A survival rate model for naturally regenerated longleaf pine

An individual tree annual survival rate model was developed for naturally regenerated, even-aged longleaf pine (Prunus palustris Mill.). Development was based on 44,000 survival observations on 15,000 trees occurring on 202 permanent sample plots located in central and southern Alabama, southern Mississippi, southwest Georgia, and northern Florida. Variables used in the model were predicted diameter increment and diameter at breast height (dbh). Predicted annual survival rates ranged from 0.92 for a tree with a 1 in. dbh and an annual diameter increment of 0.05 in., to over 0.99 for any tree larger than 6 in. in dbh. Stand level verification was based on 102 comparisons of observed and predicted trees per acre (tpa). Mean residuals, expressed as a percentage of observed final tpa, were 3% and 6% for projection periods of 5 and 10 yr, respectively. The model predicts noncatastrophic mortality. In conjunction with a basal area increment model, it can be used to predict changes in the structure of longleaf pine stands