Determination of Canopy Structural Parameters in an Urban Forest Stand Using Hemispherical Photography

Two canopy parameters,i.e.,leaf area index(LAI) and canopy openness,of an urban forest stand in Maofengshan,Guangzhou,were estimated using hemispherical photography in parallel with quadrat plant census.The forest community exhibited significantly high dominance in species composition, but the majority of stems fell into the small DBH class categories.LAI estimated from the 100 quadrats ranged from 1.10 to 5.08,with a mean value of 2.88 and coefficient of variation(CV) 23.97%,while canopy openness from 7.72% to 21.86%,with a mean value of 11.70% and CV 22.42%.The value of LAI showed quite uniformed distribution in the whole stands,with no significant difference existing between transects from west to east or from south to north;whereas significant difference in canopy openness was detected between transects from south to north(P=0.000 3).As a short-range remote sensing method,hemispherical photography is a rapid,easy-to-use and low-cost method for canopy analysis,and will find wide applications in forest studies,especially in forest ecological monitoring and assessment.