Loose End Ideas…
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Loss of perennial snowfields important for municipal water supply

Past 40 yr volume of glaciers worldwide declined by 10%
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Local climate and disturbances confound the larger climate change impact. –local
disturbance more frequent on cool-aspect slopes (glacial forefields usu. Nfacing…) Dating disturbances which might otherwise go unnoticed and be
counted as effect of climate change (or lack thereof)- krummholz and vegetation
cover rates are lower at disturbed (avalanche, frost damage, etc) sites but higher
than at mass movement sites (Daniels and Veblen 2003)

Detect early manifestations of effects of rise in temperature, focus on vegetation
types most likely to have a response to varying climate (Copenhagen 1997)
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Treelines are predicted to be much more continuous than they actually are.
Common patterns, though, are fingering and floating tree islands. S+H –
chronology can assist in investigating patterns within the treeline ecotone. i.e.
disturbances, microsite conditions etc (Cairns 1998)

No significant effect of hemisphere on treeline (Jobbagy and Jackson 2000)
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Understanding primary succession vs. establishing dating controls for substrate
exposure???
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Play up “climate change” angle more?
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ESH can support a student for ~3 yrs
Background
The current warming trend seen over the last century and especially the last few decades
has most notably occurred in climatically sensitive high mountain regions of the earth
(Luckman 1994). An especially climatically responsive ecosystem is the alpine glacial
forefield as exposed by retreating glaciers. Much effort has been put into gaining higher
and higher resolution chronosequences of this glacial retreat (Glasser 2004, Glasser 2001
Villalba 1990, Luckman 2000, Calkin 2001). Glacial retreat has been studied with
exceptionally high precision in many areas, the Canadian Rockies, the Sierra Nevada, the
Swiss Alps and parts of the north and southern Patagonian Ice Field through repeat
photography, historical documents and using natural archives such as tree-rings
(dendrochronology) and lichens (lichenometry) (Winchester 2000, Villalba 1990,
Luckman 2000, Hostetler 1996). Importantly, these techniques have been applied in both
the southern and northern hemispheres in order to focus on the interhemispheric
teleconnections climate patterns exhibit (Luckman and Villalba 2001, Scmittner 2003,
Markgraff 2000).
While methods such as repeat photographs and historical records provide a high
resolution chronosequence for many glacial retreats, a majority of glaciers, the study of
which is crucial to understanding current warming, have no such data (Glasser 2004).
Where these resources do not exist, natural archive dating is utilized. Methods such as
dendrochronology are excellent for precise dating of glacial advance, as ice-damaged,
tilted and killed trees are datable with annual precision (Luckman 2000). Glacial retreat,
however, is somewhat trickier to absolutely date as trees initiated after a glacier recedes
can take anywhere from 7 to 100 years to establish (ecesis time) (McCarthy and Luckman
1993, Winchester and Harrison 2000). This lack of high precision chronologies for
glacial retreat is greater in the cordillera of South America than it is in the Northern
hemisphere.
As dated reference surfaces on these newly exposed forefields are scarce and ecesis rates
for trees and lichens vary so widely it is high time for the relatively new method of herbchronology to be applied to this problem of how to obtain higher resolution retreat
chronosequences for high elevation glaciers.
Shrub- and herb-chronology is a technique adapted from dendrochronology and analyzes
the growth rings in the secondary xylem of plant roots, rather than in the xylem of stem
tissue as in the case of trees (Fritz 1976, Schweingruber 1988, Schweingruber 1996,
Schweingruber 2001). These growth rings are noticed to be widespread in the strongly
seasonal zone of the northern hemisphere, which is where the main body of research on
this subject has been carried out (Dietz and Ullman 1997, Schweingruber and Dietz 2001,
Erschbamer and Retter 2004). Recent finding suggest that many of these rings are annual
in nature, with several studies currently in progress to verify this. The lengthiest study on
the annual nature of these growth rings is one decade long, currently confirming the
annual nature of the growth rings. The presence of annual rings when found in one
species of a genus is usually found to hold true for all species of that genus (Dietz and
Ullman 1997, Dietz and Fattorini 2002, Dietz and Von Arx 2005).
Glacial forefields are ideal sites for utilizing the information these plants yield, as optimal
conditions for certain pioneer species of herb and shrub initiation appear almost
immediately upon deglaciation. Herbaceous plants are known to respond rapidly to
climatic fluctuations (Dietz and Von Arx 2005) further underscoring their value in dating
newly exposed surfaces. Maximum ages of certain species of shrubs and herbs found in
the Alps have ranged from 60 to 100 years (Schweingruber and Dietz 2001). In the
White Mountains of California, USA, high alpine sage-brush has been accurately dated at
200+ years old (Ferguson 19xx). These shrub- and herb-chronology-derived ecesis
values for surfaces of known age can then be applied to surfaces of unknown age. The
annual nature of the growth rings combined with the long lives of these alpine plants
make them an exceptional resource for acquiring high resolution dates for the retreat of
glaciers in areas with a dearth of documentation on glacial retreat.
The vast majority of research on shrub- and herb-chronology has been carried out in
Europe, mainly in the areas of Austria and the Swiss Alps. To the best of our knowledge
no one has looked at glacial forefields in the Americas with a view to using this new
technique to more fully understand glacial retreat and hence, recent climate change. In
this “natural laboratory” space can be substituted for time and as the spatial
chronosequence is examined, events over time unfold in an increasingly clear manner.
To get a fully integrated view of glacial retreat and primary succession, this new
technique can be combined with dendrochronology (to establish higher accuracy in
studies of colonization rates of trees growing on or adjacent to glacial forefields) and the
analysis of high resolution sediment cores (analysed for pollen rain) from periglacial
tarns, or small alpine lakes, on the glacial forefields. While conventional piston corers
obliterate the top layers of sediment, rendering them usually unfit for analysis, a modified
piston corer constructed and used at the University of Arizona is able to extract a
sediment core and produce from it pollen containing sediments from the top unstable
layer suitable for annual dating using 210Pb and 137Cs. These annually resolved pollen
samples will serve to validate results obtained using herb- and shrub-chronology (Owen
Davis 2005, pers. comm.). This method of combining these three techniques in order to
obtain a fully integrated annually resolved view of glacial retreat has not yet been
attempted in any part of the globe, let alone as a way to compare glacial retreat/climate
fluctuation along the pole-equator-pole transect. When completed this will be a valuable
tool to help understand patterns of recent glacial retreat and recent climate fluctuations in
some of the most climatically sensitive areas of the American Cordillera.
Goals of Research

