本文系统地介绍了世界黄金资源的地理分布,产出状况,成因探讨与远景储量,工业储量及开采量,黄金价格与市场等方面的较为严格的数理统计资料,在前人工作的基础上,将中国黄金资源与世界黄金资源进行了比较研究,提出了中国和世界黄金资源的开发方向与黄金市场及价格方面的预测: 世界黄金资源的找矿方向正从高品位——大储量或高品位——小储量的找矿及采矿方向转移到低品位——大储量方向上来,在中国亦应该及时把寻找低品位——大储量的黄金矿床作为主攻方向。 世界的黄金市场将会更加开放,随着宇航事业的发展与新材料科学的进步,黄金的工业用途将进一步加大,用量将会逐渐增长,世界黄金产量的增长,将会抵消黄金价格的上涨。

The so-called arid regions of China in this paper do not include the semiarid regions and only refer to such lands as Xinjiang, the Hexi corridor of Gansu, the Qaidam basin of Qin-ghai, northern Ningxia, western Inner Mongolia, etc.The runoff in China's arid regions shows horizontal zonality and vertical zonality, the latter being more obvious. The lofty mountain masses, such as Altai, Tianshan, Qilian, Kun-lun, Altun, Helan, ect., are capable of intercepting moist air currents to produce mere precipitation than that occurring on the surrounding plains. Therefore, from the viewpoint of runoff situation, the arid regions can clearly be divided into the belts of the runoff formation and those of the runoff disappearance. The runoff formation belts and the runoff disappearance belts in arid regions have fundamental difference in hydrological regime.The hydrological regime of the river and its evolution depend mainly upon the supply sources of the runoff. The diversity of the runoff supply sources is one of the hydrological cha-racteristilies in the arid regions. The melt water from the alpine ice and snow has great impact on the hydrological regime of the river.The groud water of the piedmont plain comes mainly from surface water, while the river water below the plain comes partly from ground water. Between the river water and the ground water exists a relation of mutual supply, i.e., mutual transformation.

In the South of China, in order to reach thee middle- and long-term strategic targets of making the industrial strength match the population scale, according to the current industrial basis, and the environmental factors of resources exploitation as well as the situation of domestic and international economic development, the tactics of industrial development in this region should include the following: take the market as the lead, utilize the resources both domestic and overseas, take the beneficial economy as the core and the technique advance and industrial structure adjustment as the basis, establish the industrial structure in which the introversion and extroversion are combined, carry out an industry-inclination strategy that takes the light industries as the dominant sectors and the basic industries as the pushing sectors of the whole industry, and so on. The ultimate aim is to promote the industry development of the whole region and strengthen the economic status of his region in China.

The Yellow River Delta is one of the three biggest deltas in China. Its area is about 5930 km2 and it has rich land resources.In the first place, this paper divides the land into five kinds and nineteen sub-kinds. Then it divides the land quality into eight grades and thirteen classes by applying the method of two-stage fuzzy synthetical judgement. It has been found that the land mainly suitable for agriculture makes up 28.83%, that mainly suitable for animal husbandry makes up 34.44%. and that mainly suitable to fishery makes up 27.98%.At last, the method of the Analytic Hierarchy Process (AHP) is used to analyse and inquire into the countermeasure of rational exploitation and utilization of the land resources. The authors lay the emphasis on abiding by the general principle that the economic benefit is subordinate to the social and ecological benefits. Under this premise, this paper puts for-word six exploitive tactics headed by pledging the land to be used in industry and mine, and twenty exploitive measures headed by diverting the Yellow River water and using its sediment to improve the saline-alkali land.

