Fire and the evolution of pine life histories
Many pines species are fire adapted. In 1998, JE Keeley & PH Zedler provided a seminal paper showing the various fire adaptations of pines, and the relation between the different adaptations and the different fire regimes . Recent phylogenetic [2,3] and conceptual [4,5] advances in fire ecology have allowed to better understand the evolutionary role of fire in plants, and specifically in pines [2-6]. In a recent paper, JE Keeley provides a new review on the ecology and evolution of pine life histories . Pinus originated ~150 Ma in the mid-Mesozoic Era and radiated across the northern continent of Laurasia during the Cretaceous period, when fire activity was high . Pines have followed two evolutionary strategies interpreted as responses to competition by the newly emerging angiosperms: 1) The Strobus lineage mostly has radiated into stressful sites of low nutrient soils and extremes in cold or heat; ans 2) The Pinus (subgenus) lineage has radiated into fire-prone landscapes with diverse fire regimes. Based on the life history traits associated to fire, JE Keeley define four pine syndromes : fire-avoiders (no fire-adapted; with thin bark), fire-toleraters (adapted to surface fires; with thick bark and self-pruning of dead branches; tall pines), fire-embracers (adapted to crown fires; with retention of dead branches and serotinous cones), and fire-refugia (with marked metapopulation dynamics) strategies.
Figure: Basal fire scar (a) and cross-section of pine with previous fires delineated (b) demonstrating fire survival after recurrent fires. Photos by JE Keeley from .
 Keeley J.E. & Zedler P.H. 1998. Evolution of life histories in Pinus. In: Ecology and biogeography of Pinus (ed. Richardson DM). Cambridge University Press Cambridge (UK), pp. 219-250.
 Schwilk D.W. & Ackerly D.D. 2001. Flammability and serotiny as strategies: correlated evolution in pines. Oikos, 94, 326-336. [doi]
 Keeley J.E. 2012. Ecology and evolution of pine life histories. Ann. For. Sci., 69, 445–453. [doi]