Deforestation Dispute

The last post advocates the theory of deforestation as a contributor towards collapse and a potential cause of the droughts. However (there is always a however) the hypothesis has been disputed by many who have observed present-day sustainable farming practices by the modern Maya, resisting the idea that the Classic Maya would have done things differently and willingly wreaked havoc on the land. If you cast your minds back to post 4, you may think this is very contradictory considering I commented on the fact that these sustainable methods were not utilised across the Maya region and only at a few sites, but recent evidence by McNeil (2011) has made me think otherwise...

Since the mid-1980s the archaeological site of Copan, Honduras, has been held up as the ‘type site’ for the deforestation hypothesis. It has regularly been used to exemplify how human ignorance of environmental limits  can destroy a city and has been used as a warning for modern populations, in particular by Diamond (2005).

However, recent analysis of pollen in a sediment core taken from the same pond as a previous study that suggested major deforestation occurred, does not support this (Figure 1). Indeed the 3000-year old record does show two periods of heightened deforestation during the Middle Preclassic and the Late Preclassic/Early Classic period (when the Maya began to construct their magnificent cities). Yet surprisingly, the landscape near the city centre was MORE forested during the Late Classic period than the Early Classic, contrasting to many predictions.  

Graph of pollen percentages from the sediment core from Petapilla Pond. 

Interpreting the diagram:

An abundance of the microscopic charcoal and the presence of Zea species of pollen imply that the deforested landscape is a product of human clearance and agriculture and not a product of natural grasslands. During the most dramatic level of deforestation (occurring at 512 cm into the core), 89% of the pollen record is composed of herb pollen that is indicative of human disturbance.

At the second peak of deforestation, coyol palm (acromcomia aculeate), a plant new to the pollen profile, is shown to increase in abundance, likely reflecting agroforestry practices.  

In contrast, during the Late Classic (shown between 270.5 and 250.5 cm) the pollen sequence indicates rapid RE-forestation where terrestrial arboreal pollen increases in composition from 59.8% to 89.8%. Herb pollen is actually much less than expected, especially in comparison to the biggest peak of deforestation.

The decline in herb pollen doesn’t support the environmental degradation hypothesis either; similar patterns have also been found in other pollen profiles from Lake Tamarindito and Coba, both of which were heavily populated during the Classic period. In fact there is ample evidence of how the Maya took care of the surrounding land, creating terraces to reduce erosion, wetlands to maximise their use of land and water along with raised fields and dams. Despite this, it is still widely believed that the Maya devastated their environment.

As you can see, there is great controversy surrounding the deforestation hypothesis, much like Easter Island (see Jenny’s blog for more information)!

Just to add...an interesting hypothesis is that the series of droughts may have actually led to re-forestation as populations starved and migrated elsewhere in search of water and food, allowing the forest to recover. OR perhaps this new evidence actually contributes to the mosaic pattern of collapse, where some cities were not deforested as much as others. Who knows?