The region along the Xijiang River is a developing region with a great superiority in industrial resources. Its resources include metal minerals (mainly nonferrous metals and manganese), nonmetal minerals, hydroelectric resources, and agricultural products (mainly sugarcane and fruits of the south subtropical belt). It also has a favourable environment for industrial development. The author points out that the exploitation of the superior industrial resources must adopt the tactics which take the light industry as leading industry and must lay stress on the construction of the industry bases of sugar, fruits processing, hydropower, nonferrous metal materials. In regional industrial development, the tactics of "combine the points with the axes and move forward gradually" should be taken.

The Kashi-Hotan region is an extremely arid area located in the southern part of Xinjiang, the westernmost territory of China. On the basis of the survey and investigation of the animal husbandry and it's ecological conditions, including the social-economic situation, the author points out four features of animal husbandry in this particular geographical region, and outlines the relation between the animal production and the ecological environment. This region is an inland area. The climate here is very dry. It is surrounded by high mountains. The oasisfarm-ing is well developed. All there have important influences on the local production. Then, the author puts forward five oppinions and suggestions about the strategy for the development of animal husbandry in this region: (1) Develop the intensive oasis animal husbandry as the main business. (2) Reform the feeding and management system. (3) Strengthen the feedstuff production, especially the forage crops and the feedstuff industry. (4) Improve the livestock with attention to their adaptation to local environment. (5) Combine the recent commercial production with the self-supporting production.

This paper first expounds the definition of the wetland and takes the Honghu wetland as an example to discuss the wetland ecosystem's nature including hydrology, soil, biological composition and function. Then it proceed to set forth the preservation and utilization problems of the wetland. Finally, this paper points out that only full preservation can make the wetland constantly favourable to the human race.

This paper elaborates the functions of sweet water lakes in China. These include regulating the river flow, generating electricity, irrigation, and shipping. Taking the Dong Ping Lake as an example, the paper also discusses systematically the charateristics of the sweet-water labe resource (natural environment, physical and chemical properties, fish habitat, tourism environment) and their exbloitation situation. The Dong Ping Leke is divided into three levels. The habitat and ecosystemastic charateristics of each level are analysed seperately.The main problems of the sweet water lakes in China are: the shortage of water resources flowing into the lakes, the pollution by industrial effluent, the impediment to passages between rivers and lakes caused by hydraulic structures, the siltation due to flood detention, and so on. All these result in the deterioration of water habitat, the extinction of migratory species, the shrinkage of lake's body, etc.At last, the paper sets forward some countermeasures for tapping and administrating the Dong Ping Lake. These include designing a drainage plan for tapping the aquatidrresoures in the lake, enhancing soil and water conservation in the drainage basin, cleaning the silt on the bottom of the lake in a planned way, dredging the passage between the lake and the river, setting up more fishways, working out a project of water transport and irrigation worts which will benefit the habitats of aquatic animals and aquatic plants, designing an effecient scheme for exploiting the stagnant water resource, and so on.

The plain lakes in Xinjiang have changed a great deal as a result of human's activities. Besides that some of them have become smaller or dried up, water salinzization of the lakes gives rise to a very conspicuous problem either. For example, the water mineralization of the Bosten Lake, the largest interior freshwater lake in China, raised from 0.25-0.40g/l in 1958 to 1.80-1.90g/l in 1986 and this freshwater lake has changed into a saltwater one to a certain extent. The water mineralization of other lakes such as the Buluntuo Lake and the Ailike Lake has increased notably. The water salinization of plain reservoirs is becoming more and more serious from day to day. The water salinization of lakes and reservoirs could exert an unpleasant influence on fishing, irrigation, reed growth, drinking water, and people's health. It is mainly the deterioration of salt balance and water balance that resulted in the water salinization. For the prevention and control of the water salinization, we have to drain less farm fields water into the natural river courses and lakes in order to ensure the water supply for ecologic purpose and put an end to the loss state in which the water balance of lakes has been for a long time.

The Changbai mountains are famous mountains in China with a large area and abundant tourist resources. The exploitation of tourist resources is to bring the superiority of tourism resources into full play, to carry out tourist activities of many levels according to the characteristics of tourist resources, to pay attention to the overall effect and the protection of ecologlc environment, and to utilize tourist resources rationally. It is the strategic goal to build the Changbai mountains into a famous tourist region at home and abroad.

