egionalization for estimating the wheat yield by using remote sensing data is the foundation of estimating the wheat yield in a large area by using remote sensing data.It is a special applied regionalization.It intends to offer a spatial framework suitable to the system of the estimation of wheat yield, and to provide the scientific bases for the selection of information sources,temporals of remote sensing,information processing,wheat discrimination,and the estimation methods of wheat area and yield.First,this paper puts forward some regionalization principles.They are the principle of combining the integrative analysis with the analysis of leading factors,the principle of combining the regionalization with classification,the principle of combining crop analysis with the condition analysis of remote sensing,the principle of combining the spatial analysis with the process analysis,the principle of combining the analysis of elements with the analysis of their relations, and the principle of keeping the grass roots administrative regions unbroken.Secondly,it analyses the bases of this regionalization which comprise the spatial differences of ground types and combinations, the succession of crop aspects,the relation of wheat yield to vegetation indices and environmental factors,the atmospheric and soil spectral noise the variance of solar elevation,etc.Thirdly,it works out the schemes about the optimum temporal for the estimation of wheat yield by remote sensing, the information sources of space remote sensing and the land use structure. Finally, it divides the country into 14 regions of crop yield estimation using the optimum temporal as a leading index and the total growing period,the ecological type,the climatic yield and the cropping system as reference indices and 32 subregions of yield estimation taking the ratio of farmland area, and the ratio of planting area of wheat as leading indices and the days of clear sky and the days of overcast sky as reference indices.

his paper analyses the main features of the climatic change, natural disasters of agriculture and grain yield in China during the past 15 years in comparison with the situation of the last 50 years. The conclusions are as follows: (a) During the last 15 years, the average temperature increased by 0.1～0.9℃ in China. The temperature increase was higher in the north than in the south. The average increase in the north was 0.5～o.9℃ .The precipitation increased or decreased by 3%～10%. The regions with precipitation increase were the northern part of Northeast China, Xinjiang, East China, the northern part of Central China and Sichuan and Guangxi Provinces. In general, the increase was between 1% and 5%. (b) During the last 15 years, flood, water 　logging and drought were the main natural hazards of agriculture in China. The drought stricken areas and flooded areas covered 17.6% and 8.1% of the sowing area in the corresponding periods respectively. The proportion of the drought stricken areas of each province was about 5%～19%. The proportion of flooded areas of each province was about 2%～10%. (c) The grain yield change due to the climatic change has obvious regional laws. The law shows that in the whole country the rich harvest year and the poor harvest year occur alternately and that the east and the west or the south and the north supplement each other in grain yield. In the past, we pointed out the law that “the south will have flood when the north has drought ”or “the south will have drought when the north has flood”. Actually it is not very exact. (d) During the last 15 years, the range of the grain yield decrease due to natural hazards occupied about 15% of the grain yield in the same period.The loss induced by meteorological disasters occupied about 40%. That was 6% of the grain yield in the same period. The continuous uptrend of the grain yield decrease proportion in the main grain production regions is one of the major reasons for the slow increase in grain yield in China since 1984.

This paper presents an index system and a method for calculating the comprehensive index of land use degree. The latest data from two projects titled “Remote Sensing Macro Investigation and Dynamic Study of National Resources and Environment” and “Resources and Environment Database of China”have been fully applied. In addition, this paper analyzes the regularity of the regional differentiation of land use degree in China and the socioeconomic and physical factors which affect the change of land use degree in China.The“polar” model and the “Longitude Distance” model of land use degree of China are also developed.

Desertification has become a global social environmental problem and is closely related to fragile ecoenvironment. From the viewpoint of landscape, mountain system lies in the agriculture forest cross zone. The fragility of its ecosystem shows on many hands, such as inner fragility, dependence on vegetation, transition of landscape, backward productive force, etc. Desertification is relatively severe. In this paper, by analyzing the hillside cascade system and the inner feedback mechanism of the system, the operating mechanism of mountain desertification is discussed and furthermore some thoughts about the prevention and control of desertification are raised.

