Abstract: Based on the differences of physical geography, the forest in the upper reaches of Minjiang River was divided into four types,i. e. , dark coniferous forest, other coniferous forests, broadleaf forest, and shrubbery. The benefits of water conservation by these forest types were calculated by using relevant indicators such as annual rainfall, crown cover interception, runoff coefficient, and ‘shadow price’, and the variations in water conservation were analyzed according to the four remote sensing images in different times. The results indicated that in 2000, the annual water conservation by the forest ecosystems was 1.3892×10¹⁰ m³, and the economic value was 93.07 hundred million Yuan RMB. After deducting the rainfall effect, the annual water conservation and economic value were 1.3348 ×10¹⁰ m³ and 89.43 hundred million Yuan RMB in 1986, and 1.2320 ×10¹⁰ m³ and 82.54 hundred million Yuan RMB in 1995 , respectively, with the water conservation and economic value in 2000 being at the similar levels in 1995. The main reason of these variations was that in 1990s, the forest landscape in the upper reaches of Minjiang River was severely destroyed by human activities, while the policies ‘protecting natural forest’ and‘returning cultivated land into forest-and grassland’ implemented subsequently promoted the establishment of artificial vegetation, improved forest ecosystem, and gradually restored the water conservation by forest ecosystem.

Key words: 　Cotton, Blossing and boll-forming stages, Shading, Fiber Quality