Mortality of silver fir and norway spruce in the Western Alps: a semi-parametric bayesian approach combining size-dependent and growth-dependent mortality

Question: Tree mortality can be modeled using two complementary covariates, tree size and tree growth. Tree growth is an integrative measure of tree vitality while tree diameter is a good index of sensitivity to disturbances and can be consider as a proxy for tree age which determines senescence. Few mortality models integrate both covariates as classical model calibration need large permanent plots data-sets which are rare. How then to obtain a multivariate mortality model including size and growth when permanent plots data are not available? Location: To answer this question, we studied A. alba and P. abies mortality in the French and Swiss Alps. Method: Our study proposes an alternative semi-parametric Bayesian method which includes a random sample of living and dead trees with diameter and growth measurements. Results: We were able to obtain a mortality model combining both size-dependent and growth-dependent mortality. We demonstrated that A. alba had a lower mortality rate (10%) than P. abies (18%) for low growth (