Devi et al 2009

See comments introducing this extremely interesting article.

UPDATE: Since some readers are having routing issues downloading/reading this Devi et al paper, I have mirrored it here (PDF) for your convenience. – Anthony


  1. a reader
    Posted Nov 6, 2009 at 3:48 PM | Permalink

    If you google treeline yamal larch you get some papers which discuss treeline movement. The Devi paper in Global Change Biology (2008) discusses a movement of 20-60m during the last century.

  2. bender
    Posted Nov 6, 2009 at 5:51 PM | Permalink

    Holocene Treeline in the Yamal region

  3. a reader
    Posted Nov 6, 2009 at 8:56 PM | Permalink

    Look at figure 8 in the Devi et al paper I referenced above. The graphic of multi-stem tree growth is extremely similar to the “Cru-10”. The burst of growth even occurs at about 1910 where the horizontal stem becomes vertical. Shiyatov was one of the coauthors. In any of the datasets Briffa used, do they specify what tree form of larch they measured?

    In the body of the paper they state that “one to two decades after the stems had started to grow vertically, ring widths increased 2-to 10-fold, which were much greater than the increases in ring width of single stemmed trees during the same period.”

    • bender
      Posted Nov 6, 2009 at 11:00 PM | Permalink

      Re: a reader (#108),
      Devi, N., F. Hagedorn, P. Moiseev, H. Bugmann, S. Shiyatov, V. Mazepa, and A. Rigling. 2008. Expanding forests and changing growth forms of Siberian larch at the Polar Urals treeline during the 20th century. Global Change Biology 14:1581-1591.

    • bender
      Posted Nov 6, 2009 at 11:06 PM | Permalink

      Re: a reader (#108),

      In the body of the paper they state that “one to two decades after the stems had started to grow vertically, ring widths increased 2-to 10-fold, which were much greater than the increases in ring width of single stemmed trees during the same period.”

      I just read this part of your statement now. In effect, a crosspost. You are on to it.

    • Layman Lurker
      Posted Nov 7, 2009 at 2:48 AM | Permalink

      Re: a reader (#108),

      An excellent find. If I am interpreting this right, old living trees (200+ years) are allmost just as likely to be multi stem as single stem overall. According to figure 6 the only trees older than 300 years were multi stem. The relative proportion of old multi stem vs. old single stem trees varies among the 3 altitudinal gradients sampled – one is mixed, one is dominated by single stem, and one by multi stem. IMO It looks to me like a bi-modal growth population of old trees.

      Besides being pertinent to the population homogeneity issues, it is a case example of the metadata analysis which IMO should accompany every published chronology. It also sheds light on increased precipatation during the 20th century and the physical dynamics between open and closed canopies at a shifting ecotone. Not exactly the conditions we would envision for a stationary and homogeneous growth population.

  4. bender
    Posted Nov 6, 2009 at 11:00 PM | Permalink

    Located here:

    Click to access 081119_GCB_Ural.pdf

  5. bender
    Posted Nov 6, 2009 at 11:04 PM | Permalink

    The ongoing climatic changes potentially affect plant growth and the functioning of
    temperature-limited high-altitude and high-latitude ecosystems; the rate and magnitude
    of these biotic changes are, however, uncertain. The aim of this study was to reconstruct
    stand structure and growth forms of Larix sibirica (Ledeb.) in undisturbed forest–tundra
    ecotones of the remote Polar Urals on a centennial time scale. Comparisons of the current
    ecotone with historic photographs from the 1960s clearly document that forests have
    significantly expanded since then. Similarly, the analysis of forest age structure based on
    more than 300 trees sampled along three altitudinal gradients reaching from forests in the
    valleys to the tundra indicate that more than 70% of the currently upright-growing trees
    are o80 years old. Because thousands of more than 500-year-old subfossil trees occur in
    the same area but tree remnants of the 15–19th century are lacking almost entirely, we
    conclude that the forest has been expanding upwards into the formerly tree-free tundra
    during the last century by about 20–60m in altitude. This upward shift of forests was
    accompanied by significant changes in tree growth forms: while 36% of the few trees that
    are more than 100 years old were multi-stem tree clusters, 90% of the trees emerging after
    1950 were single-stemmed. Tree-ring analysis of horizontal and vertical stems of multistemmed
    larch trees showed that these trees had been growing in a creeping form since
    the 15th century. In the early 20th century, they started to grow upright with 5–20 stems
    per tree individual. The incipient vertical growth led to an abrupt tripling in radial
    growth and thus, in biomass production. Based on above- and belowground biomass
    measurements of 33 trees that were dug out and the mapping of tree height and diameter,
    we estimated that forest expansion led to a biomass increase by 40–75 t ha1 and a carbon
    accumulation of approximately 20–40 gCm2 yr1 during the last century. The forest
    expansion and change in growth forms coincided with significant summer warming by
    0.9 1C and a doubling of winter precipitation during the 20th century. In summary, our
    results indicate that the ongoing climatic changes are already leaving a fingerprint on the
    appearance, structure, and productivity of the treeline ecotone in the Polar Urals.

    There’s something goofy about 3-6 sigma upticks in radial growth at latitudinal treeline and this transition from lateral to vertical growth may hold the clues.

  6. bender
    Posted Nov 6, 2009 at 11:08 PM | Permalink

    Steve, Kenneth, you guys definitely want to read this paper.

    • Steve McIntyre
      Posted Nov 6, 2009 at 11:19 PM | Permalink

      Re: bender (#113),

      Yes, that’s a terrific explanation of the 6 sigmas. I’ll start a new thread on it tomorrow.

  7. MrPete
    Posted Nov 6, 2009 at 11:58 PM | Permalink

    I mentioned this to Leslie, who replied offhandedly this kind of effect is pretty common!

    Her example, familiar to me if I’d only known what I was looking at:

    One of the most common trees in the high Rocky Mountains is Engelmann Spruce (Picea engelmannii), which easily grows 30m tall.

    However, at treeline (such as Cottonwood Pass, which we often visit), you’ll find a low shrubby bush. That bush is the exact same genus species. Engelmann Spruce, in shrub form.

    In between treeline and lower/wetter elevations, you get a variety of intermediate forms.

    A very complex growth interaction with various climate factors.

    I’ll look around; probably have photo examples of this.

    • Joe Black
      Posted Nov 8, 2009 at 8:13 AM | Permalink

      Re: MrPete (#10),

      Nice photo of Engelmann Spruce log section showing asymmetric and non-linear ring widths.

  8. kim
    Posted Nov 7, 2009 at 1:39 AM | Permalink

    Like gardening.

