What is Amazonia?

This is not a trivial question.  Researchers writing about Amazonia very rarely provide a  definition. This ambiguity has important research implications, as often when discussing Amazonia those involved have different ideas of what is being discussed…  For example, In Meggers’ paper which I reviewed in my previous post, she disagrees with another archaeologist’s definition of Amazonia. Erikson, in his article entitled “Amazonia: the historical ecology of a domesticated landscape”, refers to Amazonia as “the entire region drained by the Amazon River and its tributaries”(Erickson 2008: 158). So, how would you define Amazonia? You could say, like Erickson , that it coincides with the basin of the Amazon River, but then you would be including a big portion of the Andes. But glaciers located 6000 m.s.l. don’t match  our idea of a lush Amazonia, do they? Another option could be to consider Amazonia only that part of the Amazon Basin that is covered by rainforest. Well, this looks better, but you would exclude important areas like the savannahs. Moreover, the size of the rainforest changes over time: the boundaries of the rainforest we see today are different from those it had 15000 years ago, and, with the expansion of industrial agriculture, forested areas have been shrinking significantly in the last 20-30 years. It is very unpractical to have to change the limits of what we call Amazonia each time the boundaries of the rainforest move. Meggers (2011) states that: “Amazonia is defined by geographers and ecologists as the portion of tropical lowland South America below 1,500 meters, where the average difference in annual temperature does not exceed 5ºF, rain falls on 130 or more days of the year, and relative humidity normally exceeds 80%. Typical vegetation consists of rainforest, with small enclaves of savannah where soil conditions inhibit plant growth.” However, she doesn’t say who are these “geographers and ecologists” and does not provide any references for this.

While looking for a good paper that defines Amazonia I found out that the European Commission, in collaboration with the Amazon Cooperation Treaty Organization, created in 2005 a task force of experts with the objective of defining the geographical boundaries of Amazonia. Scientists from different disciplines, such as climatology, hydrology, botany, zoology, ecology and biogeography, came together in a two day workshop to reach a consensus (Eva et al. 2005).

The criteria used to draw the map of Amazonia (Fig. 1) were Hydrography, Ecology and Biogeography.

You can download the study here

Figure 1 -

UNIT I = Amazon and Tocantins river basins [“Amazon Basin” or “Hydrographical Amazonia”]

Ia = Lowland rainforest biota of the Amazon and Tocantins River basins [“Lowland Amazon

Basin rainforest” or “Amazonia sensu stricto”]

Ib = Andes (non-lowland biota of the Andean Amazon Basin, > 700 m asl)

Ic = Planalto (non-lowland biota of the southern Amazon Basin)

UNIT II = Amazon lowland rainforest types outside Unit I

IIa = Guiana

IIb = Gurupí

Ia + IIa + IIb = Entire Amazon lowland rainforest biome [“Hylaea” or “Amazonia sensu lato”]

I + II = Amazon and Tocantins river basins + Amazon lowland rainforest biome outside the basin

[“Amazonia sensu latissimo”]

As you see in Fig. 1, they have defined Amazonia sensu stricto (the “real” Amazonia) as the area enclosed by the polygon Ia; and Amazonia sensu lato as the area enclosed by the polygons Ia+IIa+IIb (it is not the “real” Amazonia but you can call it Amazonia because it all looks alike). It would be great if, from now on and to avoid misunderstandings, archaeologists, geographers and paleoecologists that work in Amazonia could use this definition.  Eva et al. have provided us  with valuable operative tools that we can all use. Unfortunately, the European Commission forgot to make their file of the Amazonian boundaries available for download! I have been looking for it everywhere, but haven’t found anything. I asked for it through the EC web page, but I got no answer. A bit disappointing, considered that we paid for it!

