4.1 Wanzhou Eco-Environmental Experimental Station

In 2002, Wanzhou Eco-Environmental Experimental Station conducted experimental observation on compound cultivation of grain, economic crops and fruits on ridges in slope fields, experimental observation on hedgerow technology in slope land, and experimental observation on high-quality grazing grass cultivation. Demonstration and extension were conducted in 200 mu in Tangpu Village of Changling Town, Wanzhou Region, and Zhuxi Town in Kai County, using compound cultivation of grain, economic crops and fruits, and hedgerow technology in slope farmlands, respectively. King Grass was extended in regions of Longbao, Changling, Changtan, Guyu, Xintian Farm, Zhuxi and Fuling Farm by 500 mu, which gave out good results of demonstration and extension.

4.1.1 Experiment on compound cultivation of grain, economic crops and fruits on ridges in slope farmlands

In 2002, three modes of cultivation were tested and observed, including compound cultivation of grain, economic crops and fruits on ridges, compound cultivation of grain, economic crops and fruits on flat lands, and compound cultivation of grain and economic crops on flat lands. The crops were corn, wheat, peanuts, soybeans and shaddocks. The results indicated that the mixture cultivation of grain and economic fruits changed the level cultivation along the slope cultivated land to grid ridge culture crossing the slope, and changed the single grain cultivation to the mixture of agriculture and forestry, which had a significant effect on the increasing the activating soil layer of the cultivated slope land, increasing the water holding capacity and fertility of the soil, reducing drought and soil erosion and the productivity of the cultivated land system on the slopes.

4.1.2 Experiment on hedgerow technology in slope fields

In 2002, the hedgerow technology using King Grass - shaddock - peanuts and all-crop technology using wheat - corn - sweet potatoes were tested. As compared with the all-crop technology, the hedgerow technology using King Grass showed significant effects for reducing angle and length of the slope, improving physical and chemical nature of soil, lowering soil erosion, and raising productivity of the lands.

4.1.3 Cultivation of high-quality grazing grass

The King Grass was selected for testing cultivation of high-quality grazing grass. Experimental observation was conducted on its biological characteristics and cultivation modes.

● Biological characteristics of King Grass

The biological nature of King Grass varied according to their location at different altitudes. In low, medium and high altitude areas, the growth periods of King Grass were 317, 264 and 245 days, respectively.

King Grass is not cold resistant. At temperature above 0 ℃, the aboveground plant can live through the winter safely, but the gemmules on top of stalk can be damaged. At temperature below minus 2-3 ℃, the gemmules will be frozen to death, while the stem beneath the ground can live safely through winter. Regarding preservation, both the method of burying and the method of covering can achieve good results in low-altitude areas. In middle or high altitude areas, the burying method is better for preservation of axillary buds.

● Modes of King Grass cultivation

King Grass can grow healthily in many kinds of soil like purple soil, yellow soil, alluvion soil and lime soil. Under the different land conditions in the reservoir area, various cultivation modes can be applied accordingly, for example, the mode of King Grass + economic woods, herbs and grazing grass, the mode of cultivation on sharp slope, the mode of cultivation on ridges and banks, the mode of green fence around fruit gardens and planting on the slope road sides, and the mode of cultivation in belts dying out.

4.2 Zigui Eco-Environmental Experimental Station

In 2002, the monitoring and research continued on soil erosion in the front of the Three Gorges reservoir area and the impact of different levels of nitrogen and kalium fertilizers on ginger production in light yellow soil areas at altitude of 600-900 m in the front of the Three Gorges reservoir area.

4.2.1 Monitoring of soil erosion

Soil erosion is one of the major characteristics in the slope dry lands in the reservoir area. The Station adopted multiple methods of soil conservation for monitoring their effectiveness.

The results showed that for fruit gardens, under different conservation methods, the runoff coefficients ranged between 0.01 and 0.12, the sand losses ranged between 0.004 and 0.935 kg, and the soil erosion were 0.09 - 20.63 t / km². For grain fields, under different conservation methods, the runoff coefficients ranged between 0.01 and 0.39, the sand losses in each small area were 0.004 - 0.357 km, and the soil erosion was 0.01 - 8.59 t / km².

