Ecological flow analysis of network collapse II: Indicators of ecosystem level vulnerability

Using donor-controlled, bottom-up equations to describe network collapse we systematically investigate the impact each species has on the survival or extinction of other species. Short of extinction, one can determine the integrated losses experienced by the ecosystem. These losses are aggregated into system level indicators, such as entropy, average gain/loss, average time to extinction, etc. The methodology is applied to 18 ecological flow networks available in the literature. We calculate the correlations between various indicators and determine high positive correlation between: number of nodes & maximal trophic level; connectedness & average entropy losses; number of nodes & average number of extinct nodes; and, maximum trophic level & evenness of links. A high negative correlation was found between: number of nodes & connectedness; connectedness & maximal trophic level; maximum tropic level & average entropy loss; and, connectedness & evenness of flows. Lastly, a low correlation was found between: average number of extinct compartments & evenness of flows; number of nodes & evenness of stocks; and, evenness of flows & evenness of stocks.
KEYWORDS: Ecological network analysis; Ecosystem flows; Extinction; Indicators; Vulnerability

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