ustainable development is a new type of development mode ,which is proposed to overcome the disadvantage of tranditional development mode. The disadventage is to develop the social economy at the expense of the environment. The essence of sustainable development is emphasizing the coordination between the social economy development and the resources and environment protection to ensure the sustainability of the social economy development.Under the great transformation of development mode of human society, the environmental impact assessment (EIA) of water resources engineering which is at intersection between environmental science and resources science also should fit the demand of this new transformation. In this paper, on the basis of an analysis of the tranditional mode of the EIA of water resources engineering and its five problems, we give the EIA of water resource engineering the connotation of sustainability and study its theory and method, then proposes the mode system of the EIA of water resources engineering of sustainable development which adapts the situation of China. It includes the theorical basis,evaluating contents,evaluating methods,evaluating index system , evaluating criterions and working procedure of the EIA of water resources engineering of sustainable development.

his study represents an exploratory undertaking to analyse the positive aspects of mineral activity in regional development based on China's industrialization during the past 40 years. The results of addressing at a framework of factor analysis and cluster analysis can be generalized below.(a)The Socio Economic Development Factor dominates the regional pattern of China's industrialization and it implies that the present formation of regional disparities in socio economic development in China is a part of its historical process. The coastal zone is still the most favoured area assemblage of regions in China's modern economy while the interior zone continues to lag behind it.(b)Moreover, the remaining three factors—the Mineral Processing Led Growth Factor, the Coal Mining Led Growth Factor and the Oil Exploitation Led Growth Facto—change nothing regarding the original centre periphery structure. On the contrary, they reinforce the structure through improving the leading position of core regions as a result of the developments in raw material manufacturing.(c)The spatial distributions of social development attaching to both the factor analysis and the cluster analysis indicate that mineral industry can act as a key instrument to stimulate and sustain regional development in most developing areas only in terms of their resource perspective: plentiful resources equals good growth prospects; scanty resources equates with much poorer prospects.(d)Another great contribution of mineral activity to regional development is afforded by the fact that through effecting great improvement in transport infrastructure, the development of mineral industry is critical to the formation of an integrated national transport network: in itself far more effective in promoting regional and interregional development than mineral production alone.(e)Finally, there are only four variables in the whole factor pattern, namely energy consumption, fixed assets of raw material manufacturing, freight traffic volume and number of hospital beds, which have positive loading across all factors. These variables provide an insight into the characteristics of early industrialization in China. First, the structural transformation from an agrarian society to one rooted in industry in a country can cause a great increase in mineral consumption. Second, under this pressure, the social production becomes heavil yengaged in the development of mineral processing. Third, mineral development can further regional development through the inception of a national integrated transport system. Finally, all the developments can provide the region with great opportunities for achievement of social well being conductive with the “take off” point.

here is a complex multiple feedback mechanism between the man production system and the resource environment. The modern desertification process is caused by improper human activities . In this paper, we take Wushenqi of the Maowusu sand region as the research object and use the relevant theory of systematology to analyze the correlation mechanism between farming,animal husbandry, forestry, industry and population on one side and modern desertification on the other side. We also use the system dynamic method to simulate the development trend of the modern desertification in Wushenqi. The results indicate that in the modern desertification process the change rates of various indices do not remain unchanged, they have clear steps. It may be concluded that combining the control of the population increase speed with the increase of material and technology inputs in agricultural and animal husbandry production, increasing intensive level, and practicing comprehensive management are the main measures to prevent desertification.

The area of the waste hillsides of the hilly region in the middle part of Sichuan Province occupy a considerable proportion of that province. Preventing and curing soil erosion and rationally utilizing the water and soil resources, play an important role in developing the local economy. In this paper, through mesh point observation the reasonable utilization ways are explored. This provides a policy making basis for the development and utilization of the waste hillsides.

