Modeling Survival for Unthinned Slash Pine Plantations in East Texas Under the Influence of Non-Planted Tree Basal Area and Incidence of Fusiform Rust

A stand level survival model for unthinned slash pine (Pinus elliotti!) plantations in east Texas was developed that incorporates density of non-planted tree basal area per hectare competition and the incidence of fusiform rust (Cronartium quercuum). Survival data on planted slash pine trees were collected on 197 permanent research plots that represent a broad range of site, age, and competitive status combinations. A system of two equations was fit to the survival data using simultaneous nonlinear regression. All model parameters were significant at the 0.05 probability level. The model showed that the number of surviving planted slash pine trees decreased with increasing density (trees per hectare) of non-planted trees as well as increasing site quality (site i&dex). The model further allowed the transition ofthe slash pine trees from being uninfected to being infected by fusiform rust.