To enable greater dating accuracy and higher resolution of glacial retreat
chronosequences in areas that lack records with annual resolution, especially in
the Southern Hemisphere (dating controls for substrate exposure)

Defining ecesis rates for trees establishing on recently exposed glacial forefields

Establish which genera common to alpine ecosystems are suitable for shrub- and
herb-chronology: presence of annual growth rings (or annual nodes of some sort)

Establish which genera of the above shrubs and herbs exhibit a response to
climatic fluctuations

Substantiate results from relatively new technique of dating presence of shrub and
herb species via shrub- and herb-chronology with traditional technique of annual
dating of pollen rain from sediment cores taken from local tarns

Identify possible recent teleconnection patterns in interannual ENSO-like
variability exhibited in resulting herb/shrub indices from glacial forefields in
north and south American cordillera (1st PC of Alaskan and Patagonian tree-ring
chronologies significantly correlated at 10- 15 yr. Can these shrubs and herbs
express that signal as well? Less prominent peaks were noticed at 2, 3.2 and 5.2
yrs. (Markgraff et al 2000) Possibly these shorter oscillations (associated with
interannual mode of ENSO variability) can be picked up as stronger signals in
shrubs and herbs, as they have been shown to exhibit an extremely rapid response
to climate fluctuations (Dietz and Von Arx 2005))

Methods
Year 1
Identify which plant genera are common to the group of plants found to have annual
growth rings in secondary root xylem and also to the set of plant genera commonly found
at high elevation on North American periglacial surfaces.
List so far consists of: Potentilla
Dryas
Salix
Erica
Astragalus
Trifolium
Silene
Artemisia
Identify well studied periglacial sites which:
1. support the aforementioned genera
2. contain periglacial tarns suitable for coring
3. have well documented (dendrochronologically) rapid recent glacial retreat
4. have extensive historical photo-documentation for dating control of shrubs and herbs
Sites so far:


