The distribution and abundance of coast redwood (Sequoia sempervirens) is influenced by a variety of complex ecological and climatic controls. Current redwood distribution is limited to a maritime climate zone with relatively infrequent fire, but the species possesses numerous adaptations to fire (i.e., thick bark, vigorous post-fire sprouting, seedlings that favor establishment in post-fire soils) that suggest fire may favor redwood abundance. Modern redwood distribution and abundance is influenced by fire and climate, but we lack the context of historic and pre-historic records to inform our understanding of the historical relationship of climate and fire on the postglacial redwood biogeography. We hypothesize that regional climate variation influenced redwood abundance by means of regulating fire frequency, though human activity may also explain some fire patterns. To test that hypothesis, we use a novel combination of lake sediment records and soil charcoal samples from the Headwaters Forest Reserve in northern California. We collected sediment cores from a small pond in the Headwaters Forest Reserve and sampled soil macro-charcoal in soil profiles from cut-banks and stream banks.
Results/Conclusions
Our preliminary results include radiocarbon dates from macro-charcoal fragments sampled from soil that indicate fire events taking place as far back as 4,894 calendar years BP. Ongoing work will address: (1) the variability of fire frequency and biomass burning in the Headwaters Forest Reserve; (2) how fire and climate have regulated the spatial extent of redwood; (3) detecting potential anomalies within larger trends in fire frequency that may indicate human activity within coast redwood forests. Initial results from the full analyses of soil profiles and lake sediment records will be presented, informed by our synthesis of the existing literature on regional paleoclimatic trends. Information from this multi-proxy analysis will contribute to our understanding of the relationship between climate, fire and redwood and may help clarify the current uncertainty regarding the future distribution of coast redwood.