Abstract: Taking high yield (2 000 kg穐m^-2) cotton (G.hirsutum L.) in North Xinjiang as the object,the niche-fitness values regulated by density and tip cut date was studied.The results showed that the optimum niche values tended to increase with the increasing density.Compared with one time tip cut (7/5),two times (6/20,7/20) and three times (6/20,7/5,7/20) tip cut reduced the optimum niche value and yield at density of 150?10³ plants穐m^-2,but increased optimum niche value and yield at density of 225?10³ and 300?10³ plants穐m^-2.Lower LAI was the main limit factor of treatment at density of 150?10³ plants穐m^-2,as less solar quantum being captured for lower LAI during seedling and bud developing periods.The measures of increasing density and different tip cut date increased the fitness because of optimized LAI during all periods of cotton growth.The LAI increasing speeds during blooming period of 225?10³ and 300?10³ plants穐m^-2 were limited to a certain extent because the tip cut date(7/5) was about 5 days ahead practice(7/10),which avoided excessive LAI.So,advanced tip cut date for once or different tip cut date for 2 or 3 times could increase optimum niche values of 225?10³ and 300?10³ plants穐m^-2.

Key words: Virtual forest landscape, Forest fire spreading, Forest fire model, Particle system, 3D visualization