Fire structures pine serotiny at different scales.
OBJECTIVE
Serotiny (delayed seed release with the consequent accumulation of a canopy seedbank) confers fitness benefits in environments with crown-fire regimes. Thus, we predicted that serotiny level should be higher in populations recurrently subjected to crown-fires than in populations where crown-fires are rare. In addition, under a high frequency of fires, space and resources are recurrently available, permitting recruitment around each mother to follow the seed rain shadow. Thus, we also predicted spatial aggregation of serotiny within populations.


METHODS
We compared serotiny, considering both the proportion and the age of serotinous cones, in populations living in contrasting fire regimes for two iconic Mediterranean pine species (Pinus halepensis, P. pinaster). We framed our results by quantitatively comparing the strength of the fire-serotiny relationship with previous studies worldwide.


RESULTS
For the two species, populations living under high crown-fire recurrence regimes had a higher serotiny level than those populations where the recurrence of crown-fires was low. For P. halepensis (the species with higher serotiny), populations in high fire recurrence regimes had higher fine-scale spatial aggregation of serotiny than those inhabiting low fire recurrence systems. The strength of the observed fire-serotiny relationship in P. halepensis is among the highest in published literature.


CONCLUSIONS
Fire regime shapes serotiny level among populations, and in populations with high serotiny, recurrent fires maintain a significant spatial structure for this trait. Consequently, fire has long-term evolutionary implications at different scales, emphasizing its prominent role in shaping the ecology of pines.
CIDE-CSIC, Ctra. Nàquera Km. 4.5 (IVIA campus) 46113 Montcada, Valencia, Spain.
Ana
A
Hernández-Serrano
Miguel
M
Verdú
Santiago C
SC
González-Martínez
Juli G
JG
Pausas
D005075:Biological Evolution; D004463:Ecology; D017753:Ecosystem; D005390:Fires; D019083:Mediterranean Region; D028223:Pinus / Q000235:genetics / Q000502:physiology*; D063245:Plant Development; D012639:Seeds; D013045:Species Specificity
Pinaceae; Pinus halepensis; Pinus pinaster; fire ecology; seed bank; serotiny; spatial structure