Saturday, 18 June 2011

Soybean industrial production is bulldozing pre-Columbian archaeological sites in the Bolivian Amazon and nobody gives a damn

The journal Applied Geography and the journal Land Use Policy have recently published two papers, “Spatiotemporal modeling of the expansion of mechanized agriculture in the Bolivian lowland forests” and “Deforestation dynamics and policy changes in Bolivia’s post-neoliberal era” respectively, that depict a desolating panorama. The rate of deforestation under Evo Morales’ government is even higher than it was during the previous governments. Muller et al. say that “While overall dynamics remained relatively stable over time, the expansion of mechanized agriculture between 2001 and 2005 became more tolerant to excessive rainfall and less dependent on fertile soils. This mirrors the increasing penetration of mechanized agriculture into humid and less fertile Amazonian rainforests in the northern portion of the study area [Santa Cruz]. The map of deforestation probability substantiates these patterns and shows the highest propensities for future deforestation in the north”, while Redo et al. point out that: “Although neoliberal policies triggered an unprecedented level of forest clearing in Bolivia, rates have generally continued to increase and can be indirectly linked to the administration’s new agrarian reform and pro-environmental regulations”. The “pro-environmental” regulations of Morales’ government have actually increased deforestation rates!
The Northern Bolivian lowlands are not only an extremely important reservoir of biodiversity and home of many indigenous communities; they also hold an impressive amount of archaeological sites, most of which have never been studied or surveyed. As deforestation for industrial soybean production is moving northward, it now starts to affect the Llanos de Moxos, where most of these archaeological sites are found. Soy producers cut down the trees using bulldozers, and, in this way, they also destroy all the archaeological sites they encounter on the way. In the eastern Llanos de Moxos, in a stripe of forest called Monte San Pablo, between the River Cocharca and the River San Pablo (Fig. 1), Bolivian Mennonites are bulldozing pre-Columbian human-made earth mounds, which hold valuable remains and information about past Amazonian cultures. The destruction of pre-Columbian archaeological sites in the Bolivian Amazon is taking place while national and local governments look another way, and regrettably, with the complicity of some of the indigenous leaders who live in the area. 
Figure 1 Shaded areas are forests. Continuous line indicates the area of pre-Columbian monumental mounds. Monte San Pablo is east of the area (dashed lines) shown in Fig.2. (Lombardo and Prümers, 2010)
Figure 2. Modis Image taken a few days ago. The yellow stripes highlighted by the arrow are the portions of Monte San Pablo that have already been cleared for soybean production. The deforested area is already larger than 10.000 hectares

I have surveyed more than one hundred pre-Columbian monumental mounds and hundreds of Km of pre-Columbian canals and causeways in the area east of Trinidad, in the Beni (see map in fig.3). The monumental mounds are huge earthworks (the average mound covers 5 hectares and is 9 meters high) entirely human made, built from 400 AD to 1500 AD. They are full of pottery and burials and only very few of them have been excavated by archaeologists. The Monte San Pablo, just east of the area I surveyed, is full of monumental mounds. Those are the mounds that are being destroyed by the Mennonite bulldozers to make room for soybeans.

Figure 3. Triangles are pre-Columbian monumental mounds, lines are canals and causeways, shaded areas are forests. (Lombardo and Prümers, 2010)

Daniel Redo, Andrew C. Millington, & Derrick Hindery (2011). Deforestation dynamics and policy changes in Bolivia’s post-neoliberal era Land Use Policy : 10.1016/j.landusepol.2010.06.004

Robert Müller, Daniel Müller, Florian Schierhorn, & Gerhard Gerold (2011). Spatiotemporal modeling of the expansion of mechanized agriculture
in the Bolivian lowland forests Applied Geography : 10.1016/j.apgeog.2010.11.018

Umberto Lombardo, & Heiko Prümers (2010). Pre-Columbian human occupation patterns in the eastern plains of the Llanos de Moxos, Bolivian Amazonia Journal of Archaeological Science DOI: 10.1016/j.jas.2010.02.011

Sunday, 12 June 2011

New data about Amazonian Dark Earth (ADE).
The Journal of Archaeological Science has just published a new study on ADE. The study, of Birk et al. is entitled: “Faeces deposition on Amazonian Anthrosols as assessed from 5b-stanols”. I have just read it and this is my very first impression:
The new data are extremely interesting. The authors look at the presence of coprostanol (a marker for faeces) in Amazonian Dark Earth (ADE). They have found a clear change in the index used to asses different sources of stanols, when comparing samples from the topmost 10 cm with samples coming from a depth of 30-40 cm. It seems that litter degradation is responsible for this change. Moreover, it also seems that the normal indexes used to assess the human origin of the stanols do not work very well in Amazonia. This paper is going to be a valuable reference to similar studies performed in Amazonia in the future.
Natural Oxisol on the left; Terra preta on the right

However, while Birk et al. correctly notice that one of the most debated topics about ADE is its origin, they do not do very much to assess why the faeces were there and what is their meaning from an archaeological point of view. ADE is found in two different forms, terra preta and terra mulata. Terra preta is darker, contains more organic matter, P and charcoal and also contains lots of fragments of ceramic. Terra mulata is like a light version of terra preta, it contains more nutrients and charcoal compared with “natural” soils from the surroundings, but less compared to terra preta. Moreover, in the terra mulata sites there is no pottery. Terra preta is found in small patches of about 1 hectare and terra mulata if found surrounding the terra preta sites. Terra mulata can cover as much as 200 hectares. An interpretation could be that terra preta resulted from settlements while terra mulata resulted from agriculture. If this thesis was correct, the high fertility of terra preta would be a side effect of human waste disposal and not the intentional result of land fertilization. In the case of terra mulata, if we assume it has been produced by agricultural use, fertilization must have been intentional. In this case, it would have been very important to see if there is any coprostanol in terra mulata! But the study did not look at terra mulata. Many scholars talk about ADE as synonymous of terra preta, without making a distinction with terra mulata, despite the fact that the differences between the two are key to understanding the past of Amazonia (estimating past population density, the region’s carrying capacity, the levels of social complexity achieved, pre-Columbian settlement patterns, the extent of the human impact on pre-Columbian forest etc.)
Birk et al. only compared samples from 4 terra preta sites with samples from natural soils. I think they missed a great occasion. If they had also looked at 4 samples from terra mulata sites they might have been able to shed new light on the matter. Perhaps they did look at terra mulata and just decided to publish the results in a second paper…keeping us waiting GRRRR J

Birk, J. J., Teixeira, W.G., Neves, E.G., & Glaser, B. (2011). Faeces deposition on Amazonian Anthrosols as assessed from 5β-stanols Journal of Archaeological Science, 38 (6), 1209-1220 : doi:10.1016/j.jas.2010.12.015