Prolific Post-fire Persistence: Resilience and Resprouting in the Iconic Coast Redwood

Background Historically frequent-fire forest ecosystems are now facing increased size, frequency, and severity of fires attributed to climate change, intensive forest management, and fire exclusion. Understanding post-fire resilience in forest ecosystems is critical amidst escalating challenges posed by recent increases in fire activity. Coast redwood ( Sequoia sempervirens ) provides a model system for examining post-fire persistence via resprouting in a highly fire resilient ecosystem. Here, we identify the most informative fire-damage metrics for post-fire basal resprouting, quantify the relative influence of tree-, stand-, and climate-level drivers of post-fire basal resprouting, and examine the relationship between epicormic and basal resprouting following fire for redwood. Results Post-fire redwood basal resprout responses (presence and abundance) were most strongly associated with bole char ratio, a relativized measure of fire damage (ratio of bole char height to total tree height). Both the presence and abundance of basal resprouting did not detectably decline with increasing fire damage but rather increased continuously. In addition to fire damage, the probability of basal resprouting, total resprout biomass, and other responses decreased with higher climatic water deficit. Epicormic resprouting of the tree bole was positively related to basal resprout probability. Conclusions As climate change drives increased fire activity and severity in many forest ecosystems, prolific post-fire resprouting can facilitate rapid recovery and the long-term persistence of redwoods. These positive post-fire outcomes are slightly tempered by observations of reduced resprouting abundance (both basal and epicormic) in warmer and drier locations, suggesting there may be climatic limitations in the post-fire resprouting ability of redwoods. While further study is needed to examine the long-term trajectory of redwood forests following high-severity fire, our study provides forest managers with sound expectations that resprouting will promote redwood persistence, though may be hindered in the future by extreme drought events.