Anyway, as I wanted to have a file that can be used in ArcGis, I resolved to digitalize the map of Amazonia myself. I also decided to distribute it. But, for now, you have to contact me via e-mail because I don't know yet how to upload it :-). I will put a link as soon as I figure out how to do it. I hope there is no copyright infringement in this… well, if there is, they will say something …

References

Erickson, C. L. 2008. Amazonia: the historical ecology of a domesticated landscape. In Handbook of South American archaeology, eds. H. Silverman and W. H. Isbell, 157-183. Berlin: Springer.

Meggers, B. J. 2011. Handbook of South American Archaeology Reviewed by Betty J. Meggers. Revista de Antropología Chilena 43 (1):147-157.

Eva, Hugh D., Huber, Otto, Achard, Frédéric, Balslev, Henrik, Beck, Stephan G., Behling, Hermann, Belward, Alan S., Beuchle, René,, Cleef, Antoine M., Colchester, M., Duivenvoorden, Joost F., Hoogmoed, Marinus Steven, Junk, Wolfgang Johannes, Kabat, P., Kruijt, Bart, Malhi, Yadvinder, Müller, Jan Marco, Pereira, José M. C., Peres, Carlos, Prance, Ghillean, Roberts, John, & Salo, Jukka (2005). A proposal for defining the geographical boundaries of Amazonia Office for Official Publications of the European Communities : EUR 21808-EN

Review of Betty J. Meggers‘ review of the Handbook of South American Archaeology

Betty J. Meggers has been working in Amazonian archaeology for more than 50 years. She has recently published a review of the Handbook of South American Archaeology, which is of great relevance to all of us working on the paleoecology of Amazonia during the Holocene. You can download her paper here.

The paper discusses 3 fundamental aspects of the South American archaeology: i) how contemporary Amazonian archaeologists’ interpretation of the archaeological record has been biased by the abandonment of the classical archaeological methods of pottery analysis; ii) the origin of new world pottery and iii) the relationship between environmental conditions and cultural development in Amazonia.

Classical archaeologists spent months on end drawing and analysing thousands of pieces of pottery. In the first part of her paper, Meggers explains why this meticulous work is a fundamental step in scientific archaeology: “Pottery can be decorated using an essentially unlimited number of techniques and motifs without affecting the utility of the vessel, making independent duplication of identical decoration unlikely”. Therefore, the analysis of pottery’s details and decorations allows us to distinguish diffusion (cultural aspects which are transmitted form one cultural group to another) form independent invention, where a cultural trait arises spontaneously in a given population. According to Meggers, some of the authors of the Handbook omit this important task, undermining the strength of their interpretation of archaeological records

Pottery analysis is the criteria that Meggers uses to discuss, in the second part of her paper, the origin of new world pottery. Many archaeologists that have contributed to the Handbook believe that pottery was independently invented in Amazonia. In Meggers’ view, the similitudes between Japanese Jomon pottery and the Valdivia pottery (which is the oldest pottery in America, dating 6000 BP) are too many to be the result of some form of “cultural convergence”. Moreover, she highlights that the period of Valdivia pottery coincides with a catastrophic volcanic eruption in Japan, which could have pushed groups of Japanese fishermen towards the American coasts. Hence, these Japanese fishermen would have influenced the pottery of early Americans. .

In the Handbook, Amazonia is depicted as a “manufactured landscape” or “anthropogenic cornucopia”. In the third part of her paper, Meggers assesses whether or not such descriptions of Amazonia are supported by the archaeological evidence. She shows that the evidence is actually very weak: the idea of widespread human occupation of pre-Columbian Amazonia is not supported by pollen, phytolith and charcoal analysis, which indicate that vast areas of Amazonia have never faced human disturbance; no systematic archaeological excavation has ever been performed that supports the assumption that large permanent settlements were common in Amazonia; many of the earthworks often cited in support of the “manufactured landscape” idea are concentrated in the Llanos de Moxos, which are ecologically quite different from the tropical rainforest that covers most of the Amazon basin; there is no evidence suggesting that ADE was created for intensive agriculture or to exclude that slash and burn agriculture was a common practice among pre-Columbian people.