In the south of China, the economy is prosperous, the population is large, but the energy resources are very deficient. The contradiction of energy supply and demand is a main problem for a long time in that region. In order to meet the needs of economic development, the speed of economic development should be properly controlled, the water resources should be fully developed and the nuclear power construction should be put in an important place. While dealing with the problem of bringing in the energy resources from outside the region, economizing the energy should be paid more attention. In addition, solving the problem of rural energy resources is another key point for the regional economic construction and energy development.

The complex geological structure, the frequent activities of volcanos, and the strong neo-tectonic movement are the favourable conditions for the natural mineral spring water to form and emerge. The basic characteristics of the carbonated mineral spring water in the Chang-Bai Mountains are: the contents of CO₂, and H₂SiO₃ are very large, the mineralization degree is very high, and it is rich in some trace elements such as Sr, Li, Zn, ect. The majority of the silicic acid mineral spring water contain Srand some contain Zn.The natural mineral spring water is widely distributed in Jilin Province. Its exploitation has many advangeous conditions such as rich resources, concentrated distrution, and the excellent quality of the water. The basic strategy for exploiting the mineral spring water includes overall planing, protecting resources, making rational exploitation, increasing advertisement, etc.The recent activities of volcanos and the active faults are the two mechanisms to form the mineral spring water. So volcano groups and active fault belts in the province are the most hopeful locations to find the mineral spring water.

Industrial resources (IR) are all the resources that can be utilized in industry, including natural resources and humanistic resources. They belong to the industrial category of resources. The study of IRD may be regarded as a discipline, and the economical development is the main aim of this discipline. The main characteristics of this discipline are the systematism and the applicability and the research contents are: the basic theory of industrial resources, the theory of industrial resources exploitation, strategy and tactics of the exploitation, types of the combination of industrial resources and the case of regional exploitation, management and the policy of resources exploitation and conservation and research methods and means of industrial resources exploitation.This paper discusses how to study this discipline and sets forward the main points of the study at the present stage.

Meteorological elements, such as the atmosphere pressure, temperature, precipitation, humidity, sunshine duration, etc., are usually considered as scalars. We use such a method that mean monthly precipitation at a station can be treated as a vector. The magnitude of the vector is the amount of rain, and the direction angle of the vector is the angle expressed in units of one representing that month. When monthly figures are added vectorially, the resultant vector can be used to compute the seasonality index, which is the ratio of the magnitude of the resultant vector to the mean annul rainfall. The direction of the resultant vector represents the seasonal concentration of precipitation distribution. Data from about 296 stations on the Loess Peateau are analyzed by this method. The maps of seasonality index are presented in Fig.3.The seasonality index characterizing the degree of seasonality of precipitation and the seasonal concentration of precipitation distribution are more useful parameters to describe the agricultural respect of climate of a district. They provide a simple method which condenses the 12 monthly rainfalls into an expression containing 5 digits only.The seasonality index of precipitation on the Loess Pleateau is between 0.44 and 0.66. The distribution of the isolines is closer in the Weihe River basin and the lower reaches of thet Yellow River and sparser in the northern part. It means that the precipitation is more concentrated in the northern part and decreases toward the south.The seasonality index of precipitation has good relations with the crop water stress. The precipitation is concentrated in the mouths of July and, August. So the crop of wheat fells severe deficiency of water, the millet fells almost enough and the situation of corn is between them.

