The modified niche model: Including detritus in simple structural food web models

Halnes G, Fath BD, & Liljenstroem H (2007). The modified niche model: Including detritus in simple structural food web models. Ecological Modelling 208 (1): 9-16. DOI:10.1016/j.ecolmodel.2007.04.034.

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Abstract

Food webs are constructed as structural directed graphs that describe "who eats whom," but it is common to interpret them as energy flow diagrams where predation represents an energy transfer from the prey to the predator. It is the aim of this work to demonstrate that food webs are incomplete as energy flow diagrams if they ignore passive flows to detritus (dead organic material). While many ecologists do include detritus in conceptual and mathematical models, the detrital omission is still commonly found. Often detritus is either ignored or treated as an unlimited energy source, yet all organisms contribute to the detritus pool, which can be an energy source for other species in the system. This feedback loop is of high importance, since it increases the number of pathways available for energy flows, revealing the significance of indirect effects, and making the functional role of the top predators less clear. In this work we propose the modified niche model by adding a detritus compartment to the niche model We demonstrate the effect of structural loops that result from feeding on on detritus, by comparing empirical data sets to five different assembly models: (1) cascade, (2) constant connectance, (3) niche, (4) modified niche (original in this work), and (5) cyber-ecosystem. Of these models, only the last two explicitly include detritus. We show that when passive flows to detritus are included in the food web structure, the structure becomes more robust to the removal of individual nodes or connections. In addition, we show that food web models that include the detritus feedback loop perform better with respect to several structural network metrics.

Item Type: Article
Uncontrolled Keywords: Niche model; Detritus; Food webs; Energy cycles
Research Programs: Dynamic Systems (DYN)
Bibliographic Reference: Ecological Modelling; 208(1):9-16 (24 October 2007) (Published online 27 June 2007)
Depositing User: IIASA Import
Date Deposited: 15 Jan 2016 08:39
Last Modified: 14 Sep 2016 10:02
URI: http://pure.iiasa.ac.at/8121

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