July 14th, 2012 by Joanne Howl
http://earthobservatory.nasa.gov/blogs/ ... a-features
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Fires are a part of the larch forest ecosystem. Although there are no fires at this time, there is evidence of widespread fire in the past. A fire burned in this location about 60 years ago, leaving scattered large trees dead and dying. A strong surge in new larch growth followed. The post-fire forest is characterized by a same-age stand of young larch, punctuated by scattered old, dead trees.
....Dr. Ranson reports:
We fought the river again today, but in the end, we have been successful. We’re now tucked away in camps – the one we wanted to reach yesterday. Again, our trip was a long struggle against the shallows and small rapids. Each spot is about 50 to 100 feet long, and filled with rocks. To get around them, we have to get out and pull the boat. Slava calls these rocky ripples “dragon’s teeth”, because they are sharp and will eat our boats if we let them. We’ve been careful, but the bottom of our boats have suffered, anyway....
We were fortunate in our campground last night. This morning, Slava walked over the hill, and discovered an area where fire had burned about 60 years ago. This morning Slava and Sergei worked that area, collecting samples for the fire return studies. He was quite pleased, and gathered a good deal of useful samples.
Collecting data for fire return studies is a bit more invasive than our tree measurements. To learn a tree’s history, unfortunately, the tree must be sacrificed. We need to collect a disc all the way through the truck, so that we can count the age, look at growth rings, as well as to see when fires singed the bark. We get a tremendous amount of information out of each sample, but Slava makes careful selections, because we don’t want to be cutting down the forest. We sample very carefully and selectively. When we measure trees, we take measurements of every tree above 5 cm in diameter in our study plot. When Slava takes fire return samples, however, he will take only one or two carefully selected trees in the forest.
In order to gather his samples, Slava begins by locating an area that appears to have been affected by fire in the past. He likes to find trees that have a burn scar visible on the trunk. That way, once the sample has been collected, we have a positive date for one fire. He can then carefully analyze the growth pattern, and if there are any other fire scars inside, he can date the years between the fires....