permaculture

[Lawrence London <lfljvenaura@gmail.com>]

Fractal planting patterns yield optimal harvests, without central control
https://phys.org/news/2017-06-fractal-patterns-yeild-optimal-harvests.html

Fractal planting patterns yield optimal harvests, without central control June
9, 2017
[image: Fractal planting patterns yeild optimal harvests, without central
control]
<https://3c1703fe8d.site.internapcdn.net/newman/gfx/news/hires/2017/fractalplant.jpg>
Rice terraces in Bali. Credit: CCO public domain

Bali's famous rice terraces, when seen from above, look like colorful
mosaics because some farmers plant synchronously, while others plant at
different times. The resulting fractal patterns are rare for man-made
systems and lead to optimal harvests without global planning.

To understand how Balinese rice farmers make their decisions for planting,
a team of scientists led by Stephen Lansing (Nanyang Technological
University) and Stefan Thurner (Medical University of Vienna, Complexity
Science Hub Vienna, IIASA, SFI), both external faculty at the Santa Fe
Institute, modeled two variables: water <https://phys.org/tags/water/>
availability and pest <https://phys.org/tags/pest/> damage. Farmers that
live upstream have the advantage of always having water; while those
downstream have to adapt their planning on the schedules of the upstream
farmers.

Here, pests enter the scene. When farmers are planting at different times,
pests can move from one field to another, but when farmers plant in
synchrony, pests drown and the pest load is reduced. So upstream farmers
have an incentive to share water so that synchronous planting can happen.
However, water resources are limited and there is not enough water for
everybody to plant at the same time. As a result of this constraint,
fractal planting patterns emerge, which yield close to maximal harvests.

"The remarkable finding is that this optimal situation arises without
central planners or coordination. Farmers interact locally and take local
individual free decisions, which they believe will optimize their own
harvest. And yet the global system works optimally," says Lansing. "What is
exciting scientifically is that this is in contrast to the tragedy of the
commons, where the global optimum is not reached because everyone is
maximizing his individual profit. This is what we are experiencing
typically when egoistic people are using a limited resource on the planet,
everyone optimizes the individual payoff and never reach an optimum for
all," he says.

The scientists find that under these assumptions, the planting patterns
become fractal <https://phys.org/tags/fractal/>, which is indeed the case
as they confirm with satellite imagery. "Fractal patterns are abundant in
natural systems but are relatively rare in man-made systems," explains
Thurner. These fractal patterns <https://phys.org/tags/fractal+patterns/>
make the system more resilient than it would otherwise be. "The system
becomes remarkably stable, again without any planning—stability is the
outcome of a remarkably simple but efficient self-organized process. And it
happens extremely fast. In reality, it does not even take ten years for the
system to reach this state," Thurner says.

Spatial patterning often occurs in ecosystems as a self-organizing process
caused by feedback between organisms and the physical environment. "The
centuries-old Balinese rice terraces are also created by feedback between
farmer <https://phys.org/tags/farmer/>'s decisions and the ecology, which
triggers a transition from local to global scale control," explains
Lansing. "Our model shows for the first time that adaptation in a coupled
human-natural system can trigger self-organized criticality."

The Balinese rice fields could serve as an example that under certain
conditions it is possible to reach sustainable situations that lead to
maximum payoff for all parties, wherein every individual makes free and
independent decisions.

<https://phys.org/news/2017-06-fractal-patterns-yeild-optimal-harvests.html#>
*Explore
further:* Phase transitions of rice farmers may offer insight into managing
natural resources
<https://phys.org/news/2017-05-phase-transitions-rice-farmers-insight.html>

*More information:* J. Stephen Lansing et al, Adaptive self-organization of
Bali's ancient rice terraces, *Proceedings of the National Academy of
Sciences* (2017). DOI: 10.1073/pnas.1605369114
<http://dx.doi.org/10.1073/pnas.1605369114>

*Journal reference:* Proceedings of the National Academy of Sciences
<https://phys.org/journals/proceedings-of-the-national-academy-of-sciences/>
[image:
search and more info]
<https://phys.org/journals/proceedings-of-the-national-academy-of-sciences/>
[image:
website] <http://www.pnas.org/>

*Provided by:* Santa Fe Institute
<https://phys.org/partners/santa-fe-institute/> [image: search and more
info] <https://phys.org/partners/santa-fe-institute/> [image: website]
<http://www.santafe.edu>


Read more at:
https://phys.org/news/2017-06-fractal-patterns-yeild-optimal-harvests.html#jCp