- Weber, Frederick P.
A photo sampling method for estimating cubic foot volume losses of white sprue and balsam fir required the identification and study of stand variable that could be accurately measured on large scale (1:1584) 70 mm aerial color photographs. Two photo measurements that can be made on large scale color transparencies were found to have a high correlation with cubic volumes of dead hosts tree (spruce-fir). These measurements are average stand height of dominant and codominant host trees and crown closure percent of host type. When these two variables were used with ground measured volumes, two multiple regression equations were developed to predict the cubic volume of dead balsam fir and white spruce in northeastern Minnesota. By combining the two regression equations (one for high volume mortality and one for low volume mortality) a useful photo volume table was constructed. The aerial volume table and the photo measurement methods reports here provide knowledge in a new concept in aerial survey techniques.