Laser, ultrasonic and manual measurements of citrus tree canopy volume

Abstract

Tools that rapidly quantify tree canopy volumes would be valuable to citrus industry. This study was conducted to compare ultrasonic and laser measurements of citrus canopy volumes with manual measurement methods. Fifteen trees with different canopy heights and volumes were selected for the study. The manual and ultrasonic measurements were used to compute a canopy volume in cubic meters whereas laser measurements were used to compute ‘laser canopy volume index’. The three approaches were statistically compared. It was found that ultrasonic and laser methods have good correlations to the manual methods (R2 >0.85, RMSE<2.15 m3). Laser showed better prediction of canopy volume than the ultrasonic because of the higher resolution. Therefore, ultrasonic or laser sensors can be used for automatic mapping and quantification of the canopy volumes of citrus trees.