Despite the fact that the bibliography of Meggers’ paper is not as large as it could have been, it can still serve as a good introduction to the archaeology of Amazonia for anyone who wants to get into the heart of the current debates.

Betty J. Meggers (2011). Handbook of South American Archaeology reviewed by Betty J. Meggers Revista de Antropología Chilena, 43 (1), 147-157

Special Issue: Environmental changes and pre-Columbian human influence in the Amazon region

The last number of Geographica Helvetica is a special issue about Amazonia entitled “Environmental changes and pre-Columbian human influence in the Amazon region”. Among the authors there are two prominent pollen specialists, Behling, H. and Mayle, F.E.; the phytogeographer Langstroth, R.; and several members (and ex members) of the paleo-geoecological group at Bern University, including myself. Abstracts can be accessed here.

Our paper, co-authored by Canal-Beeby, E. and Veit, H., is entitled “Eco-archaeological regions in the Bolivian Amazon. An overview of pre-Columbian earthworks linking them to their environmental settings”.

The discovery of extensive pre-Columbian earthworks in north-eastern Bolivia has been seen as evidence that Amazonia was once densely populated by complex societies. This has led some scholars to believe that culture evolved in Amazonia regardless of environmental constraints. However, this view does not take the diversity of earthworks and geo-ecological regions into account, nor their uneven distribution. This paper offers an initial explanation of the possible links that exist between the different types of earthworks in north-eastern Bolivia and their environmental settings and identifies six distinct eco-archaeological regions. Results show a spatial overlap between those areas with greater evidence of past complex societies and areas where environmental constraints were fewer. This suggests that local hydrology and soils influenced the development of pre-Columbian societies in the region.

Lombardo, U., Canal-Beeby, E., & Veit, H. (2011). Eco-archaeological regions in the Bolivian Amazon. An overview of pre-Columbian earthworks linking them to their environmental settings Geographyca Helvetica, 66 (3), 173-182

The extent of human disturbance in pre-Columbian Amazonia

Understanding the extent to which pre-Columbian peoples altered and deforested the Amazon basin is key in order to assess i) the impact that pre-Columbians had on global climate during the Holocene [Dull et al., 2010] and ii) the resilience of the Amazon rainforest to human disturbance [Bush and Silman, 2007]. The first point is essential to our understanding of the major drivers behind climate fluctuations during the Holocene, and hence to help predict future fluctuations. The second point is important to inform conservation and development policies in Amazonia. Unfortunately, the scarcity of archaeological and paleoecological data from the Amazon Basin has favoured the proliferation of “reconstructions of the past” that are hard to test.  Some of these theories have reached broad audiences thanks to the echo provided by popular media and books [Mann, 2005]. New archaeological findings that suggest the existence of complex societies in pre-Columbian Amazonia have led some researchers to define the Amazon Basin as a “manufactured landscape” or an “anthropogenic cornucopia” [Balée and Erickson, 2006; Erickson, 2008].  There are 3 different lines of research that can help assess whether or not these reconstructions are accurate. One is to focus on those regions that host important archaeological remains and study the evidence of complex societies. This work is already being carried out by some archaeologists such as Heiko Prümers. The second area of research is to examine if and how the development of complex societies in the region were influenced by local environmental constraints and opportunities. This is the kind of work that I am carrying out in the Llanos de Moxos and  hope to discuss in another post quite soon J (briefly introduced here…). Another area of research that can help us understand the Amazon’s past is to test if the level of human disturbance associated with the sites where evidence of complex societies has been discovered can be extrapolated to the rest of the Amazon basin.  A milestone paper that looks at the latter, and that has been often cited in this blog, is Bush and Silman (2007).

