9.1 Monitoring on Ecological Environment of Wanzhou Model Zone

Standard runoff trial for the study and monitoring of ecological environment of Wanzhou model zone continued in 2006. The trial carried out comparison observation and investigations on soil water content, nutrients and soil erosion under different modes of land use.

9.1.1 Trial of Compound Farming of Grain Crops, Cash Crops and Fruit Trees on Ridges of Slope Cropland

The pattern of compound farming of grain crops, cash crops and fruit trees on ridges of slope farmland (Pattern I) had been developed for 5 years with evident improvement in soil water retention capacity. The findings on comparison trial among Pattern I, compound farming of grain crops, cash crops and fruit trees on flat farmland (Pattern II) and the planting of only grain crops on flat farmland (Pattern III as the control pattern) showed that Pattern I enjoyed the highest water content, followed by Pattern II and Pattern III. The comparison of soil water content at different monitoring time showed that soil water content of Pattern I on 2, 4 and 8 days after raining day was 22.44%, 22.61% and 10.83% more respectively than that of the control group. The soil water content of Pattern II on 2, 4 and 8 days after raining day was 5.09%, 10.76% and 1.25% higher than that of the control group. The soil water content after rainfall had the maximum change in Pattern III, followed by Pattern II and Pattern I. In the four seasons to the same Pattern, soil water content had bigger change rate in the third season compared with that of the first & second season. This had something to do with higher demand of crops for water, dense vegetation, drought and continuous extremely high temperature in the season.

With no or little tillage, Pattern I enjoyed obvious improvement in soil structure with relatively stable soil moisture. Under the same application of fertilizers, the concentrations of various nutrients in the soil of Pattern I farmland were obviously higher than that of the soil of Pattern II and III. Compared with the soil of Pattern III, the soil of Pattern I had 26.81% more organic matter, 33.44% more TN, 5.52% more TP, 4.12% more TK, 37.59% more Kjeldahl nitrogen, 14.41% more quick-acting phosphorus and 16.57% more quick-acting potassium. Pattern II also enjoyed higher efficiency in soil improvement and retention of nutrients than that of the control group due to combination of crops and trees as well as contour tillage, which contributed to the improvement of soil fertility. As a result, it also had the following higher level of soil nutrients compared with that of Pattern III: 17.14% higher of organic matter, 26.11% higher of TN, 3.87% higher of TP, 1.41% higher of TK, 24.40% higher of Kjeldahl nitrogen, 9.69% higher of quick-acting phosphorus and 11.34% higher of quick-acting potassium.

In Pattern I, past deep tillage in slope direction had been transformed into contour tillage along the ridges that block and retain the runoff and sediment. The combined planting of grain and cash crops and fruit trees increased vegetation and reduced the annual average of soil erosion and surface runoff by 54.24% and 83.00% respectively compared with that of Pattern III. For Pattern II, the prosperous branches and leaves of fruit trees reduced the naked land area, retain some rainwater, and decreased the soil erosion by rain drop impact. Well-developed roots of fruit trees fix the soil and reduce the erosion by runoff. The annual average of soil erosion and surface runoff was reduced by 5.09% and 23.17% respectively compared with that of Pattern III.

9.1.2 Trial of the Pattern of Steep Slope with Biological Fence

The pattern of steep slope fenced with shaddock-king grass hedgerows (Fence Pattern) had been established and developed for 5 years. The coverage of grass stems and leaves, fruit-tree branches and leaves as well as cut-down stems and leaves among the fences reached as high as over 95% with continuous rise of the conservation and retention capacity of soil moisture. The soil moisture of the Fence Pattern 2, 4 and 8 days after rainfall was 12.99%, 10.88% and 24.49% higher than that of Pattern III (control group). The change rate of soil moisture of different depth of the soil of Fence Pattern after rainfall was smaller than that of the control group, indicating the role of plant fence in stabilizing soil moisture of the slope farmland.

