Fire on the Mountain: A Fire Chronology of North Lake Tahoe

Abstract

Significant shifts of wildfire regimes in the Sierra Nevada montane pine-fire system have occurred in the past four centuries due to European-American settlement, logging, and grazing. This study examines the fire history of the Stateline Fire Lookout on the north shore of Lake Tahoe, California. We used dendrochronological methods to document the fire history from the year 1580 to 2022. Our research aims to emphasize the influence of land-use changes and climate on wildfire regimes since 1680 on an old-growth mixed conifer forest. We surveyed for fire-scarred Pinus jeffreyi and Abies concolor to collect samples for dendrochronological analysis and found 17 living trees, remnant stumps, and logs. Thirteen of seventeen samples crossdated span from 1685 to 1906. The fire scar chronology showcases the frequency and distribution of fires, revealing an 8-year interval for all fires and a 20-year interval for large fires emphasizing key years of more extensive fires within the site. We filtered fire events to identify large fires, 25% of recording trees scarred with at least 2 scars. These results highlight the impact of regional climatic phenomena, with years of high fire synchrony correlating with specific years of known drought, using the Palmer Drought Severity Index with a 10-year spline. Additionally, seasonal analysis demonstrates a range of fire occurrences across earlywood, latewood, and dormant periods. Results provide valuable insights into the complex dynamics of wildfires in North Lake Tahoe, offering a historical perspective essential for shaping effective wildfire management strategies into the future.