The Jiulong River basin is situated in the south subtropical zone of China with favorable climate conditions, fertile land and rich products. It is a hinterland of economic development of southern Fujian. As the policy of special-zone and open-zone is carried out in recent years, the economy of the cities and villages develops very fast. But it is faceing serious challenges of soil and water loss, water pollution, and geomorphological calamity at present, because it has neglected the management and protection of the envir3nment at the same time. On the basis of investigation, we put forward three ideas about the management of the Jiulong River and the development direction, countermeasures, main ways and measures, for the comprehensive exploitation and utilization of the economy of the Jiulong River basin. All these have important meaning to the management and development of the Jiulong River basin.

The Panzhihua Iron and Steel Base is located in a paleorift belt west of the middle section of the Kang-Dian axis. It is the complicated geological structures of the rift valley belt that makes the area have favourable conditions for mineralization. There is a complete range of types of mineral resources and the amounts of their reserves are great. The geological reserves of Titanium and Vanadium ores in Panzhihua are both the greatest in the country. Titanium ore is also the richest and Vanadium ore is the third richest in the world.The mineral resource system of the Panzhihua Iron and Steel Base consists of kernel resources (including iron ore and coking coal) and auxiliary raw material resources (including power coal, flux limestone, dolomite, refractory clay, magnesite ore, etc.). There is a pendulum-like transport system between Panxi and Liupanshui for kernel resources transportation, transporting iron ore from Panxi to Liupanshui and coking coal from Liupanshui to Panzhihua. The mineral resources system and pendulum-like transport system of Panzhihua Iron and Steel Base can basically meet its needs of mineral resources.The formation of these two kinds of systems makes it necessary that the second base of Panzhihua Iron and Steel must be built in Panxi area (from Dukou to Xichang), otherwise it will lead to grave consequences-

Soil water is an important natural resource. This article has introduced the dynamic regularity of soil water and the calculated results of water storage. And it has also appraised the water quality briefly. According the main problems found in the study, an effective way is put forward to mitigate the shortage of water resource and to serve as a scientific basis for protecting the water resource.

The modern Yellow River delta is extremely rich in land resources. Because of larger sa-linized areas, lower index of cultivated land, fragile ecological environment, and the exploitation and utilization of the land being affected by the annual of seasonal distribution of the fresh water, the level of the present land productivity is rather low. However, despite of this, the potentiality of its exploitation and utilization is great, Such a task is increasngy pressing.For the time being, the main measures for developing the delta may be considered as follows: 1. Improve the low-yield fields and develop the productive potentiality of the land. 2. Improve the environment by expanding the forest land of the plain and establishing the windbreak belts. 3. Develop the present grazing land step by step into a productive base of livestock. 4. Utilize the seabeach and the internal water resource for breading and planting. 5. The relations between the land development and the oil-field construction must be treated correctly so as to give full play to the advantages of both land and oil. 6. In order to make necessary and timely changes about the utilization of the land according to scientific data to fully exert the proctive potential of the land resources, the remote sensing materials should be employed to monitor the dynamic changes of the land resources.

There are about 2902×10⁴ mu hilly wastelands in the Ganjiang River catchment. Of them, 2867 ×10⁴ mu stretch out continuously. The other 35×10⁴mu scatter as small plots (mainly on roadsides, banksides, ditchsiles and so on). The total area of the wastelands accounts for half of the area of the current woodlands, being slightly larger than the area of the current caltivated land. Three-fourths of the wastelands are distributed in red soil hilly ari'as (low hills 388×10⁴mu, accounting for 13.5%; middle hills 1236 ×10⁴ mu, 43.1%; high hills 605×10⁴ mu, 21%; and moutainous areas 638×10⁴mu, 22.3%). Most of them are distributed in the upper and midde reaches of the Garjiang River (upper reaches 60.2%, middle reaches 25.4%, lower reaches 14.4%).Exploiting and controlling these wastelands comprehensivly and utilizing them rationally are the most important keys for the peasants living in the upper and middle reaches to escape from poverty and become well-to-do.

