Woodhouse versus Graybill

Reviewing the bidding: at Niwot Ridge, a short drive from UCAR world headquarters, we have disparate chronologies from Graybill and Woodhouse for limber pine at similar elevations (with Graybill’s chronology also discrepant from nearby chronologies from Kienast and Schweingruber for very close PCEN series). Despite the disparate appearances, the correlation between the Graybill and Woodhouse chronologies was a surprisingly high 0.46.

To shed a little more light on this, I’ve plotted up spaghetti graphs and grassplots for the measurements by individual trees. On the left is Woodhouse (co511) and on the right is Graybill (co545). As you can see, the Woodhouse sample has a lot of trees which started growing in the 15th century, while the Graybill sample has trees starting later. The majority of the Woodhouse trees have a fast start; the Graybill sample has quite a few cores with elevated 20th century ring widths – which are not present in the Woodhouse sample.

Both samples appear to have 2 cores per tree. The Woodhouse sample has trees numbered up to 21, lists 21 unique trees and shows 40 cores. The Graybill sample has trees numbered up to 18, but only lists 15 unique trees and only shows 27 cores. Auditors never like missing invoice numbers.

Pat Frank wondered whether the differences might result from the construction of the ecological station – who knows? However, the 20th century ramp is typical of Graybill series and I’d be more inclined to think that it results from something in Graybill’s methodology, as opposed to the sewage. Remember that Graybill was seeking out strip-bark trees: I’d be more inclined to think that the answer lies there. For example, Graybill and Idso [1993] showed a difference between strip-bark and whole-bark trees in the 20th century at Sheep Mountain. I’ll check, but I’ll bet that the difference is comparable to the difference between Woodhouse and Graybill here.

But something is sure different between these series. You’d think that someone from UCAR world headquarters in Boulder would put down their latte and find out.


  1. TCO
    Posted Apr 8, 2006 at 8:31 PM | Permalink

    1. Something is happening with the webpage so that the figures and post text box are interfered with by the side panel.

    2. Ok. This is one more publication that needs to be done (comparison of nearby sites by different samplers). But you won’t publish. Or you will wait for an omnibus paper instead of doing a buinch of LPUs.

  2. Steve McIntyre
    Posted Apr 8, 2006 at 11:07 PM | Permalink

    It’s not the webpage, it’s just that I made the figures a little too big. They were not so big that the effect was lost, so I didn’t bother going back and making the figures a little smaller.

    No, I’m not thinking in terms of omnibus papers. I’m more of a memo type of writer, which suits little papers.

  3. TCO
    Posted Apr 9, 2006 at 5:45 AM | Permalink

    1. Maybe it’s worse for me, when on a laptop (small screen).
    2. Great. You could publish this post as a little letter. Would get the field thinking. You or someone in the field could do follow ons. Put it in a specialty journal. Not nature or science, not nescessarily wherever these guys published.
    3. I think you need to make caveats in your conclusion/discussion that you are presenting things to look at, worry about. Rather than a hard-core stake through the heart. Because it isn’t that yet, until you do do the longer paper. But that’s fine.

  4. TCO
    Posted Apr 9, 2006 at 5:47 AM | Permalink

    I just had a post rejected. (I haven’t checked, but likely this will erase some of my earlier ones.) Had this experience a week ago and never got the other ones out of purgatory.

  5. Posted Oct 9, 2006 at 3:27 AM | Permalink

    Nice site I found … Plan on coming back later.

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