As indicated from the results, the runoff amount, runoff coefficients, sand contents and soil erosion were all relatively small under different treatment methods like covering the fruit gardens with live plants (cultivation of aged trifolium repens under navel orange trees), covering the fruit gardens with dead plants (laying crop straws under navel orange trees) and building plant filtration belts in grain fields.

4.2.2 Experiment and demonstration on integrated treatment of dry slope lands and fertilization of soil with high productivity, high stability and high quality

Experiment and research were conducted on the impact of different level of usage of nitrogen and kalium fertilizers on ginger production in light yellow soil area in the front of the Three Gorges reservoir area. The results indicated that in the yellow soil area at altitude of 1000 m, the use of kalium fertilizers, organic fertilizers, compound fertilizers (organic and chemical fertilizers) and organic biological compound fertilizers was good for increasing production of ginger grown in one year. The most satisfactory way for raising ginger production was to use organic fertilizers plus appropriate amount of carbamide. Excessive use of kalium fertilizers could not result in increase of productivity, and appropriate amount ought to be used. It was good when using kalium fertilizers at the rate of 15-16 kg/mu. Further experiment will be needed to see whether the use of organic fertilizers with nitrogen, phosphorus and kalium fertilizers together could result in a better result.

4.3 Xiaogang Eco-Environmental Monitoring Station

In 2002, continuous observation was conducted on ground water dynamics and soil gleization indicators under different levels along the route between Xiaogang and Shi Dock, and the water balance regarding precipitation and evaporation within Xiaogang Station. Research was also conducted on the relationship between underground water level and the water level of the Yangtze River using the data of water level of the Yangtze River and Honghe River in 2002.

4.3.1 Monitoring of ground water dynamics

The area of Hong Lake is geographically plain and broad. The altitude ranges between 22.0 and 25.0 m, with relative altitude difference less than 2 m and slope less than 5%. The ground water includes mainly the pore water in the Fourth type of unconsolidated rock (phreatic water and pressure water) and deep crackwater. The Fourth type pore pressure water is formed from Holocene sand and sandy gravel, and abundant in quantity. The elevation of the top plate of water resisting layer is above 9 m, while the altitude of channel line is generally below 5 m above Yellow Sea Baseplane. Therefore, the Yangtze River influences the pressure water by cutting through the top plate.

In 2002, the highest monthly mean water level occurred in August in all observation wells, while the lowest were found mostly in February and sometimes in January. The annual average of groundwater level ranged between 21.45 and 22.64 m, while highest groundwater level was 21.90-23.34 m and the lowest was 20.89-21.55 m. The variation of groundwater level was 0.89-2.41 m.

The analysis on correlation between groundwater level and the water level of the Yangtze River indicated that significant linear correlation among pressure water level, groundwater level and the water level of the Yangtze River.

Table 4-1 Correlation coefficients between groundwater level and water level in the Yangtze River

Observation well	A	B	C	D	E
Groundwater	0.779	0.796	0.939	0.901	0.442
Pressure water	0.884	0.775	0.857	0.857	0.391

4.3.2 Monitoring of soil gleization indicators

In 2002, the monitoring of soil gleization indicators was continued for sections with different gleization levels from Xiaogang Farm to Shi Dock. The indicators were the same as 2001. According the monitoring results, the soil gleization indicators were not only varied under different gleization level of the soil, but also influenced by the land utilization status.

According to the observation on gleization indicators in different cross-sections of soil, the Eh, total reduced materials, activated reducing materials and Fe2+ showed different changing patterns with deepening of the soil layer. The Eh and Fe2+ decreased gradually from surface layer to plow sole layer and core soil layer. The highest contents of total reducing substances and activated reducing substances were found in the surface layer, while the lowest contents were in the plow sole layer.

4.4 Terrestrial Plant Species Protection Station

In 2002, the experiments and monitoring in the station included meteorological monitoring, setting up a sample belt for monitoring biodiversity, ecological research on Adiantum reniforme var. Sinense and Myricaria laxiflora, and the conservation of rare and endangered plants using ex-situ approach.

