Dendrochronologia 30 (2012) 195–197
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Dendrochronologia
journal homepage: www.elsevier.de/dendro
Miscellaneous
The “dendrochronological community” at Rovaniemi, Finland, 2010: Lessons
learned from the past and perspectives for the future
Dieter Eckstein a,∗ , Paolo Cherubini b
a
b
University of Hamburg, Dept. of Wood Science, Division Wood Biology, D-21031 Hamburg, Germany
WSL Swiss Federal Institute for Forest, Snow and Landscape Research, CH-8903 Birmensdorf, Switzerland
During the past 50 years, dendrochronology has developed into
a highly diversified field of research. A world conference, such as
the last one hold at Rovaniemi, Finland, in June 2010, provides
an overview of current research activities and various interlinking
opportunities between research topics and the people involved.
However, conference presentations can only offer a limited focus
on the generations of preceding scholars to whom we owe the
existence of our acquired body of knowledge. This is why here,
we are not summarizing or evaluating the conference presentations. Rather, we aim to use some examples from different lines of
dendrochronological research history to illustrate that our achievements have not appeared out of the blue from nowhere but have
their origins anchored somewhere in the past. Herewith, we want
to point to a typical symptom of our present time, that is to say,
to the loss of historic continuity. In addition, we will outline a few
thoughts based on the achievements presented during the conference.
To begin with, we want to highlight that dendrochronologists
over the course of time have accomplished the establishment of
a world-wide scientific community, aided by the collaboration
opportunities presented by past world and regional conferences.
Accordingly, our scientific activities have become a social process
and our results have become public knowledge open to criticism, as
well as verification or falsification. These are the minimum requirements for a discipline to be accepted as a science. As long as we
dendrochronologists feel part of such a scientific community (as a
voluntary association), we submit ourselves to strict social control
that ensures the reliability of our scientific statements.
The oral and poster presentations accompanied by stimulating discussions during the WorldDendro2010 conference days at
Rovaniemi again illustrated the highly interdisciplinary nature of
dendrochronology. Its roots lie in tree biology and its results radiate
into a wide spectrum of individual sciences ranging from cultural
history to geophysics. The creation of this wide and rich diversity
within the discipline does not indicate that the various subfields are
drifting apart, but rather shows that they are closer together than
∗ Corresponding author.
E-mail address: [email protected] (D. Eckstein).
1125-7865/$ – see front matter
doi:10.1016/j.dendro.2011.02.001
ever before. This is due to the fact that these subfields profit of each
other be it from the exchange of techniques or data or from a deeper
understanding of tree growth. All in all, the tree is and will remain
our smallest common denominator (Fig. 1). A tree is influenced by
several growth controlling factors whose impacts are received primarily by the foliage and the roots and then transformed by the
cambium into new cells. The metabolic pathways involved can be
traced through time and on various structural levels of a tree. But
only on the anatomical, cellular, and chemical level are the effects
of exogenous influences permanently archived, provided that an
influence had been limiting tree growth for a certain period of time.
Each of the resulting measurable quantities (e.g., tree-ring width,
vessel size, cell-wall thickness, wood density, or stable isotopes)
record a different detail of the tree’s environment.
We do not know when dendrochronology came into being, at
least as an idea in a philosophical sense. It is as with a river, which
is supplied from uncountable, partly subterraneous rivulets, whose
onsets seem to appear suddenly from nowhere. It may have been
the Greek Theophrastus (ca. 300 BC) the first who observed tree
rings, although he never documented an explanation for the radial
growth of trees. The idea of dendrochronology resurfaced, this
time distinctly more perceptible, in Leonardo da Vinci’s work in
the late Italian Rinascimento towards the end of the 15th century.
He described the relation between summer rainfall and tree-ring
width. During that time, tree-ring formation was understood as
a periodic transformation of the inner bark layers into sapwood
which later condensed into heartwood. The term cambium was
already used to describe a layer between wood and bark, although
this layer was assumed to consist of some kind of liquid. Only during
the 19th century did tree rings become part of collective awareness.
This was the century of the microscope and of far-reaching biological discoveries, for example of the cell nucleus and of cell division,
and in consequence of the existence and function of a meristem
between bark and wood – that is to say, the basic nature of the
cambium was correctly identified.
One milestone event out of several pioneer gatherings was a
workshop in 1974 in Tuscon, Arizona hosted by Hal Fritts, two years
before his book on “Tree rings and climate” was published (Fritts,
1976). This workshop unknowingly was the birthplace of the now
so-called “WorldDendro” conferences. Today, dendrochronology
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D. Eckstein, P. Cherubini / Dendrochronologia 30 (2012) 195–197
Fig. 1. Tree growth and its control (Eckstein, 2007).
has expanded worldwide, from the Tibetan Plataeu to the Amazon
Basin, from Greenland to New Zealand.