A few weeks ago, The Holocene published on-line a new paper that delves deep into this question, providing interesting new data [McMichael et al., 2011].  McMichael et al. test the hypothesis that human disturbance was widespread in the Amazon Basin during pre-Columbian times (as some authors have suggested). If this hypothesis is true and the disturbance was widespread then, the authors argue, the sites where permanent settlements were likely to have established should show sedimentary evidence of that disturbance. Hence, they cored lakes (considered by the authors as preferred settlement sites) and sampled soils in the vicinity of the lakes and looked at charcoal and phytoliths. They found that charcoal record was discontinuous and localized. They then concluded, based on the sedimentary evidence: “Our data suggest that while all of the settings examined were occupied or used, the halo of influence around each was limited. It should not be assumed that intensive landscape transformations by prehistoric human populations occurred throughout Amazonia or that Amazonian forests were resilient in the face of heavy historical disturbance”. The paper suggests that pre-Columbians developed into complex societies and substantially altered their environment in those areas where environmental conditions were favourable. They predict that these sites can be found along the main rivers and in those parts of the Amazon Basin that are characterized by a strong seasonality (like the Llanos de Moxos).

In my opinion this paper is a beautiful piece of Science and I invite you to read it!

References:

Balée, W., and C. L. Erickson (2006), Time, complexity and historical ecology, in Time and complexity in historical ecology: studies in the neotropical lowlands, edited by W. Balée and C. L. Erickson, pp. 1-17, Columbia University Press, New York.

Bush, M. B., and M. R. Silman (2007), Amazonian exploitation revisited: ecological asymmetry and the policy pendulum, Frontiers in Ecology and the Environment, 5(9), 457-465.

Dull, R. A., R. J. Nevle, W. I. Woods, D. K. Bird, S. Avnery, and W. M. Denevan (2010), The Columbian Encounter and the Little Ice Age: Abrupt Land Use Change, Fire, and Greenhouse Forcing, Annals of the Association of American Geographers, 100(4), 755-771.

Erickson, C. L. (2008), Amazonia: the historical ecology of a domesticated landscape, in Handbook of South American archaeology, edited by H. Silverman and W. H. Isbell, pp. 157-183, Springer, Berlin.

Mann, C. C. (2005), 1491 New revelations of the Americans before Columbus, Vintage books, New York.

C. H. McMichael, M. B. Bush, D. R. Piperno, M. R. Silman, A. R. Zimmerman, & C. Anderson (2011). Spatial and temporal scales of pre-Columbian disturbance associated with western Amazonian lakes The Holocene : 10.1177/0959683611414932

About maize, manioc and agricultural production in pre-Columbian Amazonia

A new paper from Dickau et al., recently published on-line by the Journal of Archaeological Sciences, brings us back to one of the favourite themes of this blog: pre-Columbian agriculture in the Amazon Basin. The work of Dickau et al. confirms the findings of Bruno (2010), also a co-author in Dickau et al., and provides more data from new sites. They have analysed botanical remains from 2 pre-Columbian monumental mounds east of Trinidad (Loma Salvatierra and Loma Mendoza) and from another site, a ring ditched village called “Granja del padre”, about 200 Km far from the mounds, close to Bella Vista(see location in Fig 1 and photo of the ring village in Fig 1a). Analysis of macro and micro botanical remains from Loma Salvatierra and Mendoza and from Granja del padre suggests that the most common cultivated species was maize (Zea mais L.). It was present in almost all samples and fairly abundant. The second most common cultivated species seems to have been manioc  (Manihot esculenta Crantz). Interestingly, maize was also more frequently encountered on ceramic graters, which were thought to be processing tools for grating manioc . They recovered starch grains from artefacts and clearly identified 5 grain of yucca vs. 115 of maize.  This is really surprising because manioc is a good source of energy and far easier to cultivate than maize. Ceramic graters  can be found all over the Llanos. It can be easily assumed that manioc was cultivated all over the Llanos de Moxos because, provided good drainage, manioc can grow even on very bad, acid, aluminium rich soils. I was actually persuaded that raised fields, elevated earth platforms that were user as agricultural surface, were built to provide drained land for manioc. But now, it seems that maize, and not manioc, was the most important crop in the Llanos de Moxos.