4.4.1 Meteorological monitoring

In 2002, the annual mean temperature in Longmen River area was 10.4 ℃, while the highest was 32.5 ℃ and the lowest was -8.8 ℃. The average temperature was 20.8 ℃ in July and 1.1 ℃ in January. The monthly mean temperatures varied little compared with those in 1997 - 2002. The annual precipitation was 1421.9 mm, while the precipitation in August reached as high as 347.0 mm. There was little difference between the precipitation in 2002 and the multi-year annual average (1391.4 mm), but the monthly distribution of precipitation varied significantly. The precipitation in April, May and August increased significantly compared with the average of the past years. The precipitation in April, May and August reached 207.5mm, 217.2mm and 347.0 mm, increasing by 97.2mm, 50.8mm and 94.4 mm, respectively.

4.4.2 Monitoring of biodiversity

In October 2002, the setting-up and investigation of monitoring belt in Zigui was completed. The fixed monitoring belt of Zigui was located at Shuitianba Town, Zigui County, Hubei Province, with altitude of 208-1045 m. Shuitianba Town is geographically located at 31°04' north latitude and 110°40' east longitude. Due to the long period of influences of human activities, the forests in this area have almost completely destroyed, with only some Pinus tabufaeformis Forest, Pinus massoniana Forest, Cunninghamia lanceolata Forest and Cypressus funsbris Forest growing above altitude of 800 m. Natural vegetation (mainly scrub or grassland) is rare seen below altitude of 600 m. Most of the vegetation has been transformed into farmlands or fruit gardens. In recent years, many mountainous areas in Shuitianba Town were designated as zones in which chopping is prohibited. As the influence of human activities was relatively heavy, the research in this area on the impact of human activities on terrestrial vegetation as well as their restoration is valuable.

The Zigui monitoring belt is composed of 8 fixed monitoring quadrats varying with altitude gradient varied continuously. The investigation in the quadrats was conducted on over 60 species higher plants. The species were mainly from Gramineae, Rosaceae, Cyperaceae, Myrsinaceae, Symplocaceae, Rubiaceae, etc. A total of 8 types of vegetation were found from lower to higher altitude in the entire monitoring belt, including young Cunninghamia lanceolata Forest, young Robinia pseudoacacia Forest, Pyracantha fortuneana Scrub, Cypressus funsbris Forest, Ligustrun quihoui Scrub, Pinus tabufaeformis Forest, Coriaria sinica Scrub, Heteropogon contortus Grassland.

4.4.3 Ex-situ conservation of rare and endangered plants

At the end of 2002, a total of 35 rare and endangered plant species in the reservoir area had been conserved using ex-situ approach. Most of them were in good condition. The major work of 2002 was to strengthen cultivation management and breeding experiment, and to further increase the quantity of the rare and endangered species for cultivation to ensure long-term conservation of these species.

The plants that need particular conservation in the reservoir area include Myricaria laxiflora, Adiantum reniforme var. Sinense and Chuanminshen violaceum. According to literatures and the finding in recent years, except in areas at altitude of 80-380 m in the Three Gorges reservoir area, Chuanminshen violaceum is also grown in Qingbei River, Jintang, Jianyang, Cangxi, Weiyuan, Beichuan, Pingwu and Bazhong of Sichuan Province as well as in Dangyang of Hubei Province. The Three Gorges Project places no much negative effect on its survival. Myricaria laxiflora is mainly distributed with limited amount in the reservoir area at altitude of 80-430 m. Adiantum reniforme var. Sinense is distributed in the reservoir area at altitude of 80-130 m. When the second phase water impounding starts and the power generation begins, all of the Adiantum reniforme var. Sinense in the area will be submerged. Currently, the rescuing protection methods have been applied to Myricaria laxiflora and Adiantum reniforme var. Sinense, which basically safeguards the long-term survival of the two species.

4.5 Estuary Eco-Environmental Monitoring Station

In 2002, the station continued its monitoring and research on the water salinity dynamics in the border section between land and sea as well as the water eco-environmental monitoring in estuary areas.

4.5.1 Water salinity dynamics

Three monitoring sections in Yinyang Town, Daxing Town and Xinglongsha High-quality Seed Farm were set up at the border of land and sea, about 4, 22, and 35 km away from the river mouths. Three monitoring points were established for each section, mainly for monitoring water quality of the main streams, water quality inside the water gates near the sections, soil electronic conductivity, soil water contents (indicated by negative pressure of the soil), groundwater level and the groundwater electronic conductivity.

