Re: How should I core krummholz in New England?    Edward Frank
   May 17, 2007 19:25 PDT 

We have on occasion discussed the nature of stunted trees such as atop Mt. Greylock, and other places around the country. This post from the tree ring list discussed a sampling strategy that I thought might be of interest to others on the ENTS list.

Ed Frank



I'll send you a paper of interest under separate cover, the question of
how to sample krummholz may have more general application, so here goes:

Krummholz - stunted trees near the alpine timberline in general - are
sometimes poor subjects for dendrochronology due to missing rings and
poor circuit uniformity. You should be aware of and test for both
possibilities.   Testing requires securing cross-sections which are
examined for circuit uniformity and crossdated against a reliably dated
living tree chronology to assess missing ring frequency. Cutting of
live trees for cross sections is preferably avoided, though you may find
opportunities to get such material e.g. new trail construction, road
maintenance etc. Fortunately there will often be dead stems on living
trees, as well as dead trees. You will look for recently dead stems,
decay class 1 or 2, i.e. bark still attached. Even in the best of
circumstances crossdating between such stressed individuals will be
sketchy so the ring width records from the dead material should be
referred to a live tree chronology derived from sampling of larger
(preferably mature or old, open-grown) erect-growth trees from a nearby
site at slightly lower elevation. Such a reference site may also give
you a local climate-sensitive chronology against which you can test for
ecological signals in your study site material.

Note that many timberline trees, and Abies in particular, reproduce by
layering. Thus dates of growth form changes are often more informative
than dates of "establishment" or "death." Growth form change dates are
derived by inspecting the tree to determine growth changes it has
experienced (such as initiation of an erect leader) and sampling above
and below the change to date the timing of the morphological response.

If your krummholz specimens have pretty good circuit uniformity, you
will find that you can core very small trees - say, 4 cm diameter.
However there is a high risk that such sampling will kill the tree
simply because the corer removes a significant portion of the wood. I
have revisited such small trees and found that they are vulnerable to
death or severe injury from falling over, I suspect in response to
winter snow loading, which breaks the stem at the core point.

Christopher J. Earle


I am a first-year PhD student at the University of Vermont Botany
department. I am studying change at tree line in New England over the last
100-150years. I am using repeat historical landscape photography, aerial
photography, and dendrochronology to look for change in elevation of
timberline and physiognomy of high elevation trees. I hope to use
dendrochronolgy at sites on Mt. Mansfield, Vermont, Katahdin, Maine and Mt.
Washington, New Hampshire.
I am new to dendrochronology and could use advice on methods of coring
balsam fir krummholz (possibly black spruce and heart-leaved birch also).
My current plan is to have one ridge and one gulf transect on the East and
West sides of each mountain. The transects would extend from full-sized
trees through prostrate forms with two cores taken at the base of the tree
and two at the snow pack line. I hope coring at the snow-line will tell me
when a former krummholz individual was able to send up a successful upright
leader that became the current tree. I will also age seedlings by counting
I am wondering how many trees I should core (how wide a transect etc) and
whether two cores will give me reliable data. Would it be a good idea to
take discs from a small subset of trees to check my accuracy? If discs are
not allowed by land managers, will I still be able to trust my data? If
anyone has suggestions on how to work with krummholz, from coring to reading
the cores, please let me know.
    Kimmie Beal
Re: How should I core krummholz in New England?  

A small point, but aging seedlings by counting branch nodes is a risky
endeavor. For one thing, firs and spruces can form branch buds in the axils
of many of their needles along the shoot, not just where lateral buds form
at the base of a terminal bud. This is unlike the simpler species of pines,
where node counting can work for a few years along any axis. Even
ring-counts are difficult in beat-up, slow-growing seedlings because of
missing rings in years of no growth or very little growth. Trees you
identify as seedlings may turn out to be much older than you expected.

Ronald Lanner

Re: How should I core krummholz in New England?  
Well, counting nodes is also possible at spruce - but they must be clearly
identified as nodes. You should look for the bud scales (remainings appear
as grooves around the shoot) at the base of the shoot. They indicate a real
node, while the preventive twigs at the internodes (often above the base of
the shoot) do not show this feature.

With best regards
Dr. Constantin Sander

Re: How should I core krummholz in New England?  

Quite right, Constantin, but identifying the nodes becomes difficult when
bark formation obscures the bud scale scars after a few years. This may be
less of a problem in smooth barked firs, where the grooves are more obvious.

Ronald Lanner