Unnatural Histories – the Amazon

Recent research has revealed over 400 massive anthropogenic earthworks (geoglyphs), built by ancient cultures, underlying supposedly pristine ancient rainforest. These findings challenge the long-held assumption that Amazonia is a largely pristine wilderness and that indigenous peoples have only ever had a negligible impact upon Amazonian rainforest. Frank Mayle and John Carson are palaeoecologists who are collecting sediment cores from lakes located close to these geoglyphs to try and learn more about the type and scale of land use associated with these cultures. Did they make small forest clearings to build these structures or instead practice large-scale clear cutting, or maybe build them in an open landscape when past climate was too dry to support rainforest? To what extent did they alter the biodiversity of these forests by selecting economically important species over other less useful species? Analysis of fossil pollen and charcoal from these lake sediments can reveal Amazonia’s ancient history and potentially provide answers to these questions.

Frank Mayle

Frank Mayle

John Carson

John Carson

 

 

 

 

 

 

 

 

 

 

If you are interested in discovering more about pre-Columbian Amazonia then you may like to watch ‘Unnatural Histories: Episode 3, the Amazon.  This is available on BBC iPlayer – http://www.bbc.co.uk/iplayer/episode/b0122njp/unnatural-histories-3-amazon

In fieldwork patience is a virtue

One of the valuable lessons from my fieldwork was that progress can be SLOW, and that working in the field can be a test of patience, as much as it is an opportunity to be energetic and resourceful. My PhD fieldwork took place in the south-west Amazon region, in lowland Bolivia. When I tell people this, the first word to come up is usually “exciting”. The excitement of visiting an exotic country, and travelling to its remotest parts for some real Indiana-Jones-style adventuring. While it is true that doing this kind of fieldwork offers unique experiences, I remind people that it’s fieldWORK, not fieldHolidays. What one seldom hears about is the potential for boredom and frustration. Fieldwork often involves a lot of waiting around for things to happen, people to get back to you, for conditions to be right. These are all especially so when you are in a foreign and/or developing country, where bureaucracy, social customs and ideas of urgency and timeliness can be quite different to what you are used to. In these circumstances there are two options: 1) continue to worry and drive yourself crazy or 2) accept that things will take as long as they take (whilst still doing what you can to make sure things don not take any longer than they need to). The following is an example of an occasion when I learned about the advantages of being patient.

 

In summer 2011 we were in a remote town called Bella Vista, near to Bolivia’s north-east border with Brazil. This was all work for a palaeoecological project looking into the historical environmental impact of ancient Amazonian societies, who have left an incredible legacy of monumental earthworks in this region. Our aim was to take sediment cores from a number of target lakes that we had identified as promising, because of their close proximity to archaeological sites of interest. Since being in Bella Vista, we had already successfully cored one small lake close to the town. This was hard work done floating out in the open in conditions so hot it was difficult to do simple mental arithmetic. Still we managed to get a nice deep core and finish in only one day. Now it was on to our next target lake, Laguna Orícore, where I was hoping for a similarly rapid outcome. A juddering speedboat ride up the river took us to our camp, on the edge of a small estancia (cattle ranch), that occupied a wedge of grassland between the river and the lake. That first day after landing, we went to take a look at the lake and its surroundings. It was a big lake, 3.5 km across, but like all of the enigmatic square-shaped lakes in this part of Bolivia, it was shallow, at only about 2 meters deep throughout. Around the edges of the lake there was a thin strip of forest. The girthy buttress roots of the trees intertwined and overhung the water’s edge to make a natural jetty; quite handy for getting into and out of the water. We had arrived reasonably early and much of the day was left. As such, I was eager to get started, but there was a problem. What seemed like only a moderate wind was agitating the water surface and creating some reasonable sized waves. This was a product of the “fetch” or accumulative effect across the surface of such a big lake. These were bad conditions for coring. To get a vertical sediment core it needs to be taken from a stable platform. Trying to take one from a coring rig that was bobbing around on choppy water was not a way to do that. Being impatient, I was keen to press on anyway, but speaking from his position of experience, my supervisor Frank recommended that we wait for things to settle. Waiting around in that grassland did not seem like fun to me. In the town we had left behind the relative comfort of the WWF ranger’s station, which had hammocks, (cold) showers and beds protected by mosquito netting. At the estancia however, we slept in tents, which were no barrier to columns of biting ants on the march, and at night the cows attracted apocalyptic swarms of mosquitoes. They were undeterred by the smoke from our fire and we found that the only thing that would keep them away was spraying ourselves with copious amounts of high potency DEET.

 

It took two days for the weather to calm down enough for coring. In the meantime, we decided that, given how big the lake was and how long it would take to paddle to the middle on our not very hydrodynamic coring rig, it would be useful to move the steel speedboat that we had driven up the river, across to the lake. The boat and its engine were HEAVY, and helping to move it across the c. 500 meters of grassland between river and lake taught me that a 5 ft Bolivian park ranger was worth about 3 of me in terms of carrying strength. Over the two days we also took the chance to wonder around the landscape. I walked through the riverine wood with our botanist colleague Daniel as he surveyed the plant species. A group of us climbed a rocky outcrop, which lined the north-west margin of the lake, to get a better look at the landscape, and to take pictures, like the one above (see picture 1). We noted that the outcrop supported drought-tolerant tree species, which would be significant later on for our interpretation of the lake sediments. We also discovered that the cracks in the rock were filled with colonies of writhing, squeaking bats, hiding from the sun.

Picture 1

Picture 1

 

 

 

 

 

 

 

 

 

 
After surveying the wider landscape, we went fishing for piranha in the river, using lines with no poles and bits of beef jerky as bait. My first taste of barbecued piranha was a positive experience. One of the most pleasant things was going for a swim during the late afternoon in the bath-warm water of the lake, and washing off the dirt and the DEET.
When the weather finally settled and the lake was still, we constructed our coring rafts, hitched them to the speedboat and cruised easily into position in the centre of the lake. The conditions were ideal for coring. Had we gone straight in on the first day when I wanted to, we would probably have had the added frustration of a failed attempt. We also used the time wisely by scouting out and getting a better feel for the landscape, and by moving the speedboat over to the lake. In the end, that made our work easier and more efficient, and allowed the chance for a great photo opportunity (picture 2 and 3)…

 

Picture 2

Picture 2

 

Picture 3

Picture 3

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

A bit about today’s blogger: John Carson

 

JohnCarson_w[1]John’s research interest lies in investigating both human influences on the environment and natural past environmental change over the Holocene period (past ~10,000 years), especially in the Amazonian Neotropics. There is growing evidence for a long history of pre-European (pre-AD 1492) human occupation in Amazonia, by populous societies whose lifestyles were settled. As such, a more complex story of the development of Amazonian ecosystems over the Holocene, which involved the interaction between climate, vegetation and human land use, is emerging. John’s approach is a palaeoecological one (past – ecology), which uses biological proxies to reconstruct how environments have changed over time.

He also applies palaeoecological data to help answer archaeological questions about pre-European Amazonian societies. Fundamental questions remain regarding these societies in many regions. How large were their populations? How did they manage the landscape? What is the chronology (timescale) of their occupations? What was their subsistence strategy/what crops did they grow?

John received his undergraduate degree in Geology and Archaeology (BSc) from the University of Birmingham in 2008, completed a Masters in Environmental Monitoring, Modelling and Reconstruction (MSc) at the University of Manchester in 2010, and in 2014, gained his PhD in Tropical Palaeoecology at the School of Geosciences, University of Edinburgh.