Modelisation de la structure d'un peuplement et simulation de sylvicultures locales et selectives | Population structure modeling and simulation of local and selective silviculture
1997
Pierrat, J.C. | Herve, J.C. | Peyron, J.L.
A method to predict the diameter distribution of a stand after a local and selective thinning is presented, knowing the initial distribution and taking into account the spatial structure of the stand. It is supposed that trees can be ranked according to some criterion (e.g., diameter) and that the selection of trees to be thinned is based on their local rank (i.e., rank in a plot). The stand is considered to be divided into plots containing a constant number of trees and a plot is described by the vector of numbers of trees in each class. For a randomly sampled plot, the probability law of this vector is modeled by a mixture of multinomial distributions, which reflects the spatial structure at the plot scale. The parameters of the mixture are estimated by maximum likelihood with the EM algorithm, using a sample of plots. Then, for each component of the mixture, the probability laws of the order statistics are computed, from which the expected number of thinned trees by class and by component is deduced. Summing over the components gives the expected number of thinned trees by class for the whole stand. The model is applied and validated on a real oak stand. In conclusion, other possible applications are described, in particular to local and selective thinning strategy in mixed stands.
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