Figure 1. The Llanos de Moxos. Red triangles are the Salvatierra and Mendoza mounds. a) Google Earth photo of the Granja del padre with the approximate locations of the archaeological excavations in yellow.

We have to consider that starch grain analysis is still a developing technique and the variables that affect preservation of different taxa are not yet fully understood. But, if this data is confirmed by other researches, we could start considering ceramic graters (Fig 2) as a proxy for maize consumption. As ceramic graters are found everywhere in the Llanos de Moxos, a direct link between ceramic grates and maize would indicate that maize was used all over the region.

Figure 2. Fragment of a ceramic grater from the Llanos de Moxos

This opens up a very interesting topic for future research: was maize cultivated in all the sites where it was consumed? This is not a trivial question because maize is a very demanding crop: it needs many nutrients and a lot of water, but rots if the soil is waterlogged. In the Llanos de Moxos soils and hydrology change a lot from one place to another. For example, while soils in the region of the Salvatierra and Mendoza mounds form over fertile mid-Holocene fluvial sediments (Lombardo et al. coming soon, I hope J ), la Granja del padre is found on saprolites (rotten granite rocks), very acid and poor in nutrients. Moreover, in the region of Bella Vista, no raised fields or Amazonian Dark Earths have been reported. So, did they grow maize using slash and burn agriculture? If so, this would have greatly limited potential population density in the area, as slash and burn agriculture is considerably extensive. Each family needs at least 30-40 hectares of forest for cultivation and far more as a reservoir for hunting and medicinal plants. Or was maize “imported” from other regions? Exchanged for other goods? The estimation of pre-Columbian population density, and the extent of pre-Columbian de-forestation, is a controversial issues among ecologists, geographers and archaeologists working in Amazonia. More studies like that of Dickau et al. are needed in order to shed some light on the past of Amazonia during the late Holocene. Their work adds important new data to the discussion, although we are still far from fully understanding what was going on in the Bolivian lowlands between 2000 and 500 BP.

Ruth Dickau, Maria C. Bruno, José Iriarte, Heiko Prümers, Carla Jaimes Betancourt Irene Holst, & Francis E. Mayle (2011). Diversity of cultivars and other plant resources used at habitation sites in the Llanos de Mojos, Beni, Bolivia: Evidence from macrobotanical remains, starch grains, and phytoliths Journal of Archaeological Science : 10.1016/j.jas.2011.09.021

Stone axes and the Little Ice Age (LIA)

What do stone axes have to do with the LIA ?

In his famous paper entitled “The anthropogenic greenhouse era began thousands of years ago” Ruddiman [2003] put forward a fascinating idea: “CO2 oscillations of ∼10 ppm in the last 1000 years are too large to be explained by external (solar-volcanic) forcing, but they can be explained by outbreaks of bubonic plague that caused historically documented farm abandonment in western Eurasia. Forest regrowth on abandoned farms sequestered enough carbon to account for the observed CO2 decreases. Plague-driven CO2 changes were also a significant causal factor in temperature changes during the Little Ice Age (1300–1900 AD)”. There has been a lot of controversy surrounding Ruddiman’s paper.

More recently, the idea that plagues caused farmland abandonment and were followed by re-forestation has been applied to the Amazon Basin and the LIA. Several scholars have proposed that the depopulation caused by the diseases that Europeans brought to the Americas after 1492 induced a large scale re-forestation which, in turn, decreased the amount of atmospheric CO2 and contributed to the LIA [Dull et al., 2010; Faust et al., 2006; Nevle and Bird, 2008]. In order to assess the likelihood of this hypothesis we need to know i) population size in pre-Columbian America and ii) the kind of agriculture pre-Columbians practiced.

