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Are drunken trees (no, it's not the vodka!) a sign of alarming Siberian climate change?

By 0 and 0 and 0
07 August 2012


Team together: l-r, Guoqing Sun, Ross Nelson, Jon Ranson, Slava Kharuk, Sergei Im and Pasha Oskorbin. Behind the group is a basaltic hill, with a forest killed by fire. A small regeneration is apparent under the dead trees. A band of healthy larch, unburned by fire, lines the river bank.

This follows the latest field trip of a US-Siberian team led jointly by Dr Jon Ranson, Chief of the Biospheric Sciences Branch at NASA's Goddard Space Flight Center and Slava Kharuk of the Sukachev Forest Institute, Krasnoyarsk.

In a series of compelling postings from his July rafting journey covering hundreds of miles on the remote Embenchime River, starting close to the Arctic Circle,  Dr Ranson explains why we should all be worried by startling changes observed by this international team. 

The apparently intoxicated trees are by no means the only, or even most serious, phenomenon found by these scientists on what is their tenth trip to such remote locations in search of an understanding of the impact of climatic changes. 

Yet this lurching larch is a form of proof that change IS happening in the boreal ecosystem - named after Boreas, the Greek God of the north wind and comprising worldwide almost 20 million square kilometres (over 7.7 million square miles) of forest (in Russian mainly larch) in an area 29 times the size of Texas.

He explains in a posting from the Embenchime carried on the NASA website: 'As we move further south, we see other signs suggestive permafrost degradation.  We've seen a few areas of 'drunken forest'.

'That's a rather poetic term for a forest stand where the trees no longer stand upright, but lean at odd angles - some to the right, some to the left.  This odd-angled forest gives the appearance, I guess, of a group of drunks walking home from the bar, unable to stand up straight.  I don't know about that, but I do know that drunken forests have nothing to do with alcohol.  It has to do with soil.  Where the permafrost melts and the soil warms, the shallow roots can no longer hold up the taller trees, so they 'slip', ending up growing at odd angles.

'Larch trees have shallow root systems, and often grown in thin layers of soil that lay above permafrost. When permafrost begins to melt, the soil begins to shift and can no longer support the trees. As a result, the trees begin to lean, usually in various directions. This is known as a 'drunken forest', because the trees can no longer stand upright.

NASA expedition, consequences of the global warming

NASA expedition to study consequences of global warming

Larch trees have shallow root systems, and often grown in thin layers of soil that lay above permafrost.  When permafrost begins to melt, the soil begins to shift and can no longer support the trees. Pictures: NASA Dr.Ranson blog

'We also are seeing slumps and landslides along this section of the river.  When permafrost lies below a layer of soil, that permafrost is frozen and firm - and it doesn't easily shift or slide.

'As it melts, however, the soil layer deepens and becomes moist and soft.  The weight of the trees and vegetation can make the soil sink or slide, depending on topography and soil depth.  If the slope is steep, large landslides can occur as permafrost melts.  We're seeing both slumps (small sagging areas) and landslides as we move down river.'

This last description was towards the end of the party's trip down the Embenchime, often camping on river islands for the night. 

Throughout their arduous journey, they compared  what they see on the ground with detailed satellite data.  Their trip took on a special significance since it coincided with fires raging across Siberia. This happens annually, and while this year maybe worse than many, it is still a phenomenon normally taken in their stride by Siberians.  Perhaps, after reading Dr Ranson's account, we will not be so sanguine in future. 

In one posting earlier on the route, he explains: 'Today we had quite a lot of measurements to make.  We walked the lines where the GLAS instrument on the ICESat satellite had collected data, and we planned to measure all of the GLAS footprints.  

'We discovered that some of those footprints fell in burned areas.  That wasn't a total surprise, but we found that in several of those plots, there were no trees at all to measure.  The fire had taken everything, and there was no regeneration at all.  In other GLAS footprints there had been fire as well, but also some reproduction. In those plots, we took made our standard measurements.

'Slava collected some fire-return data, including several discs in the general area.  He said that, based on his quick field examination, the last fire here had burned about 25 years ago.  If that is accurate, then there has been remarkably little regeneration here over the last 25 years. Larch grows very slowly, and they don~t take up a lot of carbon until they get big.  We cut one tree that was 7-8 feet tall and it was only 17 years old.

'The fires here appear to have been really extensive, as well as really frequent.  In some locations, there are drainage ditches and wet areas, and in those wetter areas stands of older trees have resisted fire and survive.  

'These survivors provide a source of seed, so some regeneration is occurring.  And many stands show normal heavy regeneration after the fires.  However, the lasting impression I have of today's work is walking in the burned areas, and seeing very little regeneration in some of them.  Such a thing is so unexpected that it was an amazing, and sobering, experience.

'As we've travelled down river, my mind keeps turning over what I've seen.  The lack of regeneration in some of these areas challenges the traditional notion of vigorous regrowth of larch after fire.  

