Which trees dominate the Tanana River valley in Alaska?

[Borek]

During our trip through the northern Europe I have seen something that I don't understand. I was always under impression, that in a harsh climate - that is up in the mountains, or up North - coniferous trees are those best suited to live in the place and hence they should dominate the landscape. However, it turned out to be wrong - at least in the places we have seen. Northern Scandinavia was dominated by some kind of birch. Lower than the birch that grows further south, and with slightly twisted branches, still a birch.

Baffles me.

Expected:

Seen:

Second picture was taken further north than the first one, and it was not an accidental place where birch dominated - that was the general trend.

 

[arildno]

Birch is VERY hardy, particularly the twisted dwarf type.
It is the uppermost-growing tree at the tree limit in the mountainous regions of Norway.

Winter picture near the tree limit:
http://www.google.no/imgres?imgurl=...&ndsp=16&ved=1t:429,r:14,s:0&biw=1259&bih=627

 

[Borek]

That's what I have seen in July, but if you have seen BBC's Planet Earth it talked about coniferous trees growing far north and it was even illustrated with a nice shot of forest that ended and was replaced by tundra. Movie was just confirming what I thought to be the reality for over 30 years...

 

[turbo]

I was a ski-patrol member throughout most of my teens and worked at some ski areas that were on some pretty harsh mountains. The birches might have been twisted, knarled, and stunted, but there always seemed to be birches near or at the peaks.

The dominance of conifers in the boreal forests might have more to do with the critters that live there than we think. Trees are pretty stationary, so they can self-seed with the help of wind, and they can propagate with the help of animals that gather their seeds for food and drop some seeds, lose some, bury some and not return for it... Here in Maine, we have lots of voles at higher elevations - they might have a hard time surviving in the boreal forest, though. Might have to watch the Planet Earth segment on the boreal forests to see if there is a distinct animal population to do this for the trees.

 

[arildno]

The critter dwarf birch goes under the name Betula Nana, with the following cozy distribution, according to Wiki:

Distribution
B. nana is native to arctic and cool temperate regions of northern Europe, northern Asia and northern North America and it will grow in a variety of conditions.It can be found in Greenland. Outside of far northern areas, it is usually found only growing in mountains above 300 m, up to 835 m in Scotland and 2200 m in the Alps. Its eastern range limit is on Svalbard, where it is confined to warm sites.

http://en.wikipedia.org/wiki/Betula_nana

 

[Borek]

According to wiki dwarf birch doesn't grow higher than about 1.2 meters (say 4 feet for those not used to meters) - trees Ihave seen where much higher. Not as high as normal birch here in Poland, but we are still talking about 10 feet instead of 4.

 

[arildno]

According to wiki dwarf birch doesn't grow higher than about 1.2 meters (say 4 feet for those not used to meters) - trees Ihave seen where much higher. Not as high as normal birch here in Poland, but we are still talking about 10 feet instead of 4.

You're right!
It is the Betula pubescens you saw, white/downy birch.
It grows on Iceland and Greenland as well:

Downy Birch extends farther north into the Arctic than any other broadleaf tree. Specimens of the subarctic populations are usually small and very contorted, and are often distinguished as Arctic Downy Birch, Betula pubescens subsp. tortuosa. This subspecies is notable as being the only tree native to Iceland and to Greenland, where large specimens can reach 5-6 m tall.

Normal size in Norway is 10-20 metres.

http://en.wikipedia.org/wiki/Betula_pubescens

 

[Pythagorean]

Palm Trees in Barrow, Alaska:



(just kidding, that's baleen)

We have black spruce, sitka spruce, ash, cottonwood, and birch in Fairbanks, AK.

 

[alxm]

Betula pubescens and pendula. Those ones look like pubescens (also judging from where they're growing).

But the latter species sometimes gets a genetic defect (Betula pendula carelia, English 'curly birch', Swe/Nor 'masurbjørk') that makes it grow all twisted, as well. And a quite beautiful wood (http://img224.imageshack.us/i/reevefox31758ua.jpg/" ), which is held in high regard in the Nordic countries.

 

[Gannet]

From Flannery, Tim; The Eternal Frontier, an ecological history of North America and its peoples; Atlantic Monthly Press, New York, NY; 2001; p031.

He states "The optimal shape for the tree to collect this polar light would be a cone, standing alone, with no neighbors within shadow range to steal the precious lateral light."

This makes me wonder if the average included angle at the apex of the conical shape is twice the Earth's tilt axis = 2 x 23.5 = 47 degree?

 

[Jon Richfield]

That's what I have seen in July, but if you have seen BBC's Planet Earth it talked about coniferous trees growing far north and it was even illustrated with a nice shot of forest that ended and was replaced by tundra. Movie was just confirming what I thought to be the reality for over 30 years...

