CHINA has replaced Japan as the top importer of Australian wool in a trend that captures the explosiveness of mainland consumer demand. Statistics released yesterday by the International Wool Secretariat (IWS) show that while Japan has been the leading importer of Australian wool since the mid-1970s, China imported 58 million kilograms of clean wool in the first half of 1992. Recession-hit Japan imported 39 million kg in the same period. China's imports accounted for 21 per cent of all exports over the same period and 40 per cent of all Australian wool exports to Asia, a trend that the IWS expects to continue. ''China is the only country where we have a genuine boom in demand,'' said Mr Helmut Schumacher, the IWS's Asia-Pacific director. ''It's not a situation where increased demand in China is coming because production facilities are moving from somewhere else.'' Mr Schumacher said that his group estimated 70 per cent of China imports were for domestic use, primarily knitwear and worsted suiting fabrics for menswear. ''There is a consumer boom in China fuelled by strong purchasing power and people fortunately see wool as a quality product they want,'' said Mr Schumacher. The IWS saw China as its market with the greatest potential over the next five years. China's demand for wool fell sharply during the last economic slowdown in China. It rebounded sharply in 1991-92, and grew strongly in 1992-93. ''We're forecasting a growth of five to seven per cent on a year-on-year basis in the coming years,'' said Mr Schumacher. China has not restricted its buying to Australian fine wools. The IWS estimates China imported 40 per cent of Uruguay's clip, a coarser type of wool primarily use in hand-knitting yarns, last year. Statistics suggest China also took 25 per cent of New Zealand's most recently measured annual production.