期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2016
卷号：113
期号：48
页码：13684-13689
DOI：10.1073/pnas.1609775113
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：SignificanceTwenty-first-century climate change is projected to increase fire activity in California, but predictions are uncertain because humans can amplify or buffer fire-climate relationships. We combined a tree-ring-based fire history with 20th-century area burned data to show that large fire regime shifts during the past 415 y corresponded with socioecological change, and not climate variability. Climate amplified large-scale fire activity after Native American depopulation reduced the buffering effect of Native American burns on fire spread. Later Euro-American settlement and fire suppression buffered fire activity from long-term temperature increases. Our findings highlight a need to enhance our understanding of human-fire interactions to improve the skill of future projections of fire driven by climate change. Large wildfires in California cause significant socioecological impacts, and half of the federal funds for fire suppression are spent each year in California. Future fire activity is projected to increase with climate change, but predictions are uncertain because humans can modulate or even override climatic effects on fire activity. Here we test the hypothesis that changes in socioecological systems from the Native American to the current period drove shifts in fire activity and modulated fire-climate relationships in the Sierra Nevada. We developed a 415-y record (1600-2015 CE) of fire activity by merging a tree-ring-based record of Sierra Nevada fire history with a 20th-century record based on annual area burned. Large shifts in the fire record corresponded with socioecological change, and not climate change, and socioecological conditions amplified and buffered fire response to climate. Fire activity was highest and fire-climate relationships were strongest after Native American depopulation--following mission establishment (ca. 1775 CE)--reduced the self-limiting effect of Native American burns on fire spread. With the Gold Rush and Euro-American settlement (ca. 1865 CE), fire activity declined, and the strong multidecadal relationship between temperature and fire decayed and then disappeared after implementation of fire suppression (ca. 1904 CE). The amplification and buffering of fire-climate relationships by humans underscores the need for parameterizing thresholds of human- vs. climate-driven fire activity to improve the skill and value of fire-climate models for addressing the increasing fire risk in California.
关键词：anthropogenic landscapes ; fire ecology ; land use ; regime shifts ; climate variability