One should be careful about generalisations in biology. Plants often have specialisations to particular physiological limits, so that one finds a particular species growing at a given temperature plus or minus say 10C, and surviving say 5C above or below those limits. But exactly which families or even orders they might be in may depend on the evolutionary history and lots and lots of hand-waving. Pines eg grow far north, but, as you point out, not all the way, and not all species! One also get them all the way to the equator, but again, not all species! In fact, some conifers that do fine in a warm country can't take cold, and vice very much versa. Many simply stop growing around say 20-25C. Some barely start growing at nearly those temperatures.
As for the angiosperms such as birches, what else is new? There are all sorts of phorbs growing in the tundra, right? Why should birches be excluded? And some of the phorbs are perennial, right? In fact, a vivid hint is the fact that Betula nana (that on the tundra seldom grows anything like 1m high) is evergreen! It can't afford to regenerate its leaves every season.

But why bother with wimps like birches? Try this site:
http://en.wikipedia.org/wiki/Salix_arctica
I quote: "Despite its small size, it is a long-lived plant, growing extremely slowly in the severe Arctic climate; one in eastern Greenland was found to be 236 years old."
That small size is cm rather than m high. Such organisms leave me with a sense of uncanniness. And again:
"The Arctic Willow is a food source for several Arctic animals. Muskox, caribou, Arctic Hare and lemmings all feed on the bark and twigs while the buds are the main food source of the ptarmigan.
Both the Inuit and the Gwich’in make use of the Arctic Willow. Twigs would be used as fuel, while the decayed flowers (Suputiit) could be mixed with moss and used as wicking in the kudlik."
"A sense of uncanniness"? Should I add: "A sense of humility" ... "tenderness"...?

 

[Borek]

What are phorbs?

I am far from overgeneralizing, and single birch here and there would not surprise me, what I was surpsised by was the birch forest. After all conifers (at least some) evolved to survive in harsh, snowy climate - conical shape to catch the light, branches that easily go down to get rid of snow, evergreen thin leaves and so on. In Poland I don't remember seeing trees other than conifers in upper parts of the mountains, thus I expected similar situation far north. Is the birch forest standard in whole northern hemisphere, or is it just a scandinavian thing?

I didn't know Betula nana is evergreen, that's interesting - logical, but unexpected.

 

[Jon Richfield]

What are phorbs?

Apologies. That is the way I always had spelt it, and the root is the Greek for pastures: "phorbe", but it seems that the popular spelling nowadays is "forb", which btw, you may find in Wikipedia. However, in case you don't want all the sordid details, it is roughly speaking, any herbaceous plants other than grasses and similar plants such as restios and sedges. Typical examples of forbs would be alfalfa, daisies and so on.

To make matters worse, I suppose I could simply have said non-woody plants (i.e. including the grasses etc) without having to change the sense of what I wrote.

I am far from overgeneralizing, and single birch here and there would not surprise me, what I was surpsised by was the birch forest.

Sorry again; I hope I did not give you the impression that I was being snotty. I was referring to the tendency of many people to accept such simplistic rules of thumb, for example that one gets conifers last and coldest, as being definitive. (They commonly do, you know!)

After all conifers (at least some) evolved to survive in harsh, snowy climate - conical shape to catch the light, branches that easily go down to get rid of snow, evergreen thin leaves and so on. In Poland I don't remember seeing trees other than conifers in upper parts of the mountains, thus I expected similar situation far north. Is the birch forest standard in whole northern hemisphere, or is it just a scandinavian thing?

I don't wish to sound knowledgeable about alien things like tundra and sastrugi and ptarmigan and all those other cosy things you have up there, living as I do more than 10 megametres from the nearest specimens, but afaik, Arctic birch is a Eurasian thing. In America the treeline seems to peter out in conifers. but as you can see, the fact that one can have birch beyond conifers, and Salix arctica beyond birch, means that conifers are not the only permafrost-hardy trees in the arctic. Interestingly, in South America the corresponding southernmost tree is Antarctic Beech, Nothofagus antarctica, the southernmost tree species I know of on the planet (or elsewhere, but then I don't know other planets.) We have fewer indigenous conifers down here anyway.
And no permafrost that I know of.

I didn't know Betula nana is evergreen, that's interesting - logical, but unexpected.

Interesting, logical, but unexpected -- that pretty well sums up half of biology if you like!

 

[Borek]

Thanks for the information

Interesting, logical, but unexpected -- that pretty well sums up half of biology if you like!

I am from a chemistry background, nothing surprises me

 

[Gokul43201]

From my experience, treeline on mountains is dominated by conifers (especially fir, pine, and spruce) in the US. And this is true of the Cascades and Sierra Nevadas out west as well as the Appalachians in the east. I can't recall anywhere that I remember seeing birches at high elevation (plenty at lower elevations though).

 

[Jon Richfield]

I am from a chemistry background, nothing surprises me

You reckon? hm?

