Plant Ecology

, Volume 171, Issue 1, pp 69–79

Reproductive traits of Pinus halepensis in the light of fire – a critical review

Article

DOI: 10.1023/B:VEGE.0000029380.04821.99

Cite this article as:
Ne'eman, G., Goubitz, S. & Nathan, R. Plant Ecology (2004) 171: 69. doi:10.1023/B:VEGE.0000029380.04821.99

Abstract

Fire is known to be a major factor in shaping plants and vegetation worldwide. Many plant traits have been described as adaptations for surviving fire, or regenerating after it. However, many of the traits are also advantageous for overcoming other disturbances. The fact that fire in the Mediterranean Basin has been almost exclusively of anthropogenic origin, and thus is of short duration in an evolutionary time scale, cast doubt on the possibility that fire can act as a selective force in the Mediterranean Basin. Our aim here is to review the ecological advantages of Pinus halepensis traits and their possibility to be selected by fire. The non-self pruning of cones and branches, and the high resin content increase the probability of canopy fires and consequent death of P. halepensis trees. Post-fire regeneration of P. halepensis depends totally upon its canopy-stored seed bank. The seedlings grow quickly and they first reproduce at an early age. Young reproductive trees function first as females with a high percentage of serotinous cones. Thus, young P. halepensistrees allocate many resources to seed production, reducing their `immaturity risk' in a case of an early successive fire. The proportion of serotinous cones is higher in post-fire naturally regenerating stands than in unburned stands, and seeds from serotinous cones germinate better under simulated post-fire conditions. The extremely high pH of the ash-bed under the burned canopies creates the post-fire regeneration niche of P. halepensis exactly under their parent trees. All these traits are advantageous for post-fire regeneration, but could they also be selected during the time scale of anthropogenic fires in the Mediterranean Basin? Pinus halepensis is a relatively short living tree with almost no recruitment under forest canopy. The longest estimated fire-return interval and generation length are about 125 years. The earliest solid evidence for the first hominid-controlled fire in the Mediterranean basin is 780,000 years ago, and thus the estimated number of post-fire generations is 6240. We suggest that such a number of generations is sufficient for the selection and radiation of fire adaptive traits in P. halepensis.

Aleppo pineCone serotinyFlammabilityGerminationMediterraneanNatural selection

Copyright information

© Kluwer Academic Publishers 2004

Authors and Affiliations

  1. 1.Department of BiologyThe University of Haifa – OranimTivonIsrael
  2. 2.Department of Evolution Systematics and Ecology, Alexander Silberman Institute of Life SciencesThe Hebrew University of JerusalemGivat Ram, JerusalemIsrael