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“… a conversion of tundra to boreal forest as temperatures increase.”
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ECOLOGY: Fire in the Far North
Andrew M. Sugden
Paleoecological data sets contain historical
records of biotic responses to changes in
climate. Currently, high-latitude regions are
suffering a particularly aggressive regimen of
climate change; hence, an understanding of past
vegetation dynamics in these regions is
especially pertinent. Higuera et al. have
analyzed pollen records from north-central Alaska
and find that a combination of drier climates and
shrubbier tundra during the late glacial period
14,000 to 10,000 years ago led to regular fires.
Given present-day increases in shrub biomass and
temperature, tundra fire activity might increase
again, with consequences for vegetation dynamics
and carbon cycling. Tinner et al. have analyzed
pollen and other records from the past 700 years
(a period that includes the Little Ice Age of
1500 to 1800 CE) in southern Alaska, and find
that temperature fluctuations of 1° to 2°C,
together with changes in moisture balance, led to
conversions between boreal forest and tundra with
concomitant alterations in fire regimes. Taken
together, these findings are consistent with
models predicting a conversion of tundra to
boreal forest as temperatures increase. — AMS
PLoS ONE 3, e0001744 (2008); Ecology 89, 729 (2008).
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