  9. MrPete
    Posted Nov 7, 2009 at 6:36 AM | Permalink

    Steve, Bender, etc,
    Devi08 Fig 9 is a great illustration of visual communication challenges.

    Here’s the figure without scale numbers. The puzzle: what season(s) and what climate change trends are most and least significant?

    Orig caption: Fig. 9 Average winter and summer temperature, as well as average winter and summer precipitation at the meteorological station of Salekhard, 50 km south-east of the study area. Winter lasted from November to March, summer from June until August. Lines represent moving averages of ten years.”

    Got your sense about this? OK, now peek at the numeric scale in the original figure.

    How different is your answer now?

    Note: The paper’s body, and especially table 4, make their answer to the question quite clear. I’m suggesting this key graph is poorly done; it too easily miscommunicates.

  10. Posted Nov 7, 2009 at 1:11 PM | Permalink

    Dear Steve, sorry for this meta-comment. But aren’t you seeing a decrease of viewers – because of some routing problems? I can only get here through a proxy. And just-ping says that a vast majority of the packets from 38 of their centers are lost:

    The same problem occurs for,, and probably many others. Compare the just-ping script e.g. with

    Best wishes, Lubos

    • Anthony Watts
      Posted Nov 7, 2009 at 7:16 PM | Permalink

      Re: Luboš Motl (#19), Lubos, must be a EU thing, no routing issues here from two separate networks. – Anthony

  11. stephen richards
    Posted Nov 7, 2009 at 1:19 PM | Permalink

    IMO moving averages on graphs with such scatter are totally and utterly meaningless

    • bender
      Posted Nov 8, 2009 at 7:56 AM | Permalink

      Re: stephen richards (#20), There is precious little “scatter” on the winter precip trend 1900-1950. The scatter on the other plots is part of MrPete’s point.

  12. Posted Nov 7, 2009 at 1:23 PM | Permalink

    Lubos, I have not experienced or heard anybody speak of connectivity issues to this site either in the U.S. or U.K.

  13. JWDougherty
    Posted Nov 7, 2009 at 1:41 PM | Permalink

    Why hasn’t anyone mentioned the words “Little Ice Age?” The correlation between grow habit and a known climatic phenomenon is remarkable.

  14. deadwood
    Posted Nov 7, 2009 at 1:45 PM | Permalink

    Strange that nobody noticed this change in form earlier. One would think that this would be documented in the metadata for the proxies.

    • MrPete
      Posted Nov 7, 2009 at 3:03 PM | Permalink

      Re: deadwood (#23),

      One would think that this would be documented in the metadata for the proxies.

      Traditional dendrochronology metadata includes:
      * Date collected
      * Who collected
      * Tree species (standard four letter code)
      * Location of stand to nearest degree (i.e. with a few miles)
      * (Core vs slab source?)

      More modern collections contain more metadata, but don’t get your hopes up for collections to typically contain a full panoply of bio information. Particularly not in the public archives.

      • deadwood
        Posted Nov 7, 2009 at 4:26 PM | Permalink

        Re: MrPete (#26),
        Perhaps not in the archives, but still this change in morphology would seem to me (a mere geologist) as being an important observation to accompany a collection somewhere in its description and thus preserved in the record.

        Perhaps dendro-chronologists didn’t catch this as it did not make it into English language publication, but one would think the Russians would have noted it within their own journals. My experience with the Russians is that are meticulous note takers and would not have missed this important feature.

        Most Russian journals are now routinely translated, a least in abstract form. While I can imagine not taking the extra effort to read the original description in the Russian literature, I would expect researchers for the UN would have access to translation services most other would not. Thus in my estimation, if the change in morphology is the source of the six sigma diffrence, there is no reasonable excuse for not reporting it.

        BTW Bender, thanks for the link above to Glen MacDonald’s paper. I had the good fortune of working with him back in the early 1980’s in the Nahanni River area of Canada’s NWT. He’s a great wit and even better scientist.

      • Good Captain
        Posted Nov 8, 2009 at 5:32 PM | Permalink

        Re: MrPete (#26),

        More modern collections contain more metadata, but don’t get your hopes up for collections to typically contain a full panoply of bio information. Particularly not in the public archives.

        I trust your judgment on your quote above but do not understand the reason why this would be the case. From my readings here it appears as though regular high school and undergraduate students are required to submit more back-up data, source info and the like for their own project reports than Team members. What am I missing (excluding the underlying data)? How atypical is this in other disciplines?

  15. Craig Loehle
    Posted Nov 7, 2009 at 1:47 PM | Permalink

    If we assume that in the 1600-1750 period (the little ice age) the tree line area was dominated by shrub forms because of the cold and then gradual warming allowed some single-stem forms to be successful in the 1800s, then at 1990 all old trees will be multi-stem and there will be a growth form inhomogeneity between the “few good men” of Briffa’s 10 best and the rest of the population. The younger trees in 1990 will be single-stem and the fossil trees which grew at a time before the LIA will be single-stem. Question: when is a tree not a tree? When it is a shrub.

  16. PatrickG
    Posted Nov 7, 2009 at 1:59 PM | Permalink

    Wow! This is the kind of cross discipline correlation that just does not happen in academia. Obviously the paleoclimatologist have not been keeping up on the biology preprints.

  17. Gary
    Posted Nov 7, 2009 at 3:28 PM | Permalink

    This kind of stunted growth is called “Krummholz” (German: krumm, “crooked, bent, twisted” and Holz, “wood”) and found in subarctic and subalpine tree line landscapes. Exposure to freezing winds dwarfs and deforms the stems. Apparently when the exposure becomes less extreme, the stems revert to more normal growth.

    • bender
      Posted Nov 7, 2009 at 3:34 PM | Permalink

      Re: Gary (#27),
      krummholz is kown to everyone here. “revert to normal” would not surprise anyone either. We’re talking about stratospheric 3-6 sigma growth. bcp land. That ain’t “normal”.

  18. bender
    Posted Nov 7, 2009 at 3:40 PM | Permalink

    Are there NO Canadian examples of this kind of hockey-stick shaped anomalous growth? Or do the Canadians simply know better than Briffa to treat that pattern as though it were a temperature proxy?

  19. MrPete
    Posted Nov 7, 2009 at 3:51 PM | Permalink

    BTW, this is the kind of thing that first opened my wife’s eyes about some of the dendro work. As a bio person, she could not believe that people would use tree ring data as proxies without any serious examination of the context…the comprehensive metadata.

    She honestly assumed our metadata collection for the CA Almagre adventure was a minimal and probably amateur effort; that dendros must be much more comprehensive in their metadata collection and analysis. We’ve since learned that her assumptions may not have been valid.

