The thick, layered bark of a young Ponderosa Pine tree. Photo by Maya Walters. |
Pine trees depend on fire in order to grow in areas
which would otherwise be taken over by oaks. Pines have thick bark which does not burn easily, protecting the wood underneath. The
buds on their stems are surrounded by thick clumps of needles which do burn, but at a low temperature which does not damage the bud.
The broad-leaved oak trees don't have these defenses, and will be killed even in a small fire. This means that in areas with frequent,
relatively small fires, the oaks never have time to grow large enough to take over from the pines. Some pines even require fire to release
the seeds in their cones.
North America's Jack pine forests are particularly dependent on fire -- without it, the jack pines would be shaded out and replaced by firs, spruce, and certain hardwoods. The seedlings of these other species are, however, killed in the fires that occur every hundred years or so (not long at all in the life-span of a tree). The Jack pines are completely shade intolerant, and could not survive if these other trees grew too tall. |
coniferous forests -- page 2 of 4
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related topics
[fire] [broadleaf forests] [forests through time]
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