A LIGHTWEIGHT CCD CAMERA TECHNIQUE FOR ESTIMATING 3-DIMENSIONAL DISTRIBUTION OF FOLIAGE DENSITY IN TREE CROWNS

A method was developed for non-destructively estimating spatial densit y of foliage mass and area in crowns of small individual trees. A ligh t-weight CCD camera with a capability for wireless image transmission is mounted on top of a telescoping height measuring pole so that it vi ews the zenith. A daisy flap, a thin 10-cm diameter plastic plate with 12 equally-spaced incisions along its radii, is placed horizontally 2 0 cm above the camera. Then, images are recorded while the CCD camera is lowered at 10-cm increments from the top of the crown. The number o f contacts between the daisy flap and the foliated portions of shoot s egments are counted while the CCD camera goes through each 10-cm segme nt The number is evaluated (i) by simply counting the contacts regardl ess of the size of touching shoot or proportion of the daisy flap that makes a contact (referred to as simple CCD method), and (ii) by count ing the number of flaplets (12 parts of the daisy flap that are separa ted by radial incisions) that touch the foliated shoots (weighted CCD method). The methods are repeated five times for the same column of 20 cm x 20 cm base area. Then the foliage density was calculated for eac h 20-cm cube from regression equations relating the mean contact numbe r among the ten 10-cm segments searched within a 20-cm cube and the fo liage density in dry mass or area. The foliage mass estimated by the w eighted CCD method was comparable to direct measurement by harvesting, when the method was applied to estimation of total leaf mass of a tre e. The calculated value of foliage mass density was also comparable to that estimated by the direct harvesting method of Sainome cutting whe n 40-cm or larger cubes are used as the unit volume. Advantages and di sadvantages of the CCD camera technique are discussed in comparison to other methods available for estimation of foliage distribution in tre e crowns and forest canopies.