    • EW
      Posted Nov 7, 2009 at 4:44 PM | Permalink

      Re: MrPete (#30),

      Actually, the same thing got me interested when first reading CA articles about dendro proxies. I’m also a biologist and it seemed to me that the non-temperature factors were put at the backburner a bit in the climate reconstructions.

  20. Dave Dardinger
    Posted Nov 7, 2009 at 4:05 PM | Permalink

    I’m a bit confused as to how this change of stance works. If the trees were ground huggers for long periods of time, then when they started putting out multiple stems, just how was the wood that contained the whole growth collected? Did the corers core as close to the ground as possible? If they saw that the tree now had lot’s of stems growing out of a larger base, didn’t they know collecting the whole core would produce a huge growth spurt? Why wouldn’t this have been mentioned in the literature at some point? And why wouldn’t Briffa or any other dendro have been on the lookout for such a growth pattern if it’s so common?

  21. Howard
    Posted Nov 7, 2009 at 4:33 PM | Permalink

    Davi shows the true horrors of climate change: a frozen desert tundra to a lush forest.

    tree remnants of the 15–19th century are lacking almost entirely

    Seems like it would be quite difficult to reconstruct a coherent temperature history across these periods when the forest periodically gets wiped out. If this was geology, I would conclude this was an area where only qualitative conclusions could be made.

  22. Posted Nov 7, 2009 at 4:57 PM | Permalink

    Re Lubos Motl #19 – I am having trouble getting in to the Devi piece, though not into the comments.

    David Elder, Australia.

    • MrPete
      Posted Nov 7, 2009 at 5:22 PM | Permalink

      Re: david elder (#35), The original article is hard to download. See here for a cached version in Google docs.

  23. Posted Nov 7, 2009 at 7:27 PM | Permalink

    david elder #35 – I’ve mirrored the Devi et al paper due to the routing issues raised. I also had trouble getting the paper, but not to CA.

    Link is here (PDF)

  24. Posted Nov 7, 2009 at 8:24 PM | Permalink

    This paper probably could do better with a review of Liebig’s Law and Liebig’s Barrel.

  25. bender
    Posted Nov 7, 2009 at 10:25 PM | Permalink

    Origin and long-term dynamics of a subarctic tree line

    Fig. 3b shows some large-sigma MWP anomalies

    • Craig Loehle
      Posted Nov 8, 2009 at 7:02 AM | Permalink

      Re: bender (#41), Yes, I highly recommend Payette and associates. He meticulouly dissects a site, considers topography, and understands trees. None of this “core and run” stuff. In most of the sites he has studied, trees are either growing worse in recent decades or have not recovered to the MWP rates of growth.

  26. bender
    Posted Nov 7, 2009 at 10:33 PM | Permalink

    p. 140:

    The climate warming of the 20th century was accompanied by wetter conditions. Increased wetness, which started ca. 1750, is attributable to increased winter precipitation (Payette & Delwaide, 2004). Humid conditions favoured the lateral expansion of the western part of the peatland into the surrounding forest, gradually killing the spruces growing there and rooted in the mineral soil (Figure 3d). Interestingly, the long-term growth trends of spruce of the northwestern fen are the opposite of those of spruce growing in the hummocks zone (Figure 3c, d). This [divergence] can be explained by the differential response of these individuals to moisture fluctuations: increased moisture was detrimental to spruce growing in the peatland but beneficial to those growing on the periphery.

    Moisture limitation …
    Divergence …

    • Craig Loehle
      Posted Nov 8, 2009 at 7:06 AM | Permalink

      Re: bender (#42), As I have observed here before, the effects of warming can be opposite within a 100m in complex subarctic terrain with bogs, peat, thin soils, and permafrost. I admit that I learned this (though suspected it before) from reading Payette’s excellent papers.

      • bender
        Posted Nov 8, 2009 at 7:48 AM | Permalink

        Re: Craig Loehle (#48),
        Re: Steve McIntyre (#49),
        I find it interesting that no 20th c. hockey-stick graphs are coming out of Payette’s lab. As Craig notes, his studies are remarkably detailed. When you read them as a set, one gets the sense that nothing would ever escape his attention. I wonder if there has been a precipiation trend in Siberia which has not been mirrored in Canada?

  27. bender
    Posted Nov 7, 2009 at 10:43 PM | Permalink

    Climate change and the northern Russian treeline zone

    The Russian treeline is a dynamic ecotone typified by steep gradients in summer temperature and regionally variable gradients in albedo and heat flux. The location of the treeline is largely controlled by summer temperatures and growing season length. Temperatures have responded strongly to twentieth-century global warming and will display a magnified response to future warming. Dendroecological studies indicate enhanced conifer recruitment during the twentieth century. However, conifers have not yet recolonized many areas where trees were present during the Medieval Warm period (ca AD 800–1300) or the Holocene Thermal Maximum (HTM; ca 10000–3000 years ago). Reconstruction of tree distributions during the HTM suggests that the future position of the treeline due to global warming may approximate its former Holocene maximum position. An increased dominance of evergreen tree species in the northern Siberian forests may be an important difference between past and future conditions. Based on the slow rates of treeline expansion observed during the twentieth century, the presence of steep climatic gradients associated with the current Arctic coastline and the prevalence of organic soils, it is possible that rates of treeline expansion will be regionally variable and transient forest communities with species abundances different from today’s may develop.

  28. Geoff Sherrington
    Posted Nov 8, 2009 at 3:24 AM | Permalink

    About 2 years ago I mentioned on CA that living camellia trees known to be several hundred years old in China were useless for dendro work because of their propensity to sucker. With Camellia spp., eventually the original trunk dies and rots away and the roots support a different mass of growth. I have seen a number of these and photographed a couple.

    Little did I know that the larch also suckers. There is simply NO WAY that you can do comparative dendro on a many-trunk tree compared with a single trunk tree. For a start, you probably cannot tell if a single trunk started out as multi and lost some suckers – whether it is alive today or whether it has been preserved 1,000 years. Likewise, in an intermediate case, you cannot tell if a large tree with suckers shared them from birth or from a later date. In any case, the sharing of the root system with multiple trunks absolutely demolishes the later tree ring reconstruction. There is no way to fit a function to the ring properties over time, when the roots are offering variable amounts of nutrition to various parts of the tree at various times. This is before even considering treeline advances, altitude, etc.

    Aplologies to the Bard:

    Hark! hark! the larch at heaven’s gate sings,
    And Phoebus ‘gins arise,
    His steeds to water at those springs
    On chalic’d flowers that lie;
    And winking Mary-buds begin
    To ope their golden eyes;
    With everything that pretty is,
    My lady sweet, my arse:
    Arise. Arise.

