Geoscience Reference
In-Depth Information
Polylepis
stands are almost exclusively restricted to volcanic slopes, with a
strong preference for well-insolated north-facing slopes. Extensive collections
of
P. tarapacana
were conducted in Bolivia, Chile, and Argentina (16
◦
-
22
◦
S) as part of the IAI-CRN program to reconstruct climate variations from
chronologies range between 98 and 705 years in length, and represent the
climatic variables controlling
P. tarapacana
growth, interannual variations in
tree growth were compared with regional records of precipitation and temper-
ature. Correlation functions indicate that the radial growth of
P. tarapacana
is
influenced by water balance during the summer previous to the ring formation.
At the sampling sites, precipitation explains around 50% of the total vari-
ance in growth. Summer temperatures, which increase evapotranspiration and
reduce soil water supply, are negatively correlated with tree growth (Argollo
1.6
1.4
1.2
1.0
0.8
0.6
0.4
1400
1500
1600
1700
1800
1900
2000
Box Fig. 7.14
Composite chronology resulting from merging the
Polylepis tarapacana
ring width series from Caquella and Soniquera in the Bolivian Altiplano
Traditionally, the wood of
Polylepis tarapacana
has been used by local
populations in the Bolivian Andes for construction, particularly for house and
church roofs. Wood from old buildings offers the possibility of extending the
upper-elevation records of
P. tarapacana
back in time for the past millennium.
These records offer the unique opportunity for reconstructing precipita-
tion variations across the altiplano during the past five to seven centuries
or more.
—Jaime Argollo, Claudia Soliz, Jorge Moya, Janette Pacajes, Mariano S.
Morales, and Ricardo Villalba
