FIRE EFFECTS
SPECIES: Pinus sylvestris | Scots Pine 



IMMEDIATE FIRE EFFECT ON PLANT : 
Young Scots pine trees are easily killed by fire due to their thin bark
and shallow roots.  Based on the ability to recover after defoliation,
the fire resistance of 8-year-old Scots pine trees is rated as low
[36].  The heat tolerance of 1-year-old Scots pine seedlings is low
compared to a number of other conifers, including eastern white pine
[24].  Mature trees are better able to withstand fire; old trees in
Muddus National Park, Sweden, have numerous fire scars, showing that
they have survived repeated fires (intensity unreported).  However,
severe fire will kill even mature trees [52].  

A 1974 surface and crown wildfire in Scotland killed 74 percent of all
Scots pine burned.  All Scots pine less than 2 inches (5 cm) dbh were
killed outright.  Trees greater then 15.2 inches (38 cm) in diameter did
not have immediate mortality, however [60].

Scots pine seeds are moderately resistant to heat damage, and have a
good chance of surviving fire when buried.  Seed germination is
good even at depths of up to 4.6 inches (10 cm) [52]. 

Scots pine bark is more resistant to heat than that of Norway
spruce, sugar maple, or white ash (Fraxinus americana) [14].


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
NO-ENTRY


PLANT RESPONSE TO FIRE : 
In Sweden, establishment of Scots pine seedlings at high elevations
increased after fire [15].  Total pine pollen increased after fires in
Swedish core samples dated from 1,430 years BP [4].  A survey of a
burned stand of mature Scots pine in northern China showed numerous
seedlings, but no saplings [50].

Following the 1974 wildfire in Scotland, Scots pine reproduction was
densest on plots with heather.  Very few seedlings occurred on sites
where sapling stands had been killed by fire.  Regeneration was 2,500
seedlings per hectare at postfire year 6.  By postfire year 12, some
seedlings had overtopped the competing vegetation.  Postfire mortality
of burned trees was high.  By postfire year 6, 45 percent of trees
greater than 2.5 inches dbh was died.  Much of the postfire mortality
was attributed to pine shoot beetle (Myelophilus piniperda) attacks on
fire-damaged trees [46,60].  

Scots pine may regenerate from seeds released from cones of burned
trees [60] as well as from seed from off-site parent trees.  Twenty-four
years after a wildfire in Sweden, numerous Scots pine seedlings
occurred on burned sites, concentrated around surviving trees and near
the edges of the burned areas [52].


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
The climatic conditions that are conducive to fire in Scandinavia are
also conducive to the production of large seed crops [52].


FIRE MANAGEMENT CONSIDERATIONS : 
Fires in Sweden have given rise to uneven-aged stands of Scots pine,
particularly in virgin types that have not been disturbed by humans
[59].  Fire exclusion in Europe has resulted in a conversion of
pine-dominated forests (including Scots pine) to hardwoods [26].

Prescribed burning followed by tilling, followed by natural
reforestation (known as swaling), has been practiced in Europe for many
years.  It has been noted that the more frequently a site has been
swaled, the more likely it is that hardwoods will regenerate on the
site.  Sites that have been burned and tilled only once often result in
good Scots pine regeneration [55].

Scots pine does not regenerate on dry sites occupied by Norway spruce
due to excessive humus buildup and shading.  Such sites can be made more
conducive to Scots pine regeneration by prescribed burning.  The humus
layer is directly reduced by fire.  In succeeding years, it continues to
decrease in thickness, probably due to decreased root mass.  Prescribed
burning improves many external growth factors needed for Scots pine
establishment, including nutrition, moisture availability, and soil
temperature [55].

Prescribed burning has been used in site preparation for the sowing of
Scots pine seeds in Norway and Finland [3,48].  Performance of Scots
pine approximately 10 years after planting was best on burned sites when
compared to performance on sites that were unburned but had slash
removed, or sites that were unburned and retained slash [55].  Rhizina
undulata root rot has been associated with postfire plantations of
Scots pine.  As a result, prescribed burning for site preparation has
been discontinued in Finland and Sweden [1,54,55].  It is possible that
the appearance of Rhizina is associated with prescribed fires that are
too low in intensity [55].  However, the rarity of appropriate fire
weather for prescribed burning, and the labor-intensive expense of
prescribed burning have also contributed to the reduction in prescribed
burning in Scandinavia [3].

Related categories for Species: Pinus sylvestris | Scots Pine