FIRE ECOLOGY
SPECIES: Pinus attenuata | Knobcone Pine 



FIRE ECOLOGY OR ADAPTATIONS : 
Knobcone pine is an obligate fire type with a strict closed-cone habit.
This adaptation, along with the general absence of animal agents that
might open cones, leaves the species dependent upon stand-replacing
crown fire for reproduction.  Continued production and accumulation of
cones throughout the life of a tree assures that large quantities of
seed are released when fire opens cones.  The open, multitrunked growth
form of knobcone pine promotes fire crowning [41].

Fire creates seedbed conditions favorable for germination and seedling
recruitment.  It temporarily raises soil pH and increases soil nutrient
content, particularly phosphorus and nitrogen.  A longer-term benefit of
fire to the species is the retrogressive role it plays in soil genesis.
By removing litter and ground cover vegetation, fire contributes to soil
erosion.  Wind-felling of fire-killed trees results in further churning
up of nutrient-deficient soils.  Most plant species cannot compete with
knobcone pine on such poor sites.  The discontinuous nature of
serpentine prevents all the pines in an area from being killed by any
one fire [41].

Natural fires are probably less frequent in knobcone pine forests than
in other western closed-cone communities [25].  The infertile sites
where knobcone pine occurs support little undercover.  Litter layers
are usually moderate [13].  A 20-year-old plantation in the San Dimas
Experimental Forest, southern California, produced 10.9 tons of forest
floor per acre (24.5 t/ha) [17].  The average interval between fires is
undocumented.


POSTFIRE REGENERATION STRATEGY : 
   Tree without adventitious-bud root crown
   Crown residual colonizer (on-site, initial community)

Related categories for Species: Pinus attenuata | Knobcone Pine