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As seen in figure 4, the reintroduction of a basal species affects the food web the most, thus the food-web is bottom up controlled.

It is almost inevitable to avoid secondary extinctions, however there can be more or less secondary extinctions depending on the parameters in the model. For producer species there is a significant difference between a 0%, 40% and 75% change, this is not the case for producer species

Figure 4. Secondary extinctions due to reintroduction divided into three different trophic levels. This figure is based on both connectances with 6000 reintroduction attempts.

The absolute numbers of species going secondary extinct in the 0.22 connectance-model was in all cases higher than when the model with 0.11 connectance, except for 0% change; basal species. The risk for a basal species causing secondary extinctions is mitigated the more change you add to the reintroduced species, this is also the case for the other two trophic levels.

Figure 5. The number of secondary extinctions/ replicate due to the reintroduction of a species, divided into tropic levels. In this figure the same setup as in figure 4 is used, except with absolute numbers instead of percentage. The bars with a gradient color are the models with a connectance of 0.22.

In figure 4 and 5 it is clear that the removal and later reintroduction of basal species has the largest effects on the food-web. However relative to intermediate and top predator species, the basal species effect on how the ecosystem reacts to its reintroduction decreases, as changed attributes from captivity increases.


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Last updated: 05/26/11