R. Tapias et al., Canopy seed banks in Mediterranean pines of southeastern Spain: a comparison between Pinus halepensis Mill., P. pinaster Ait., P. nigra Arn. and P. pinea L., J ECOLOGY, 89(4), 2001, pp. 629-638
1 Canopy seed banks were analysed in post-fire stands of Pinus halepensis,
P. pinaster, P. nigra, and P. pinea. We determined age when flowering begin
s, age of first cone bearing, presence of serotinous cones and cone-opening
2 By 15 years after the fire, P. halepensis had developed a large canopy se
ed bank (3-100 x 10(4) seeds ha(-1)). Fruiting started at 5 years of age. M
ore than 86% of the cones were serotinous and had opening temperatures from
49.3 to 51.3 degreesC. Cones from adult trees opened at lower temperatures
than those from young trees.
3 A 16-year-old P. pinaster stand had a smaller seed bank (12 000 viable se
eds ha(-1)) and a lower percentage of serotinous cones (66.7%), with lower
cone-opening temperature (45.8 0.8 degreesC) and later first fruiting (12 y
ears) than any of our three P halepensis populations.
4 Populations of P. nigra and P. pinea did not show any fire adaptations: f
lowering was insignificant even 15 years after fire, and none of the cones
produced were serotinous.
5 Serotinous cones represent a fire-survival strategy for P. halepensis and
P. pinaster. Early flowering is also necessary for successful post-fire co
lonization in species or populations where crown fires are frequent. Late f
lowering and non-serotinous cones of P. nigra and P. pinea suggest that the
y may have evolved where ignition leads only to low intensity ground fires.