Eighteen new tree-ring chronologies have been developed
to examine warm season precipitation, maize yield, and the
history of Aztec droughts in Mexico. The chronologies were
derived from Pseudotsuga menziesii, Pinus montezumae,
and Taxodium mucronatum. They are located in
southwestern Texas, northwestern Mexico, northeastern
Mexico, and southern Mexico as far south as Oaxaca. Seven
of these chronologies are among the first precipitation
sensitive tree-ring records from the American tropics.

Analysis of the new latewood chronologies indicates that
the primary modes of tree growth are variable across the
Tropic of Cancer. Latewood chronologies in southern
Mexico are sensitive to rainfall in April through June and
are significantly correlated with the onset of the North
American Monsoon. Latewood chronologies in northern
Mexico are most sensitive to monsoon rainfall from June
through August.

Climate-induced crop failures with profound
socioeconomic impacts have punctuated Mexican history.
Reliable records of the Mexican maize harvest are not
available until very recently. Maize yield in the central
highlands of Mexico is strongly dependant on adequate
rainfall early in the growing season (April through June),
and is highly correlated with latewood tree growth. We have
developed a continuous, exactly-dated, tree-ring
reconstruction of maize yield in central Mexico from 1474
to 2001 that provides new insight into the history of
climate and food availability in the heartland of the
Mesoamerican cultural province for the past 527 years.

Aztec codices record at least 13 drought years in central
Mexico during the prehispanic and early colonial period.
Most of these Aztec drought dates (9 of 13) are confirmed
by climate sensitive tree-ring records from Mexico,
including the extended drought related to the infamous
‘Famine of One Rabbit’ in 1454. Aztec folklore suggests
that the occurrence of One Rabbit years heralds famine and
other catastrophe. Tree-ring data from Mexico indicate that
severe drought occurred immediately before 10 of 13 ‘One
Rabbit’ years from A.D. 882 to 1558. This relationship
between drought and the year before One Rabbit suggests
a real climatic origin for the ‘Curse of One Rabbit.’

More information is available at http://www.uark.edu/
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