Citing Denevan, Nevle and Bird [2008] write that “Evidence for the habitation and modification of American landscapes by tens of millions of Pre-Columbian agriculturalists [Denevan, 1992] exists in the widespread distribution of anthropogenic Amazonian Dark Earth soils, raised fields, irrigated terrace zones, roads, aqueducts, and numerous large-scale earthworks distributed throughout Amazonia, the Andes, Central America, and parts of North America”.

Many of the papers addressing this topic cite Denevan with regards to pre-Columbian population densities and agriculture. So, what are Denevan’s views on the matter? I will focus on Amazonia, as it is the largest forested area in the world and most of the work on pre-Columbian population density and agriculture that is cited to support this hypothesis have been done in Amazonia (for example the works of Denevan himself, Erickson and Heckenberger).

How many people lived in Amazonia in 1491?

The first estimate was given by Betty Meggers who said that population density in pre-Columbian Amazonia was 0.3 people Km^-2. She didn’t do any distinction between floodplains (varzea) and uplands (terra firme) because varzea’s fertility was offset by unexpected and destructive floods, which made varzea as unsuitable for people as terra firme.

Denevan then proposed a model in which people settled on the rivers’ bluffs. They were able to take advantage of the varzea but avoided the danger of the floods. According to [Denevan, 1992] population density was 14.6 people km^-2 in the varzea and 0.2 people km^-2 in the terra firme forests. It is interesting that Denevan’s estimate for terra firme is lower than Meggers’ estimate. This is important as terra firme represents 98% of the Amazonian rain forest.

In 2003, Denevan changed idea and wrote: “For varzea population density would be 10.4 per square kilometer […] For terra firme forests it is impossible to estimate an average population density and a total population […] Estimating average population densities for the savannas with any confidence is impossible.” Then, he concluded: “...consequently I now reject the habitat-density method I used in the past to estimate a Greater Amazonia population in 1492 of from 5.1 to 6.8 million. I nevertheless still believe that a total of at least 5 to 6 million is reasonable” [Denevan, 2003].

The stone axes

Although Denevan has rejected his own estimate of 0.2 people km^-2 for terra firme, it is still important to highlight how he justified that his estimate was smaller than Meggers’. Denevan defends that pre-Columbians did not practice slash and burn agriculture because they did not have metal tools and cutting the forest with stone axes would have been too much work. Hence, they preferred to live in savannahs, where they developed raised field agriculture, or on the river bluffs, where Amazonian Dark Earth (ADE) sites are actually found. In Denevan’s view, raised fields and ADE developed in order to minimize the need of clearing the forest: pre-Columbians preferred to build raised fields and ADE because such type of agricultural intensification required less work than cutting the forest with stone axes.

The very same archaeological evidence that Nevle and Bird [2008] use to infer high rates of pre-Columbian deforestation are used by Denevan to infer that pre-Columbians actually did not cut the forest!

The questions I have should now be clear: 1) could have such a small population of 0.2 people km^-2 significantly modified the Amazon forests? 2) How did they have such an impact if they had to cut the forest with stone axes? 3) Do raised field agriculture and ADE suggest high levels of deforestation? Or is it the other way round?

I don’t want to be misinterpreted here; I am not saying that pre-Columbian population was small or that they did not have an important impact on atmospheric CO2 content. I am just saying that we do not know how many people lived in Amazonia in 500 AD or in 1491AD and what impact they had on the Amazon forests. We need far more field and lab work before reliable estimates can be put forward. 

Ref.

Denevan, W. M. (1992), The Native Population of the Americas in 1492, The University of Wisconsin Press, Madison.

Denevan, W. M. (2003), The native population of Amazonia in 1492 reconsidered, Revista de Indias, 63(227), 175-188.

Dull, R. A., R. J. Nevle, W. I. Woods, D. K. Bird, S. Avnery, and W. M. Denevan (2010), The Columbian Encounter and the Little Ice Age: Abrupt Land Use Change, Fire, and Greenhouse Forcing, Annals of the Association of American Geographers, 100(4), 755-771.

