Wednesday, August 4, 2010: 4:40 PM
324, David L Lawrence Convention Center
Background/Question/Methods
Ecosystems are often described as flows among compartments, which form ecological networks. These networks can be fairly large and complex. Decomposing an ecosystem model into smaller subnetworks for detailed analysis is often tempting. However, essential ecosystem behavior may be lost by breaking connections, or excluding compartments.
Although ecosystems seem to be made up of compartments and flows, neither flows, nor compartments can function by themselves. Therefore we propose a new building block for ecosystems, called fluxes. A flux is a smaller subnetwork defined according to specific mathematical rules. In ecological terms, a flux represents the smallest process within the ecosystem that can theoretically sustain itself. This can be a material cycle within the ecosystem, or a simple foodchain in a complex foodweb. Fluxes have interesting mathematical properties that render them extremely useful for ecological representation and studies. For example, any ecological network has a unique set of fluxes. And any ecosystem model, steady-state or dynamic, can be expressed as a linear combination of its fluxes.
Results/Conclusions
Fluxes provide a unique opportunity to study complex and large ecosystems. Since no connections are broken during this decomposition, system-wide properties of the full ecosystem can be studied using individual fluxes. For example, the amount of material cycling that occurs within the whole ecosystem equals the sum of material cycling that occurs within each of its fluxes. This result holds regardless of the size or complexity of the model. Many other system-wide ecosystem properties are conserved by this decomposition.
Identifying important fluxes for an ecosystem model might be as important as identifying important compartments (eg. keystone species) or important flows (eg. betweenness measure). Furthermore, flux decomposition can be used to identify essential compartments or flows, because a compartment or a flow may appear in multiple fluxes.
This original development is motivated by Flux based analysis (FBA) and metabolic control analysis. In this talk, we define what a flux is and describe its properties. We demonstrate this decomposition using the intertidal oyster reef and the Georgia salt marsh ecosystem models. We discuss how system-wide properties of an entire ecosystem can be studied using only fluxes, and demonstrate this using the cycling index. Finally, we show how to decompose a model into its fluxes using EcoNet (http://eco.engr.uga.edu), a free online software we have developed.
Ecosystems are often described as flows among compartments, which form ecological networks. These networks can be fairly large and complex. Decomposing an ecosystem model into smaller subnetworks for detailed analysis is often tempting. However, essential ecosystem behavior may be lost by breaking connections, or excluding compartments.
Although ecosystems seem to be made up of compartments and flows, neither flows, nor compartments can function by themselves. Therefore we propose a new building block for ecosystems, called fluxes. A flux is a smaller subnetwork defined according to specific mathematical rules. In ecological terms, a flux represents the smallest process within the ecosystem that can theoretically sustain itself. This can be a material cycle within the ecosystem, or a simple foodchain in a complex foodweb. Fluxes have interesting mathematical properties that render them extremely useful for ecological representation and studies. For example, any ecological network has a unique set of fluxes. And any ecosystem model, steady-state or dynamic, can be expressed as a linear combination of its fluxes.
Results/Conclusions
Fluxes provide a unique opportunity to study complex and large ecosystems. Since no connections are broken during this decomposition, system-wide properties of the full ecosystem can be studied using individual fluxes. For example, the amount of material cycling that occurs within the whole ecosystem equals the sum of material cycling that occurs within each of its fluxes. This result holds regardless of the size or complexity of the model. Many other system-wide ecosystem properties are conserved by this decomposition.
Identifying important fluxes for an ecosystem model might be as important as identifying important compartments (eg. keystone species) or important flows (eg. betweenness measure). Furthermore, flux decomposition can be used to identify essential compartments or flows, because a compartment or a flow may appear in multiple fluxes.
This original development is motivated by Flux based analysis (FBA) and metabolic control analysis. In this talk, we define what a flux is and describe its properties. We demonstrate this decomposition using the intertidal oyster reef and the Georgia salt marsh ecosystem models. We discuss how system-wide properties of an entire ecosystem can be studied using only fluxes, and demonstrate this using the cycling index. Finally, we show how to decompose a model into its fluxes using EcoNet (http://eco.engr.uga.edu), a free online software we have developed.