Abstract 

The practice of integrated bio-systems in China can be traced back to 3000 years ago. Chinese philosophers elaborated the harmonious relationship of Tian (heaven or universe), Di (earth or resource) and Ren (people or society) into a systematic set of principles for managing the relationships between man and its environment. Dao-Li is the natural relationship with the universe, geography, climate, etc.), Shi-Li is for planning and management of human activities, such as agriculture, warfare, politics, family and others, and Qing-Li for ecological ethics, psychological feelings, motives and values towards the environment.  Other theories like Yin and Yang theory, Wuxing theory, Zhong Yong and Feng-Shui theory are some of these principles that emphasized  holism, symbiosis, recycling and self-reliance in ancient China. 

Agro-ecological engineering (AEE) is now being encouraged by the Chinese government and practiced from grassroots level. AEE is rapidly expanding over the country through projects that include eco-farming, eco-forestry, eco-husbandry and eco-fishing. The success of AEE can be attributed to networks for extension, administration, as well as advisory, technology service, monitoring, training, legislation and research. There are currently more than 2,000 AEE pilot projects in levels of villages, townships and counties involving some 10 % of the Chinese population and land of the whole country. 

The paper provides an overview of the various types and levels of integrated bio-systems for agricultural practices (e.g. to maximize horizontal and vertical space, resource utilization, agro-industrial production systems, pest control and management), solid waste and waste water treatment and utilization, sustainable community development and restoration of degraded environments in China.

Contrasted with the mechanical engineering thoughts dominated in modern technology, the human ecological thoughts in ancient China emphasized a holistic view of man and its environment. The harmony between Tian (nature) and Ren (man), society and individuals and between this generation and next is the final objective of all human activities. An excellent example of application of the holistic view is traditional Chinese medicine in which human body is considered as a functional entity closely connected with its physical and social environment. The patient is cured ecologically through regulating the Yin and Yang relationship between the body and its environment and between the different functional units of the body. 

The main characteristics of ecological engineering in China are as follows: 

• Strong connection with economic benefit, and spontaneous development from the demand for alternative  resources in production and daily life
• Stress on multi-layer and multi-purpose utilization of resource and wastesl 
• Focus on comprehensive or system's design of material and energy flow through encouraging symbiotic relationship between different walks, sectors and regions
• Stress on integration of traditional ecotechnology with modern high-tech, natural science with social science
• Well cooperation between experts and ordinary residents with a strong support from government agencies
• The effort paid is not only to hardware (technical instruments), but also software (institutional instruments) and mindware (behavioral aspects)
• Better developed in rural areas than urban areas, small scale than large scale, less developed areas than well developed areas

Encouraged by Chinese government and practiced from grassroots, agro-ecological engineering (AEE) is rapidly expanding in China and there appeared a series of pilots for AEE over the country including eco-farming, eco-forestry, eco-husbandry and eco-fishing. To ensure the success of AEE, a serious of network were set up in many areas, such as the administrative network for AEE,  the advisory network, technology service network, monitoring network, training network, legislation system and research network. There are currently more than 2,000 AEE pilot projects in levels of villages, townships and counties, which cover 10 % of population and land of the whole country.  They can be divided into following categories: 

(A) Make efficient use of local resources according to crops and animal niches differentiation 

According to their different environmental requirements, the farming and livestock raising are arranged together to formulate a comprehensive production system with multi-layer in space and multi-sequence in time in order to make full use of solar energy, water and mineral nutrients so as to gain high economic benefit in given land and period. The types of these engineering include: 

• inter-cropping crops with cotton and wheat, corn and soybean, corn and winter wheat and so on; 
• inter-planting crops and forest or fruit trees, such as inter-croping paulownia trees with arid crops, inter-cropping metasequoia trees with rice, a model popular in south China; 
• inter-planting cash trees together, such as fruit trees with tea, and rubber trees with tea. The forest trees, rubber trees and tea are planted together to form an multi-layer artificial community, as the case in Nanhai State Farm in Hainan Province.. 
• inter-planting trees or crops with fungi, such as cultured edible fungi under trees (eg. fruit or mulberry trees) in forest area of China. 
• multi-layer raising in aqua-culture as the model of raising silver carp on the top stratum, grass carp at middle and black carp at bottom which is very popular in China. 

