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IPFS News Link • Natural Disasters

How Trees Survive and Thrive After A Fire

• National Forest Foundation

Big or small, gradual or sudden, change rhythmically punctuates human life. In the natural world, change is just as intrinsic and pattern-based. Seasonal fluctuations in temperature, shifts in sun light, and natural disturbances, like fire, are all part of nature's cycle.

Most people resist change, especially change they consider destructive. Perhaps that's why uncontrolled wildfires have been suppressed since the early 1900s. Fire can be damaging, and its effects certainly scar once verdant landscapes. But this destruction can also prove beneficial. In recent decades, ecologists and land managers have realized more fully how important fire is to the natural patterns of many ecosystems. This pattern, known as a "fire regime," is different for each ecosystem. Each fire regime is important to maintaining forest and grassland health, even if it seems harmful at first glance.

Of course, no species is adapted to live in fire itself, but animals and plants can adapt to a fire regime. A fire regime includes, among other things, fire frequency, fire intensity and patterns of fuel consumption. Plants have a distinct disadvantage, compared to animals, in the face of fires. They can't run, fly, creep or crawl out of a fire's path. But they have adapted to survive, and even depend on, regular fire.

From armoring themselves with thick bark to developing ways to protect precious seeds, trees have developed several fascinating adaptations in response to a predictable fire pattern.

Thick bark. 

Trees in fire-prone areas develop thicker bark, in part, because thick bark does not catch fire or burn easily. It also protects the inside of the trunk, the living tissues that transport water and nutrients, from heat damage during high-frequency, low-intensity fires. Ponderosa pine (Pinus ponderosa, also commonly known as the bull pine, blackjack pine or western yellow pine) is a great example. This signature tree in the western United States has a thick and flaky bark, sometimes compared to pieces of a jigsaw puzzle, which perfectly withstands a low-intensity, surface fire. The species also drops lower branches as the trees grow older, which helps prevent fire from climbing up and burning the green needles higher up the tree.

Fire-induced sprouts. 

This fire-survival strategy allows for the complete destruction of above-ground growth. Typically, species that regenerate by re-sprouting after they've burned have an extensive root system. Dormant buds are protected underground, and nutrients stored in the root system allow quick sprouting after the fire. Shortleaf pine (Pinus echinata, also occasionally called southern yellow pine or the shortstraw pine) employ this technique.


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