    • Steve McIntyre
      Posted Nov 8, 2009 at 7:34 AM | Permalink

      Re: Geoff Sherrington (#44),

      To connect things in an unexpected way –

      Doug Larson of the University of Guelph, a leading world expert on cedars, connects strip-bark to multi-stem.

      Ross and I interviewed him in 2004 when we were interested in the Gaspe cedar chronology (which is resurrected in recent studies under aliases: St Anne’s.) There are some very old cedars in southern Ontario on cliffs. They’re pretty interesting. Larson and associates have studied them for decades. Cliff cedars are strip bark and multi-stem.

      Cedars are multi-stemmed as well. Larson’s idea is that different roots connect to different “pipes”. As one root dies, it’s associated part of the tree dies, thus strip bark.

      Larson’s surmise was that bristlecones would have similar structure to eastern cedars.

      • Geoff Sherrington
        Posted Nov 8, 2009 at 7:15 PM | Permalink

        Re: Steve McIntyre (#49),

        Steve, I’m not troubled by the “pipe” analogy except that the “pipes” are not necessarily discrete, but can merge into each other. The subsequent effect on tree rings is not capable of hindsight modelling because there is no way to reconstruct how much of which pipe fed what, and when.

        Stationarity is highly suspect, method fails.

        My knowledge of “stripbark” is inadequate to make a comment. The tree flora, mainly eucalypts, that I have been exposed to are quite different in many aspects to northern sub-polar like Toronto.

  29. Posted Nov 8, 2009 at 4:47 AM | Permalink

    Thanks very much to Anthony Watts #38 for kindly making the PDF version available. It opened with no problems.

    David Elder, Australia

  30. a reader
    Posted Nov 8, 2009 at 6:22 AM | Permalink

    What we don’t know is if these forms of larch are even included in tree ring data bases and if they are, are they excluded from studies like Briffa’s.

  31. Craig Loehle
    Posted Nov 8, 2009 at 9:29 AM | Permalink

    When vegetation is protected by snow from extreme cold, it can happen that warm winter events paradoxically cause plant damage (as Payette has noted)– see also:
    SF Bokhorst, JW Bjerke, H Tommervik, TV Callaghan, GK Phoenix. Winter warming events damage sub-Arctic vegetation: consistent evidence from an experimental manipulation and a natural event Journal of Ecology, 2009, Vol 97, Iss 6, pp 1408-1415

  32. a reader
    Posted Nov 8, 2009 at 10:37 AM | Permalink

    Mr. McIntyre

    Some of the best pictures and explanations I’ve ever seen of Bristlecone Pines in the White Mountains was in March 1958 National Geographic by Edmund Shulman of LTRR. There is a cross section pictured on p. 363 from Methuselah Walk which clearly shows the multistem rings–they called it a “pickaback” tree. Apparently this tree was cut down in 1957 for study. Kind of a shame really as they reckoned it to be 4000 years old. On page 359 is a good picture of two 50 year old stems surrounded by a wreath of horizontal stems at the base.

  33. nevket240
    Posted Nov 8, 2009 at 6:10 PM | Permalink

    “Economy: The Yamalo-Nenets Autonomous Area is a resource-producing region. The oil and gas industry is the leading economic sector, with a 93% share in total industrial production. More than 90% of Russia’s natural gas and 12% of its oil are produced here. Due to the severe climate, agriculture in the region is limited to reindeer herding, hunting, fishing, and fur farming.”
    from Russia Profile.Org

    In the early 20th century one of the most important Industrial achievements of all time occurred. N2 fertilizers. These became readily available just prior to WW1. Did the Soviets attempt to increase crop yields, therefore regional independence by applying N2 based “crop steroids”?? I know from personal experience what affect N2 fertilizers have on Radiata pine and it is not good for the wood.
    They grow far too quickly, have multiple heads and are usually only good for chipping or posts. I’m just wondering if some of this rapid 20th/C growth is due to un//intentional application of these crop boosters.

  34. Alan S. Blue
    Posted Nov 8, 2009 at 9:29 PM | Permalink

    When “suckers” gets mentioned above, is it referring to just “replacement right at the base of the main trunk” type of suckers? Or does this also refer to the much longer distance sucker propagation of, say, a Black Locust? Where the two trunks can be fifty feet apart but connected underground.

    Because if that type of plant in included… wow. Any adverse condition affecting any of the plants in that type of sucker network should have massive effects on every plant’s growth. Cutting down a subordinate plant causes an astonishing array of suckers to arise in the same general area during the next year as the parent plant uses stored energy reserves for propagation purposes.

    Early plant growth is also markedly faster than what I’d call typical.

    • Geoff Sherrington
      Posted Nov 8, 2009 at 10:57 PM | Permalink

      Re: Alan S. Blue (#58),

      I’m not a botanist except by contamination and long-term hobby, but I would think in this context that a sucker would be a tree-like structure that did not grow from a seed of its own. It’s more like a branch that springs from below soil. Think bamboo. It is likely to have the same DNA fingerprint as the putative parent. Whether it shares the same root structure is moot. I guess some do and some don’t and some might share overlapping parts. There are other variations on this theme, like plants that create aerial new growth and plants with aerial roots like the Ficus aurea (“strangler fig”)

      The latter are outside the above rough definition, but they point in the direction of complexity.

      Here, we have a further complication illustrated by the West Australia Christmas Tree, Nuytsia floribunda on which one web site comments

      Nuytsia is a monotypic genus which occurs naturally only in Western Australia. The plant is at least partly a root parasite in that its roots attach themselves to the roots of other plants and gain part of their growth requirements from the host species. It is reported that plants up to 150 metres away from N.floribunda may be parasitised.

      However, this is taking the divergence problem to extremes and is mentioned for interest only.

      My concern is with the overlap in a normal root system when there are suckers. The main stem cannot possibly record a single climate factor when it takes (unknown?) time out now and then to direct resources to a new sucker, some of which can later assume the appearance of having been the parent trunk in the beginning.

      The tree ring pattern is complicated enough without effects like humans have with Bulimia, Anorexia and planned or unplanned parenthood producing youngsters who won’t leave home and eventually kick forebears out to a kennel.

  35. Tim Channon
    Posted Nov 8, 2009 at 10:05 PM | Permalink

    “Ageing the Yew- no core, no curve?” this might tie in. I seem to recall the Yew (common in England) being able to do ring growth (multi-stem) where originally these were thought to be separate trees.

    Here is a fascinating web page with some extraordinary photos (including multistem not mentioned but there is a photo). These yews are all over the place on what they do, perhaps pertinent.