Recycling and Regeneration of Substances

sugar cane-fish system

(C) The Recycling and Regeneration of Substances 
 
The mulberry grove-fish-pond system is an effective, multi-objective measure in agriculture in the Guangdong area of China. The White Mulberry (Morus alba) tree produces organic biomass (Mulberry leaves etc.) through photosynthesis. The leaves of Mulberry are used to feed Silkworms (Bombyx mori), which in turn produce their silk and chrysalids. The withered and fallen parts of the Mulberry tree, as well as the excrements of the Silkworms, are applied to fish-ponds, where they are converted into fish biomass through the process of another food-chain. The excrements of the fish, as well as other unused organic matter and bottom mud, after being broken down by benthic microorganisms, are returned to the Mulberry grove as fertilizer.  This type of exchanging and complementing nutrients between water and land is extensively used in the marshy areas of China. 

The picture above shows another type of system "sugar cane-fish system" where the crop is fertilized with the mud from the fishpond and irrigated with nutrient rich pond water. 

(D) Symbiosis Systems of Planting-Breeding 

Ecological engineering of symbiosis systems of planting-breeding is designed by modeling the relation of symbiosis and mutual benefit in biotic community. The typical processes include the forage crop which provides the livestock with green forage, and the excretions of livestock are used as raw material of biogas pits, the residues of which, then, are returned to farmlands. This model is similar to previous one in structure, but it is more self-sustainable. Through energy flow and material recycling, both planting and breeding can get benefits from each other. The photo provides a unique example where the effluent from a cow-manure-fed biogas digester is used for the cultivation of water hyacinth. Note that the cultivation is done on the roof top of the cow shed. This technique also provides a cooler environment for the cows especially during the hot summer. 

Other examples can be found in all regions of China, such as crop-poultry-fish-crop recycling system, crop-domestic animals-(biogas)-fish-crop re-cycling system, domestic animals-fish-edible fungus re-cycling system, domestic animals-biogas-fish-forest (fruit, vegetables, feed and other crops) re-cycling system. 

(E) The Multi-Functional Agro-Industrial Combined Production System 

The principles of endless recycling of materials and incessant regeneration of organisms in ecosystems is applied to the processing industry, with agricultural products as raw materials, so that agro-industrial products (including by-products) compensate for raw materials. In this manner the production system of a region may be kept relatively stable, with reduction of wastes, prevention of pollution, and improvement of rural ecological environments. Such technical systems have in fact long been extensively employed in China, particularly in rural industries. An ideal model of the general structure of an agro-industrial combines production system, including farming, forestry, animal husbandry, sideline production, and fish-pond, as well as the planning of the village. This agro-industrial combined production system is an ideal sustainable model of rural development in current China. 

(F) Integrated Pest Management 

China is the first country in the world to use natural enemy to prevent and control pests of crops. As early as 1700 year ago, Chinese managed to use "red tree ants" to control insect pests of citrus in south China. During last few decades, the integrated pest management combined with the knowledge of population ecology, community ecology, ecosystem ecology and agronomy, has been applied in most main crops and main pests.  Integrated pest management is designed to maintain a kind of situation of crop community which is unsuitable for pest population growth and reproduction, such as, protecting and increasing pest natural enemy population, altering the key environmental factors to limit pest reproductive capacity. The locust, for instance, used to be the most harmful insect pest in history of China, it was controlled completely after changing its reproductive habitat into crop-land or wetland in 1950's. 
Since 1980's, there have been seven Chinese ecological agriculture villages who were honored the title of "Global 500 " by UNEP and 9 Chinese cases of ecological engineering have got the IEES (International Ecological Engineering Society) Awards. 
 

Ecological engineering for wastes treatment and utilization 

Ecological engineering for wastes treatment and utilization is developed rapidly in China. There are lots of successful application cases in productive environmental protection. According to the nature and the main objectives of engineering, ecological engineering for wastes treatment and utilization falls roughly into following categories: 
 
(A) Self-Purification and Substance-Regeneration System 

Ecological engineering for wastewater treatment and reutilization has been paid more and more attention in China. Examples include combining of wastewater treatment with the protection, restoration and utilization of water body. For example, in Suzhou and Yangzhou, China, the Nile tilapia (Tilapia nilotica L.), which is not suitable for overwinter in nature in eastern China, is cultured in greenhouses built near electric power plants. The waste heat is used for overwintering, advancing maturity and breeding, and increasing production of this fish. In Shenyang, Northeast China, the waste heat from some factories is used to cultivate water hyacinths (Eichhornia crassipes), which can be incorporated into food for domestic animals, whose excrement is then applied to fields and gardens as manure. This utilization of waste heat will help to reduce the carbon dioxide that is released from the combustion of fossil fuels in the factory. 

