Tree Rings and Climate: Sharpening the Focus - Dendroclimatology - page 343

Thus, tree-ring, historical-documentary, and archeological lines of evidence can
be combined in the evaluation of past human societal and behavioral responses to
climate variability and change (e.g., see Stahle and Dean, Chapter 10 , this vol-
ume). Potential exists to further develop such interdisciplinary studies in various
areas of the world having rich human histories and tree-ring resources. These nar-
ratives are of great interest to the public and have potential to offer new insights
into human history and our role in both causing and responding to environmental
change.

11.10 Prospects for Dendroclimatology

In a review of the 'state of the art' of dendrochronology in climatology, Hughes
( 2002 ) , referring to tree rings as natural archives of climate variability, stated:

The greatest strengths are: the capability to date tree rings to the calendar year, with a very
high degree of confidence; the existence of large geographic-scale patterns of common year-
to-year tree-ring variability; the development of very extensive, shared networks of tree-ring
chronologies meeting common standards; the surprising effectiveness of very simple linear
models of tree-ring/climate relationships; and the growing understanding of the mechanisms
leading to variability in tree ring features.

During the past 1-2 decades, these strengths have been put to good use by many
researchers to provide relatively robust climate reconstructions on large regional to
hemispheric spatial scales for the past several centuries to millennia.
Improvement of such reconstructions is limited by the relative lack of high-
quality records in important regions, especially in the tropics, and for times before
the past five or six centuries. Without adequate networks, knowledge of such regions
and times cannot benefit from the robust spatiotemporal patterns tree rings can
provide for climate reconstruction. With them, the prospects for climate reconstruc-
tion are greatly improved. The accelerating pace of network building and temporal
extension of chronologies exemplified in Villalba et al. ( Chapter 7 , this volume)
augurs well for the continued contribution of dendroclimatology to knowledge of
Late Holocene and recent climate. Moreover, new kinds of records based on ratios
of stable isotopes are emerging that provide information not available from ring-
width and density records, in boreal, temperate, and tropical regions (see Gagen
et al. Chapter 6 , this volume). The experience of recent decades also suggests that
there are many other new tree-ring archives of past climate to be discovered and
developed, even in regions where dendrochronologists have been active for some
decades.
Hughes ( 2002 ) also summarized the major weaknesses of dendrochronology in
the study of climate:

[T]ree-ring chronologies only capture a fraction of climate variability; their response may
be limited to specific seasonal 'windows'; some do not respond directly to a single monthly
or even seasonal climate variable their use to reconstruct past climate is based on the

assumption that the same factors, acting in the same way, controlled the formation of tree
rings in the past as in the twentieth century and, the techniques used to remove non-climatic

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