The fire ecology and management of maritime pine ( Pinus pinaster Ait.)

Abstract

Maritime pine ( Pinus pinaster Ait.) is an important conifer from the western Mediterranean Basin. Fire is the most significant threat to maritime pine plantations but also a disturbance that plays a vital role in the perpetuation of natural stands. The species has physical characteristics that allow survival after low-intensity fire, namely thick bark, and reproduction processes that facilitate recovery after stand replacement fire from seeds stored in serotinous cones. These traits are consistent with the opposing strategies of fire resistance and fire evasion and can be interpreted as evolutionary adaptations to fire, but their development and coexistence are highly variable between populations, thus invalidating the classification of maritime pine in a general fire regime category. When the two strategies are concurrent the species should be able to persist under a variable or mixed fire regime. The quality, quantity and structural arrangement of fuels in maritime pine stands explain why they are so flammable. Thorough descriptions of the litter and understorey fuel complex are available in the literature, which makes custom fire behaviour prediction possible with software tools based on Rothermel's fire spread model; empirical fire behaviour models developed from experimental fire data are also available and are preferred to plan prescribed burning operations. There is ample evidence, although largely anecdotal, that surface, ladder and canopy fuel treatments mitigate wildfire intensity and burn severity and avoid crown fire in maritime pine stands. The optimization of fuel hazard management is nevertheless curtailed by the current state of knowledge about crown fire behaviour and fuel dynamics in relation to stand development and silviculture. The conservation and sustainable management of maritime pine in fire-prone landscapes should integrate the active use of fire and understand that effective protection from high-severity wildfire is not possible without sacrificing some stand volume.