in 1987 which is consistent with air temperature over the northwest region,but the abrupt change occurred earlier than that in northern hemisphere.The precipitation in winter and spring presented an increasing trend in the 1980s and the mid 1970s,and abrupt change in annual evaporation appeared in 1986-1988.Due to global warming,the evapotranspiration on land surface and evaporation on ocean has been increasing;as a result,the water-vapour cycle was accelerated,which is the main cause of warming/wet variation over the "Sanjiangyuan" region.

A blueprint(FH69 blueprint) for a physically-based digitally simulated hydrologic response model was published by Freeze and Harlan in 1969,which initiated the studies on the distributed hydrological models(DHMs) at the watershed scale.Nevertheless,in spite of three decades of modeling development,distributed hydrological models are today being used in practice only at a fraction of their potential.The applications of DHMs based on the FH69 blueprint are confronted with difficulties because of deepening in theory,which simultaneously indicate that the complex models are not always good ones.According to the scientifically modeling protocol,a simple monthly subbasin-based water balance model is put forward,where the revised Bagrov evapotranspiration model is developed to parametrize the distinguishes between various land covers,and a parameter set is introduced to represent the impacts of human activities on runoff generation and evapotransipiration processes.In the case study of the Chaobai River Basin in North China,the model was used to quantificationally identify the impacts of climate changes and human activities on runoff.In the Bai River Basin,the annual mean precipitation of the 1980s(1980-1988) and 1990s(1989-2001) decreased by 9% and 5% com-pared with that of the 1970s(1961-1966 and 1973-1979),but the runoff reduced by 54% and 52% respectively.The simulation results indicate that the contribution rates of climate changes and human activities are 44% and 54% respectively.In the Chao River Basin,such contribution rates are 24% and 74%,i.e.,human activities are the main reason for runoff decrease.

Using data of 171 observations from 1961 to 2003 in Northwest China,mean monthly temperature,highest temperature,lowest temperature,accumulated temperature ≥0℃,≥10℃,and negative accumulated temperature <0℃ were collected to analyze response of climate warming on heat resource and impact of climate warming on agricultural production.The results showed that mean monthly temperature,highest temperature,lowest temperature and accumulated temper-ature ≥0℃ and ≥10℃ of 1987～2003 were significantly higher than that of 1961～1986,especially the lowest temperature increment markedly increasing and the increment of winter greater than that of summer,the lowest temperature rising played a main role on climate war-ming over Northwest China.The negative accumulated temperature <0℃ reduced obviously.As the trends of climate change appeared warming since the late 1980s in Northwest China,thermal resource increased,planting areas of heliophilous crops expanded,the planting area of north boundary of crops would extend northward which is favorable for animals to overwinter and spend spring.The negative impacts of climate warming on agriculture is greater than the positive.

Global warming caused a dryer and warmer climate in the hinterland of the Qinghai-Tibet Plateau.Does it cause any responses from the plants ecology,and how?Based on field works and statistical data collected in 2002 and 2003,we basically concluded warming trend of the climate is the major reason for the succession devolution of alpine plants in the central part of the plateau.In the study area,it is specially causing a devolution from alpine Kobresia meadow to Alpine Stipa steppe at a rate of 14.2km/10a.Accordingly,the total biomass of the area is declining.With contrast to some relative researches,we basically concluded a dryer and warmer climate should take the responsibility for vegetation devolution accompanied with biomass decline in the area.Changes of the surface vegetation will be the negative factors influencing the capability of the environment self-adjustment and the development of the local economy.

Since the second half of the 20th century,many researchers at home and abroad have studied global temperatures rising and its impacts on crops and environment.But most of the studies have been only limited to the change of mean temperature.For the terrestrial ecosystem, the daily maximum temperature is the important factor determining the normal photosynthetic mechanism control,fruit quality and glaciers melting.Moreover,the minimum temperature at night is important for crop respiration,dry material accumulation,and crops overwintering.Therefore, changes of the maximum and minimum temperatures are more important than the mean temperature in terms of their impacts on environment and physiological activities of plants.In terms of the seasons,the rising rate of temperature in winter is higher than that in summer.In terms of regions,the rising rate of temperature in the northern part of northern China is higher than that in the southern part of northern China.The maximum temperature in summer tends to decline in Huang-Huai-Hai plain.In terms of the temperature types,the rising rate of the minimum temperature is higher than that of the maximum temperature.A sudden change test was made for the maximum and minimum temperature of northern China by using Mann-Kendall climate sudden change statistics check method.The results show that the sudden change point of annual mean maximum temperature was in 1992,and the temperature evident rising occurred in 1994.The evident rising of annual mean minimum temperature occurred in 1981,and the time of the occurrence in sudden change point of minimum temperature is far prior to that of maximum temperature.These facts indicate that the change of the minimum temperature is more sensitive than that of the maximum temperature.It is concluded that the main contributor of climate warming in northern China is the rising of the minimum temperature.Meanwhile,since the occurrence of global evident warming in the 1980s, the growing area of thermophilic crops in northern China has been expanded and the north limit of crops cultivation has been shifted northward.

Evaporation(evapotranspiration),on the one hand,is an important component in the heat and water balance of the Earth's surface,and is the component of the hydrologic cycle most directly influenced by land-use and climate change.On the other hand,evaporation(evapotran-spiration)consumes much of the water and energy that are available on the surface of the earth and therefore influence all hydrological and most meteorological processes.Basic knowledge for evaporation change over global or regional scale redounds to understand the law and causations of climate change.Up to now,studies on global climate change are,more and often,concerned with temperature and precipitation.Researches on the influence of climate change on evapora-tion(evapotranspirtation)are in small numbers.Based on observational data from1960～2000of123meteorological stations,near and in the Yellow River Basin,the spatial and temporal distri-butions of trends for pan evaporation are studied.The results show that,although the annual mean air temperature over the Yellow River Basin has,on average,increased0.6℃over the past40years,the rate of pan evaporation over the Yellow River Basin has,on average,steadily de-creased,especially in summer and spring.Compared with the1960s～1970s,the rate of annual pan evaporation of the1980s～1990s has decreased136mm or7.5%.Spatial distribution of the change rate shows that this trend is general but not universal,pan evaporation has significantly decreased over the upper and lower reaches of the Yellow River Basin,and increased in a small degree over the middle reaches of it.