Compared with Pattern III, the farming practice of Fence Pattern has evidently improved soil structure and the capacity in raising and conserving soil nutrients due to the retention and fixing of the soil by dense stems and roots added by the decomposition of cut stems and leaves. As a result, the level of organic matter, TN, TP, TK, Kjeldahl nitrogen, effective phosphorus and quick-acting potassium went up by 18.93%, 29.41%, 21.95%, 6.93%, 42.40%, 56.33% and 34.19% respectively.

In Fence Pattern, plant fences form the belt one after another which interrupt the slope, create smaller slope between neighboring fence, block and retain surface runoff and accumulate soil particles in front of each fence with dramatic water and soil conservation effect. In 2006, no surface runoff was observed in the Fence Pattern farmland after each rain.

9.2 Monitoring on Ecological Environment of Zigui Model Zone

In 2006, centering on the control of water and soil erosion and non-point pollution of the slope land in the head of the Three Gorges reservoir area, Zigui Model Zone continued its monitoring and study on the effects of plant fences, stalk & mulch covering technique and grass coverage technique on the control of soil erosion and loss of nitrogen & phosphorus fertilizers of slope farmland in order to explore effective approach for the control of water and soil erosion of slope farmland.

9.2.1 Trial on Crop Planting, Orchard and Orchard-Crop Farming Pattern on Slope Land

The findings of 6-year field trial showed that the runoff coefficient, the loss of soil and nitrogen & phosphorus of navel orange orchard slope land were similar to or higher than that of crop planting pattern. The ratio of runoff coefficient and loss ratio of soil, nitrogen and phosphorus of naked land of navel orchard against that of wheat-groundnut plots were 1.02:1and 2.54:1, 1.51:1 and 1.59:1 respectively. This indicates that we should enhance the prevention and control of water & soil erosion and non-point pollution if the dry land is changed for navel orange orchard.

In comparison with slope orchard practice, slope orchard-crop pattern would have different influence on such factors as annual runoff coefficient, soil loss and loss of nitrogen & phosphorus nutrients due to tillage and increased fertilizers. The trial findings showed that the runoff coefficient, soil loss and loss of nitrogen & phosphorus nutrients of orchard-wheat-groundnut pattern was 129%, 58%, 139% and 82% of that of the navel orange orchard pattern. This indicates that orchard-wheat-groundnut pattern has raised the annual runoff coefficient and nitrogen loss but lowered the loss of soil and phosphorus. Therefore, slope orchard-crop pattern must avoid deep tillage in wet season and excessive application of fertilizers. In addition, it should adopt no or little tillage practice with fertilizer saving technique to improve nitrogen efficiency.

9.2.2 Plant Fence and Grass Covering Technique for Dry Slope Land

Plant fences on dry slope farmland generate significant effects on lowering the runoff coefficient and reducing the loss of soil, nitrogen and phosphorus. Compared with the conventional wheat-groundnut pattern, the annual runoff coefficient, soil loss and loss of nitrogen and phosphorus of wheat-groundnut-Chinese toon pattern went down by 35.13%, 88.34%, 60.02% and 73.91% respectively. A reduction by 21.00%, 88.46%, 46.15% and 71.20% respectively occurred for wheat-groundnut-alfalfa biological fence pattern. Among them, cutting short and well-arranged Chinese toon fence pattern generated better run-off blocking effects than that of alfalfa biological fence. In addition, plant fences have very significant effects in the control of the loss of soil and phosphorus nutrient.

Perennial herbage coverage pattern also generates remarkable effects in lowering the runoff coefficient and reducing the loss of soil and nitrogen & phosphorus nutrients. Compared with the conventional wheat-groundnut growth plot, the annual runoff coefficient, soil loss and loss of nitrogen and phosphorus of perennial alfalfa plots was reduced by 17.77%, 90.67%, 55.18% and 74.63% respectively. However, seasonal growth of herbage did not help to control the loss of nitrogen and phosphorus nutrients. The ration of the loss of nitrogen and phosphorus nutrients of ryegrass-soybean rotation plots against that of wheat-groundnut plots was 1.07:1 and 1.09:1, showing slightly more loss in the former pattern.

