Climatic Inferences from Dendroecological Reconstructions - Dendroclimatology - page 288

where both fire-scar and lake-level data were compared with tree-ring climate
reconstructions). In some cases, regional ecological time series may be less noisy
and/or higher-resolution indicators of climate variability than glacier- and lake-level
fluctuations.
It is clear that dendroecological data, especially networks of such data, can
be very useful for clarifying and identifying climatic variations and changes that
are important to ecosystems . We refer to this as 'ecologically effective climate
change,' and we think that this category of climatic variability deserves special
attention by ecologists and other researchers. As climate change due to greenhouse
gas-induced warming continues and perhaps accelerates, it will be increasingly
important that climatologists, ecologists, managers, policy makers, and the pub-
lic focus their attention on understanding and anticipating the impacts of climatic
change on ecosystems. This will require more effective integration and compara-
tive analyses of dendroclimatic and dendroecological studies. It may well be that
the ecologically effective climatic changes that dendroecology can address will pro-
vide some of the most sensitive and insightful information about climate change
impacts. The great potential for ecological indicators is exemplified by time series
of plant phenology, such as the timing of plant flowering (Cayan et al. 2001 ) . These
records (especially in networks) are now widely recognized and embraced as a key
and valuable ecological indicator of climate change.
The final example we offer of the potential of using dendroecological responses
to identify ecologically effective climate changes for guiding future research, and
for applications, is the finding of the importance of wet/dry oscillations in fire
occurrence in the western United States (e.g., Fig. 9.4 ) . It was tree-ring analysis
that first identified a strong statistical association between the wet/dry sequence
of 1-3 wet years, followed by a dry year, and widespread fire occurrence during
the dry year (Baisan and Swetnam 1990 ; Swetnam and Betancourt 1992 ; Swetnam
and Baisan 1996). This finding has been replicated by numerous dendroecology
studies, particularly in relatively dry ponderosa pine ecosystems where grass and
other fine fuel production was important for historical fire ignition and spread (e.g.,
Veblen et al. 2000 ; Brown et al. 2001 ; Donnegan et al. 2001 ; Stephens et al. 2003 ;
Brown and Wu 2005 ) . Subsequently, analysis of modern fire and climate records
(i.e., twentieth- and twenty-first-century data) confirmed that this pattern was impor-
tant over large portions of the western United States during recent times (Knapp
1995 ; Westerling et al. 2002 , 2003 ; Crimmins and Comrie 2004 ) . Now, this wet/dry
pattern, in combination with ENSO-based climate forecasts (and ENSO-fire associa-
tions), is used to develop seasonal 'outlook' (forecasting) products for fire managers
(see Predictive Services at National Interagency Coordination Center, Boise, Idaho:
http://www.nifc.gov/nicc/predictive/outlooks/outlooks.htm ).
In conclusion, we are optimistic that dendroecological contributions to den-
doclimatological research, and vice versa, will greatly expand in coming years.
The interest in ecological responses to climatic variability and change is already
very large and will certainly increase as global warming continues and its impacts
increase. The signs of this scientific interest are already evident in increasing
numbers of dendroclimatic and dendroecological papers with a climate focus in