Development of crown profile models for Pinus pinaster Ait. and Pinus sylvestris L. in northwestern Spain

Abstract

We used data from Pinus pinaster Ait. and Pinus sylvestris L. trees growing in single-species even-aged stands in northwestern Spain to develop crown profile models. Such models are key components of growth and yield models, and they are also important for assessing competitive level, microclimate, tree vigour, mechanical stability, biological diversity, fire susceptibility and behaviour under wind stress, amongst other features. The equations used in crown profile estimation (i.e. those including crown radius, largest crown radius, height to the largest crown radius and height to the base of the live foliage) were fitted simultaneously to take into account correlations between the different variables. The fitting technique also enabled us to consider an autocorrelated, heteroscedastic error structure and to use a different number of observations for the different variables involved in the fitting process. The fitted models explained between 66 and 94 per cent of the variability in crown radius, with a mean error between 0.15 and 0.64 m. The crown profile models developed can be used to estimate the crown profile when only diameter at breast height, total tree height and height to the base of the live foliage are measured. Inclusion of more variables (such as largest crown radius) provides more accurate results. © Institute of Chartered Foresters, 2013. All rights reserved.