Miller et al. [2004] studied fossil evidence of forest levels in 9 locations in the western U.S. over the past 3500 years, including Whitewing Mountain and San Joaquin Ridge, Inyo Craters Chain in the eastern Sierra Nevadas, near the bristlecones of the White Mountains (about which I’m going to post an interesting graphic on their altitude changes), reporting that:
A volcanic eruption of the Glass Creek vent (Inyo Craters chain, eastern Sierra Nevada) during medieval times buried forests in the adjacent region under several meters of tephra. Large, mostly downed, dead trees on nearby Whitewing Mtn (3052m) and San Joaquin Ridge (3105m) appear to have been killed by the eruption and preserved in arid, cold environments; tentative radiocarbon analysis (Univ AZ, Lab of Tree Ring Research, 1980) gave dates in the eruption era. The presence of these stems suggests a tall forest existed at the time the trees were alive. Conditions at this time were warm with two 150-200 year dry periods between AD 900-1350 in the Sierra Nevada (Stine 1994). The dead stems contrast with current conditions of these habitats, which are treeless or have only occasional krummholz whitebark pine. Live forests of whitebark pine downslope suggest cycles of shifting treeline in more recent centuries, during the cool centuries known as the Little Ice Age. No previous studies have examined the paleoecological, climatic, or eruptive-sequence implications of the downed logs or downslope contemporary forests….Medieval-age (AD 900-1350) forest composition, structure, and growth on summits were typical of forests currently 300-500m lower, suggesting an effectively warmer climate during medieval times
Figure 1. Subfossil log on Whitewing Mountain.
The above is from a poster Miller et al. [2004]. It discusses some other interesting sites, which I’ll mention separately in the future. The location of the sites is shown in the maps below (I apologize for the scale – I’ve blown up the original pdf, but it’s still not easy. Inyo County is on the Nevada border in eastern California. The AD1350 Glass Vent eruption looks like it was a big deal in regional geology and is reported on by geologists. You can find informaiton by googling and I’ll try to post up some info some time. (It’s nice to get a little geological hook every now and again.)
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Figure 2. Location Maps of Whitewing Mtn and San Joaquin Ridge, eastern California
Miller et al. go on to say:
“⠠Relative to present, sugar pine has been regionally extirpated and species diversity declined from 7 to 1; crown form altered from upright, straight stems to stunted krummholz, growth rates declined significantly, conditions went from forest to mostly barren
“⠠500 years ago (AD 1500, Little Ice Age), whitebark pine grew 100m below its current optimum; this zone has been moving upslope since, and at present whitebark is colonizing barren slopes above 2900m. Alternating zonal decline and increase may reflect response to Little Ice Age cool/dry climates and then warming of the 20th century.
“⠠Best estimate Glass Creek Vent eruption: AD 1350 (~650 years ago)
“⠠Vegetation trajectories in this area likely influenced by combined climate change and volcanic effects
They provide a couple of interesting graphics showing the ages of trees at these sites:
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Figure 3. Left: Species identified from summit dead wood (currently krummholz P. albicaulis, rarely P. flexilis): Pinus albicaulis (37), P. monticola (20), P. flexilis (7), P. contorta (7), P. jeffreyi (6), P. lambertiana (2) (spp currently exotic east of crest), Tsuga mertensiana (1). Right: Date Ranges of Whitebark Pine Downslope of Whitewing Mtn: 1. Upper forest border (2900m) live whitebark pine invading current barren uplands. 2. Mid-slope (2800m) live whitebark pine in current western white pine, whitebark pine, and red fir forests. 3. Lower-elevation (2700m) dead whitebark pine stems in current lodgepole pine and red fir (Abies magnifica) forests.
They conclude that:
Climate variability as a primary driver of ecological shifts at these scales has not been fully recognized as a significant natural force of change, nor have implications been integrated into conservation analysis and planning.
Reference:
http://www.x-cd.com/mcss04/papers/P47.pdf Miller, Constance et al. , Climate as an ecosystem: decadal scale variability and century scale variability.
Climate Audit 
23 Comments
1. Where was this published? Peer reviewed?
2. Is elevation change considered a better proxy than ring size?
I just saw it on the internet.
The Hockey Team prefers ring size indices to elevation change. I’m not convinced that that’s the end of the story.
It seems pretty obvious that elevation change is related to changing climate. You can see this on a big scale – from the last Ice Age to the present. So why wouldn’t it be useful on a century scale? It has not been used by hte HOckey Team. I presume that it’s because theyu don’t like the results: you have higher trerelines in the medieval period all over the world.
There are a few sites where the changes have been quantified as changes in treeline e,g, Polar Urals, bristlecones. I’m going to put a little bit of a full-court press to see if I can find enough which have been similarly quantified to make up a “low-frequency multiproxy index”. It would have just as much validity as Moberg.
If anyone sees papers containing graphs of treelines over the past 1000 or more years, please let me know.
It seems like a comparison of the two proxy methods would be interesting and could be done outside the scope of the MBH vs MM kerfuffle (just as a lot of the botany foundational studies for tree-ring growth make sense outside the effect on MBH).
That should be Millar et al.
If you google Millar Westfall, you will notice that they have several “posters” that the present to various audiences, including AGU meetings, on various aspects of tree/forest history.
1. They should publish. presumably a seperate paper for the experimental results in the sierras and then a paper with the more expansive speculations/insights wrt wildlife management.
