Resource Category: Journal Papers and Book Chapters

This paper has examined the relative significance of uncertainty in future climate
projections from a subset of the coupled model intercomparison project phase 5
(CMIP5) global climate models for the Prairie Provinces of western Canada. This
was undertaken by determining: (a) the contribution of model and scenario uncertainty and natural variability to the total variance of these future projections, and
(b) the timing of climate signal emergence from the background noise of natural climate variability.

ABSTRACT: The performance of eight National Center for Environmental Prediction (NCEP2) reanalysis-driven regional climate models (RCMs), seven from the North American Regional Climate Change Program (NARCCAP) and one from the Coordinated Regional Downscaling Experiment (CORDEX), in simulating the 1980–2004 climate of western Canada was assessed at a number of spatial and temporal scales. Results indicated that the RCMs were more successful at capturing the seasonal spatial distribution of mean temperature than precipitation and that inaccuracies in the spatial distribution of the summer climate moisture index were likely due to the errors in precipitation distribution and amount. All RCMs performed less well in simulating summer precipitation, most likely due to continued problems with the simulation of convective precipitation

In South America, the arid and semiarid subtropical regions through the Atacama Desert and north-central
Chile between 19° and 32°S are currently a gap in the tree-ring chronology network. Only a short tree-ring
chronology has been published for this vast region and little is known about the suitability of many woody
species for tree-ring analysis and dendroclimatology.

In western Canada growing demand for water resources has increased vulnerability
to hydrological drought. The near full allocation of water supplies in the Oldman and
Bow River subbasins of the South Saskatchewan River Basin has resulted in a moratorium
on new surface water licenses. In this region, short instrumental records limit the detection
of long-term hydrological variability.

