Spatial-Stochastic

Stochasticity and Space Project

Things we Need:

• Explicit hypotheses
• links to papers,
• state variables
• definitions of agent traits w.r.t. space variables,
• forcing conditions
• sample code?

Looks like we can do anything on a square grid in NetLogo, and even import GIS data.

Proposed:

State variables:

• Limiting resource (which can also be in excess)(E.g., water, nutrients)
• Patch/cell/region ability to conserve resource (E.g., soil organic matter)
• Patch connections (e.g., elevation -> horizontal flow)
• Connectivity (i.e. how well patches are connected)

Agent characteristics:

• Efficiency in capturing resource
• Efficiency in surviving low-resource conditions
• R-k strategy
• Spatial reach, for getting resource or spreading offspring
• Interactions? One kind of agent more efficient in the presence of another?
• Threshold responses to external inputs, or saturation
• What ecological processes does an agent do?

    - growth 
    - water uptake
    - nutrient uptake?
    - death?
    - dispersal?

Forcing conditions:

• Input of resource, variable in space or time
• Variance of input

Hypotheses:

• Variable resource input favors different agent traits than reliable inputs with the same mean value
• Agents develop spatial variability to gather sparse resources
• Unreliable resources favor cooperative strategies (Demetrius, e.g.)
• Hubler's hypotheses: with little noise, the system minimizes dissipation and is efficient; with much noise, the system maximizes dissipation and is robust.

Papers:

• Self-Organized Patchiness and Catastrophic Shifts in Ecosystems
• The diversity-stability debate
• File:Reinterpreting Space, time lags, and functional response in ecological models.pdf
• File:Ecology of Tropical Dry Forest.pdf
• File:Mechanism of plant survival and mortality during drought.pdf
• File:Ecophysiology of trees of seasonally dry tropics.pdf

Contact:

maybe we need emails to facilitate communications.

• Xiaoli: xiaolidong2008@gmail.com
• Xue: xue.feng@duke.edu
• Χλοε: chlewis (at berkeley edu)

we are looking for the unknown X in Xeriscapes.