Attenuation caused by trees should be estimated for the purpose of high altitude platforms link design. Thus, the knowledge of vegetation depths for different tree types (conic, ellipsoid, spherical, hemispherical) and elevation angle distributions in a coverage area is required. For this purpose, bivariate histogram of vegetation depths and probability density function of elevation angles are calculated. Then, by utilizing the vegetation depths and the probability distribution of the elevation angles in a coverage area, the calculation of the joint probability distribution is made. For a possible link design, when tree shape differences and elevation angle possibilities have been taken into account, average single tree attenuation ranges are estimated and presented for 2-6 GHz frequency band.