9.2.3 Navel Orange Orchard with Plant Fence and Ground Covering Techniques

Slope navel orange with interplanting of plant fences with the same height also showed relatively high efficiency in the control of the loss of water, soil, and nitrogen & phosphorus nutrients. The annual runoff coefficient and soil loss of the navel orange –day lily fence plot was reduced by 12.14% and 93.10% respectively against that of navel orange orchard without any interplanting. The loss of nitrogen and phosphorus was decreased by 47.83% and 60.15% respectively. Navel orange orchard with straw mulch coverage could not only raise the levels of organic matter and nutrients in the soil, but also mitigate impact energy of raindrops, block runoff and conserve water and soil. The annual runoff coefficient and soil loss of the navel orange plots with straw mulch coverage went down by 8.97% and 76.60% respectively compared with that of navel orange plots without other plants. The loss of nitrogen and phosphorus was decreased by 22.81% and 39.89%, too. Navel orange orchard interplanted with perennial herbage creates double coverage on the ground conducive to the reduction of rainwater erosion energy. The soil-fixing function of underground root system has been greatly strengthened with dramatic effects on conserving soil. Compared with the navel orange plots without other plants, annual soil loss and loss of nitrogen and phosphorus of navel orange-whiteflower clover plots was reduced by 91.90%, 19.52% and 59.40% respectively. Because the navel orange-white flower clover plots have not been cultivated for 6 years leading to hardened soil cover and reduced permeability, so the runoff coefficient was 22.69% higher than that of the navel orange plots without other plants.

Among the above three protective techniques for slope navel orange orchard, navel orange- high plant fences including day lily had the best effects in terms of comprehensive control of water and soil erosion and agriculture non-point pollution.

9.3 Monitoring on Groundwater Table and Soil Gleization

In 2006, the monitoring on groundwater table change and the observation of gleization indicators of the soil from Shimatou to Xiaogang Farm of the Honghu Lake located at the "Four lakes" at the middle reaches of the Yangtze River continued.

9.3.1 Monitoring of Groundwater Table

In 2006, the groundwater monitoring section consisted of 10 long-term observation boreholes in 5 groups. The distances from the 5 groups of boreholes marked with the code of A, B, C, D and E to the bank of the Yangtze River was 1.5 km, 3.0 km, 5.0 km, 8.5 km and 13.0 km respectively with borehole internal diameter of 0.11 m. The depth of boreholes of confined water was about 35 m while that of phreatic water boreholes was 5-7 m.

The monitoring results showed that the annual average groundwater level of all observation boreholes ranged from 21.35 m to 22.52 m with maximum of 21.88-23.28 m and minimum of 20.48-21.69m. The annual fluctuation was 0.45-2.03 m. The phreatic surface changed from 21.03-23.05m and the water table of confined groundwater varied from 20.48 m to 23.28 m. The water table of borehole A, B and E for confined groundwater was slightly higher than that of the 2005 and 2004 but slightly lower in borehole C and D. The phreatic surface boreholes A, B, C and D had slightly lower water table than in 2005 (nearly the same) with some rise in borehole E.

The monthly average of the phreatic surface of all phreatic surface boreholes was 21.34-22.85 m and the water table of all observation boreholes for the monitoring of confined groundwater ranged from 20.67 m to 23.01 m. High water table occurred during May-October and low water table from December to March. The highest average monthly water table occurred mostly in July-August. For example, the highest average monthly water table appeared in July for borehole A and B and in August for borehole C, D and E. The lowest average monthly water table occurred January and February with January in dominance. Borehole E was quite abnormal with the monthly average of both phreatic surface and confined water table at about 22 m with very small fluctuations.

In 2006, the analysis of the dynamic correlations among the confined groundwater table, phreatic surface and the water level of the Yangtze River indicated that both the confined groundwater table and phreatic surface had very significant correlation with the water level of the Yangtze River.