There are abundant natural oil and gas resource, land resource, biological resource and water resource in the modern delta of the Yellow River. And the delta also has conditions for constructing deep water ports. But the scale, level and speed of economic development in this area are far inferior to those in the Yangtze River and the Pearl River deltas because of the frequently changing water course in the lower reaches of the Yellow River, late discovery of natural oil and gas resource, delicate ecologic environment, and poor culture and education. In order to exploit the rich natural resources and promote econonic development in the Delta, four countermeasures have been put forward in this paper: stabilize the water in the lower reaches of the Yellow River and speed up the construction of the deep water ports, develop industry focusing on the oil production and agricultural products processing, devote major efforts to improving the middleand low-yield fields and coustructing the bases of farming, animal husbandry and fishery, protect the natural environment and build a fine-circulation ecosystem.

Through an analysis of the growth of the annual ring of Pinus Koraiensis the progressive regression of Pinus Koraiensis production and 23 climatic elements was made. The result shows that the production of Pinus Koraiensis closely correlates with the average temperature of July, the cumulative temperature of ≥5℃ and the annual precipitation. According to the three climatic elements mentioned above, the suitable districts for the growth of Pinus Koraiensis are demarcated into three kinds: suitable, relatively poor, and unsuitable regions. These three kinds of regions are fit for the actual distribution of Pinus Koraiensis. It seems to prove that the growth of Pinus Koraiensis is suitable to modern climate. The mixed broadleaved trees-Pinus Koraiensis forest is a stable climate in the mountainous region of Northeast China. This result also provides a scientific basis for the distribution of the artificial Pinus Koraiensis forests.

The wind-drift sand process refers to the process by which the wind-drift sand activities occur on the ground surface and the wind-drift sand geomorphic landscapes form in the areas outside the arid and semi-arid zones. It is a branch research following the research of desertification. The wind-drift sand land is both an available land resource and a source of pollutants of environmental pollution. For the wind-drift sand land, it ought to adopt the measures of management and effective utilization simultaneously Through investigation and demonstration, it has been found that the construction of biological engineering and the development of eco-ag-riculture are the best ways to manage and utilize the wind-drift sand land.

Climatically, the Loess Plateau is located in a transitional zone between the subhumid and semiarid regions. Water shortage for crops is the key limiting factor in agricultural production. The precipitation and evaporation, the relation between the water demand of main crops and precipitation, and the moisture situation in farmland and the surplus and deficiency of water are discussed in this paper. Based on these, the conclusions are: (1) developing rain-fed farming should be a fundamental policy in agricultural production in the Loess Plateau; (2) apart from millet, other crops are greatly limited by local conditions; (3) the basic way for increasing the production of crops should be to raise the moisture content of the soil and to increase the utilization coefficient of available moisture. So, levelling land, increasing the application of fertilizers and so on should be adopted in order to realize the above purposes.

This paper is a part of the results of applying Chinese Territory Scatellite (CTS) materials to investigate forest resources in the Beijing-Qinhuangdao region. It has computed and analysed the distribution areas and main features of every type of forest resources and pointed out their development pontential. Statistics tell that the total area of forests is about 616 thousand hectares and the cover degree is about 11%. The forests are mostly distributed on mountains. But there are many lands suitable for afforestation. Such lands reach 862 thousand hectares and are distributed mainly on lower hills and in plains. The development potential is rather high as it may increase the cover degree of forests by more than 10% and their productivity by about 4-5 times.