On the basis of the prediction of the impact of the Three Gorges Project on the water level at the Hukou hydrologic station of the Changjiang river, this paper studies the impact of the Three Gorges Project on the water level of Poyang lake through setting up the water level correlation between the Hukou hydrologic station and the Poyang lake hydrologic stations which represent different parts of the lake.

ecause of land deterioration, soil erosion, desertification, salinization, alkalization, swamping, occupation of arable land for nonagriculture use, and the effect of natural calamity, the amount of arable land of China has declined to 957 billion ha. This means the per capita arable land area is less than 008 ha. With the increase of population, the pressure on the land resource becomes greater and greater. At present, China is among those countries of which the per capita land area is the smallest and the population supporting capacity of land is the largest. The total population in China will reach 13 billion by the end of this century. Then China will support a population which is 22% of the world total with the arable land which is 7% of the world total, and the man land conflict will become more and more acute. As a potential land resource, the tidal flat will be the new growing point of the national economy of China.This paper mainly deals with the distribution, formation factors, classification, and the existing problems in exploitation and utilization of the tidal flat of China. The total length of coastline of tidal flat is 4000 km and distributes at the margins of Bohai Sea, Yellow Sea, East China Sea and South China Sea, mainly in Liaodong Bay, Bohai Bay, Laizhou Bay, Shandong peninsula, along the coast of Liaodong, northern part of Jiangsu province, Shanghai, Zhejiang province, Fujian province ,Guangdong province, Guangxi province, and Hainan island. The total area of the tidal flat of China is 235 ha (among them the cultivable area is 797 ha) and it still grows at the rate of 20～30 thousand ha each year. The important thing is that all the tidal flats distribute in the eastern regions of China where the economy develops rapidly but lacks land resource, so the exploitation of the tidal flat of China is becoming extremely urgent.There are many factors which control the development of the tidal flat, such as the sediment supply in coastal zone, original coastal slope, intensity of wave action, tidal range, etc. The major factors are the supply of fine grained sedimentary material and the tidal range.The tidal flat of China can be classified into two major types: the plain type and the embayement type. The tidal flat of plain type distributes in Liaodong Bay, Bohai Bay, along the coast of northern Jiangsu province, Changjiang estuary, Hangzhou Bay, and Zhujiang estuary. The embayment type distributes along the coasts of Zhejiang province, Fujian province and Guangdong province.In exploiting the tidal flat of China, there exist lots of problems, such as backward technique, relatively low economic benefits, drastic natural calamity, relatively low exploiting level, and lacking the scientific guidance.The realization of sustainable development of the tidal flat is to meet the increasing material demands of the people during the process that improves the utilization coefficient of the tidal flat. To realize the sustainable,stable and coordinative development of the tidal flat we should consider not only the needs of ourselves but also the necessary requirement of the next generation. So we should take as a goal the increase of social wealth during the process of exploitation and management rather than only care about the present benefits that usually may destroy the natural environment of the tidal flat.The ecological development of the tidal flat is one of the ways that can realize sustainable development. It means the improvement of the quality of ecological system under the coordination among human beings, creatures and environment. The combination of research and exploitation and of utilization and protection will make possible the realization of sustainable development of the tidal flat.According to the natural characteristics of the tidal flat, the economic and technical conditions, and the present utilization situation, 5 utilization zones are divided and the general aspects of each zone are illustrated for further exploiting and utilizing the tidal flat resource of China.

and sustainable use has become one of important environment issues in the world. It is necessary to have the proper land use technology and an appropriate method for land use evaluation. This paper deals with the development of a new method for land sustainable use evaluation. We attempt to combine the classical land evaluation method with the landscape ecology method. The classical land evaluation method emphasizes the abiotic factors, such as soil, landform,climate and so on, while the landscape ecology method pays more attention to the spatial relation and processes.In the newly proposed evalution system, we select a series of factors as the evalution indices. Some of the factors reflect the quality, attributes and the use process of the land; others are ecologic, economic and social factors that restrain the land sustainable use. At last, a model of land sustainable use evaluation is given.

he grain yield per unit area sown in China has been increasing from 1949 to 1992, with an annual fluctuation which, besides some policy influences, was mainly resulted from the annually climatic variations, because of the monsoon climate characterized by annually considerable variation mainly in the temperature and rainfall and various na tural disasters such as floods and draughtThe law of temporal and spatial variation of climatic yield which is determined by the three natural factors including light,temperature and precipitation, was analyzed in this paper. It showed that the years with lower grain output per unit area are identified with the years of severe natural disasters. The per unit area yield of grain in the eastern China is higher and more fluctuating than that in the western region. Stabilizing the grain yield in the east and increasing the grain output in the west are of the major options in terms of strategy. The result of EOF analysis indicated that regional unanimity of climatic yield variation is a main spatial pattern besides the other spatial patterns of north south difference and east west variation in some years. From the temporal point of view, the climates in 1950's and 1980's are good for the grain production.