9.3.2 Monitoring on Indicators of Soil Gleization

In 2006, 8 soil monitoring sections were arranged from Xiaogang Farm to Shimatou in order to continue the monitoring of such indicators as the pH, oxidation reduction potential, the total amount of reduction material, active reduction materials and the level of ferrous iron of the soil under light, intermediate and heavy gleization. The monitoring was conducted once in the winter and once in summer.

Monitoring results showed that the total amount of reduction materials was 0.14-11.56 cm*mol/kg with the average at 3.62 cm*mol/kg. The concentration of active reduction materials was 0.074-10.02 cm*mol/kg with the average of 2.76 cm*mol/kg. The ferrous concentration was 0.015-0.836 cm*mol/kg with average of 0.375 cm*mol/kg. Compared with that in 2005, the monitored gleization level had certain reduction especially for the total reductive materials with certain decrease in both the summer and winter. This has something to do with lowered groundwater table in particular declined phreatic surface due to less precipitation in the year.

9.4 Monitoring on Terrestrial Plant Community

A total of 390 fixed monitoring sample plots were established in 20 districts or counties of the Three Gorges reservoir area with 798 quadrats under the monitoring of terrestrial plant communities. Among them, 204 were forest sample plots with 612 sample quadrats involving 61 types of forests. 186 bushwood and grassland sample plots involved 49 types of bushwood and grassland with 168 quadrats.

In the 61 types of forests, 9 were coniferous forests including 8 warm coniferous forests and 1 coniferous forest; 50 were broad-leaved forests including 18 evergreen broad-leaved forests, 14 evergreen deciduous and broad-leaved mixed forests, 17 deciduous forests and 1 hard evergreen broad-leaved forest; 2 were bamboo forests being warm scattered ones. Field investigations indicated that masson pine  and cypress  forests were still the dominant vegetation types with widest distribution in the low and intermediate altitude zones of the reservoirs area. Most forests at low altitude were artificial forests. At intermediate altitude, there was a significant proportion of natural forest. However, most forests at high altitude were natural ones.

Among the 49 types of bushwood and grassland, 10 were deciduous broad-leaved bushwood in mountain areas; 5 were deciduous broad-leaved bushwood in lime rock mountain areas; 4 were deciduous broad-leaved bushwood in river valley; 5 were evergreen broad-leaved bushwood; 1 was mountain bushwood and thick grass; 11 were thick grass types and 13 were wetland vegetation types. Most bushwoods and thick-grass land were degraded secondary types, mainly distributed in the low altitude (<1000 m) region where is the main region of human activities. The degraded bushwoods and thick-grass land had poor species composition and severe loss of biodiversity. Among the 186 bushwood and thick-grass land sample plots, only 281 species of higher plants were recorded most with low frequency, and most bushwoods and thick-grasslands had less than 10 plant species some even with only 1 species.

In general, the vegetation of the reservoir area was in degradation. Among them, the disturbance of serious human activities at low altitude region damaged the original ecosystems leading to large areas of degraded bushwood, barren mountains or even naked rock and land. The evergreen broad-leaved forests were only fragmentary and conserved in local areas with more or less secondary nature. In Low altitude mountain areas forests were dominated by masson pine and cypress. Quercus variabilis, Quercus aliena and Quercus acutissima forests were major secondary broad-leaved forests. The evergreen deciduous and broad-leaved mixed forests at intermediate latitude mountain areas have evolved into large area of deciduous broad-leaved forests including such species as Quercus serrata var. and Quercus alien var. forests after degradation. Local natural mountain evergreen deciduous and broad-leaved mixed forests have many rare, ancient and unique plant species in China such as dove tree, Tetracentron sinense, Cercidiphyllum japonicum, Euptelea pleiospermum, Emmenopterys henryi, Cyclocarya paliurus, Dipteronia sinensis and Taxaceae, therefore play a very important role in the vegetation of the reservoir area.