In Jianjian, for example, wastewater discharged from a pharmaceutical factory after producing antibiotics contains a concentration of organic matter of more than 20,000 ppm. It is used as the raw material to produce yeast. An other examples include combining aquatic plants with fishes to absorb nutritious salts in some large or middle lakes such as Tai lake, Dian lake etc.; or increasing the accesses and quantity of migration, transference and output of organic matter, nitrogen and phosphorus in lakes to improve the structure of food web so as to realize ecological balance, improve and protect the quality of water, meanwhile, gaining economic benefits from it. 

Regarding to the wastewater from brewery and starch factory, the dissolvable wastes in it can be used by some aquatic plants through absorbing, transforming and also removing after some things(such as sugar, protein) retrieved. The plants then are used to feed animals. The wastewater which contain noxiousness such as heavy metals mostly is treated to get products not joining into food web. 

(B) Treatment and Utilization of Sewage by Soil Ecosystems 

The farmland, grassland, and forest ecosystems, all based on soil, can not only degrade and purify many kinds of pollutants in wastewater, but also produce many useful products by utilizing these pollutants. There are numerous species of microorganisms that can decompose many kinds of organic materials in soil. Inorganic salts, especially nutrient salts decomposed from organic materials and contained in sewage, then are absorbed by plants that grow in soil. This results in the production of many useful farm products, forage grasses, or forest products. The soil itself also seems to be a natural sieve, effectively filtering out most of the pollutants in waste water, namely, suspended solids, degradable organic pollutants, nutrient salts, and some pathogenic bacteria and viruses. The rate of removal may exceed 90 % for BOD, total nitrogen, suspended solids, and colon bacilli, and nearly 50-80 % for phosphorus. 

In China, the area used for sewage irrigation is more than 1 million ha. The use of sewage for irrigation mitigates the scarcity of water resources, especially in dry or semiarid regions, and supplies needed water for the development of industry and agriculture. It also increases farm production and reduces fertilizer expenses by utilizing nitrogen, phosphorus, potassium, and some trace elements from the sewage, which are required by plants. The farm ecosystems in a sewage irrigational region play an important role in decreasing pollution in the river system in that region because they have the capacity of purification described above. The cases on ecological engineering of wastewater land treatment system can be meet in Tianjin, Kunming, Wuhan and Shenyang. The purification efficiency of land treatment systems for nitrogen and phosphorus in wastewater and the uptake rates of these nutrients by crops show that crop yield increased 20-80 % after irrigation, and the purification efficiency of land treatment system was 94.12 % for nitrogen and 98.12 % for phosphorus. The final effluent from the soil-plant system delivered to the receiving body of water is expected to match the latest standard of rank 2-3 of surface water quality standards issued by the State government. 

Another case study on ecological engineering of land treatment systems is the sewage land treatment system for the Haolin River Mining Area of semi-arid grass region. The optimum plan put forward is to set up a multiple land treatment system of sewage reservoirs-forest-lawn. The guiding ideology establishing this system is that, on the ecological engineering principle, the sewage can become innocuous and a reused resource through the multi-functional metabolic processes of a multiple land treatment system. 
 
(C) Solid Wastes Treatment 

Chinese people have not only a long-traditional systems philosophy of "man and nature be in one" as mentioned above, but also an ecological tradition of efficient resource use including waste recycling and goods repair.  Wasting grain,  paper, and clothes, no matter how plentiful they are, was considered immoral behavior that would be punished by God according to ancient tradition.  There were salvage stations in every city, which are in charge of collecting used paper, glass, metal, plastics, etc.  Newspapers, books, packing boxes, rusted metal utensils, tins, bottles and even toothpaste tubes were sorted there for recycling.  Excrement and wasted vegetables were collected by farmers for manure. Night-soil was collected  by farmers door to door in the early morning.  Reuse of plastic bags is encouraged.  As a result,  the components of urban refuse in China, usually slag and construction wastes, were simpler than those of western cities.  Buses and bicycles, the main urban vehicles in China, saved large amounts of transportation energy compared with western cities.  There were various kinds of repair services in cities to help citizens repair shoes, pots, radios, furniture, bicycles, automobiles, and a variety of other items. Unfortunately, the rapid transition of industrialization and urbanization is dismantling this ecologically sound tradition. In recent years, several pilot projects being developed are discussed in the conference such as: 
 

