摘要:Forest fires resulting from long periods of drought cause extensive forest ecosystem
destruction and can impact on the carbon balance and air quality and feed back to the
climate system, regionally and globally. Past fire frequency is reconstructed for Tuvan
Scots pine stands using dendrochronology and statistics. Central Tuvan Scots
pine (Pinus sylvestris) stands are subject to annual fire regimes; however high
intensity fires are rare but they are responsible for most of the damage. Low,
medium, and high severity fires have shaped the multi-story Scots pine communities,
locally and regionally. Fire type and frequency are directly related to weather and
climate and are also dependent on anthropogenic influences. The primary dry
period, which promotes fire ignition and spread, in Tuva occurs in April and
May. In some years, the precipitation deficit combined with high air temperatures
induces long periods of drought. Unlike the typical surface fire regime, forest fires
that burn during these extreme droughts often become crown fires that result
in substantial forest damage and carbon release. The mean fire interval (MFI)
is found to be 10.4 years in Balgazyn stands, and the landscape-scale MFI is
22.4 years. High severity, stand-replacing crown fires have a longer MFI. The
warmer and dryer weather that is predicted by global climate models is evident in
Tuva, and we believe that these changes in weather and climate have resulted in
increased fire intensity and severity, rather than fire frequency in the Tuvan region.