Published: November 29, 2016

TREE-RING RESEARCH, Vol. 73(1), 2017, pp. 53–56
DOI: http://dx.doi.org/10.3959/1536-1098-73.1.53
SCIENTIFIC ADVISORY
THE FIRST MILLENNIUM-AGE ARAUCARIA ARAUCANA IN PATAGONIA
ISABELLA AGUILERA-BETTI1*, ARIEL A. MUÑOZ1, DANIEL STAHLE2, GINO FIGUEROA1,3,
FERNANDO DUARTE1, ÁLVARO GONZÁLEZ-REYES4,5, DUNCAN CHRISTIE6, ANTONIO LARA6,
MAURO E. GONZÁLEZ6, PAUL R. SHEPPARD7, DAVID SAUCHYN8, ANDRÉS MOREIRA-MUÑOZ9,
ISADORA TOLEDO-GUERRERO1, MATÍAS OLEA1, PABLO APAZ1,10, and ALFONSO FERNANDEZ11
1Laboratorio de Dendrocronología y Estudios Ambientales, Instituto de Geografía, Pontificia Universidad Católica de
Valparaíso, Valparaíso, Chile
2Department of Earth Sciences, Montana State University, Bozeman, MT, USA
3Universidad Andrés Bello, Viña del Mar, Chile
4Departamento de Geología, Universidad de Chile, Santiago, Chile
5Instituto de Ciencias de la Tierra, Universidad Austral de Chile, Valdivia, Chile
6Laboratorio de Dendrocronología y Cambio Global, Instituto de Conservación, Biodiversidad y Territorio, Universidad
Austral de Chile, Valdivia, Chile
7Laboratory of Tree-Ring Research, University of Arizona, Tucson, AZ, USA
8Prairie Adaptation Research Collaborative, University of Regina, Regina, Canada
9Instituto de Geografía, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
10Paisaje Antofagasta LTDA, Antofagasta, Chile
11Departamento de Geografía, Universidad de Concepción, Concepción, Chile
Keywords: Araucaria araucana, Pehuén, Llaima Volcano, Parque Nacional Conguillio, Endangered
Species, Millennium-old Araucaria.
GENERAL BACKGROUND ON
ARAUCARIA ARAUCANA FORESTS
The iconic conifer Araucaria araucana (Araucaria), called Pehuén by native people, is an endemic species of the Andes of northern Patagonia in Chile and Argentina. Its range encompasses
only three degrees of latitude (37◦20 – 40◦20
S)
with a small outlying presence in the coastal mountains of Chile (Veblen et al. 1995). The species
is classified as endangered (Premoli et al. 2013)
because of extensive logging and human-set fires.
Araucaria araucana has a long history of ethnobiological importance. For centuries the Pehuén
fruits have been a vital sustainable food source for
the Pehuenche people (Mapuche) and today the
growing industry of ecotourism indirectly serves
to protect these forests (Aagesen 1998; González
* Corresponding author: isabella.aguilerab@gmail.com
et al. 2013). After a long history of human destruction of A. araucana forests, which reduced
its range to half its original distribution, Chile
and Argentina now legally protect this endangered
species. These ecosystems continue to be threatened by logging, fires, and extensive livestock use.
These factors, and the potential threats posed by
climate change, are among the main challenges
to A. araucana conservation (González and Lara
2015).
THE CHALLENGE OF FINDING OLD
A. ARAUCANA TREES
In the mid-1950s, Edmund Schulman was
the first dendrochronologist to carry out sampling
in Argentina and Chile, and he built the first
chronologies of Fitzroya cupressoides and A. araucana (Schulman 1956). After Schulman, from 1973
to 1978 Richard Holmes and Valmore LaMarche
Copyright C 2017 by The Tree-Ring Society 53
54 AGUILERA-BETTI ET AL.
Figure 1. (A) An image of the A. araucana tree-ring collection site at Captrén, Llaima Volcano, Chile. (B) Five of the longest A.
araucana tree-ring growth series of individual trees from different sites across the Andes are plotted. Notice that the millennium-age
tree from Captrén displays a continuously crossdated growth series over a thousand years in length. (C) A map of northern Patagonia
displays the distribution of Araucaria araucana in blue, green triangles indicate the locations of A. araucana tree-ring collection sites,
and orange circles indicate the locations of the longest growth series plotted in (B).
were the first researchers to extensively collect treering samples of A. araucana, crossdate the tree rings
and develop chronologies (Holmes 1978; LaMarche
et al. 1979, Suarez et al. 2014). Additional information about the first dendrochronological sampling
campaigns in the Southern Andes can be found
in Suarez et al. (2014). During these early collections, some of the oldest individuals of A. araucana were discovered, reaching more than 800 years
old. After more than 50 years of tree-ring research
and contrary to the popular belief in Chile and
Argentina of the existence of millennium-aged A.
araucana trees, not a single tree-ring sample reaching one thousand years old had been documented.
Over these five decades of tree-ring research in A.
araucana forests, challenges to building long treering chronologies have been (i) the scarcity of virgin stands of old trees given the high impact of logging and human induced fires, (ii) the difficulty of
finding well-defined growth rings in samples from
sites experiencing growth-limiting conditions such
as high elevations or well-drained volcanic substrate, and (iii) A. araucana wood decomposes at a
high rate. Sub-fossil wood quickly degrades on the
forest floor, although some living trees experience
heart-rot, where the core of the stem rots out, making it impossible to reach the pith and accurately
determine the age of the tree. The examination of
