Which of the following is a consequence of excessive nitrogen in ecosystems?

Excessive nitrogen in ecosystems leads to a reduction in plant diversity primarily because nitrogen enrichment often favors a small number of fast-growing plant species over others. These nitrogen-loving plants, such as certain grasses or broadleaf species, can outcompete less aggressive species that do not thrive as well in high-nitrogen environments. This process, known as niche domination, can result in monocultures, where the rich diversity of native plants is depleted, negatively impacting overall ecosystem health and resilience.

In ecosystems where nitrogen is excessively introduced—often through agricultural runoff or atmospheric deposition—there can be a shift in community composition, which diminishes the variety of species present. This reduction in plant diversity can, in turn, affect other organisms in the food web, leading to diminished habitat quality for herbivores, pollinators, and other wildlife that depend on a rich variety of plants for food and shelter.