摘要：Fire is the dominant disturbance in forest ecosystems across Canada and Alaska, and has
important implications for forest ecosystems, terrestrial carbon dioxide emissions and the
forestry industry. Large fire activity had increased in Canadian and Alaskan forests during
the last four decades of the 20th century. Here we combined the Palmer Drought Severity
Index and historical large fire databases to demonstrate that Canada and Alaska forest
regions experienced summer drying over this time period, and drought during the fire
season significantly affected forest fire activity in these regions. Climatic warming, positive
geopotential height anomalies and ocean circulation patterns were spatially and
temporally convolved in causing drought conditions, which in turn enhanced
fuel flammability and thereby indirectly affected fire activity. Future fire regimes
will likely depend on drought patterns under global climate change scenarios.