Through typical surrey and scientific investigation of the exploitive state of metal mineral resources in the Naling area and considering the economic geology, economic geography, advances of science and technology, and market forecast of the area, we think that the conditions of ore genesis in the area are excellent. The exploitive direction should be:1.Concentrate funds, deploy qualified personnel and adopt advanced industrial methods to form a joint management group of nonferrous- metals in the Nanling area; carry out a systema-lized production system of looking for minerals -exploration-exploiting-smelting-industrial products; carry out a policy of looking ahead and behind; and establish various industrial bases of the nonferrous metals in the Nanling area on the basis of the large and medium cities which lie along the trank lines of the Zhejiang-Jiangxi, Hunan-Guangxi and Beijing-Guangzhou railways.2.Bring into full play the superiority of local rich natural resources and cheap labour and make use of the characteristics that by processing the primary products of rare metals, rare-earth metals and dispersed element minerals it is relatively easy to build up the industrial bases of rare metal raw materials in large and midium cities along the Zhejiang-Jiangxi railway and the industrial bases of rare-earth metal raw materials in large and medium cities along the Guang-dong-Jiangxi railway.3.Develop the existing medium and small iron and steel enterprises steadily and take as the direction the creation of new iron and stell industry materials and products by comprehensive processing and utilization of ferrous metals, nonferrous metals, rare metals, rare-earth metals and dispersed elements. Another direction is to strengthen the study of geologically basic theory and prospecting work to expand deposits and increase the iron ore reserves for the development of the iron and steel industry.

The author conducted two surveys of the wild animals in the region under consideration in the years 1987 and 1988. This paper presents scientific results obtained in order to afford some information on the status of the wild animal resources.Altogether, 21 species of wild animal resources are found in this region, belonging to 5 orders, 10 families and 18 genera. A list of these species with their geographical distribution is given in Table 1.Zoogeographically, in regard to the characteristics of the distribution of the wild animal resources in the region, we may take note of the following three facts.1.In the western parts of the Karakorum and western Kunlun mountains, the components of the wild animal resources mainly belong to the Central Asian pattern, .such as Snow leopart Panthera unica, Goitred gazelle Gazella subgutturosa, Ibex Capra ibex, Argali sheep Ovis arn-mon, Longtailed marmot Marmota caudata, etc., while the remaining belong to the Northern Eurasian species or the widely distributed species, such as Red fox Vulpes vulpes, Stone marten Maries foina and Cape hare Lepus capensis.2.In the region from the above-mentioned areas eastward to eastern Kunlun mountains (including their branches-Altyn Shan and Qimantag Shan), the endemic species of Qinghai-Xizang Plateau are comparatively common and the large ungulates are especially dominant. The representative species are Tibetan wild ass Asinus kiang, Wild yak Poephagus mutus and Tibetan antelope Pamholops hodgsoni. Besides, Himalayan marmot Marmota himalayana, High-land hare Lepus oiostolus and Tibetan fox Vulpes fcrrilata are also observed, and they have respectively replaced Marmota catidata, Lepus capensis and Vulpes vulpes in the above-mentioned region according to the data of geographical distribution.3.In the east part of the western Kunlun mountains, the elevation of the southern slopes (southern wing) fluctuates between 4900-5100m with numerous lakes and lacustrine flats on the expansive plateau. The natural landscope of the northern slopes (northern wing) differs greatly from that of the southern slopes. Thus, Tibetan wild ass, Wild yak and Tibetan antelope find their excellant habitats on the south slopes. Here they live in quite good conditions and their population is generally large. For example, we have counted more than 200 Wild yaks and over 600 Tibetan antelopes. By contrast, only about 50 Will yaks and less than 10 Tibetan antelopes have been observed on the northern slopes, and they apparently survive in small numbers.In addition, Ibex Capra ibex is only found in the western and northern parts of the Tax-korgan Reserve which is situated in the southwest corner of Xinjing Uygur Autonomous Region, which Blue sheep Pseudois nayaur occurs in the eastern and southeastern parts of it (Sch-aller et al., 1987). Because these two species are similar in the author considers that the ecological separation may be able to reduce the competition pressure for food, and that it may be favourable to them in the struggle for existence in nature.Finally, some existing problems of wildlife management in the region are presented. Also some suggestions for scientific conservation and exploitation of the wild animal resources are discussed.