The monitoring results showed that the burial depth of ground water decreased when precipitation increased, but increased when surface evaporation increased. The water content of the soil is controlled jointly by burial depth of ground water, precipitation and evaporation. The impact of burial depth of ground water is more significant and direct. The negative pressure of soil is in consistence with the changing pattern of the burial depth of ground water, in that it increases when the burial depth of ground water increases. It changes seasonally during the year. Generally, the soil negative pressure has the lowest value in winters and springs when the water content of soil is the highest. The biggest soil negative pressure occurs in summers and autumns when the soil water content is the lowest. Particularly, the maximum soil negative pressure is measured in August and September.

The burial depth of groundwater in estuaries is generally less than 1 m. In recent years, there is a tendency of groundwater level rising with very small hydrolic grade and poor condition of water salinity discharge. Precipitation, evaporation, groundwater level and groundwater mineralization are generally the most important factors affecting the salt content of soil. This is particularly true for soil layer over 40cm. Among these factors, the groundwater mineralization has more clear and direct control of the salt content of soil. Soil electroconductivity increases when the groundwater mineralization increases. In spring and summer, the precipitation increases; the groundwater level rises; more salt in soil is eluviated. Therefore, the salt content of soil decreases, with the lowest in summers. In autumn and winter, the precipitation is reduced and evaporation is dominant, resulting in a decrease of groundwater level and the salt content of soil increases due the accumulation of salt.

Except for meteorological factors, groundwater level and its mineralization, the salt dynamics in soil water is also affected by the Yangtze River, in land waters and conditions of irrigation and drainage. The river water and in-land water can influence the salt content of groundwater in the sensitive area at the Yangtze River mouth. Within 500 m inside the levee of the Yangtze River, the river water is the dominant factor affecting salt content of the groundwater. Beyond this range, the groundwater is more related with in-land waters. The mineralization of river water is in negative correlation with the river water level, in which the mineralization of river water increases when the river water level drops.

In view of the changing pattern of salt content of soil between different years, the salt content of soil in the ploughing layer at the Yangtze River mouth showed a tendency of decreasing for many years, which indicated a state of natural eluviation of salt.

4.5.2 Non-biological environment

● Hydrological factors

The distribution pattern of water temperature, salinity and transparency were the same as previous years. The monitored water temperature and salinity were slightly higher than those of 2001. The temperature of water inside the Yangtze River mouth was between 14.86 and 21.55 ℃, with an average of 17.75 ℃. The salinity within the Yangtze River mouth was less than 3, while the salinity outside the river mouth ranged between 7.76 and 33.72, with an average of 29.93. The monitored transparency dropped to some extent with the lowest 0.1 m and the highest 8.0 m.

● Water chemistry factors

The average monitored values of 7 indicators including dissolved oxygen, pH, COD, nitrate, nitrite, ammonia nitrogen and total nitrogen were lower than those of 2001, but the averages of other 3 indicators including phosphate, silicate and total phosphorus were higher than those of 2001.

● Sedimentation factors

The distribution of ignition loss of soliquoid was the same as the soliquoid, and this coincided with the previous investigations. The content of soliquoid in the investigation area ranged between 0.8 and 1682.0 mg/L, with an average of 93.3 mg/L, about 48.3% of that in 2001. The ignition loss of soliquoid ranged between 0.1 and 78.0 mg/L, with an average of 8.7 mg/L, about 58.0% of that in 2001.

4.5.3 Biological environment

● Chlorophyl A and primary productivity

In 2002, the content of chlorophyl A and primary productivity were all significantly lower than the previous years. The content of chlorophyl A ranged between 0.053 and 1.028 mg/m³, with an average of 0.265 mg/m³. In most stations, the content of chlorophyll was below 0.3 mg/m³. The primary productivity was 0.616-285.454 mg C/m2·d, with an average of 45.571 mg C/m2·d. The primary productivity at each station in the river channel was very low, i.e., below 3 mg C/m2·d.

● Phytoplankton

A total of 89 species of phytoplankton were collected and examined during the monitoring and investigation, including varieties and modifications. Among these, there were 64 species of diatom, 22 species of inoflagellate, and one blue algae and one green algae. The number of phytoplankton in the investigation area was 1.26×104 - 741.4×104/m³. The average number of phytoplankton in the investigation area was about 1/200 of 1998 and 1/100 of 2000 respectively.

