Nathan Stephenson, Anthony Caprio, David Soderberg, Adrian Das, Eva Lopez, Park Williams

In some areas burned by recent wildfires, most or all giant sequoias were killed. Sequoia managers wish to know whether post-fire seedling establishment in those areas has been adequate to regenerate the locally extirpated sequoias. To provide a yardstick for interpreting sequoia seedling densities measured after the recent severe wildfires, here we calculate mean seedling densities measured one, two, and five years after several mixed-severity fires of the past. Our analyses are based on 42 sites in eight different sequoia groves in Sequoia and Kings Canyon national parks, California, which burned in 26 different fires spanning a 48-year period. Conservatively (i.e., without correcting probable errors of underestimated densities), mean sequoia seedling density the first summer following fire was 153,278/ha (Bayesian estimated median = 173,742/ha; 95% credible interval [CI] = 63,319/ha to 850,336/ha). Mean seedling densities the second and fifth summers following fire were, respectively, 34,870/ha (Bayesian estimated median = 39,562; 95% CI = 14,181/ha to 181,011/ha), and 8,601/ha (Bayesian estimated median = 9,513/ha; 95% CI = 3,827/ha to 34,057/ha). Case-study comparisons showed that measured post-fire seedling densities across the Board Camp Grove and in the severely burned portions of the Redwood Mountain Grove were significantly lower than our second-year reference seedling densities.