9.5 Monitoring of Water and Salt Concentration Trend at Estuary

In 2006, monitoring work at estuary (land-sea interface) continued to focus on the monitoring on dynamic change trend of salt concentration of the water at land-sea interface. Three monitoring sections were established at the north tributary of the Yangtze River, about 4 km, 22 km and 35 km from the land-sea interface respectively. At each section, 3 south-north monitoring points were arranged. Major monitoring items included the water conductivity, soil conductivity, soil negative pressure, groundwater table and groundwater conductivity.

Monitoring results showed that the water level of the estuary of the Yangtze River was lower than the historical average in 2006 with obviously more sea water invasion. The dynamic change pattern of the conductivities of the water of the Yangtze River, groundwater and soil was similar within the year. The sections near the river mouth recorded higher salinity. The monitored conductivity would gradually decrease inward the river with the highest at Yinyang section, followed by Daxing section and Xinglongsha section. The water level of the Yangtze River has a close relationship with its water conductivity with very significant negative correlation. The change of water level of the Yangtze River would impose evident impacts on the monitored salinity of the water at the estuary.

l  Conductivity of the Water of the Yangtze River

In 2006, the dynamic change pattern of water conductivity of the Yangtze River was similar to that of normal years: gradual decline during January-May with the lowest in the summer and continuously going up from that time. In the last 6 months of 2006, there was significant increase of water conductivity of each section of the Yangtze River compared with that of 2005 and the annual average from 1998 to 2002. Water conductivity of Yinyang section during June-December was higher than that of the same period last year with maximum rise (79%) in September. The water conductivity of Daxing section was dramatically higher than that of the same period last year since August with the maximum in September, nearly 10 times of that of 2005. At Xinglongsha section, water conductivity of the Yangtze River was significantly higher than that of the same period last year since July.

l  Groundwater Table

In 2006, the order of groundwater table of each section from high to low was Yinyang>Daxing>Xinglongsha with higher groundwater table in winter and spring than in the summer and autumn. The change pattern of groundwater table was similar to that of water level of the Yangtze River with some time lag and smaller fluctuations. At Yinyang section, the change of groundwater table was not big in the first 6 months with higher-than-average level. In the second 6 months, groundwater table went down with the lowest in August. At Daxing section, the groundwater table was the highest in January and lowest in August. At Xinglongsha section, the groundwater table of each month was higher than that of the same month last year.

l Groundwater Conductivity

In 2006, the order of groundwater conductivity of all sections was the following: Yinyang > Xinglongsha > Daxing. The groundwater conductivity went up with the reduction of the distance from the monitoring site to the dam of the Yangtze River. On the whole, groundwater conductivity was low in summer but high in other three seasons.

Compared with that of the past few years, the groundwater conductivity during June-December was on the rise at Yinyang and Daxing but went down at Xinglongsha section. The groundwater conductivity of Yinyang section kept rising from August and exceeded the level same period during 2003-2005 with 25% rise of annual average compared with that of 2005. At Daxing section, the groundwater conductivity rose during August-December, which was obviously higher than that of 2005 and the average before the impoundment. The annual average of groundwater conductivity went up by 13% and 11% compared with that of 2005 and historical average of 1998-2002. At Xinglongsha section, the groundwater conductivity in the spring and autumn was lower than that of the same period of the past years.

l Soil Conductivity

In the second half of 2006, soil conductivity of each section had some increase compared with the same period last year and the historical average before the impoundment. Within a year, it is high in early spring and reaches the lowest during May-June followed by continuous rise. Soil conductivity of Yinyang section has kept rising year on year since 2004. At Yinyang and Daxing, the soil conductivity was evidently higher than the average level before 2003. The soil conductivity of at Xinglongsha section was lower than the average level before 2003, keeping the trend of salt removing.

