How does amensalism affect one species without affecting another?

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Diagram showing energy flow in a food chain from a tree to a caterpillar, then to a bird, and finally to microbes, with red arrows illustrating energy transfer and heat loss at each stage. — community ecology Energy transfer and heat loss along a food chain.

In community ecology, amensalism is an interaction between two species where one is harmed or destroyed while the other remains unaffected. This interaction occurs through two primary mechanisms:1

Competition: A larger or stronger organism may exclude a smaller or weaker one from a specific living space or deprive it of necessary food resources.1
Antibiosis: One organism produces a chemical secretion that damages or kills the other, while the producer itself experiences no negative or positive impact.1

A well-known example of antibiosis is the relationship between the bread mold Penicillium and certain bacteria; the mold secretes penicillin, which inhibits or destroys the bacteria. Similarly, the black walnut tree secretes a chemical called juglone that inhibits the growth of or kills nearby herbaceous plants, effectively clearing its root zone without the tree itself being affected by the process.1