Weblog: Dr. Jon Ranson in Siberia
 

Friday, August 10, 2007

From Evenkiyskiy Region, 10:15 p.m. Siberia (10:15 a.m. EDT)

From Jon Ranson

It has been a long day on the river. The weather was blustery. Wind came up the river at us on and off all day. For the first time we were covered in spray from the river, and I got pretty chilly.

Tonight, we are camping on a beach that is a boulder field. The rocks here are the biggest yet: anywhere from 3 inches to 3 feet in diameter. I’m glad they are smooth! I was impressed by the stony beach the first night of our trip. I had just set up my tent right on the rocks—no other choice. Slava came up to me, smiling, and then said in his quiet way, “Oh, this is not the worst place we’ll camp.” Well, I’m used to sleeping on rocks, but I can say that tonight’s camp IS the worst place. But when you are tired, it is all good.

Today we traveled about 90 kilometers down stream. We made three stops to take samples of fire-scarred trees. Slava showed me one that was fascinating. It was from a tree that had been growing quite slowly for many years. The tree rings were quite close together. Then there was the fire scar—a dark spot that showed the tree had been burned by fire but not killed. After that, the growth rings were huge. The tree had put on enormous growth for several years after that fire. Fires kill the underbrush and reduce competition, so the larches that survive have better access to nutrition and light. This one took advantage of that and grew beautifully. I don’t think I have ever seen growth rings that large on a larch before.

 
  Growth increments
 

Yesterday we saw our first birch tree; it was very small, but still a birch. Today we saw more birch and our first spruce. The forest is still dominated by larch, but it is changing.

I haven’t said much about this river, but it is really such a part of our experience! I have been really impressed with how the waters rise and fall so quickly. We’ve had to break camp and move to higher ground because the waters rise so fast. And we’ve had to drag our boats a long, long way back to the river, when the water fell so far overnight. The rhythm of the river is almost like breathing—inhaling and exhaling, rising and falling. It almost seems alive.

The Kochechum looks really big to me; it’s over 100 meters wide in many spots. That’s about the length of an American football field. But for Russia, this is a very small river. The waters run into the Lower Tunguska, which is a big river, and then to the Yenisey, which is huge. Then into the Arctic Ocean.

Now, that’s an important thought.

These rivers carry a huge volume of fresh water into the salty Arctic Ocean each day. As the temperatures in Siberia increase, there will be more melting of snow and permafrost. The rivers will carry a greater volume of fresh water, spilling it into the ocean. What happens to the ocean as the salinity drops? What changes will we see in the ocean ecosystems? How might that change affect Earth—the climate and the ecosystems? Hydrologists want to know, and they are actively studying the changes in the world’s rivers and oceans. There is much to learn, here in Siberia.

 

This photo compares tree cross-sections for post-fire larch growing on soil with a deeper root level (left) and one restricted by permafrost (right). After the latest fire, the insulating moss layer and nearby trees were removed. In both cases, the post-fire growth increase resulted from increased available nutrients and light. The wider rings of left tree result from deeper root levels from deeper permafrost melting. The implication is that, given better growing conditions, the larch might sequester a lot of carbon in the wood. This is not the only thing that will happen since more soil carbon would be released with increased temperatures, and the larch would eventually lose its competitive advantage with fewer cold-adapted conifer species, primarily Siberian pine and spruce.

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