Séance Séminaire

Séminaire de Probabilités et Statistique

Does climate affect the intensity of defoliation in Québec? Adjacent-Category Autoregressive modeling approach (Séminaire SupAgro)

Due to its ecological and economical damages, spruce budworm outbreaks (SBW) become one of major research topics in forestry in Canada. There is a growing consensus among scientists that SBW outbreaks depend on climate conditions. In this paper, we investigate the effect of climate on the intensity of defoliation of white spruce in two regions of Québec : Témiscamingue and Matawinie. Autoregressive model for adjacent-category time series is then proposed. The model’s parameters are estimated via the maximum likelihood approach. We show that this estimator is consistent and asymptotically Gaussian distributed. Portemanteau test for goodness-of-fit is proposed. The quality of the proposed method is shown with small numerical experimentation for finite samples. Our method is then applied to real data consisting of defoliation levels in Témiscamingue and Matawinie recorded as categorical data with four levels and climate data. In Témiscamingue, precipitations reduce the intensities of defoliation. However, in Matawinie, when the variation of range of daily minimum temperatures in summer increases, the level of defoliation is high. However, it appears that there is no statistical evidence to conclude a difference between corresponding defoliation processes.