  36. bender
    Posted Nov 8, 2009 at 10:12 PM | Permalink

    Briffa (and anyone using the Yamal chronology) has goofed up big-time and he clearly knows it. He will back-pedal, claiming – as he did in his second reply – that a surge in treeline growth is not the anomalous pattern, that a decline in growth (à la Schweingruber) is what is abnormal. But, Keith: the issue is linear calibration using a univariate model. If these nonlinear responses are indeed “normal” then you need a nonlinear reconstruction model, and one that includes precipitation. Briffa will dodge this question as long as is humanly possible – because the answer is fatal to his program. And one of the ways that he hopes to dodge it is to placate, by seeming reasonable. But a dodge is a dodge.

    • Steve McIntyre
      Posted Nov 8, 2009 at 11:40 PM | Permalink

      Re: bender (#60),

      bender, did you notice the phrase “the Briffa bodge” in a recent publication? I’ve been biting my tongue.

      • TAG
        Posted Nov 9, 2009 at 6:22 AM | Permalink

        Re: Steve McIntyre (#62),

        “the Briffa bodge

        Readers not familiar with UK slang might be unfamiliar with the word bodge. The word klugr or lkludge has a similar meaning and may have a broader or perhaps just North American usage

        • Steve McIntyre
          Posted Nov 9, 2009 at 7:28 AM | Permalink

          Re: TAG (#64),
          The adjustment described as the “Briffa bodge” in a recent article was discussed in a CA post, where per descibed the bodge as “gobsmacking” – another UK-ism, making it, I guess, a gobsmacking bodge.

        • Hoi Polloi
          Posted Nov 9, 2009 at 9:51 AM | Permalink

          Re: TAG (#64),

          from the Urban Dictionary:

          A quick and dirty job, something done very hastily. Make it look good for the next day or two and if it falls down after that, it’s alright.

          1> You bodged together that doghouse, didn’t you?
          2> How can you tell?
          1> The walls look like they can cave in at any time.

          snip – irrelevant

        • Posted Nov 9, 2009 at 9:53 AM | Permalink

          Re: TAG (#64), BODGER/ˈbɒdʒə/Help with IPA

          [pre-slang definition] An itinerant chair-leg turner.

          This term was once common around the furniture-making town of High Wycombe in Buckinghamshire, between London and Oxford. Bodgers were highly skilled itinerant wood-turners, who worked in the beech woods on the chalk hills of the Chilterns. They cut timber and converted it into chair legs by turning it on a pole lathe, an ancient and very simple tool that uses the spring of a bent sapling to help run it.

  37. Steve McIntyre
    Posted Nov 8, 2009 at 11:45 PM | Permalink

    I’ve uploaded the Huston 1986 cited by Craig Loehle (thanks Craig) which contains a very remarkable and interesting analysis of how bimodal distributions can arise in random spatially distributed networks. – all the more interesting in the present context.

    It is additionally interesting because one of the cited authors (Diggle) is something unknown in the entire corpus of Team literature – an experienced statistician with well known articles and texts for random effects.

  38. a reader
    Posted Nov 9, 2009 at 7:29 AM | Permalink

    By just googling around the web you can find really good pictures of the old multistem pines in Methuselah Walk. Surely dendros have taken the multistem issue into account when doing studies, as this habit of trees at treeline seems very well known.

    • MrPete
      Posted Nov 9, 2009 at 7:51 AM | Permalink

      Re: a reader (#66),
      Don’t get your hopes up. That was not typical metadata, at least not until recently.

    • Steve McIntyre
      Posted Nov 9, 2009 at 8:12 AM | Permalink

      Re: a reader (#66),

      one of the many frustrating features of underlying studies in this area is that huge-sigma variations are simply left without inquiry. For example, let’s suppose that you have a tree whose growth has declined to something little more than survival – which then surges to 7-sigma for 60 years or so. You’d think that the scientists would inquire as to what happened.

      What seems to actually take place is that the measurements take place in the lab after the field expedition, no one kept track of the locations of the original samples and no one ever went back to see what accounted for the surge. Plus there seems to be no negligible metadata.

      In any event, there is NO archived metadata that provides any information except the approximate lat-long-alt of the site. Nothing on individual trees. And, as we’ve seen, there has been no publicly archived measurement data whatever on the key Briffa sites until a month ago.

      • bender
        Posted Nov 9, 2009 at 8:51 AM | Permalink

        Re: Steve McIntyre (#68),
        But this is where a Team social network structure becomes indispensable. Briffa warns that the Yamal chronology should be “used cautiously” (but without stating what constitutes incautious use). Then it is up to another team member to take on the risk of incautious use, for example, in a temperature reconstruction. It’s not Briffa’s fault if Kaufman uses a linear univariate reconstruction model. Briffa did his due diligence. And the Team gets the job done.
        But what, Dr. Briffa, is the difference between “careful use” and “careless use”? Could you draw that line for us? For example, was Dr. Wilson’s use “careful” and Dr. Kaufman’s “careless”? Help us out here.

        • Steve McIntyre
          Posted Nov 9, 2009 at 9:21 AM | Permalink

          Re: bender (#69),

          Briffa is also a user e.g. in Briffa 2000 and in AR4.

          Briffa in Briffa 2000 used the Yamal reconstruction as is – with no mention about “caution”. Briffa used the Yamal reconstruction in the AR4 spaghetti graph without attaching any warning labels. Indeed, he refused my request that the sensitivity of results to use of Polar Urals instead of Yamal be disclosed.

        • bender
          Posted Nov 9, 2009 at 9:33 AM | Permalink

          Re: Steve McIntyre (#71),
          Clarification noted.

      • bender
        Posted Nov 9, 2009 at 8:59 AM | Permalink

        Re: Steve McIntyre (#68), This is why I ask: what is the most egregious hockey stick recon to come out of, say, Serge Payette’s lab? If he isn’t producing any, then why not? Craig Loehle had a great line about Team “core and run” practices. I suspect there is a correlation between the amount of time you do NOT spend studying a site and your probability of generating a hockey stick.
        Payette has some papers showing MWP upticks in eastern Canada, but nothing in the present day. The OPPOSITE of what Briffa, Mann and Clapton et al. are singing about. Are these upticks the result of a wetter past in eastern Canada and a wetter present in Siberia? Pretty compelling alternative hypothesis given the importance of a snowpack for winter cover and summer moisture availability.

  39. bender
    Posted Nov 9, 2009 at 9:38 AM | Permalink

    Somebody should go measure cambial auxin concentrations in these “positive and negative responders”. My guess is that’s the proximal source of the nonlinearity in all these species, Yamal larch, western US pine. And someone should do a watering experiment. My guess is moisture is the ultimate driver that induces the nonlinear response caused by auxin. Anyone measured auxin concentrations in these multi-stemmed plants?

