Relationship between Urban Forest Canopy Cover and Heat Island Effect in Xiamen Island Canopy-Based Greening Pattern in the Urban Region of Guangzhou Characteristics of precipitation distribution in Pinus tabulaeformis plantations under different canopy coverage in Taiyue Mountain Diagnosis of cotton N status using digital image analysis technique Estimating the canopy coverage of Picea crassifolia forest using digital hemispherical photography in Qilian Mountains