Tag Archives: self-organization

Ecological memory of Amazonian agriculture

I just wrote this note on Faculty of 1000 on the paper (doi:10.1073/pnas.0908925107) I mentioned the other day:

Pre-Columbian agricultural landscapes, ecosystem engineers, and self-organized patchiness in Amazonia
McKey D, Rostain S, Iriarte J, Glaser B, Birk JJ, Holst I, Renard D
Proc Natl Acad Sci U S A 2010 Apr 12  [related articles]

This fascinating study describes how ecological engineers (such as ants, termites, and earthworms) maintained a newly described pre-Columbian agricultural landscape. The authors describe sites along the Guianan coastal plain (in Guyana, Suriname, and French Guiana) where pre-Columbian farmers constructed raised fields in flat, marshy locations.

The paper is particularly interesting because it combines new archaeological evidence in favour of the relatively new, and somewhat controversial, idea of a fairly densely settled pre-Columbian Amazonia with an ecological analysis of i) how spatial self-organization of ecosystems was likely used by pre-Columbian agriculturalists to enhance the yield and resilience of their agriculture system and ii) how these same processes have preserved aspects of the agricultural system during about five centuries of abandonment. This study is also interesting for its demonstration of how ecological memory can maintain patterns produced by past disturbance (whether natural or human), and in its hints of how different types of agriculture that work with biodiversity could possibly be reinvented today.

Some photos from the supplementary info of the paper:

Pre-Columbian raised fields in the Guianas. (A–D) Pre-Columbian raised fields in coastal French Guiana are located in flooded depressions, in flat savannas, along sandy ridges, or in talwegs. (A) Piliwa, on the left bank of the Mana River in extreme western French Guiana. (B) Corossony, on the left bank of the Sinnamary River. (C) K-VIII, west of the city of Kourou, near the Bois Diable site. (D) Maillard, between the town of Macouria and Cayenne Island.

(E) Map of raised-field complexes along coastal Amazonia from eastern Guyana to near Cayenne in French Guiana.

Short Links: Networks, Amazonian historical ecology, and development data

Two recent papers and comments + a new data site:

1) Tom Fiddaman on a new Nature paper (doi:10.1038/nature08932) from Eugene Stanley‘s lab on cascading failure in connected networks, that shows that feedbacks between connected networks can destabilize two stable networks.

2) Wired news article Lost Tribes Used Clever Tricks to Turn Amazon Wasteland to Farms by Brandon Keim, who is writing a book on ecological tipping points,describes recent research on  newly discovered remains on novel agricultural systems in the coastal Amazon.  Its based on a paper by  Doyle McKey and others in PNAS -  Pre-Columbian agricultural landscapes, ecosystem engineers, and self-organized patchiness in Amazonia (doi:10.1073/pnas.0908925107.  The paper is really cool, combing an exploration of ecological memory with historical ecology. From  the abstract:

… we show that pre-Columbian farmers of the Guianas coast constructed large raised-field complexes, growing on them crops including maize, manioc, and squash. Farmers created physical and biogeochemical heterogeneity in flat, marshy environments by constructing raised fields. When these fields were later abandoned, the mosaic of well-drained islands in the flooded matrix set in motion self-organizing processes driven by ecosystem engineers (ants, termites, earthworms, and woody plants) that occur preferentially on abandoned raised fields. Today, feedbacks generated by these ecosystem engineers maintain the human-initiated concentration of resources in these structures. Engineer organisms transport materials to abandoned raised fields and modify the structure and composition of their soils, reducing erodibility. The profound alteration of ecosystem functioning in these landscapes coconstructed by humans and nature has important implications for understanding Amazonian history and biodiversity. Furthermore, these landscapes show how sustainability of food-production systems can be enhanced by engineering into them fallows that maintain ecosystem services and biodiversity. Like anthropogenic dark earths in forested Amazonia, these self-organizing ecosystems illustrate the ecological complexity of the legacy of pre-Columbian land use.

3) The World Bank has launched a new web site: data.worldbank.org to provide free access to development data. Their data catalog provides access to over 2,000 indicators from World Bank data.

Self-organized traffic safety

The UK County Surveyor’s Society Transport Futures group has just published a report Travel is Good that considers how to deal with problems likely to be encountered in transport over the next 20 years. They recommend increasing uncertainty and allowing the self-organization of multiple forms of traffic to increase safety, along with congestion pricing cars, and preparing for climate change.

This report is part of a trend of European traffic planners moving away from signs and regulations to increase traffic safety. Rather than legislating space for cars they are requiring drivers, pedestrians, and cyclists to think about what they are doing rather than obeying signs. This approach appears to fit many resilience principles by encouraging many small disturbances makes the overall system more resilient (see: Traffic Safety: Regulation vs. Self-Organization).

The UK’s Times Online describes the report in their article How stripping the streets of traffic lights and signs may be a life saver:

Redesigning roads to leave drivers and pedestrians uncertain about who has priority will save lives, according to a report by Britain’s most senior transport officials. The move would automatically cut traffic speed without the need for cameras, they say.

Barriers and signs such as railings, kerbs, traffic lights and white lines cause crashes because people assume they will keep them safe and therefore fail to focus on what other road users are doing. Giving drivers less information by removing signs will encourage them to slow down to negotiate a safer course along high streets and across junctions.

The report by the County Surveyors’ Society, which represents local authority directors responsible for most roads in England and Wales, recommends a revolution in road design. It calls for widespread adoption of the concept of “shared space”, pioneered in the Netherlands and better known in Britain as “naked streets”.

It says: “Paradoxically, creating barriers and divisions may worsen safety because drivers and riders feel more confident and speed up, despite the limitations on the speed at which the human mind can take in the amount of information now displayed on our roads. The human response to increased in-car and on-road safety may be to increase risky behaviour.

…Ben Hamilton Baillie, a transport consultant who contributed to the report, said it marked acceptance at the highest levels of shared space principles that five years ago were considered outlandish. Roads in Bath, Ashford in Kent, and Ancoats in Manchester are being converted to shared space. Work will begin next year on removing kerbs and giving pedestrians greater priority on Exhibition Road in West London