    • steven mosher
      Posted Nov 9, 2009 at 11:59 AM | Permalink

      Re: bender (#73), stop with the science already. we have an agenda. plus it would take a lot of heavy equipment to do such a thing and we need money for super computers!

    • Geoff Sherrington
      Posted Nov 10, 2009 at 3:47 AM | Permalink

      Re: bender (#73),
      And of course it has to be established that auxins, being able to increase or decrease growth depending on Nature’s design, are or are not responsive to temperature.

      Re: Craig Loehle (#80),
      We have a strange animal in Australia whose male eats roots shoots and leaves. Then goes to the bog.

      Ah! Language.

      Re: Lucy Skywalker (#89),

      Agreed, Several times I have suggested that the dendro community sets hurdles to see if they can jump them; and if not, discard the method.

      Now, my thoughts are more that WE have to articulate the hurdles and ask the dendros if they can be overcome, evidence please.

      There is a limit to how long we should continue to point out seemingly impossible difficulties.
      I reveived an invitation to send a paper to this conference from Keith, Rosanne, Kevin and Tom

      “We are trying to organise a session at the WorldDendro2010 in Rovaniemi (June 2010)
      The Divergence phenomenon in Dendroclimatology
      Convenors: Keith R. Briffa, Rosanne D’Arrigo, Kevin Anchukaitis and Thomas Melvin


      In declining with thanks, I noted “stationarity cannot be assumed with confidence over the centuries. Whole method fails.”

      Anyhow, we were told the science was “settled”.

  40. Posted Nov 9, 2009 at 9:57 AM | Permalink

    oh yes, the bodger used simple equipment that enabled him to easily “move on”

  41. EW
    Posted Nov 9, 2009 at 10:25 AM | Permalink

    Nice pic of Khadyta. With larches.

  42. Gary
    Posted Nov 9, 2009 at 10:31 AM | Permalink

    So who is the artful bodger?

    I vote for UU@W

  43. Just an EE
    Posted Nov 9, 2009 at 11:08 AM | Permalink

    OK; “Do Dendros Really Prefer Great Big Ones?”
    Humor me on this scenario,that ends in a question.

    Let’s say your task du jour is to go out and ‘core’ some trees.
    You’ve heard that the longest cores are the ones that make people the happiest.
    You’re required to hike to the most remote, barren spot you’ve ever seen.
    The job includes dragging old stumps out of a lake and coring those also.

    So, here’s the question; Do you pick the larger trees or smaller ones to core?

    I think we have some data on this; as I understood it, Fearless Leader SM did some coring to test the ‘Barstuck Hypothesis’.

    I’ll bet a Canadian nickel that the metadata did not capture anything like this; ” Don’t Bother with the Small Ones.”

    And I’ll bet 5 less valuable American zink pennies that a survey of those much-maligned California strippers would show rampant ‘size-ism’ in the selection of the chosen representatives of that forest.

    I’m reminded of my yardcare algorithm; “Focus on the Tallest Weeds”

    Good Day


  44. Craig Loehle
    Posted Nov 9, 2009 at 11:20 AM | Permalink

    In boreal zones I know for sure that black spruce, which grows in bogs, will sucker from branches that get buried in moss. That is, a tree growing in a bog will tend to sink some or tilt over. Branches become partially buried in sphagnum moss, and these branches produce roots and the branch can start to grow up into a tree. This is also called “layering”. According to “Silvics of Forest trees of the United States” Tamarack–Larix Laricina: “Layering is apparently the dominant reproductive mode for tamarack along the northern limit of trees in Canad and Alaska…roots are also known to produce shoots…” Traits like this are usually common across related species, and likely to apply in Yamal.

  45. Craig Loehle
    Posted Nov 9, 2009 at 11:28 AM | Permalink

    There are implications of clonal growth (due to layering, for example, or root sprouts). The resulting trees are connected by stems/root systems for decades or forever. Let’s say a tree is old and not doing very well, but then some of the other trees connected to it break off in a storm–it now retains the full root system of the connected trees and will show a growth spurt. Other weird things can happen as well. An old tree can steal nutrients from younger connected vigorous sprouts, which could also give a growth spurt. It is no longer a solitary individual but like the borg–a collective.

  46. Craig Loehle
    Posted Nov 9, 2009 at 11:42 AM | Permalink

    Larch are not happy growing in a bog, but can tolerate it better than most other species (black spruce being similar to larch in this regard). If you lower the water table a little in a bog, an old tree could show a big surge in growth. Alteration of the water table can occur due to warmer temperatures but could also result from human or animal activity at the outflow point, or for other reasons. Yes, metadata would be nice here…

    • Layman Lurker
      Posted Nov 9, 2009 at 11:59 AM | Permalink

      Re: Craig Loehle (#82),

      Metadata analysis, stationarity, homogeneity, and the interpretation of 20th century climate using negative exponential RCS…. sounds like a paper to me Dr. Loehl. 😉

    • Posted Nov 9, 2009 at 12:25 PM | Permalink

      Re: Craig Loehle (#82) (etc), it seems to me that CA has now established clearly that treerings CANNOT be used as temperature proxies without a thorough, systematic analysis of metadata, particularly in the case of extremophile trees that have more tricks up their sleeve than the KGB. Since it looks to me that Yamal is largely flat, boggy, and permafrosted with ponds and puddles, it seems that Yamal should largely be ruled out altogether for proxies – since who knows how the local puddle-and-water levels may have changed at intervals?

      • Craig Loehle
        Posted Nov 9, 2009 at 12:36 PM | Permalink

        Re: Lucy Skywalker (#89), I agree. Sometimes when you want to do something, the answer is “no” and it is not smart to proceed. Just because it would be nice if tree rings held a record of temperature, does not mean they do.

      • EW
        Posted Nov 9, 2009 at 6:38 PM | Permalink

        Re: Lucy Skywalker (#89),
        Lucy, forget about flats of Yamal, there are no larches. They grow in the river valleys, because there they are a bit protected from winter. Hantemirov wrote that they collected specimens living and sub-fossil on the alluvial “terraces” along the three rivers.

        • bender
          Posted Nov 9, 2009 at 8:32 PM | Permalink

          Re: EW (#98),
          It is VERY important, in the absence of objective soil moisture data, to know what microsites these trees are on. I had been assuming slopes, and this appears to be the case. This would argue for a positive 20th century effect of snowpack and moisture availability on radial increment. I couldn’t see that effect being beneficial in bogs. (From what I have heard, H&S do not mention excavating logs from bogs.)

