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We don’t know yet the fate of the largest and oldest redwoods at Big Basin State Park. It is possible that many trees were killed, or that only a few died by burning through old basal fire scars, or by scorching the canopies or roots. 1/10 https://tinyurl.com/y65nn7gx
Most tree-ring studies in coast redwood found remarkably high fire frequencies prior to Euro-American settlement, with intervals between surface burns typically less than 20 years, and as short as 2 years. 2/10 https://www.jstor.org/stable/41424920?seq=1#metadata_info_tab_contents
Fire use by Indigenous people was undoubtedly very important as a tool for living in these places. But as we see in the recent fires, relatively rare lighting storms also play an ignition role in redwood groves. Finney & Martin 1992 3/10
Fire scars in sequoia tree rings recorded low severity surface fires. Other evidence suggests occurrence of rare high severity fires that killed he lower canopy of trees, but many of the largest trees survived. 4/10 https://tinyurl.com/yxnsceob
The evidence is in the rings. Following rare high severity fire, the surviving trees show an increase in growth rates. This is likely a “release” from competition for light, water, and nutrients. For example, this growth release following a 1714 fire (Brown & Swetnam 1993) 5/10
Another example is from giant sequoias in Mountain Home St. Forest. Coast redwoods and giant sequoias are related but have different habitats. A growth release after a 1297 fire at Mountain Home can be seen on stump tops throughout this logged grove. 6/10 https://tinyurl.com/y4n6z6nx
Some fires in coast redwood, however, cause ring growth reductions. So it is not clear yet what range of fire severities might result in ring-width suppression versus release, as we saw after the 1714 fire in the Prairie Creek redwood grove. 7/10 https://tinyurl.com/y4wbgz3s
Extensive and rare high severity fire events in coast redwoods and giant sequoias generally correspond with extreme drought events. That is especially true for the extreme 1297 fire. 8/10 https://tinyurl.com/y42ulu6j
However, in giant sequoia groves fires were most frequent and generally lowest severity and extent during the driest, hottest periods in the past 2,000 years. Frequent fire builds resilience in sequoia groves by maintaining low fuel accumulations. 9/10 https://tinyurl.com/y2c8k4yy
Coast redwoods & giant sequoias exist in small groves that could be wiped out by future fires. Let’s hope that has not happened yet. Let’s resolve to prevent that by reducing greenhouse gases AND by restoring frequent, low severity surface fires to these world unique forests. End