'It also has bigger implications in regards to the forest response to a warming climate.  I do not think we really understand what is going to happen to our boreal forests, and how the fate of the boreal forests will affect our Earth and our own lives, in a warming climate.

'After a fire, larch stands tend to reproduce very vigorously. In some of today's plots, reproduction was very sparse or nearly non-existent. The last tree-killing fire in this area was estimated to have passed about 25 years ago - but in that time, no larch has regrown. This finding may challenge traditional thinking about the dynamics of larch forests after fire, and brings forward questions about the effect of more rapidly returning fires on the reproductive ability of larch forests.

'The traditional notion is that the boreal forests, especially these larch (larix gmelinii) forests, live in a rather symbiotic or at least balanced relationship with fire.  It is accepted that fire helps larch regenerate by improving the soil to make it more favourable for larch seed germination, and by reducing competition, allowing for the rapid growth of larch saplings.  Also, mature larch form a thick, fire-resistant bark, so most fires allow mature trees to remain, so seed sources are preserved.

NASA expedition, Dr. Jon Ranson

Dr. Jon Ranson, pictured during his 2012 visit to Siberia. Picture: Dr. Ranson NASA blog

'What we saw in the northern forests was compatible with this traditional hypothesis.  We saw burned stands with thick regeneration.  And in the northern forests, the burning seemed to be somewhat controlled, because small areas of the forest were dry, with wet areas right next to them.  

'It appeared that the dry areas would burn, but the wet areas might tend to control fires, so vast hillsides were not destroyed at one time.  Also, we know from several studies that in the northern boreal forest fire return interval in any one stand is very long. All this, put together, means that small areas of forest burn regularly but infrequently, leaving time for replacement trees to grow back to adult size, so they become seed sources long before the next fire comes through. 

'It also means that mature trees survive nearby to the burned area, and they could provide an immediate source of seed. However, as we move south, in this area, we seem to be seeing, in at least some areas, a failure of regeneration after fire.  That is a very troubling thought.

'The theory is that these forests are generally a carbon sink for the world - they are growing, and as they grow they absorb carbon. They hold carbon in their roots and trunks, binding it and helping keep it out of the atmosphere.  We know that when forests burn, carbon is released, and at that time, the forests are a carbon source.  

'However, the thinking is that the regeneration is so strong afterwards, it allows the rapidly growing trees quickly to absorb a lot of carbon, so that even with intermittent forest fires, the boreal forests remain a sink.

'There also seems to be an assumption that as the climate warms, and as permafrost thaws, that the soil will be more favourable for tree growth, so the trees will become bigger and more robust.  This should, theoretically, allow the forest to take up even more carbon, and potentially mitigate, to some degree, the effect of warming.  This all makes sense ~ but we do NOT know, for sure, if it is true.'

He emphasised: 'Based on what we see, I'm not really sure we can assume the traditional notions.  It is clear that in a warming climate, the forests become dryer and fire returns more often.  Even with strong regeneration, fire has a limiting effect on the size of the forest, however.  It is really not clear if the forests will ultimately be bigger and faster-growing in a warming world, or if fire will limit the growth potential of these forests.

'If fire returns quickly enough to kill off trees before they reach sexual maturity, then it may well be that we lose the regeneration - and without new trees, we won't have replacement forests to uptake the carbon.  A lot of current climate theory is counting on regenerating and growing forests to take up carbon, to mitigate the effects of warming.   But what if rapidly returning fires end up killing off the forest before the trees are old enough to reseed?   We need to consider this possibility in our modelling of carbon, and include the potential impact of such a scenario.

NASA 2012 summer expedition to Siberia

NASA 2012 summer expedition to Siberia 

Vivid sunset with smoke from wildfires seen above the river and, below, Dr. Guoqing Sun pictured trying to get online. Pictures: Dr. Ranson NASA blog

'In addition, there is a lot of data that suggests that as permafrost melts, it doesn't just become more fertile soil for tree growth.  As the ice melts, the highly organic soil begins to decompose.  Decomposition of permafrost releases carbon as well as methane ~ both powerful greenhouse gases.  

'It may well be that in a warming climate, when a tipping point is reached, these forests may not only be unable to mitigate the effect of the carbon we humans pump into the atmosphere, but may also become a source of carbon and methane from both thawing permafrost and repeated fires. I don't know what will happen - but we need to take a hard look at these issues, and soon....

'What we have both found is that the larch is not reproducing well here.  On both sides of the river, it appears that fire is returning more frequently, and that they may not have time to reach seed-bearing age before fire returns.  If there is no seed available, because the fire returns too soon, then the next generation of larch may be wiped out.'

They found that birch was taking root in some areas where larch was not. 'I'm not sure what this means, but it is different than what we are used to seeing.  We are used to seeing strong larch regeneration after a fire - and there is some evidence that it does not always occur. 

