Mortality as a mathematical function of organic growth and diameter structure

ABSTRACT

An indirect method to determine the exponential mortality coefficient (λ) as well as the annual mortality (m) is proposed. In this method, both parameters are deduced mathematically from a model of organic growth (von Bertalanffy) and from a model of uneven-aged population structure (De Liocourt and Meyer) used with forest trees, which relates the frequency of individuals by size classes. The resultant equations allow the determination of either the instantaneous or mean value for λ or m between any two ages t ₁ and t ₂. Both concepts of mortality were used to determine the half-life (t _0.5) as a function of λ and m . The method is applied to determine the curves of mortality and the half-life of Otoba gracilipes (Myristicaceae), a tropical tree that grows in the forested wetlands of the Colombian Pacific coast.