This paper deals with the impact of human activities on forest and ecology resources in the watershed of the Tumen River. It shows that the key factor that makes forest deteriorate and ecological conditions worsen is population growth. In the last century the population increased by more than a hundrand times. As a result, 83% of the forest vegetation was des'-royed.The statistic data give us a regression equation of population (P) with respect to time(T)P = a×*exp [bXP -c/P)] where a = 0.9378,b= 0.035694And at the same time, the area of virgin forest (S) with respect to population (P) could be expressed by the equationS (P)=2×exp [-(bXP-c/P)]where S is the area of virgin forest, P is the population number, a = 1.8023, b= 0.023, and c = 0.0289Of course, what we has lost is not only a forest itself but also its by-products. The paper tries to analyze the ill effects of vegetation deterioration on natural resources historically. For example, the fur of marten, which is a precious fur and is one of the so-called three-treasures of the Northeast, has been analyzed quantitatively.

The Northwest of Sichuan is located in the inner mainland of China, being a part of the Qinghai-Xizang Plateau. The elevation in most of the area is over 3000 m to 4000 m and the climate is bitter cold. The region is the domicile of many minority nationalities such as the Tibetans. It possesses two characteristics, namely, the economy is related to the Sichuan Basin in the east and its cultural backgroud is similar to the Qinghai-Xizang Plateau in the west. There are a lot of resource superiorities and potentialities waiting to be exploited, including livestock, forestry, ores, energy resources, tourist resources, and so on, but the economy is backward at present. For futurel development, we should deal correctly with the relationship between modernization and tradition, and set up the pillar industries, supplementary industries and basic industries which embody the regional features. In the process, it also needs to construct commercialized production bases and arrange well the order of investment and projects. The regional development should give priority to the eastern part and the existing cities and towns before spreading to the whole region. Meantime, we should devote efforts to ecological construction so as to benefit the natural protection in the upper reaches of the Yangtze River.

This study shows that under fine-weather conditions due to difference of soil moisture content the diurnal course of photosynthesis of Aneurolepidium Chinense and Stipa Grandis has two types. When the soil moisture is sufficient, there is the monopeak type with a peak occurring before midday. When the soil is dry, there is the double peak type. In both the two types, the photosynthesis is low at midday.A comparison has been made between the two species, When the soil is dry, the decline in photosynthesis of Aneurolepidium Chinense at midday is much greater than that of Stipa Grandis. When the soil is sufficient, their declines are sinilar. No matter what the soil moisture condition may be, the low atmospheric humidity is a main ecological factor of the decline in photosynthesis at midday. The intense sunlight is a direct ecological factor of the decline in photosynthesis at midday only when the soil is dry. So the occurrence of the peak after midday is due to the decline in intensity of the sunlight.The dry soil and the low atmospheric humidity together increase the degree of the decline in photosynthesis at midday. The range of decline increases as the soil moisture decreases. Therefore, increasing the soil moisture content is the main ecological way to decrease the degree of decline in photosynthesis at midday.

Ecological security is one of the important footstones of national security, and is the base of sustainable development.Regional ecological security means that the ecological condition and the main ecological issue of a region does not threaten its survival and development with a given temporal spatial environment,at the same time the natural ecosystem service meets the needs of the regional survival and development.On the basis of comprehension and analysis of ecological security conception,the evaluation indices system is established including ecological products, eco environment situation,ecological function,and regional ecological security index and calculation model is put forward.Taking Hainan Province as an example and applying this assessment method,its integrative terrestrial ecological security index is 0.610.Among three assessing aspects,ecosystem services security is highest(0.772),security depending on resource is the lowest(0.468).The result indicates that the terrestrial ecological security is better in Hainan province especially in erosion controlling,natural disaster rejecting,air quality maintenance,etc. But there is also a lot of unsafe hidden trouble about energy sources self supporting ability,biodiversity protection,waste and sewage disposal,etc.It is believed that scientific and reasonable measures should be further strengthened,and safe ecosystem should be developed,so as to realize regional sustainable development.