Estimation of leaf area and its vertical distribution during growth period

A statistical interpolation method is proposed which allows calculation of the leaf area index LAI(t), the downward cumulative leaf area index L(z, t) and the canopy leaf area density u(z, t) as the functions of height and time for any day of the growth period. The method is based on three functions: probability density of stem height, interrelationship between stem height and stem foliage area, and the shape function of stem foliage vertical distribution. The method was elaborated in detail using phytometrical measurements carried out on willow coppice (Salix viminalis L.) during the growth period of 1998 in Tõravere, Estonia. The estimated values of u(z, t) and those calculated by the method differ by about 10–15%. The interpolation model can be used when phytometrical data are available for certain days throughout the growing season. It could be applied to pure stands: young forests, orchard plantations, and maize, sorghum and cotton crops, etc.