9.6 Study on Endemic Fish Species

9.6.1 Experiment of Artificial Propagation of Endemic Fish Species

In 2006, artificial propagation experiments were conducted on domesticated mature Procypris rabaudi and Ancherythroculter nigrocauda. The findings show that artificial propagation of Procypris rabaudi had been successful but still with poor fecundation rate and unsatisfactory total egg amount. The success of artificial propagation of Ancherythroculter nigrocauda had demonstrated past findings.

Researchers had carried out second-generation artificial propagation experiments on Megalobrama pellegrini with the parent fish being the first generation of the artificially bred Megalobrama pellegrini on July 18, 2003. After 3-year breeding, they were sexually mature. They obtained over 60,000 second-generation young Megalobrama pellegrini in the trial, indicating the success of artificial propagation of such fish. This had made Megalobrama pellegrini become the fish second to Ancherythroculter nigrocauda as the endemic fish in the upstream of the Yangtze River that has been successful in artificial propagation.

9.6.2 Biological Study on Endemic Fish Species

In 2006, scientists carried study on the early growth or biological characteristics of the three endemic fish species. The early growth of large mouth bronze gudgeon had 14 growth stages from incubation to the development of ventral fin. On the 7th day, they had one chamber of swim bladder. On the 26th day, ventral fin developed. On the 80th day, they had full scale.

From embryo development to embryonic disc period to heart beating period, early Leptobotia elongate experienced 26 development stages. There were 9 development stages from the incubation to the development of ventral fins for the young fish. On the 4th day, it had one chamber of swim bladder. On the 20th day, ventral fin developed. On the 57th day, color spots of adult fish appeared.

Rhinogobio cylindricus is a kind of benthonic fish with slow growth rate. Its main food was the benthonic invertebrates. From July 2005-November 2006, the Rhinogobio cylindricus caught in the Yichang section of the Yangtze River had 4 age groups with 2-year fish accounting for 65.0%, 1-year fish accounting for 21.0%, fish length ranging from 98mm to 310 mm and weighing from 11 grams to 374 grams.

Host Organization:

Department of Reservoir Management, the General Office of the State Council Three Gorges Project Construction Committee

Chief Compiling Organization:

China National Environmental Monitoring Center

Compiling Members:

Hubei Provincial Office for Assisting the Three Gorges Project Construction Committee
Hubei Provincial Statistics Bureau
Chongqing Municipal Statistics Bureau
Chongqing Municipal Environmental Monitoring Center
Headquarters of Geological Hazard Prevention and Control of the Three Gorges reservoir Area, Ministry of Land and Resources
Environmental Protection Center of the Ministry of Communications
Water Conservation Committee of the Yangtze River
Office of the Fishery Resources Management Committee of the Yangtze River
Agriculture Ecological and Environmental Protection Station of Hubei Province
Yangtze River Fishery Research Institute, Chinese Academy of Fishery Sciences
Chinese Center for Disease Control and Prevention
Ecological and Environmental Monitoring Center of the State Forestry Administration
Institute of Hydrobiology, Chinese Academy of Sciences
Institute of Soil Sciences (Nanjing), Chinese Academy of Sciences
Institute of Oceanology, Chinese Academy of Sciences
Institute of Geodesy and Geophysics, Chinese Academy of Sciences
Institute of Mountain Hazards and Environment (Chengdu), Chinese Academy of Sciences
Institute of Botany, Chinese Academy of Sciences
National Climate Center, China Meteorological Bureau
Institute of Earthquake Science, China Seismological Bureau
Department of Financial Planning, the General Office of the State Council Three Gorges Project Construction Committee
China Three Gorges Project Corporation

Technical Guidance Organizations:

Ecological and Environmental Monitoring Center of the Three Gorges Project

Information Management Center of the Ecological and Environmental Monitoring System of the Three Gorges Project

Approval Institutions:

State Environmental Protection Administration

General Office of the State Council Three Gorges Project Construction Committee

Release Organization:

State Environmental Protection Administration

Translation:

Department of International Cooperation, State Environmental Protection Administration