The Yosemite Inferno In the Context of Forest Policy, Ecology and Climate Change 111
Lasrick writes "Andrew Revkin at DotEarthblog posts an assessment of the drivers of wildfire trends in the American West. He shows a graph of fire activity for the past 400 years in the Yosemite-Mariposa area, and a rather surreal time-lapse video of the current Rim Fire now burning in and around Yosemite."
Decrapified URL (Score:5, Informative)
http://dotearth.blogs.nytimes.com/2013/08/29/the-yosemite-rim-fire-in-the-context-of-forest-policy-ecology-and-climate-change/ [nytimes.com]
Just in case anyone wants to actually, you know, read the article rather than being taken to a login screen.
Re:so its not global warming? (Score:5, Informative)
It's a combination of factors, of which warming is one. Probably the best summation from TFA:
"When you look at the long record, you see fire and climate moving together over decades, over centuries, over thousands of years," said pyrogeographer Jennifer Marlon of Yale University, who earlier this year co-authored a study of long-term fire patterns in the American West.
"Then, when you look at the last century, you see the climate getting warmer and drier, but until the last couple decades the amount of fire was really low. We've pushed fire in the opposite direction you'd expect from climate," Marlon said.
The fire debt is finally coming due.
This is pretty much what you'd expect. Leaving aside the question of the human contribution to warming and what we can do about it, the fact of global warming is established to all but the shrieking denialists; it's also a fact that under normal circumstances, ecosystems adapt to any change in climate--sometimes better than others, but they do adapt. Our fire suppression policies for the last century or so have prevented what would have been the normal adaptation from taking place. So now we're getting it all at once.
Re:so its not global warming? (Score:5, Informative)
Trees, over their life span, may sequester carbon. But forests do not. They are carbon neutral.
This is true over the very long term--in the extreme case of Carboniferous forests, 300 million years or so; we're only now getting around to releasing their carbon back into the atmosphere by burning coal. Obviously in most cases dead trees rot and release their carbon faster than that, but "fast" is relative, and it's still a very slow process by human standards. And most of the carbon from a dead tree doesn't go straight back into the atmosphere; it's taken up by other organisms, and ultimately goes back into the soil as part of the organic waste that makes forest floors into fertile ground for the next generation of trees. Rotted wood, bits of smaller plants, bug poop ... it all looks like a buffet to a sapling.
Tree killers (Score:4, Informative)
This is exactly what I said in the last article about this fire.
If you let fuel build up you create bigger hotter fires that kill trees and cause massive damage. It is evidenced by living trees with burn scars that trees can live through fires. When the fire get hot enough and enough bark is burned the tree dies. Another issue is that most tree trunks are bare a fair way up. This allows low burning fires to move through the forest and burn the brush. If these low burning fire get hot and high enough ther start burning the tree branches which also kills the trees. It also creates a crown fire [forestencyclopedia.net] which can spread rapidly and devastate large areas.
It is well known that proscribed burns are good for forests. We just are not doing them enough. We don't want to see blackened areas in our parks even though it is necessary to protect them from bigger fires.
Re:so its not global warming? (Score:5, Informative)
Parent post is using some very incorrect assumptions.
Rotting vegetation does not release all the carbon that was sequestered during growth into the atmosphere. Much of it is transformed into other living things: termites and other insects, nematodes, fungus, etc. A log in contact with dirt becomes more soil; it does not evaporate into gases. The carbon is sequestered for as long as the ecosystem remains healthy and growing.
In a forest fire, a large amount of CO2 is released, but also a large amount remains in unburned wood (especially in the root systems) and in charcoal. The roots rot, as described above: that carbon is sequestered. The unburned wood above ground eventually rots as well; more sequestering. The char weathers into small bits over time and eventually enters the soil as biochar. That carbon is not only sequestered, but has become an important substrate to an enriched ecosystem. [One gram of biochar has an active surface area the size of a tennis court, which captures micro nutrients for slow release as the ecosystem can absorb them, and filters out heavy metals and other pollutants.]
In a forest fire, the ratio of carbon that remains sequestered to carbon that goes atmospheric as CO2 is somewhere between 1:4 and 1:2. Not all of the carbon in a forest is burned in a fire; somewhere between 25% and 33% is retained, basically forever, in the ecosystem as it recovers.
Re:so its not global warming? (Score:4, Informative)
Yes, a good bit of the carbon in rotting vegetation ends up as CO2 eventually. But not all of it; much of it moves from part of one living thing to a part of another. Trees are predominantly made of cellulose, which is polymer of a simple sugar. Much of a rotting log is literally being eaten by bacteria and animals that can consume cellulose: this feeds the ecosystem at its base level.
Temperature, humidity, and other factors affect the speed with which rot occurs, but do not affect the process or its eventual results. Some fraction of what was once a log becomes free CO2, but a much greater portion moves into the region's ecology.
The conifer forests are sometimes described as "primary soil builders". Partly because their roots begin to break up the bedrock of mountains, but also because when they die, their products of decomposition feed the nascent soils.
Re:so its not global warming? (Score:4, Informative)
Why does a 10K year old old growth forest not contain 10x the carbon of a 1K year old one?
Well, shoot. That's easy. The owls and the wolves and the raccoons and all the other critters carry the carbon away, to neighboring ecosystems.
None of this stuff is compartmentalized. The only compartments in ecology are in your head.