'We all need to consider this finding carefully.  It challenges our comforting hypothesis that the forests will be able to mitigate climate change.   To a point, we can expect to forests to help.  But when the climate is so warm and dry that fire returns to an area quickly - I don~t think we really know what will happen then.  

'It is possible that under rapidly returning fire, the forest may not be able to maintain itself.   We really need to study these questions earnestly - and quickly.   It is truly important for us to understand what is happening to our home planet, our beautiful Earth.'

As they sailed downstream towards the confluence with the Kochechum River, and their final destination of Tura, Dr Ranson noted: 'We saw our first spruce.'

They sense that a few decades earlier, such a sighting would have been nigh on impossible. 

'Spruce like warmer and milder conditions than larch, and can't survive in the farthest northern regions.  In recent times, however, spruce is moving further north and at higher elevations in many places.  Slava has said that, in the valley to the south of this one, he has seen some spruce growing.  But he did not know it was growing in the Embenchime valley.

'We are only seeing a few spruce, here and there.  We have seen them on the southeastern part of the river, the sunny side of the river.  I confirmed a small tree, maybe 10-15 years old, growing right on the southeastern shore.  We also believe we saw some older trees, further upriver.  But they were distant and we didn't have time to stop and confirm.

'Siberian spruce and Siberian Larch are both conifers, and both carry their seeds in cones. The larch cone is small and has small, winged seeds. The spruce has a larger cone. Spruces, which are dark-needled conifers and retain their needles all winter, cannot live in the extreme climates that suit the deciduous Larch. Spruce has recently begun to be found living further north and at higher elevations than its historic range.

'When Siberian spruce (Picea obovata) begins to grow where only larch once grew, it suggests a warming climate.  Larch is an extremely hardy tree, and lives in harsh, cold, dry and wind-blown conditions where no other tree can live.  It is also very shallow-rooted, so it is well adapted to the far north, where permafrost keeps the land just under the surface frozen year round.  Spruce wants to root more deeply, than is possible in frozen soil, so they don't do well in permafrost.  When spruce encroaches on larch, it can be a clue to permafrost melting underground.'

The 'drunken forest' was another sign, but so, too, was a bird he spotted. 

'There was a very curious thing I saw yesterday.  I saw a little bird, with speckles on its breast and a fairly heavy bill.  I thought it looked like a thrush of some type.  It was a remarkable little bird, so I spoke to Slava about it.  He said I had described a 'Cedar Bird', so he thinks that is what I must have seen.

'The Cedar Bird is a curious little bird, and if that's what I saw, it's even more curious that one is flying around this far north. It has a symbiotic relationship with the Siberian pine, a southerly species of tree. 'Cedar Bird' is a local name.  The scientific name is Nucifraga caryocatactes and is better known as the Siberian Nutcracker or Spotted Nutcracker.  

'Its favourite food is the seed, or nut, of pine trees.  The Siberian pine has a large seed, and it is eaten by the locals as a tasty delicacy.  The Cedar Bird competes with people for this resource - so sometimes locals aren't too fond of Cedar Birds.  

'They are friends of the pine, however, because the bird loves the pine nuts so much it gathers a lot more than it can eat, and caches the excess to come back to at a later time.  Oftentimes, the cached nuts are forgotten - and new pines can grow from them, often far from the original seed tree.  The Cedar Bird really helps expand the distribution of Siberian pine.

'The thing is - this is not where pine lives.  The climate is much too harsh.  But the cedar bird is very tightly associated with pine forests - it does not like to each much else.  The one I saw might be a just-passing-through migrant.  Or I might have seen something else. But if it was a Cedar Bird, then does that mean pine are also close?  Or is adapting to eat the seeds of spruce, as well?  I have no idea: but these seem to be interesting questions to ponder.'

* Joanna Howl in NASA Earth Observatory: 'The NASA-Sukachev scientists have been intensely interested in Siberia's boreal ecosystem for decades. Dr Jon Ranson and Dr Slava Kharuk have both committed their entire careers to improving understanding of the region, and have partnered in their study since 1991. The Embenchime River Expedition will mark their 10th expedition together in the remote forests of Siberia'.

Please see Dr Ranson's link at:

Comments (5)

Itr is a first step to make the land arable. First, there is clad as ice becomes water, but eventually that water will be absorbed by the land and by the sun. In two decades Agriculture will be possible in those lands.
Enrique, Spain
01/08/2013 19:33
That is not bad. As weather conditions improve, the land is becoming better for farm. Agriculture will be possible in those lands in two decades, so the melting permafrost and better temperatures will make the land more habitable for human beings.
Enrique, Spain
31/07/2013 09:05
this joke about vodka in any story related to Siberia is way too old! the story is interesting, though, thanks
annoyed Russian, Siberia
12/08/2012 01:42
Keep out NASA spies
Anon, Star City
12/08/2012 00:35
now thats a read for a long winter evening. interesting about melting permafrost, its like another bit of climate change jigsaw
Lisa, somewhere in Spain
09/08/2012 13:43

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