Deforestation: Evidence challenged

McNeil et al. (2010) directly challenged the results obtained and conclusions reached by Abrams and Rue (1994).

Their first criticism stems from the longevity of Abram ad Rue’s core, where the oldest sediments date to A.D. 1010 , at least 100 years after the well-documented collapse of Copan’s population and political system. McNeil et al. (2010) also found the “gradual collapse” thesis to be problematic because scholars have demonstrated that the method of dating used incorrectly models the complex weathering processes undergone by the dated artefacts. They state that this erroneous modelling produced erroneous dates that created false indications of extended collapse. In addition, McNeil et al. (2010) state that a slow demographic decline is not supported by other lines of archaeological evidence at the site. Thus, it is concluded that Abrams and Rue’s (1994) sediment core is from the Post-classic period and does not provide information concerning the environmental impact of human populations during the Classic period.

In order to disprove Abrams and Rue’s (1994) findings completely McNeil et al. (2010) analysed a longer sediment core taken from the same pond. It demonstrated that forest cover actually increased from A.D. 400 to A.D. 900, with arboreal pollen accounting for 59.8% - 71.0% of the pollen assemblage by approximately A.D. 780 - 980. The highest levels of deforestation were actually found about 900 B.C. when, at its peak, herb pollen made up 89.8% of the assemblage. It was suggested that this event likely coincided with the widespread adoption of agriculture, a pattern found elsewhere in Mesoamerica.

McNeil et al. (2010) conclude that deforestation was not widespread in Copan around the time of Classic Maya collapse and, thus, it could not have caused population decline.