sub-aquatic wood preserved in Andean lakes could
provide a new approach to extending chronologies
of the species.
INFORMATION FROM A. ARAUCANA
TREE-RING RESEARCH
Scientists from Chile, Argentina, and other
countries have analyzed more than 1780 tree-ring
samples of A. araucana, producing more than 37
tree-ring chronologies from sites across its entire
distribution (Figure 1). This valuable tree-ring material has been used for dendroclimatological studies reconstructing streamflow variability of Chilean
and Argentinean rivers (Holmes et al. 1979; Mundo
et al. 2012a; Muñoz et al. 2016), temperature (Villalba et al. 1989), hemispheric-scale variations in
modes of atmospheric circulation (Villalba et al.
2012), and to fill gaps in century-long instrumental precipitation records from the Chilean Patagonia (González-Reyes and Muñoz 2013). Araucaria araucana also has been used in dendroecological studies of forest dynamics (González et al.
2010; Hadad et al. 2015a), tree-growth, climate and
seed production relationships (Hadad et al. 2016),
spatio-temporal climate-growth analyses (Mundo
et al. 2012b; Muñoz et al. 2014), and fire history reconstructions (González et al. 2005, 2006; Mundo
et al. 2013). During the last decade, A. araucana
tree rings have been used to detect the 14C “Bomb
Peak” corroborated by the annual resolution of its
growth rings (Hadad et al. 2015b), utilized in preliminary δ13C and δ18O isotopes studies (Tognetti
et al. 2012), and in the analysis of chemical element
markers to detect the occurrence of past volcanic
The Oldest Araucaria Tree Documented 55
eruptions (Puchi et al. 2016). Furthermore, the need
for developing millennium-long climate reconstructions in the Southern Hemisphere has renewed the
interest of the international tree-ring community in
the use of A. araucana records from the northern
Patagonian Andes (Mundo et al. 2012b).
THE DISCOVERY
In the summer season of 2015–2016, colleagues from Chile, United States, and Canada,
collected samples from an old-growth stand of A.
araucana at the Captrén site near Llaima volcano
(38◦39
S, 71◦41
W) in Conguillío National Park,
southern Chilean Andes. This collection provides
the first sample of a living, annually crossdated tree
growing over 1000 years, reaching 1021 years old.
Previous to this campaign, the Captrén chronology started in the year 1664, but now this chronology is the longest of the A. araucana network, beginning in the year 994. The second oldest tree in
this chronology was 975 years old at the time of
sampling, implying the existence of more trees of
great age at the site. From the complete network
of A. araucana chronologies, only a few came from
sites located close to volcanoes, probably because
the main dendrochronological studies of the species
have been related to fire ecology and climatic signals
in the growth patterns. In addition, the existence of
these old trees on the slopes of Llaima volcano indicates the relative stability and moderate severity of
the eruptions at the site even though this volcano
is one of the most active in the southern Andes.
The relatively short historical record of the Llaima
Volcano eruptive activity starts in the year 1640
(Dzierma and Wehrmann 2010). Although some researchers have reconstructed eruptions using varve
sediments, this new A. araucana chronology from
the Captrén site could provide a higher resolution
inter-annual record of volcanic activity and serve to
corroborate both the historical and reconstructed
records.
CONCLUSIONS
Millennial-length tree-ring chronologies of A.
araucana have great potential to help answer relevant questions posed by climate change and natural
hazards such as volcanic activity and fire. Therefore,
the effective protection of A. araucana must be secured to preserve one of the world’s most important
botanical legacies. This finding serves to commemorate and recognize the efforts of the many dendrochronologists who have studied A. araucana and
reinforces the importance of future tree-ring studies of this species. Finally, this finding confirms the
popular belief of the existence millennium-aged A.
araucana individuals.
ACKNOWLEDGMENTS
Support was provided by the Chilean Research
Council (FONDECYT 1151427), the Center for
Climate and Resilience Research (CR)2 (FONDAP
15110009) and Proyectos Internos Pontificia Universidad Católica de Valparaíso (039.353/2016 and
039.329/2016). This study was completed using the
facilities of the Prairie Adaptation Research Collaborative (PARC) at the University of Regina,
Canada, where support came from the IDRC sponsored VACEA project. We thank the many researchers from different countries who have been involved in Araucaria araucana studies, in particular
we acknowledge; Ignacio Mundo, Martín Hadad,
Waldo Iglesias, César Pérez, Mauricio Espinoza,
Carlos LeQuesne, Ricardo Villalba, Paulina Puchi,
Fidel Roig, Moisés Rojas and Ricardo Moreno.
Special gratitude is extended to the Chilean Forest
Service (Corporación Nacional Forestal: CONAF)
for helping with fieldwork and giving us the support
to develop dendrochronological research in Araucaria ecosystems.
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Received 31 August 2016; accepted 29 November 2016.

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