Forest fires only help forest ecosystems that have evolved in areas prone to thunderstorms and therefore fire starting bolts of lightning. Forest ecosystems that have developed in other areas have had no reason to develop coping mechanisms for wildfires and can be utterly devastated by human lit ones. This is why the slash and burn method of clearing rainforest is so effective. Even if the cleared land is let lie, there is nothing left able to regenerate itself into forest, it has to be colonized by neighboring untouched rainforest.
Where there are natural agencies that cause relatively frequent forest fires, the native life has developed behaviors and/or anatomical (physical structure) and physiological (biological function) attributes that enable them to cope and even flourish in this situation. Animals’ senses are highly attuned to the smell of burning and wind direction, and seem able to predict changes in wind direction before they occur. Insects know to burrow into the earth or hide in tree hollows or heavily creviced bark. Plants have evolved various protective strategies, such as thick, moist bark or flaky bark that peels of and floats away when ignited leaving the trunk barely touched, a particular favorite of Australia’s eucalyptus species, and many provide their leaves with a waxy, protective coating.
Forest fires clear away the underbrush in the forest ecosystem, most mature canopy tree species survive the experience. Underbrush species have evolved their own coping mechanisms, many can regenerate from unharmed root systems for example. Even so, immediately after a fire is often a very good time for new canopy trees to grow. This has resulted in some species utilizing fires as a trigger for propagation. They produce seeds in hard cases that only crack open when temperatures reach those in a forest fire, so that the seed germinates and the sapling starts growing at the ideal time.
Because fires clear the underbrush periodically, these forest ecosystems are more open than other forests. Animals, birds and insects are adapted to this, their behavioral patterns have become dependent on it being so. When people interfere with this natural cycle by suppressing forest fires, an abnormal amount of underbrush develops that can have severe negative impacts on some of the native animal and insect populations, as well as inhibiting some canopy tree renewal. Sadly, we are also just setting ourselves up to fall. Eventually a fire will start, and because there is so much underbrush it will burn hotter, faster and longer. Where most canopy trees survive normal, natural forest fires, the intensity of these fires often kills or severely damages all the plant life over extensive areas. These fires can move at high speeds on several fronts, so frequently trap and kill many of the local birds, animals and insects too.