Faust, F. X., C. Gnecco, H. Mannstein, and J. Stamm (2006), Evidence for the Postconquest Demographic Collapse of the Americas in Historical CO2 Levels, Earth Interactions, 10(11), 1-14.

Nevle, R. J., and D. K. Bird (2008), Effects of syn-pandemic fire reduction and reforestation in the tropical Americas on atmospheric CO2 during European conquest, Palaeogeography, Palaeoclimatology, Palaeoecology, 264(1-2), 25-38.

Ruddiman, W. (2003). The Anthropogenic Greenhouse Era Began Thousands of Years Ago Climatic Change, 61 (3), 261-293 DOI: 10.1023/B:CLIM.0000004577.17928.fa

Por la vida, los derechos indígenas y el medio ambiente

Esta mañana 15 de Agosto 2011 los pueblos Indigenas de las tierras bajas de Bolivia vuelven a marchar en defensa de sus derechos, de sus tierras, de su existencia. Pero esta vez hay una importante novedad: marchan para defenderse de un gobierno "indigenista", el de Evo Morales. El defensor de la Pacha Mama ha decidido que no importa lo que opinan los pueblos originarios, la carretera que cortará el Territorio Indigena Parque Nacional Isiboro Secure (TIPNIS) se tiene que hacer, porque se tiene que hacer! Ha cambiado el color de los que mandan, pero el atropello de los pueblo indigenas sigue igual. Antes era la derecha, ahora es el MAS de Evo Morales. Donde está la diferencia??



Cerimonia inaugural de la Marcha



Los primeros pasos...Trinidad, 15-8-2011 horas 10:00. Hasta La Paz!!!!

This is what we have seen in two days of field work

More pictures

The "Bato", the biggest bird we have seen in Bolivian lowlands, nursing a baby bato

Heinz on a very nice laterite outcropping in northern Beni

First update

We are back in Trinidad, after a week travelling in the north. We visited de areas surrounding San Ramon, San Juaquin, Puerto Siles and Santa Ana. Here few photos...I will put more photos in the next days.

Me and Heinz in the Mamoré River, north of Puerto Siles

Me with our Land Cruiser in a dry lake 

El Compañero, the man who takes you to the other side of the river in San Juaquin

To Bolivia again

Hi everybody,

I have the flight to Bolivia in few hours and I will spend there the next month. No scientific post for the next weeks, but I will try to post a lot of photos, you will feel like you are there too :-)

Stay tuned!

Roadmap for amazonists to INQUA 2011

Next week (21-27 July 2011) The XVIII INQUA-Congress will take place in Bern, Switzerland.
As expected, very few contributions will deal with the Amazon Basin during the Holocene. I went through the program and I spotted the following presentations and posters that could be of interest to those who follow this blog. If I have missed something let me know and I will update the list. By the way, the first oral presentation on this list is mine :-) If you come to INQUA it would be great to meet up and have a good Swiss beer together!! Hope to see you there!!

ORAL PRESENTATIONS:

• Human occupation and environmental change in south-western Amazonia during the Holocene.

• Palaeobotanical evidences of pre-Columbian agriculture in black soils (Terra Preta do indio) in western Amazonia

• Ecological response on environmental change in tropical South America during the late Quaternary

POSTERS:

• Human occupation and paleoenvironment during the Holocene of southern Brazil: Sangão and Garivaldino sites

• Source-bordering dunes in the eastern Bolivian lowlands – geomorphic variety and paleoenvironmental significance

• Tropical Wetland Formation in Belize: Ancient Maya and Natural Interactions in the Late Holocene

• Vegetation, climate, and fire history of the Páramo of Jimbura, southern Ecuador

• Pre-Columbian human land-use and impact in the Bolivian Amazon

• Early to Late Holocene climate, vegetation and fire history in the upland savannas of Guayana, SE Venezuela: fire regimes and community structure in a savanna-dominated area

• Landscape transformation and crop cultivation in two contrasting environments in Colombia: evidences of ancient agricultural raised fields