● Zooplankton

According to historical data, the density of zooplankton in the investigation area showed a tendency of decrease from year to year. In 2002, the decrease showed particularly dramatic, with the total average density of only 86.5/m³, which was a half of 2000 and 1/10 of 1999. The total average density of zooplankton was significantly different in different geographical locations. The variation was mainly observed along the river. It gradually increased downstream from the river mouth and then decreased.

● Benthos

In 2002, the number of benthos species, its biomass and density were both higher than the investigation records of previous years. In the investigation samples, there were a total of 144 species of active benthos. Among these, 77 were polychaeta, accounting for 53.5%, 38 were mollusk, accounting for 26.4%, 16 were carapace, accounting for 11.1%, 5 were echinoderm, accounting for 3.5%, and 8 were others, accounting for 5.6%. The average of total biomass in the samples was 28.14 g/m³. The average biomass of each type was 12.51 g/m³ for mollusk, 5.78 g/m³ for carapace, 5.42 g/m³ for polychaeta, 3.25 g/m³ for echinoderm, and 1.18 g/m³ for others.

● Fish plankton

By using vertical trawl sampling, 9 fish planktons were caught including 5 spawns, all of which were floating spawns, and 4 fry fish. By using horizontal trawl net sampling, 55 fish planktons were collected including 30 spawns, 25 fry fish. There were 11 species. 7 species were identified including 2 species of eel and pipefish.

4.5.4 Fishery resources

In the investigation of fishery resources, a total of 73 species of biological resources were obtained, including 9236 fish species, weighing 61042 g totally and 7.00 g each on an average. Among these, there were 47 species of fish, 13 species of shrimp, 5 species of crab, 5 species of antispdix, and 1 species of jellyfish, cowfish and pomfret each. In all kind of species, hair tail, Pampus argenteus, yellow crucian and jellyfish belong to dominant species in autumn.

Different from the previous years, jellyfish became the dominant species. Although its number was not high, its biomass density was absolutely dominant. The phenomenon that jellyfish became dominant indicated that the ecological productivity in the Yangtze River estuary was degrading.

4.6 Peculiar Fish Experimental Station

In 2002, the major target for peculiar fish experiment was Megalobrama pellegrini. The repeating experiment on artificial propagation of Ancherythroculter nigrocauda was conducted in the mean time, and informations were further collected on biology and artificial propagation of other peculiar fish.

In 2002, a total of 759 fish were anatomized. Another 400 live Megalobrama pellegrini were used for domestication and artificial propagation experiment. According to information, the age structure of Megalobrama pellegrini was relatively simple. The fish under 3 years old took 94% of the total, with sex ratio near 1:1. Megalobrama pellegrini become sexually mature at 2 years old. In the propagation group, the number of fish at 2 or 3 years old accounted for 79.1%. The supplementary fish that were in early sexual mature accounted for 57.3%. In the spawning group, the number of male fish was larger than female fish's. The difference between numbers of male and female fish during group spawning might be very large. The fry fish of Megalobrama pellegrini mainly eat algae, while the fish with body longer than 120 mm mainly eat Limnoperna lacustris and water plants. The propagation season is from April to July, but occasional propagaton may occur from spring to autumn. Group spawning is generally in April and May. The habitat of Megalobrama pellegrini needs not only deep water for hiding and living through winters, but also the aquatic organisms represented by float grass. Its propagation requires water temperature being above 18℃ and stimulation of flowing water. Although Megalobrama pellegrini is a species laying viscid eggs, its group spawning usually takes place in tough waters at the outlets of power plants. The running water is one of the necessary conditions for its propagation.

In 2002, the Peculiar Fish Experimental Station adopted on-site artificial insemination and induced spawning to conduct 8 artificial propagation experiments on Megalobrama pellegrini. A total of 20,000 primary fry fish were obtained. Through the experiment, the knowledge and technology of artificial propagation in terms of types of medicines and doeses to be used were basically obtained. It also observed the fetation and its growing up for the first time, which laid basis for further experiment in the future.

Between April and July, artificial propagation was conducted for 8 times on Ancherythroculter nigrocauda in order to verify and complement the result of the previous year. All of the 8 experiments fulfilled their objectives. A total of 234000 germ cells were obtained and 154000 baby fish were hatched. The average fecundation rate was 65.4±31.6%, with an average birth rate of 37.2±36.1%.