• Ecological Engineering for Forage-Fuel-Fertilizer production in community level; 
• Fermentation and expansive processing of crop stalks for alternative fodder, paper making or  fuels; 
• Integrative technology for economically affordable sewage treatment and recycling;
• Systematic technology for domestic garbage sorting, disposal and composting;

The participants had an enthusiastic discussion on Prof. Miyawaki's (the president of the International Society of Ecology) plenary presentation about the method of ecological restoration using native species. Special interests were given by the Participants from Beijing and Maanshan, the two sites where ecological restoration projects cooperated with Miyawaki's Japanese Center for International Studies of Ecology are undergoing. 

Ecological Engineering for Sustainable Community Development 

In order to promote sustainable community development from grassroots, the State Science and Technology Commission of China together with other 26 state commissions and ministries initiated a project immediately after the Rio conference in 1992 to urge governments and people at province and local level over the country to take efforts on building Comprehensive Experimental Community for Sustainable Development (CECSD). More than 70 provincial and 22 national  Comprehensive Experimental Community for Sustainable Development have been set up initiated by 27 state commissions and ministries together with researchers and local communities. 51 experimental sites of eco-county development initiated over the country sponsored by the Ministry of Agriculture. And  65 ecological demonstration cases initiated by the National Environmental Protection Bureau of China. Some fruitful theoretical and applied results have been gained, and some sustainability measurements and recommendations adopted by local engineers, planners, and managers, which will be the model for other area's development. 

The focus of the project is put on comprehensive utilization of natural resource, comprehensive management of environment and comprehensive development of people through introducing total functioning technology, developing systematically responsible institution, and cultivating ecologically vivid culture. Integration, demonstration, citizen's participation and scientists and technician's catalyzing are the key in the experiment. CECSD is to promote integration that encourages a synthesis of the bio-physical, socio-economic and psycho-cultural factors, of the production, consumption and sustaining functions, of the long term, large scale and holistic policy making, of the technological, institutional and cultural instruments; a cultivation of the mechanism of competition, symbiosis and self-organization; a compromise between decision makers, entrepreneurs, experts and the publics; and an exploitation of external and internal potentials. Their evaluate indicators are: 

* Production efficiency: growth rate of economy, productivity (per capita output, profits and taxes etc.),  resource use efficiency (water, energy, main raw materials and capital),  wastes emission and regeneration (air, sewage, solid wastes),  resource potentials utilized ratio; 
* Life quality: People's satisfaction with income, housing, traffic, food, education, recreation, environmental quality and other basic conditions and facilities, social security, life expectancy, health state, and cultural diversity 
* Institutional harmony: compromise between dominance and diversity of the structure of industry and products; between self-reliance and openness to external system; and between the social governance ability and individual or sectorial creativity; 
* People's capability:  the capability of decision makers (policy appropriateness, sensitivity of information feedback, ecological responsibility),  entrepreneurs (creativity, eco-awareness and vitality) and citizens (literacy, values and attitudes); 
* Ecological order:  including social order (social mode, security and morality), economic order(sustainable resource supply, inflation rate, unemployment etc.) and natural order (landscape, waterbody, atmosphere, biodiversity etc.). 

Three types of ecological engineering have been introduced to these communities: industrial ecological engineering combining farms, factories and firms in contrast with the traditional environmental engineering and cleaner technological process;  human settlements ecological engineering for cities, towns and villages in contrast  with traditional urban planning instruments; and regional ecosystem engineering such as watershed, mine, natural reserves, forestry parks and other landscape development in contrast with the traditional regional planning and development methods. 

Integration, demonstration, people's participation and scientists and technicians' catalyzing are the key in CECSD development. 5 technological goals are being realized: 

• Capacity building and technological consultation; 
• Comprehensive utilization of agricultural resource; 
• Deepening processing and regeneration of industrial resource and wastes; 
• Town ecological construction and restoration; 
• Community service and social welfare.