This paper quantitatively expounds that the precipitation resource is one of the important factors that affect the fluctuation of the grain crop production in the dry areas of Western Henan Province. On the basis of the calculation results of crop water surplus and shortage during various growing periods and the critical period of water requirement in normal precipitation years, high precipitation years and low precipitation years of 19 counties or municipalities in Western Henan Province, the basic law of the influences of precipitation resource on grain crop production in dry areas is revealed. According to the randomness of water variation and the option of cropping system in dry areas, the macro countermeasures that use the geographic risk policy making and practise the water adaptability planting are expounded in this paper.

The “YLN” region of Tibet is the center of the politics, economy and culture of Tibet Autonomous Region and the main developmental region in short term. In this region, the agricultural resources are abundant, the production basis is good, and the agricultural development potential is great. This paper mainly reviews the quantity, quality and developmental potential of various land resources and suggests the ways and countermeasures for rational utiliaztion and protection of land resource in order to provide scientific bases and beneficial opinions for the sustained and steady development of agriculture in this region.

he Hexi corridor is one of the main economic regions in Gansu Province. The scale of economic development of the Hexi corridor in the future depends considerably on the carrying capacity of the water resource in the region. On the basis of the balance principle of water quantity this paper analyses and calculates the balance between supply and demand of water resource, the balance between the water resource and the land resource, and the potential of the carrying capacity of water resource for agriculture development in the Hexi corridor. Meanwhile the corresponding mathematical models are set up. The potential of water resource in the Hexi corridor is great. This potential can brought into play step by step only under the following conditions, namely, develo ping the agriculture of the saving water type and using the water resource rationally and efficiently.

he interference of the catastrophic wind disaster occurring on the western slopes of the Changbai Mountains results in tremendous losses of the forest resources of the Changbai Mountains natural reserve on one hand, and creates a new problem of how to strengthen protection and accelerate restoration on the other. The authors study the regeneration pattern and process and the relevant problems about the post interference management and set forth the protection methods of speeding up the regeneration and restoration from the site and landscape levels.

n the basis of the research of the relationship between temperature solar radiation and rice quality in the paste filling stage,the temperature function in relation to the rice quality is established first.Then through calculating the rice quality's descending rate caused by solar radiation change under different temperature conditions, the solar radiation revisionary function in relation to the rice quality is set up. The temperature sunlight potential calculation formula which is used to estimate the climatic resource latent force in relation to the rice quality of a certain place is obtained by combining the 2 functions mentioned above. According to this formula,the temperature sunlight potential values in relation to the rice quality are estimated in all chinese rice regions.The regional distribution of the potential reveals the following :the climate resource in relation to the rice quality has universal adaptability to the production of good quality rice;the potential varies with the space and the time, so in different regions and seasons it is different;the potential also has vertical zonality structure in the regions with complex terrain.

n order to research into the moisture balance of a small watershed covered by evergreen broad leaved forests, we have made the observation of the precipitation outside and inside the forest area and the stem flow in the Jiu lian mountainous district, Jiangxi Province, for three years. On this basis we made the estimation of the crown interception. The results of observation show that the rate of the crown interception is 78.1% of the precipitation when the precipitation is 0.4～1 mm at a time, and it declines to 3.4%～3.6% when the precipitation is 60 mm at a time. But when the precipitation is over 60mm at a time the rate of crown interception is basically stable, being 3.4%～ 3.6%. The total annual precipitation in 1988,1989 and 1990 is 1 718.5～2 116.5mm. The results of estimation show that the total annual crown interception of the three years is 300～340 mm, which makes up about 16%～17.5% of the total annual precipitation.

Following the companion paper on the laws of sediment size distribution which account for the effects of the measures of water and soil conservation as well as the geomorphologic factors, this paper further deals with the sediment reduction effect of conservation measures in different catchments. Not only is the total reduction load inflowing into rivers (including tributaries and the main stream) due to the measures of water and soil conservation discussed,but also the grading portions of reduced sediment load are predicted and verified by the measured data. The grain size corresponding to the maximum reduction of sediment yield in the non uniform suspended sediment particles is accurately predicted by the model, which is of great importance in the benefit analysis of the measures of water and soil conservation in various catchments.

