FIRE EFFECTS
SPECIES: Picea abies | Norway Spruce 



IMMEDIATE FIRE EFFECT ON PLANT : 
Norway spruce is easily damaged or killed by fire [74].  The crown
canopy of Norway spruce is often totally destroyed by even minor surface
fires [64,76].  However, there are almost always scattered survivors
even following crown fires; in most cases survival is due to local
topography which prevents fire spread [82].  In Finland, forest fire
damage is greatest in Norway spruce forests (compared with mixed or pure
Scotch pine stands) [61].  In the United States, grass fires are
reported to cause severe damage to Norway spruce plantations [17].

Norway spruce seeds buried in humus at 1.2 inch (3 cm), 1.9 inch (5 cm),
and 3.9 inch (10 cm) depths were undamaged by the heat of a prescribed
fire that measured 820 degrees Fahrenheit (438 deg C) at the soil
surface.  The humus provided excellent insulation; the temperature at
1.2 inches (3 cm) was only 80 degrees Fahrenheit (26.5 deg C) [74].

In a laboratory study in which heated air was applied to stem sections
and to whole tops of dormant 3- and 4-year-old Norway spruce seedlings,
Norway spruce was found to be more tolerant of heat than European larch
or Japanese larch (Larix leptolepis).  Active Norway spruce seedlings
were more heat tolerant than European and Japanese larch, eastern white
pine (Pinus strobus), Scotch pine, or American beech (Fagus
grandifolia), but none were very tolerant.  In this experiment, no
seedlings were killed by the heat treatment, but dormant Norway spruce
seedlings were almost completely defoliated [39].


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
NO-ENTRY


PLANT RESPONSE TO FIRE : 
Norway spruce seedlings are not usually present on burned areas; the
soils are usually too dry and hot to support good seedling establishment [74].


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
NO-ENTRY


FIRE MANAGEMENT CONSIDERATIONS : 
Prescribed fire has been used as a tool for forest regeneration in
Norway, primarily to prepare the ground for natural regeneration from
seed trees, usually Scotch pine.  Management of Norway spruce in Norway
is often based on information from other countries where Norway spruce
and Scot's pine are the dominant conifers.  After World War II, prescribed
fires were used to prepare sites for artificial regeneration, either for
sowing Scot's pine seeds or for planting Norway spruce nursery stock.
It is often difficult to conduct prescribed fires in Norway; the weather
is changeable and conditions are often too moist for burning.  These
facts, coupled with increasing costs of burning, have led to a
preference for site scarification by mechanical means instead of fire
[6].  Prescribed fires are not used much in Finland today either, due to
high costs and variable weather [78].  The average size of individual
wildfires is usually greatest in mixed stands of Scot's pine and Norway
spruce [61].

Norway spruce is known as a nutrient-demanding species; this has led to
concern that prescribed fire for site preparation burns too much of the
humus and results in soils that are not favorable for good Norway spruce
growth.  In Norway, Norway spruce seedlings showed good 12-year survival
on both burned (83 percent survival) and unburned (78 percent survival)
sites.  Overall height growth on unburned sites was slightly better at
12 years than on burned sites, although early growth on burned sites was
better [6].  In Sweden, sites that were clearcut and burned, then seeded
with Norway spruce were compared with similar sites that had not been
burned.  The unburned sites had thicker humus layers after 43 years of
growth.  The authors estimate that it takes 70 to 80 years from the time
of the fire for burned humus layers to be rebuilt to prefire levels [37].

Prescribing fire for site preparation in Scandinavia depends on the
vegetation type.  Types that are characterized by thick, raw humus
layers benefit from fire, which releases nutrients and activates the
humus [6,74].  After fire passes over humus, ashes and carbonized plants
form a thin cover over the otherwise undamaged humus layers [74].
Prescribed fires used for site preparation must be conducted with care
to prevent destruction of humus and excessive heating of upper mineral
soil.  Fires temperatures of 662 degrees Fahrenheit (350 deg C) or less
at the soil surface will release nutrients stored in litter and allow
them to condense in the humus and upper mineral soils [28].  Fires that
burn quickly enough to leave humus may be acceptable.  Decomposition
rates in northern Norway spruce forests are very slow.  In Finland, 56
years after logging, even very thin branches are left intact in slash
and litter [54].  Prescribed fires can release some of this organic
matter, and increase the pH of the soil.  Some nutrients are lost to the
atmosphere [78].  Types with thin humus layers are better unburned,
since the humus would be destroyed by fire [66,79].  Norway spruce is
unsuited for such sites, since its shallow roots render it less able to
exploit the mineral soil for nutrients than Scotch pine [37].
Prescribed burning is usually not necessary on most fertile soils, but
may be useful on sites that have experienced swale cultivation [79].

Fire suppression in Sweden since the nineteenth century has resulted in
an over-representation of aging Norway spruce forests, and it has been
recommended that prescribed fires for stand rejuvenation are necessary
in Swedish National Parks and nature reserves to improve stand health by
reestablishing a mosaic of seral stands [84].

Related categories for Species: Picea abies | Norway Spruce