Nature and Myth
Gregg Easterbrook makes a good point about forest management and our perceptions of nature:
Why is Southern California burning? Because it's supposed to, as far as nature is concerned, at least.
Before people began interfering with forests in the arid Western United States by "managing" them--and research shows that indigenous Americans were engaged in significant forest management long before Europeans arrived--a natural cycle of forest fire and regrowth was standard.
When men and women settled the American West in large numbers in the nineteenth century, they began fighting wildfires. One result was that forests became denser, because the periodic minor conflagrations that occurred naturally in the West, removing brush and tinder ("fuel," to foresters) stopped occurring. When Lewis and Clark and others of the period arrived at West Coast forests in the nineteenth century, they described open woodlands through which anyone could easily stroll. Today, most forest areas of the West are so thick you can't go off-trail without a machete. Periodic small fires no longer take out underbrush and "understory," the medium-sized vegetation that dies, dries, and provides fuel to heat trees to the temperature at which they burn. Stopping periodic small Western forest fires allows fuel to accumulate, increasing the chance of an eventual fierce, uncontrollable fire that heats trees to the flame point across a large area. Stopping periodic small fires, and thus allowing the woods to grow dense, also means the condition people think of today as "natural" for Western forests--thick growth and lots of very old trees--is in most cases artificial.
A little known but important fact about the western ecosystem is that the abundance of wildlife observed by Lewis and Clark was an anomaly. Prior to Columbus, the Native-Americans held animals numbers in check through hunting. But when European diseases wiped out most of the indigenous peoples, game numbers exploded.