China is the country having many plateaus in the world. On the plateau surface, the land resource is abandant, but the agricultural development is puzzled by long term drought and water shortage. The current productive level here is low. During the period of the eighth five year plan, the adoption of semi removable spray irrigation has succeded. The unit area grain yield can increase from present 750 kg/ha to 5 250 kg/ha. The investment cost can be returned in one year in respect of most grain varietis. Enomous potentials of grain yield in the area are of special significance to the short supply trend of China's grain production.

n this paper, the weather climate features and the laws of spatial and temporal distribution of night rain and fog rain in the Xishuangbanna area are studied. The formation mechanism of night rain and fog rain and their agroclimatic significance are analysed. The results show that the precipitation in Xishuangbanna presents a proportional state between the night rainfall and the daytime rainfall, in which the rate of night rain reaches 54.5%～57.7%. Especially during the foggy season and the hot dry season the night rain may reach 71.4% and 70.6% respectively. The formation of the night rain is mostly due to the orographic rain caused by mountainous wind circulation. Its rainfall intensity is weak and its rainfall hours is long. So it is highly efficient for the tropical crops. The night fog rain plays a very important role in the eco environment of crops, for it can partly relax the insufficiency of crops water requirement during the drought season. For this reason, the night rain and fog rain resources will become the important basis in making the drought prevention countermeasures in Xishuangbanna.

On the basis of the results of a long term fixed location observation of 5 years, this paper uses the two model parameter t test, the elasticity analysis and the marginal analysis for exploring the effects of the annual time series on the nutrient losses of controlled burning and the the constractive young Chinese fir plantation.The t test shows that the B and A parameters of the loss models of amoniacal nitrogen, nitrous nitrogen, nitrate nitrogen,phosphate, potassium and arganic matter on the annual time series are quite different under different treatments. The elasticity analysis and marginal analysis show that the effects of annual time on the above mentioned nutrients under different treatments are negative. Under the controlled burning conditions, the elasticity coefficients of the above mentioned nutrient losses are-1.215%, -1.214%, -1.215%, -1.215%,-1.214% and-1.214%respectively,and their marginal amounts are-0.394 kg,-0.033 kg-0.365 kg, -0.023kg, -30.010 kg and -59.421 kg respectively. Under the treatments without controlled burning, the elasticity coefficients of the above mentioned nutrient losses are -0.842%,-0.851%, -0.844%, -0.854%, -0.845% and -0.841% respectively, and their marginal amounts are -0.159 kg, -0.010 kg, -0.085 kg, -0.006 kg, -12.024 kg and -17.767 kg respectively.

The return water of irrigation in Ningxia includes the deep seepage water in irrigation farming soil, the tail water of cultivated land,the seepage water of irrigation canals and part of industrial waste water and city sewage. The amount of return water per year is 3～3.5 billion m³ in Ningxia. The appraisal of 20 kinds of substances in the return water which has been heavily polluted and mineralized shows that it belongs to not poisonous but harmful fresh water. There will be no bad effects on crop growth and no threats of soil salinization and alkalization if the return water is mixed with canal water or rotation irrigation of the return water and canal water is adopted for arable land watering. Therefore, the return water should be developed and used with the least hesitation.

The study results of the ridge trough culture of bush mulberry on steep sloping land show that the calamities of soil erosion are prevented. In comparison with the contrast area, at the depths of 50cm and 100cm, the soil water content of the managed land is 10. 20%～33. 67% and 8. 27%～65. 37% higher respectively, the total N is 90% of the contrast area, the total P is 2. 9% and 26. 2% higher respectively, the total K is 3. 18% and 8. 01% higher respectively, the hydrolysed N is 61. 5% of the contrast area, the available P is 39. 02% and 97. 72% higher respectivley and the available K is 91. 48% and 92. 54% of the contrast area respectively. The per heatare leaf and cocoon production is 5～10 times higher than that of the contrast area. The economic benefit is 11. 88 times higher than that of the contrast area.

