A STOCHASTIC-MODEL FOR TREE SURVIVAL IN STANDS AFFECTED BY ANNOSUM ROOT DISEASE

Mortality of trees surrounding pine stumps colonized by Heterobasidion annosum for about 35 years was monitored over a period of 20 yr in 53 eastside pine stands in northern California. The data were used to de velop a stochastic model that quantifies effects of tree characteristi cs and spatial proximities on survival of trees within 12 m of a colon ized stump. The model accommodates mortality data collected at irregul ar intervals. Variables with significant effects on tree survival incl uded trees species, size, and distance of roots from the root of a pre viously dead tree. Results from stochastic models based on actual data are useful for detecting factors affecting tree survival and for eval uating assumptions of numerical (simulation) models, such as root dise ase computer models.