High temperature of forest fires under pines as a selective advantage over oaks

Abstract

In many temperate ecosystems succession from pine forest to hardwoods is interrupted by fire, resulting in a fire climax dominated by pines^1–3. As natural selection operates through both processes of succession and fire, early serai plants that are poor competitors may exhibit fire-facilitating characteristics whereas late serai plants that are superior competitors may show fire-retarding traits. Potential fire-retarding and fire-facilitating traits of plant foliage have been measured^4–7, but then- effects on survival or reproduction have never been demonstrated in the field^7,8. We report here that maximum temperatures, recorded during fires in a mixed oak-pine woodland, were sufficiently higher under pines than under oaks to ensure elimination of the competitively superior oaks in the vicinity of adult pines.