The most frequently used tree-ring parameters at present still
are the width, density, and chemical composition of tree rings. But
the search continues for new dendrochronological variables. Such
efforts can be traced back by half a century. One of these early tracks
is deeply rooted in wood anatomy and, to the best of our knowledge, became visible for the first time around 1960 (Knigge and
Schulz, 1961). This publication was the inspiration for subsequent
studies in the 1970s and afterwards. However, only after the advent
of fully automatic image analysis systems around 1990 did wood
anatomy become more widely appreciated due to an increase in
technical capability and efficiency. Meanwhile, wood-anatomical
dendrochronology took shape as a new and lively subfield of treering research, as shown by the many presentations at Rovaniemi,
with a great potential to expand (Fonti et al., 2010).
Another example of research history within dendrochronology
has become known as dendro-provenancing (Eckstein and Wrobel,
2007). It has been developing unnoticed, quasi anonymously and
accidentally. The fact that timber has been transported over long
distances in the past has been suspected for around 50 years. An
early report, if not the earliest, on timber transport concerned the
construction of a cog that was excavated in the early 1960s in Bremen, a harbor city in northern Germany. The origin of the oaks
used to build the cog was dendrochronologically determined to be
from the upper reaches of the river Weser some 400 km south of the
shipyard where they were felled in 1385. After these early, sporadic
and accidental indications of timber transport, the determination
of the origin of historic wood became of interest only after dendrochronology began to be applied to art history. It was discovered
that until around 1650, early German, Dutch and Flemish painters,
such as Rubens and Rembrandt, were painting on oak panels from
at least two provenances with distinct tree-ring characteristics.
One group clearly represented timber of Dutch or west German
origin. The tree-ring series of the other group, many of them covering more than 300 years, were assembled to create a 400-year
floating chronology which initially remained undated. Few panels
contained wood from both provenances. The mystery was solved
years after the onset of art-historical related dendrochronology
around 1985, when a regional oak chronology had been assembled for the Gdansk area in northern Poland, then behind the Iron
Curtain (Wazny, 2002). It was proven that the oak wood used for
panel making had been transported from Polish/Baltic forests to
western European coastal countries in unexpectedly large quan-
tities over centuries until the end of the European 30-Year War
around 1650. Further, we now know the origin of timber export
from the harbor town of Riga, Latvia from as early as the 13th
century to be from present day Belarus and western Russia. That
means that considerable distances of up to 1800 km had to be covered over rivers and land from the inland forests to the Baltic
Sea coast with final destinations in such places as the British
Isles (Zunde, 1998/99). At present, dendro-provenancing is vitally
developing into a European-scale project due to the inevitable
focus that will turn to other geographic areas, such as Norway,
the Central European river systems or the Mediterranean coastal
countries. What makes dendro-provenancing so important for
the dendrochronological community as a whole? It is the urgent
question as to which climate region composite tree-chronologies,
assembled and applied as dating tools, truly represent. Therefore,
dendro-provenancing may have far-reaching consequences in the
near future.
Dendrochronology – quo vadis? What is your future? In the
future, dendrochronology will partly consist of a repetition of
established and successful approaches applied to new geographic
areas and new tree species. In fact, such activities are necessary to
consolidate the network of chronologies and to explore the potential of new tree species, mainly to reconstruct past climates. But
new topics have also emerged in the past ten years. Among them
is the study of intra-annual cambium dynamics (Rossi et al., 2008)
which again is an example for an idea that is more than 100 years
old (Knudson, 1913) whereas its ecological relevance was realized
only at the onset of the new millennium. Another example is the
study of dwarf shrubs and herbs beyond the upper and lower altitudinal tree lines (e.g., Cherubini et al., 2003), as well as the latitudinal
tree lines of our planet (Schweingruber and Poschlod, 2005). Also
in this case, the theory had been introduced about 100 years ago
(Kanngiesser, 1907; Molisch, 1938), but continuous and systematic
efforts became visible only during the last decade.
What lessons can we learn from all the presentations during the
conference? Without any doubt, the increasing use of computers
and statistics since the beginning of the 1960s has not only achieved
a noticeable quantitative increase in results, but also has yielded
a novel quality of information derived from tree rings. However,
the free accessibility of computer programmes is accompanied by
the risk that users may not look carefully and intensely enough at
the trees, the wood, and the raw measurements. Statistics should
support observations and test scientific hypotheses, but not as an
end in itself, especially if a researcher is experienced enough to see
the answer simply by careful observation.
What else should we take home? That we depend on the ideas
and achievements of our predecessors and that we will become
predecessors for our successors; since we are links in a long chain,
we should feel responsible for what we pass on to our followers.
As long as we are aware of this continuity and we do not only build
our studies on the current stage of research, we do not have to “reinvent the wheel” every now and then. Let us go to the libraries from
time to time and look out for papers written by our predecessors,
quite often not in our mother tongue and long before electronic
data banks came into existence, and benefit from the treasure of
their legacy. Let us act in modesty.
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