• Palaeohydrological variability of the Bolivian Amazon throughout the Holocene

• Paleoecological study of a Gran Sabana lake (SE Venezuela) during the last millennia: implications for Mauritia colonization and human settlement

• Late Holocene environmental changes based on diatom and pollen records from lake sediments of Laguna Encantada, in the Neotropical Gran Sabana (Venezuelan Guayana)

• Rapid paleohydrogical Holocene changes in the Amazon river and its implications on the carbon accumulation in floodplain lakes

• Paleoenvironmental trends in Venezuela during the last glacial cycle

Less than 1% of Amazonia is made of Terra Preta. Is that enough?

I’ve just read a review written by William Balée (2010) about the book ‘Amazonian Dark Earths: Origins, Properties, Management’. Balée considers that the discovery of Terra Preta is proof that people in pre-Columbian Amazonia, rather than adapting to environmental conditions, ‘created’ the environment they inhabited. This allowed the development of complex societies in the region regardless of environmental constraints (such as poor soils, floods, lack of protein...). People overcame all these problems by creating Terra Preta. This is an extract from Balée’s introduction: “This contribution refutes, in essence, the adaptationist view of Amazonian indigenous societies […]. It is intriguing that this refutation takes place in light of what constitutes less than 1% of the forested part of the region’s surface soils (Woods and Denevan 3.1:1). That small fraction, nevertheless, like the difference in DNA between humans and chimpanzees, takes on profound significance in terms of understanding […] agriculture, population, and settlement in the prehistory of the region.”

Can we really consider this 1% like the difference in the DNA between humans and chimpanzees?

An answer to this question is given by Bush and Silman (2007): “The hypothesis of widespread Amazonian landscape management is based on analyses of archaeological sites and the assumption that there was a large pre-contact Amazonian population (> 10 million people). A caveat must be applied to these data, and indeed all of the data that we have to date about human disturbance in the Amazon, which is that they are derived from just a few locations, and do not represent either a systematic or a randomized sampling design. There is no ecological component predicting which forest was most likely to be occupied. Was disturbance spread evenly across all of Amazonia or concentrated near human habitation? Is it safe to extrapolate results from sites where we know human habitation occurred to the rest of Amazonia? Ecologists are familiar with problems of scale. […] extrapolating observations from dot maps can be dangerous, especially when the dots represent discrete activities of limited spatial extent (eg terra preta formation).”

It is striking how scholars can have such differing views at such a basic methodological level! (-:

Another interesting point is where that 1% is found: terra preta sites (the “dots” Bush and Silman are talking about) are found along the courses of the major Amazon rivers (fig. 1).

Figure 1 Terra preta sites. From Glaser (2007)

The preference for settling along rivers would seem to indicate that environmental conditions (in this case closeness to fish protein and waterways) did in fact condition the development of pre-Columbian societies. If we consider terra preta as evidence of the existence of large permanent settlements established by complex societies, then its spatial distribution along major rivers would suggest precisely that social complexity developed where environmental conditions were good. And, as so many archaeologists and anthropologists have stressed before me, there is no basis to infer that large permanent settlements were also established in other areas further away from rivers, where environmental conditions would have been tougher. 

P.S.

I have just discovered a new post in the Blog of Neves about the same issue. have a look (in Portuguese): http://arqueologiadaflorestatropical.blogspot.com/

William Balée (2010). Amazonian Dark Earths Tipití: Journal of the Society for the Anthropology of Lowland South America


Bush, M., & Silman, M. (2007). Amazonian exploitation revisited: ecological asymmetry and the policy pendulum Frontiers in Ecology and the Environment, 5 (9), 457-465 DOI: 10.1890/070018


Glaser, B. (2007). Prehistorically modified soils of central Amazonia: a model for sustainable agriculture in the twenty-first century Philosophical Transactions of the Royal Society B: Biological Sciences, 362 (1478), 187-196 DOI: 10.1098/rstb.2006.1978

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

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