CHINA WETLANDS AND AGROECOLOGICAL ENGINEERING

The estimated total area of wetlands in China is 11 million ha. Using the genesis classification system, combined with a knowledge of China' s wetlands, one can divide the wetlands in China into three main categ ories: eutrophic, mesotrophic and oligotrophic. The distribution of Ch ina's wetlands basically coincides with the distribution of wetlands i n the world. Wetlands are concentrated in the frigid temperate zone an d the humid area of the temperate zone. They are also widely distribut ed in mountains and plateaus. Generally, wetlands occupy flat or gentl y sloped areas with plenty of water. They have high biological product ivity and resource potentiality, so they can be used for agriculture, forestry, animal-husbandry, and fisheries. Wetlands have also been rec laimed into rice paddies, pastures, forest land and reed production ba ses. In order to develop wetlands comprehensively, ''dike-pond'' syste ms and ''field-pond'' systems have been established in China. Complex paddy-reed-fish systems have brought about ecological and economic ben efits. Ecologically, wetlands can not only play a role in flood contro l, water storage and climate regulation, but they can also purify wate r, improve soil, and increase the species and number of wild animals. On the one hand, wetlands can be developed and utilized; on the other hand, some wetlands should be conserved in a natural state.