A 1300-Year History of West-Central Mexican Cloud Forest Climate
Figueroa-Rangel, B.L., Willis, K.J. and Olvera-Vargas, M. 2010. Cloud forest dynamics in the Mexican neotropics during the last 1300 years. Global Change Biology 16: 1689-1704.
Figueroa-Rangel et al. note that "during intervals of aridity, cloud forest taxa tend to become reduced," while, in contrast, "during intervals of increased humidity, the cloud forest thrives." And based on these facts, they determined from their data that there was a major dry period that lasted from approximately AD 800 to 1200 in the SMBR.
Quoting the four researchers, "results from this study corroborate the existence of a dry period from 1200 to 800 cal years BP in mountain forests of the region (B.L. Figueroa-Rangel, unpublished data); in central Mexico (Metcalf and Hales, 1994; Metcalfe, 1995; Arnauld et al., 1997; O'Hara and Metcalfe, 1997; Almeida-Lenero et al., 2005; Ludlow-Wiechers et al., 2005; Metcalfe et al., 2007); lowlands of the Yucatan Peninsula (Hodell et al., 1995, 2001, 2005a,b) and the Cariaco Basin in Venezuela (Haug et al., 2003)." In addition, they write that "the causes associated to this phase of climate change have been attributed to solar activity (Hodell et al., 2001; Haug et al., 2003), changes in the latitudinal migration of the Intertropical Convergence Zone (ITCZ, Metcalfe et al., 2000; Hodell et al., 2005a,b; Berrio et al., 2006) and to ENSO variability (Metcalfe, 2006)."
We additionally note that the time frame of this significant dry period coincides extremely well with the broad central portion of the Medieval Warm Period. And this correspondence further harmonizes with the dry period's temporal association with enhanced solar activity and a southward shift of the ITCZ.
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Hodell, D.A., Brenner, M., Curtis, J.H., Medina-Gonzalez, R., Can, E. I.-C., Albornaz-Pat, A. and Guilderson, T.P. 2005b. Climate change on the Yucatan Peninsula during the Little Ice Age. Quaternary Research 63: 109-121.
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