Do Giant Sequoias Regenerate in Large Crown Fire Patches?

Research indicates that the giant sequoia, a serotinous conifer and the world's most massive tree species, is positively associated with high-severity fire for effective reproduction. However, land managers hypothesize that portions of giant sequoia groves could be lost in large crown fire areas due to a lack of regeneration, extensive montane chaparral cover, and long distances to the nearest surviving sequoia seed trees. Based on these hypotheses, rollbacks of environmental laws to facilitate intensive logging and tree plantation establishment are now proposed in giant sequoia groves on national forests and national parks, in the name of wildfire management and reforestation. Yet existing research is sparse, particularly regarding postfire sequoia regeneration that reaches the size of small trees (≥ 140 cm tall), which are most likely to survive to maturity. We investigated this issue in 62 field plots within the largest high-severity fire patches in Redwood Mountain Grove, Sequoia, and Kings Canyon National Parks, four years post-fire. These patches are dominated by crown fire but also include areas of high-intensity surface fire. At four years post-fire, we found sequoia regeneration density (mean = 19,478/ha) that was more than 21 times higher than initial modeling projected. Within the high-severity fire category, we found no correlation between fire severity or percent montane chaparral cover and giant sequoia small tree density, but found the percentage of all sequoia regeneration comprised by small trees is significantly higher in crown fire areas. The mean distance to the nearest live sequoia is now significantly shorter than reported at one year post-fire, suggesting that some live sequoias were not recognized as still living in initial evaluations. Our findings indicate that giant sequoia regeneration is thriving in large high-severity fire areas dominated by crown fire.