 Because of its higher susceptibility and lower reliance on fire for reproduction , the optimal fire interval for B. prionotes is higher than for other Banksia species with which it occurs . One simulation suggested an interval of 18 years was optimal for B. prionotes , compared to 15 years for B. hookeriana and 11 years for B. attenuata . The same model suggested that B. prionotes is quite susceptible to reductions in fire intervals . On the other hand , it shows little susceptibility to increases in fire interval : although senescence and death are often observed in plants older than about 30 years , healthy stands have been observed that have escaped fire for 50 years . These stands have a multi @-@ aged structure , demonstrating the occurrence of successful inter @-@ fire recruitment . 
