Abstract

SANDOVAL, Simón; ACUNA, Eduardo; CANCINO, Jorge  and  RUBILAR, Rafael. Modeling natural mortality for different plant densities in dendroenergetic trials. Rev. Fac. Cienc. Agrar., Univ. Nac. Cuyo [online]. 2021, vol.53, n.2, pp.143-156. ISSN 1853-8665.

Mortality was modeled for the Acacia melanoxylon, Eucalyptus camaldulensis, and Euca lyptus nitens species at plant densities of 5,000, 7,500, and 10,000 trees ha-1 in a biomass production trial for dendroenergetic purposes. One setup was based on individual tree level and two modeling alternatives were evaluated involving four survival probability equations and eight difference equations. Individual tree survival modeling considered a logistics model, which is a linear combination of variables per tree at current time t and previous time as estimator. These were the main variables of the competition index vari ation and the basal area growth variation between the current and the previous growth period. The survival probability alternative involved state variables of the stand like age, dominant height, and average square diameter as predictors, while the difference equa tions were fitted according to age-based changes only. The stand level models showed better results than the individual tree models, and in general, the mortality models based on difference equations presented better precision indicators and parsimony. The relative mortality rate was constant, i.e.(∂N /∂E)/ = N α, and varied between species, revealing greater mortality, consecutively, in E. nitens, A. melanoxylon, and E. camaldulensis. Although mortality tended to be higher at greater plantation densities, stand density did not signifi cantly affect the fitted models’ parameters.

Keywords : Survival probability models; Difference equations; Relative mortality rate; Dendroenergy.

        · abstract in Spanish     · text in English     · English ( pdf )