2. and archive their data
On Friday, I went to an exhibit of photography. One of the photos was a forest of dead trees in a national park in Namibia. The photographer told me that these trees died roughly 600 years ago. Since this once thriving forest has been arid since these trees died, I thought that this might be an effect of the mini-ice age.
Dead Vlei Tree
I Googled the park, Namibia, and many words about the trees. I found many photos and tour operations, but no articles about the trees.
These trees seem to be another indication of significant climate change at the end of the mini ice age. They are located hundreds of km from the west coast of the African continent in an area that has been arid since the middle of the last millennium.
Re #1:
The work of Millar, et al., was presented as a poster at the Mountain Climate Sciences Symposium at Lake Tahoe, California, May 25-27, 2004. A full list of papers, posters, and speakers is available here. The title of the Millar poster as listed in the program is “Responses of high-elevation pines in the eastern Sierra Nevada and western Great Basin to late Holocene decadal- and century-scale climate variability.”
While the PDF is dated in 2004, it seems to be based on a PPT file from Oct 2002, perhaps related to the Millar et all poster mentioned at
http://danr.ucop.edu/wrc/snssweb/post_climate.html
for the October 2002 Sierra Nevada Science Symposium.
I’m looking at some of her stuff now. Still think she should publish in the real journals, but federal scientist don’t get pushed as much here as they should. Seems like she ought to be able to shed light on the initial bristlecone studies (her evaluation of skill, representativeness, etc.)
I haven’t found her publication list, but one of the articles showed several of her publications. There were some in journals of record. while, I’m not an expert on this area, I thought they sounded pretty small-scale (NZ Journal of Forestry and such). Seems like there’s gotta be somewhere else that’s a little higher up the food chain to publish. not Nature or Science maybe. But whatever the top specialty journals are.
Re #2:
If anyone sees papers containing graphs of treelines over the past 1000 or more years, please let me know.
No personal knowledge of such graphs …
However, I expect some of the references listed in “Impacts of Climate Change on the Tree Line” by Grace, et al. (http://aob.oxfordjournals.org/cgi/content/full/90/4/537) might include what you’re seeking.
Steve, I stumbled across this paper (thesis) http://ethesis.helsinki.fi/julkaisut/mat/geolo/vk/helama/millenni.pdf today, which unfortunately lacks curves but implies results very different from the hockey stick also. Murray
I also came across several notes that climate variation in Northern Europe has been strongly winter and spring cooling and warming, with little change in summer temperatures. What effect would this have on the validity of tree ring analyses? Since most growth is in summer, it would seem to weaken the value of tree rings as a temperature proxy. Murray
Seems to me that one concern wrt elevation change as a proxy is the time required for species to “pioneer” to new areas. For seeds to blow and grow and outcompete residents (or die if reverse). here I would think elevation movement along a mountain slope would happen much more quickly than latitude creep (Finland example). I mean sheesh, don’t you think it would take a while for a forest to move 150 miles north? I guess maybe it can go a bit faster if the oaks were already there but not dominant. Anyhow, needs to be dug into. Should I invite the pretty lady over here? I could even try to behave and not be my normal troll.
I invited her to participate in the thread. You guys behave.
RE #7 – Brooks, I couldn’t find the photo. There seems to be a correlation between dry periods in some parts of Africa and cold periods in North America.
Everyone, thanks for the various references. There’s a micro-survey by Graunlich and Lloyd which I’ll post up in a day or two. By a tree line graphic, I’m looking for somtething like the Shiyatov graphic for Polar Urals.
I think the answer from her was “no”. (Worth a shot.)
Steve,
Here are several links:
http://www.pbase.com/rhoover/namibia
http://www.slrobertson.com/namibia-namib-desert.htm
http://www.travelblog.org/Photos/62088.html
http://www.rosemarycalvert.com/id49.htm
The photos are labled “Dead Vlei Tree”. Several of these have comments that the trees have been dead for between 500 to 700 years.
Brooks, those are beautiful photographs. I like that type of stark geometry. One of the comments says:
link
I know that the LIA in parts of Africa was very arid, but are you sure that this climate here?
Steve, I am uncertain as to the climate in that part of Namibia. I was hoping to find one or more articles on the subject of these trees, but hit a dead end.
Back on the topic of this thread, I was able to download a much better map of the White Wing Mountain area. The location is between Mammoth Mountain and June Lake. This area has relatively easy access from nearby roads.
The USGS map server is at http://nmviewogc.cr.usgs.gov/viewer.htm.
The location of White Wing Mountain is N 37 43.52′ W 119 3.71′
I’m still disapointed that she did not come over to discuss the issue and engage intellectually. Maybe I need to be more charming. Thought that simple science interest and interest in her work being discussed would drive her. Oh well…
On a separate thread (Steves item on Lamb and the MWP)I posted lots of observations on the authenticated climate of Dartmoor(Southern England) close to my home, which contains habitation from the Bronze period through to the MWP. Basically we still have the buildings and fields and there have been lots of studies into crops grown and the elevations they were grown at.
Both civilisations decamped to the valleys when the climate deteriorated. In the case of the abandonment of the MWP farmsteads in the 1350’s we know the names of the people, what crops were growing and details of converting their barns to take different crops as the cultivation level dropped from around 1500 feet to around 1050 feet. I shall be there tomorrow at Hound Tor (mentioned in Sherlock Holmes adventure Hound of the Baskervilles)where the building walls and the field systems are still clear to see.
Presumably you are after observations of tree line levels rather than crop height levels to pursue your research?
Tony B
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