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Glacier National Park (Grinnell, Sperry and Blackfoot Glaciers) (Cooper et al
1997)
??? Niwot Ridge, Colorado (Arapaho and Arikaree Glaciers) (newspaper???
2004)
Athabasca and Dome Glaciers, B.C., Canada
Field season 1: Calibration of Shrub and herb dating with known periglacial surface ages
Field reconnaissance and collecting at N. American sites:
This will be done with connections at the University of Western Ontario (Brian
Luckman group), University of Montana (Lisa Graumlich group) and with the
field guidance of USFS senior researcher, Constance Millar.
Sampling Procedures:
Of the variety of techniques used for sampling glacial forefields for determination
of ecesis rates the most effective and the one which shall be employed in this case
will be that of sampling on transects running orthogonal to the last terminal
moraine. We will sample based on interpolated ages based on historical
photographs (McCarthy and Luckman 1993).
In alpine species it has been found that the largest individuals are significantly the
oldest individuals (Erschbamer and Retter 2004). Thus, we will sample the
largest individuals that are found in our transect plots.
Analysis Season 1
Sample Processing
All sample processing will take place at the Laboratory of Tree-Ring Research at the
University of Arizona, USA. My strong experience in the field of dendrochronology, the
assistance of many knowledgeable and well trained professors and researchers in the top
of their field and the state of the art facilities at the laboratory will ensure the successful
analysis of these specimens.
Based on the absolute dates obtained from historical photos of the site, dates will be
determined for subsequent locations on the transect lines. Thin sections will be prepared
from cross sections of the root tissue taken approximately 10 cm below the ground
surface (Schweingruber and Dietz 2001) so that the herbs and shrubs from within these
plots will be analyzed using dendrochronological techniques to account for annuality of
growth rings etc. These plants have the added benefit of their entire cross section being
analyzed (as opposed to 2-4 radii in the case of trees) to ensure that growth patterns that
do not cover the complete circumference of the root are duly noted.
With the results from the herb- and shrub-chronologies, a calibration can be made for the
amount of time it takes for these species to establish on newly exposed periglacial strata.
Validation techniques will also be used to confirm the validity of the calibrations of
ecesis rates derived from chronology dates and surface ages.
Year 2
Identify which plant genera are common to the group of plants found to have annual
growth rings in secondary root xylem in North America and also to the set of plant genera
commonly found at high elevation on South American periglacial surfaces.
Identify well studied periglacial sites which:
1. support the aforementioned genera (yet to be established)
2. contain periglacial tarns suitable for coring
3. have well documented (dendrochronologically) rapid recent glacial retreat
Sites so far:
Alerce Glacier
Castano Overo Glacier
Frias Glacier (Villalba 1990) (South Pat. Ice fld.)
---------------------------------Pared Norte
Steffen
Colonia Glacier (Glasser 2004) (S. end of N Pat. Ice fld.)
-----------------------------------Nef Glacier
San Quintin Glacier (Villalba 1997) (N Pat. Ice fld.) (Nauhuel Huapi National
Park)
Field Season 2
Field reconnaissance and collecting at South American sites.
This will be done with connections at the Laboratorio de Dendrochronologia, CRICYTMendoza, Argentina (Ricardo Villalba group) and help from Henry F. Diaz at NOAA,
CDC, Colorado, USA and again field guidance and instruction from Dr Constance Millar,
USFS.
Sampling Procedures
Similar techniques (modified as seen fit) will be employed in this leg of the project.
Integrity of sampling process is needed to ensure comparable results.
Sampling Processing and Analysis
Again, the same processing and analysis procedures will be employed for the samples
extracted during this leg of the project. The reliable regression formulas derived from
analysis of the paired chronologies and surface dates will now be applied to the
chronologies obtained from the South American sites.
Once the two sets of chronologies have been completed, further statistical analysis can be
carried out as outlined in the “Goals of Research” section. Principal Component Analysis
will possibly tell if there is an ENSO-like signal that can be picked up in either or both
sets of chronologies (if they are of significant length) and if there is a higher frequency
pattern that can be detected. It will be most interesting to see if these chronologies will
exhibit signs of interhemispheric teleconnections.
When both sets of chronologies have been completed and BIG PRODUCT