n this paper, using the method of multi purpose policy making, the main fire prevention tree species are screened preliminary. According to it, the fire prevention characteristics of the representative species Schima superba, Michelia macclurei and Altinggia gracilipes are compared with the inflammable species Cunninghamia lanceolata and Pinus massoniana. The results show that the fire prevention tree species have better fire prevention characteristics. Their ignition temperature is higher, their moisture content is greater, the rate of their moisture separation is faster, their activation energy is higher, and the thermal unit of their volatiles is lower. The results of principal components analysis show that ignition temperature, moisture content, the rate of moisture separation, activation energy, and the thermal unit of volatiles can be used as the main indices of judging the property of fire prevention of trees, and that the extraction matters and the crude ashes of phenethyl alcohol can be used as the supplementary indices of judgment. This paper sets forth the ways and countermeasures for the development and utilization of the main fire prevention tree species.

his paper has analysed the causes and properties of the mid summer and autumn droughts and the countermeasures of drought hazard in the low hill red soil region. The results are as follows.The main causes are that most precipitation occurs earlier than the latent high evaporation in the region, the space in red soil for water storage is limited, and less water is available for crop use. The properties are that drought and high heat occur at the same time, surface soil becomes dry rapidly, and the contradiction between supplying water from soil and requiring water for crops is obvious. The countermeasure is building a technical system for combating the drought. Of which, developing water resource and saving using water are the main body and reducing the unproductive water consumption and increasing the utilization ratio of the water resource by organisms are two wings.

In this paper the urban land grade system of the Agricultural Reclamation Towns (ARTs) of the Xinjiang Production and Construction corps (XPCC) is set up. The system includes the categories, grades and ranks of land and the datum land price. This work provides a scientific losis of the land management of different levels for ARTs of XPCC, and has comparatively good theoretical and practical research significance to deepening the reform of the land use with compensation system of China, establishing the reasonable land market, and making the land resource a property.

his paper studies the migration of nutrient element resources of the forest land after clear cutting and prescribed burning. The results are as follows: the biomass that migrates out of the forest land after clear cutting is above 80% of the total biomass of the forest land, the migration of Ca and Mg is above 60%, and the migration of N,P and K is below 50%. The nitrogen loss rate of clearing residue during burning is above 95%, and the loss rates of P,K,Ca and Mg are relatively lower. N and P reserves decrease and Ca,K and Mg increase slightly in the surface soil layer after prescribed burning. Almost all the biomass and nutrient elements of the forest land which accumulate during the whole growth stage of the forest stand are migrated out of the forest land after clear cutting and prescribed burning.

aking as the case study of the mountainous area of southern Ningxia,we have amended several parameters of AZE , Doorenbos,Chikugo, Miami, Thornthwaite Memorial models according to the crop and the natural environmental factors of the mountainous area of southern Ningxia and reckoned the photo temperature productive potential y(Q,T), the climatic productive potential y(Q,T,W), the amount of needed water Em and the amount of the insufficient water El of spring wheat. The main results are listed below: y(Q,T) is about 6.85～8.06 t /ha, y(Q,T,W) is about 2.22～5.32 t/ha, Em is about 340～450mm, El is about 70～300 mm. The amount of the insufficient water El in jointing stage and ear pregnant stage is specially serious. The above reckoned results all are conformed with its actual situation. In this region, the sustainable development strategies such as cumulating the rain water for irrigation i.e. using natural precipitation into available resource, increasing the basic cultivated area and improving water use efficiency etc. should have to be adopted.

The Zhoushan Archipelago is the largest archipelago of China. It is situated at the intersection point of the Changjiang economic zone and the coastal economic zone. It also serves as a base for exploiting marine resources. Harbour navigation channel,marine organism, tourism, salt industry, and ocean energy source are the five superior resources of the Zhoushan Archipelago. To make full use of island resources for the development of island economy, some suggestions are put forward in this paper:(a)practise regional comprehensive exploitation according to island conditions; (b)rationally exploite, protect and use the water resource; (c)exploite the deep water coastline resources;(d)continuously develop the marine fishery; (e)build bases of ocean tourism;(f)exploite the ocean energy;(g)steadily develop the salt products and the salt chemical industry.