        • EW
          Posted Nov 10, 2009 at 3:57 AM | Permalink

          Re: bender (#99),
          In the Hantemirov and Shiyatov 2002, the conditions of larches on Yamal aren’t much described. In the H’s Thesis abstract, there is more:
          Due to the harsh climatic conditions and the shortness of vegetation period, Yamal is a combination of different types of tundra, marshes and meadows. Forests are absent in much of the territory of Yamal. Only in the southern part of the peninsula forest tongues are wedged deep into the tundra in the valleys of some rivers, which flow from north to south. In the middle reaches of these rivers over floodplain terraces larch and spruce-larch border non-dense woodlands are distributed. Closed forest (larch and spruce-larch with winding birch) are insularly distributed and confined to the valleys of the lower reaches of the rivers of Southern Yamal. The northernmost tracts of taiga type are located in river valleys of Tanlova, Khadyta and Yadayakhodyyaha and their major tributaries.
          For forest massives, the formation of high-density and productive woods (otherwise not typical for high latitudes)at a young alluvium is characteristic. In river valleys the most favorable microclimatic and soil condition for tree growth are found.
          Valley habitats are best protected from the strong winds and at the same time in the winter period they are covered with powerful enough snow cover. In conjunction with the warming influence of running water and poor development of moss-lichen cover this leads to the fact that in the summer thermal regime soil in lowland habitats, especially at the floodplains is the most favorable for the growth of woody vegetation.

        • Just an EE
          Posted Nov 10, 2009 at 1:53 PM | Permalink

          Re: EW (#102),

          I realize this is a machine translation.

          But I’ll take this opportunity to restate that

          For forest massives, the formation of high-density and productive woods (otherwise not typical for high latitudes)at a young alluvium is characteristic.

          illustrates my point;
          ‘Core the Big Logs’
          on the assumption they are the oldest.

          I was initially attempting to respond to SM post 63, where he mentioned bimodal distributions in tree populations.

          I’m trying to say that human nature would cause oversampling of the big boys and undersampling scrawny trees of equal age.


        • EW
          Posted Nov 11, 2009 at 4:47 AM | Permalink

          Re: Just an EE (#104),
          It is machine translation, but human-corrected. Google translator has problems with different word order of Russian sentences to such extent that it sometimes completely reverses the meaning of the sentence. I did quite a lot of word rearranging to make the sentences readable.

    • Dave Andrews
      Posted Nov 9, 2009 at 3:15 PM | Permalink

      Re: Craig Loehle (#82),

      “If you lower the water table a little in a bog, an old tree could show a big surge in growth.”

      So, does this mean that the Yamal growth rings might actually improve when the temperature goes down? After all, presumably higher temps lead to more melting of the permafrost and more boggy conditions?

      If this is so how can we, therefore, correlate tree ring growth with temperature in areas like Yamal?

      • Craig Loehle
        Posted Nov 9, 2009 at 3:28 PM | Permalink

        Re: Dave Andrews (#95), Yes, cooling could refreeze the permafrost, preventing boggy conditions (more growth) and warming could create boggy conditions and worsen growth. But it could go the other way also on regular soil–warming by thawing permafrost could deepen the soil profile. In Payette ref, above, it is noted how change in climate at treeline can have perverse effects, such as a warm spell in winter damaging trees by reducing snow cover. There is simply no way to say “warming = more growth” in such complex tundra terrain.

  47. a reader
    Posted Nov 9, 2009 at 12:01 PM | Permalink

    Mr. Loehle

    The reference to the Kryuchkov paper I gave back in the YAD06 thread comment #168 says this very thing (layering) about treeline larches.

    E. Shulman in the N.G. article I referenced in this thread reports about a bristlecone pine called the Patriarch which he calls a “grove of trees with one root system”. It is 37 feet in circumference near the base where the multistems have coalesced. He says it had “typically insensitive ring growth of upper timberline”. He was looking for evidence of drought years in long lived pines, and what it was about them that allowed them to live such long lives. It looks like the really long lived trees were all strip bark.

  48. Posted Nov 9, 2009 at 12:09 PM | Permalink

    The definition of “a plant” becomes dubious when there is vegetative (asexual) reproduction occurring. The latter is a common phenomenon in bulbous/tuberous/cormus plants. If one encounters a population of 50 “plants” at a wooded site and all are connected via rhizomes or stolons, is it “one plant” or “50 plants”? When plants multiply vegetatively, they tend to lose diversity and ability to adapt when “stress” occurs in the local environment. It seems that the trees in this study were predominantly multiplying by vegetative means for a period, then something happened and precipitated a switch to sexual reproduction. And what happened from the 15th to 19th Centuries?

    • blueice2hotsea
      Posted Nov 9, 2009 at 2:06 PM | Permalink

      Re: Dave L (#87),

      is it “one plant” or “50 plants”?

      If I had refreshed my browser before commenting, I would have read your comment and directly addressed and endorsed your POV. My apologies. At any rate, cloning certainly limits genetic diversity, in contrast to sexual reproduction.

  49. blueice2hotsea
    Posted Nov 9, 2009 at 12:21 PM | Permalink

    May I suggest a possible explanation for the transition from lateral to vertical growth? Perhaps suckering larch were cloning themselves until the reappearance of climate conditions favorable to reproduction – similar to quaking aspen which may not have reproduced in the last 89,000 years. If true, then consider that from the MWP until the 20th century, the trees have been CO2 limited, in the reproductive sense.

  50. Posted Nov 9, 2009 at 1:11 PM | Permalink

    The funny thing is, when I looked closely at the pawprints of the Dirty Dozen trees, it seemed as if they were responding in concert to something happening at similarly-spaced intervals. It just wasn’t temperature. That page has also got some telling pictures of the Siberian larch, with a range of environments

  51. Erasmus de Frigid
    Posted Nov 9, 2009 at 3:01 PM | Permalink

    morphology is destiny.

  52. Posted Nov 9, 2009 at 5:03 PM | Permalink

    There is about 7% more river runoff over 60 years for the main Eurasian rivers discharging in the polar area, including the Ob at Yamal. This may influence tree growth especially where trees are near the border of the water/permafrost table and on slopes with rapid runoff. See Peterson e.a. in Science:

    Again, it is very important to know the local influences on growth of the “dirty dozen”…

  53. Geoff
    Posted Nov 10, 2009 at 3:49 AM | Permalink

    Just want to raise my hand (but not wave it) to bring up land use issues. The human population seems to have grown rapidly in the 20th century, espcially after 1960 due to gas exploration and extraction. See the 1999 article by Bruce Forbes “Land use and climate change on the Yamal Peninsula of north-west Siberia: some ecological and socio-economic implications” (abstract here) and the 2008 AGU presentation “Cumulative effects of rapid climate and land-use changes on the Yamal Peninsula, Russia” ( here (5.92 MB pdf) ). Also, the LCLUC site (Land Cover and Land-Use Change, Yamal Peninsula, Russia) site with numerous presentations and talks on this issue ( here). Of course this does not substitute for metadata for tree cores but is another interesting aspect of “what really happened on Yamal and when did we know it”.