I have seen almost as many surprised faces in chem labs as in bio labs! I can't remember for sure, but was it Isaac Asimov who said something like that most great scientific discoveries began not with "Eureka", but with "...That's funny...!"
Mind you, many a scientific career ended with just such a remark!

In passing, Salix arctica definitely does occur in the whole circumpolar tundra. However, as you can see if you get curious enough to check this site, tundra birch shrubbery does occur in the American North as well:
http://www.crrel.usace.army.mil/sid/personnel/sturm/pdfs/JClimateShrubs.pdf

Of course, calling Salix arctica a tree, or even the "world's smallest tree" is an arguable terminology. It certainly is a "woody plant" and the world's northernmost at that, but "sub-shrub" would be a less debatable term.
Still, in my unscientific sentimentalism, I am willing to call it a tree and Pluto a satellite of the sun, and hydrogen a metal -- in the core of Jupiter!

 

[arildno]

Can we end this nonsense about "over-generalization" that numberblind non-scientists always are blathering about, never having understood the damndest thing about distributions and frequencies?

 

[Pythagorean]

Borek, we have lots of Birch in Alaska. They're trunks are a lot straighter than the birch in your picture though and their branches are way skinnier and shorter

 

[Borek]

Borek, we have lots of Birch in Alaska.

Question is - what happens in the northern parts of Alaska? What is the latest tree present far north? And I don't mean several centimeters high salix , rather trees that form something that can be classified as a forest.

Anchorage is at about the same latitude as Helsinki and both Alaska and scandinavia end at about the same latitude, so in a way they are comparable when it comes to climate. Although one have to remember scandinavia is warmer thanks to the Gulf Stream.

 

[Pythagorean]

Question is - what happens in the northern parts of Alaska? What is the latest tree present far north? And I don't mean several centimeters high salix , rather trees that form something that can be classified as a forest.

Anchorage is at about the same latitude as Helsinki and both Alaska and scandinavia end at about the same latitude, so in a way they are comparable when it comes to climate. Although one have to remember scandinavia is warmer thanks to the Gulf Stream.

Here in Fairbanks (middle of Alaska in terms of North-South) we have whole southern hill sides full of birch (note that Anchorage is far south of us and is on the coast. The coast in Alaska tends to exhibit a lot of spruce). Here's something a bit more north, where it seems like the spruce dominate:

"The taiga, or boreal forest, reaches it northern limit at about latitude 67°30'N along the river valleys of the south slope of the Brooks Range. The extensive forest cover found south of the mountains thins into scattered stands of spruce mixed with hardwoods that follow the river valleys north into the mountains to an elevation of about 2,100 feet. This spruce-hardwood forest takes two forms. White spruce usually in association with scattered birch or aspen is commonly found on moderate south-facing slopes. Heaths, such as bearberry, crowberry, Labrador tea, blueberry, and cranberry are common, as are willows. Lichens and mosses cover the forest floor along with a variety of herbs. Some large, purer stands of white spruce occur along rivers such as the Kobuk; balsam poplar are found with spruce in such areas. On the north-facing slopes and on poorly drained lowlands, black spruce is predominant. These trees, which grow very slowly, are usually stunted and often scattered. It is not uncommon to find a 2-inch diameter tree that is 100 years old. The understory in these areas is spongy moss and low brush."

from http://www.gates.of.the.arctic.national-park.com/info.htm

 

[Jon Richfield]

Can we end this nonsense about "over-generalization" that numberblind non-scientists always are blathering about, never having understood the damndest thing about distributions and frequencies?

I cannot but admire the forthrightness of your comparatives, characterisations and attributions, but could you please elucidate your antecedents and objects? For example, how did distributions and frequencies get into this discussion? The references to generalisation, over-, under- or in between, that I have seen in this thread so far, had more to do with semiotics and isomorphisms than stats.
Once you clarify that, it should be easier to tell whether you are improperly appropriating general (you should please excuse the expression!) terminology for a specific (excuses once more!) discipline that has no statistically valid claim of precedence.

 

[Gannet]

http://dl1.yukoncollege.yk.ca/anth220pp/stories/storyReader$10"

At about the same latitude as Fairbanks, the {Tanana} river enters the Tanana-Kuskokwin lowland where it joins the Yukon River at the village of Tanana, approximately 600km as the crow flies from its sources (the Nabesna and Chisana Rivers).
The Tanana River valley is shielded from the effects of the Pacific ocean by the Alaskan Range and has a high variation in yearly temperature, ranging from a summer high of 30C to a winter low of -50C. The valley is within a region of Boreal forest in which the dominant tree species are white and black spruce (Picea glauca, P. mariana). Paper birch (Betula papyrifera), aspen (Populus tremuloides), and cottenwood (Populus spp.) are found in areas and the vegetation in the valley is largely influenced by altitude, summer temperatures, and the permafrost layer which is discontinous throughout the area. (West F.H, 1996)