Wednesday, April 20, 2016

Fire Adapted Species


Fire adapted species possess inherited traits that allow them to enhance their survivorship or fitness during or after a fire. Fire adaptations are derived from a long history of plant species evolving in ecosystems with fire regimes. In order for a trait to be considered a fire adaptation, fire must be the main selective force that allowed that trait to thrive within a species. There are many selective forces that could’ve promoted traits that improve survivorship or fitness in fire, which makes identifying a fire adaptation a difficult process. Today, there are many traits that are generally accepted as fire adaptations and are managed as such.

1.     Thick bark is considered to be a fire adaption because it can prevent the vascular cambium form being damaged. The bark acts like a medium that transfers heat from the fire to the cambium. If the bark is thick, it will take more energy to transfer enough heat to cause damage. This fire adaption will increase survivorship when exposed to low or possibly moderate severity levels of fire. A high severity fire will likely produce enough heat to damage the cambium and engulf the tree. Areas will low to moderate fire intensity regimes will likely select for trees with thicker bark since trees without this trait could have lower survivorship.
2.     Another fire adaptation could be plants with growing points below the soils surface. These plants have the ability to surface low severity fires because the soil acts like an insulator and protects the growing points below the surface. These plants can successfully remain established after a fire. High or moderate intensity fires can heat up the soil to a point of damaging the plant beyond recovery.

2 comments:

  1. Matt,
    Great post. Ponderosa exhibit the second trait you mentioned in that they have deep root systems that can typically sustain surface fires. They also have the first trait you mentioned. Some other adaptations (or exaptations) that can be seen in fire-adapted species have to do with shorter life cycles in order to drop seeds in a more timely manner, especially if frequent fires are seen within the ecosystem. I feel that this is an example of an adaptation versus an exaptation because while the trait may have been evolved, it seems to be more of a response to the environmental demands the species faces.
    Thanks,
    Ashley

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    1. Ashley,
      I think that frequent fire would be a strong selective pressure that promotes fire adaptations. I really like the short life cycle example that you provided. Figuring out if a trait is an adaptation or a exaptation is definitely not easy and requires knowledge of fire regimes and selection forces that the trait responds well to. I think its important that the traits are identified along with what fire regimes they do well in and less important to figure out if the trait is truly a fire adaptation or exaptation.

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