    Dr. Forbes has been working on the Yamal since 1991 and I’m sure could provide a lot of interesting infomation, as could Dr. Walker.

  54. Juraj V.
    Posted Nov 10, 2009 at 11:49 AM | Permalink

    Because thousands of more than 500-year-old subfossil trees occur in the same area but tree remnants of the 15–19th century are lacking almost entirely, we conclude that the forest has been expanding upwards into the formerly tree-free tundra during the last century by about 20–60m in altitude.

    MWP and LIA are nicely recognized. But we know that MWP was limited only to NW Europe, Greenland and, uhm, this tiny part of Siberia.

  55. bender
    Posted Nov 10, 2009 at 8:52 PM | Permalink

    What happens when trees finally grow tall enough for their tops to poke out of the shelter of these hollows? I wonder if these big trees had their tops snapped off from, say, an ice storm in the 1950s. What would the effect be on radial growth? Roots all intact, still lots of photosynthetic machinery in the mid-crown, just missing the nutrient sink of the apex.

    • Geoff Sherrington
      Posted Nov 11, 2009 at 2:53 AM | Permalink

      Re: bender (#105),

      Again with the caveat of not being a botanist, I understood that the primary driver of activity that eventually affects tree rings is the call of the leaves for chlorophyll, or more generally photosynthesis. If you lop off the crown, reducing the leaf demand, I guess that the tree rings relate therefter to leaf area rather than the generous surplus donation available from the root system. But I am not sure. In the sucker case, one response of out-of-balance surplus root size:leaf area might well be more suckers. So the date of emergence, the lifetime and the final dominance/demise of a sucker has a plausible effect on main stem tree rings that might not be capable of reconstruction.

      OT, remember the toothpaste jingle?

      How reeks the goat on yonder hill
      Who feeds all day on chlorophyll.

  56. PatrickG
    Posted Nov 11, 2009 at 11:14 AM | Permalink

    Just a random thought:

    Could the Yamal trees be responding to increased CO2 in the 20th century. Seems like there would be a positive correlation there.

    Personally I doubt that this is relevant to 6 sigma pulses in individual trees. It’s the 6-sigma pulses that need to be explained. Things like larch sucker growth seem more likely to me. However, the obligation for explaining the huge variances is properly the job of the specialists advocating the series.

    • bender
      Posted Nov 11, 2009 at 12:45 PM | Permalink

      Re: PatrickG (#108),
      Using artesanal dendrospeak, a six-sigma uptick is a definitive “JOLT”. Perhaps Jim Bouldin or Delayed Oscillator would care to elaborate? Guys, what’s a “JOLT”?

  57. Just an EE
    Posted Nov 11, 2009 at 12:13 PM | Permalink

    Aha, maybe I can make a contribution. I know some folks who claim to be fluent in Russky.
    If you can post the russian text which came through as Forest Massives,
    I can attempt to elicit ‘expert’ translation.
    Hopefully include some pre and post text for context.

    In your abundant free time…

    • EW
      Posted Nov 13, 2009 at 7:36 AM | Permalink

      Re: Just an EE (#109),
      Try it:

      Для лесных массивов характерно образование на молодом аллювии высокоплотных и продуктивных древостоев, не типичных для высоких широт.

      Forest (adjective) massives (subject)…can’t help it.

  58. Ian
    Posted Nov 12, 2009 at 9:33 PM | Permalink

    Payette seems firmly convinced about the MWP and LIA from his reconstructions. In Payette, Filion and Delwaide, “Spatially explicit fire-climate history of the boreal forest-tundra (Eastern Canada) over the last 2000 years,” Phil. Trans. R. Soc. B (2008) 363, 2301–2316, they had this to say (at p. 2309):

    “As was the case in our study, the magnitude and timing of post-fire deforestation throughout the northern boreal biome were closely linked to the climatic deterioration that prevailed during the Little Ice Age (Overpeck et al. 1997), i.e. after the Medieval Warmth (ca 900–1200 years ago) and before recent warming commencing at the end of the nineteenth century. The lack of post-fire spruce regeneration from 900 cal. yr BP to present is a direct indication that climatic conditions deteriorated after the Medieval Warmth. According to the distribution of fire dates and tree regeneration, the climate at the tree line was drier and warmer before 900 cal. yr BP.


    According to fire and tree regeneration data from our study, the northern part of the forest tundra in Eastern Canada has been heavily deforested over the last millennium. The main direct cause is climate deterioration coinciding with the phasing-out of the Medieval Warmth and incidence of the Little Ice Age.”

    • bender
      Posted Nov 12, 2009 at 11:43 PM | Permalink

      Re: Ian (#111),

      climate at tree line was drier and warmer before 900 cal. yr BP

      Keep this thought in mind …

      • Ian
        Posted Nov 13, 2009 at 1:45 PM | Permalink

        Re: bender (#112),

        Yes – Payette is very good at discussing the full range of potential factors affecting tree growth, from water availability and forest fires to bug infestations and regional disturbances, in addition to potential temperature changes. Unlike some others in the field, though, he is quite prepared to accept that, for the areas he is studying, the data shows there was a MWP and a LIA, and he is not trying to “eliminate” them. I’m not in a position to comment on how well (or if) he quantifies the different effects, though. I’ve certainly not waded through all of his available work, which appears to stretch back to the 1980s.

        His list of publications is long; there is at least one where he is a coauthor, along with Rob Wilson & others, of an article that tries to make sense of the divergence issue: Wilson, R, D’Arrigo. R, Buckley, Büntgen, U, Esper, J, Frank, D, Luckman, B, Payette, S., Vose, R. and Youngblut, D. A matter of divergence: tracking recent warming at hemispheric scales using tree-ring data. 2007. Journal of Geophysical Research, 112. That paper I think was examined by Steve (not surprisingly!) at:

  59. EW
    Posted Nov 13, 2009 at 7:43 AM | Permalink

    Anyway, looking on Google pictures showing лесныe массивы we can safely conclude, that these are dense older forests often covering vast areas.

  60. a reader
    Posted Nov 19, 2009 at 1:24 PM | Permalink

    Available on google books preview (some pages missing):

    Methods of Dendrochronology:Applications in the Environmental Sciences.
    Editors: Cook and Kairiukstis 1992
    Chapter 2.4 Dendroclimatological Study of Prostrate Woody Plants.

    May be of interest.

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