In other words, how are we speeding up the effects of the competitive exclusion principle and thereby altering the outcome of that ecosystem's natural succession

Overgrazing, overfishing, and forest fires

Explanation:

Competitive exclusion principle two species which have the same ecological niche cannot exists together as such species will be competing for the same resources. The species which is superior over the other will receive the resources and the other species having no competitive advantage will not survive in future.

According to the given situation, human being is the most superior species on earth and have competitive advantage of thinking ability and intelligence over other species. Succession are the changes that occur in the biotic community of an ecosystem with respect to time.

The human beings can speed up the effects of the competitive exclusion principle by various ways: Overgrazing, overfishing, and forest fires. The overgrazing of the cattle in the field can remove the vegetation cover of the region and the land will become barren so instead of progressive succession in terms of vegetation cover the succession will again re-initiate in terms of primary succession if environment supports.

Overfishing can cause the exclusion of some valuable species of fish and there will not be evolution of such species and will alter the outcome of natural succession.  

Forest fires can affect both floral and faunal species some species may tolerate the fire and will survive and some precursors like roots of the plants can support new individual plants. This will again alter the outcome of natural progressive succession in an ecosystem.

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