Abstract: The study on the effects of different shading level at blossoming and boll-forming stages on cotton fiber quality of Zhongmiansuo No.41 and Lumianyan No.18 showed that with increasing shading,the maximum fiber length of cotton decreased,while the elongation period increased. The fiber length in 70% shading treatment was 1.01 mm shorter than that in 40% shading treatment. Without shading,the fiber reached its maximum length 25 days after anthesis,while in shading treatments,the fiber reached its maximum length 35 days after anthesis. Fiber gauge tenacity was also decreased with increasing shading. Comparing with the control,both 40% and 70% shading significantly decreased the fiber maturation and maturity. Two test cotton varieties presented the same change trend under shading condition.

Key words: Gongga Mountains, Dark coniferous forest, Abies fabri, Community structure